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BIO 200: Exam 2
Cell Theory
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1) All organisms are composed of cell (s) and cell products
2) All cells arise from previously existing cells
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Truths About Cells
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- each cell must be separated from the surrounding environment y a boundary so that the appropriate pH and concentrations of cellular raw materials can be maintained inside the cell (cell membrane)
- each cell must take in raw materials and expel wastes through that boundary (cell membrane)
- each cell met absorb energy in sue form usually either as light or as the chemical bonds in molecules and alter the energy to a form useful for powering cellular activities (photosynthesis and cellular respiration)
-each cell must build biological molecules and cell parts for repair growth, and reproduction (enzymes)
- each cell must have all its activities closely regulated and coordinated (DNA)
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Organelles
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membrane bound containers within a cell
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Prokaryotic Cells
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-found in the domains bacteria and archaea
- the size is a limiting factor because they don't have the ability to transport nutrients and wastes efficiently throughout ( and into and out of the cell)
- as the cell increases so does the distance within the cell
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Eukaryotic Cells
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they have solved the surface to volume ratio by compartmentalization of the cell into structures called organelles
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Surface to Volume Ratio
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As a cell grows in size, the volume increases at faster rate than does the surface area.
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Cell (plasma) membrane
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Phospholipid bilayer that regulates what enters and exits the cell; it's selectively permeable.
Functions:
- digestion
- chemical manufacture
-respiration
- secretion
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Cytoplasm
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A jellylike fluid inside the cell in which the organelles are suspended
- the portion of the cell between the nucleus and the cell membrane
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Cytoskeleton
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A network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules.
Functions:
- gives us shape, support
- locomotion
- cell division
- intracellular transport
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Microtubules
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A hollow rod of tubulin protein in the cytoplasm of all eukaryotic cells and in cilia, flagella, and the cytoskeleton
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Cell Wall
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Found outside the cell membrane in bacteria, algae, fungi and plants. Each group uses different materials as ingredients in their cell wall
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Nucleus
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Contains DNA
Functions:
- ribosomes gets produced
- nucleoplasm, contents of the nucleus
- chromatin- DNA + Proteins (its stretched out)
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Nucleolus
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A region within the nucleus where rRNA is transribed and ribosomes are partially assembled.
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Endoplasmic Reticulum
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A cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another.
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Rough ER
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Covered in ribosomes and is responsible for the synthesis and transport of proteins and glycoproteins.
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Smooth ER
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Is ER that does not have ribosomes attached. It is a major site of lipid and carbohydrate synthesis.
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Ribosomes
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Composed of RNA and protein. Site of protein synthesis. Some scattered in cytoplasm, others attached to ER
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Vesicles
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Small membrane sacs that specialize in moving products into, out of, and within a cell.
- transport
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Golgi apparatus
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vesicles travels to the golgi apparatus. products of the ER such as proteins are modified and stored then sent to other destinations
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Lysosome
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An organelle containing digestive enzymes that can break down particles, cells, organelles such as mitochondria
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Endocytosis
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A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane.
- phagocytosis, receptor mediated phagocytosis, pinocytosis
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Exocytosis
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Moving of molecules out of the cell using active transport
- the vesicle joins with the cell membrane, emptying its contents to it surroundings
- ex: release of digestive enzymes, mucus, milk, hormones and neurotransmitters
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Microbodies
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membrane bound vesicles that distribute enzymes and modify chemicals
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Chloroplasts
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-Capture energy from sunlight and use it to produce food for the cell (photosynthesis)
-part of the endosymbiont theory
-have own DNA and double membrane
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Endosymbiont Theory
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-Chloroplasts and mitochondria were once their own cells, and were engulfed in other cells
-The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism.
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Mitochondria
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-Enclosed by two membranes with the inner membrane folded
-contains its own DNA
- used in cellular respiration
- part of the endosymbiont theory
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Vacuoles
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Cell organelle that stores materials such as water, nutrients ( starch granules), fat (adipose cells), proteins, toxins and sugars
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Vaults
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- made up proteins and vRNA
- may transport mRNA from the nucleus to the ribosomes
- may remove toxins from the cell
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Diffusion
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-the net movement of materials from an area of high concentration to low concentration by random molecular motion
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Osmosis
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Diffusion of water in response to concentration gradient ( of solute) through a selectively permeable membrane
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Tonicity
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- osmotic concentration
- A measure of the ability of a solution to cause a change in cell shape or tone by promoting osmotic flows of water
- hypertonic, hypotonic , isotonic
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Hypertonic
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- hypersmotic
-(of a solution) having a higher osmotic pressure than a comparison solution
- cell shrivels, shrinks
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Hypotonic
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- hypoosmotic
-Having a lower concentration of solute than another solution
- cell is lysed, expands
- ex: plants cells - plasmolosis
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Isotonic
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-isosmotic
-Describes a solution whose solute concentration is equal to the solute concentration inside a cell
- reaches equilibrium
- no net movement of water
- ex: animals cells - crenation
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Cell membrane structure and function
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- identification
- adhesion
- intracellular transport
- containing the contents of the cell, separation from its environment
- regulates the movement of chemicals into to out of the cell
-diffusion
-facilitated diffusion by carrier proteins
-Channel proteins
-Gated channel proteins
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Fluid Mosaic model of the cell membrane
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a model that suggests that there are membrane proteins that are anchored in the lipid bilayer, free to float laterallly within it. some proteins have hydrophobic domains enclosed by tails of membrane lipids. some proteins have hydrophilic domains that extend into cytoplasm or out in extracellular environment.
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Structure of the cell membrane lipids: Phospholipids
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made of two layers of phospholipid molecules, the outer and inner parts are polar and the middle is non polar
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Proteins
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- facilitate movement of material across the cell membrane
- gateway proteins: channel proteins, allow diffusion of specific chemicals through the cell membrane (aquaporin- special kind of protein)
- Gated channel proteins require binding with a stimulus molecule ( a ligand) in order to open
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Endocytosis : Phagocytosis
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process in which phagocytes engulf and digest microorganisms and cellular debris
- work on debris, bacteria and other particular matter
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Receptor Mediated Endocytosis
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specific chemicals are bound at specific sites (coated pits) and formed into vesicles
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Endocytosis : Pinocystosis
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-cell drinking
- cells linking blood capillaries take fluid from blood (but not red blood cells), move fluid across their cytoplasm, and release it into extracellular space surrounding cell outside the capillaries
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Specialized Cell Junctions
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-hold cell together and allow molecules to pass from cell to cell; types of junctions- desmosomes, tight junctions, gap junctions
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Quorum sensing
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-cell to cell chemical communication
- communicate and cooperate in the formation and function of biofilms
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Three stages of cell signaling
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-signal reception: The signal is detected when the ligand binds itself to the receptor protein inside the cell or on the surface of the cell.
-signal transduction: Transduction is the stage where the signaling molecule binds to the receptor and changes the receptor in some way.
-cellular response: The response is the stage where the signal triggers a certain type of cellular response.
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Biofilm
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A Community of bacteria that share nutrients. They are protected from environmental factors and they tranfer plasmids.
-ex: plaque on teeth
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Mechanisms for transport across cell membranes
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Passive Process:
-diffusion
-facilitated diffusion
-osmosis: aquaporin
Active Process:
-protein carrier
-coupled transport
-endocytosis: - phagocytosis, receptor mediated endocytosis, pinocytosis
-exocytosis
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Ligands
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- organic and inorganic
- hydrophobic or hydrophilic
- binds with a receptor medicated protein embedded in the cell membrane
-other ties of ligands pass through the cell membrane and bind with a receptor protein in the cytoplasm
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Apoptosis and examples of its functioning
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Programmed cell death
- used in embryo development to remove cells that are no longer needed
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How does smoking influence the ciliated cells lining trachea?
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-the combustion of tobacco leads to the clogging of the hair like cilia along the nasal passage and trachea. Such a clogging causes the cilia to lose its fluidity
-When the cilia slows down, the mucus is not passed along and gets clogged up along the trachea.
What smoking does to your respiratory system is that it clogs up the cilia and creates tar linings along the lungs.
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Rate of diffusion
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- temperature ( kinetic energy level)
- initial concentration of the substance ( how much solute is used)
- distance of diffusion ( how far molecules can spread out)
- size, weight, cage and barriers
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Random Molecular Motion
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Thermal energy
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Coupled Transport
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The movement of a substance against its electrochemical gradient (from lower to higher concentration, or from (antiport) opposite charge to like charge) using the energy provided by the simultaneous movement of a different chemical down its electrochemical gradient.
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phosphorylation
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The transfer of a phosphate group to a molecule
- the signal pathway (signal transduction) often involves phosphorylation
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What features of the Eukaryotic cell allow it to be recognized by other cells in the body of a multicellular organism such as humans?
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...
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What is the "fluid mosaic model" of the cell membrane? Include a simple labeled sketch of the primary components
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- Carbohydrate Chain- Located outside of the cell membrane, attached to membrane proteins, cells "sign" many function as cell identification tags
-GlycoProtein- Carbohydrate chains attached to a peripheral protein on the outer surface. Acts as a recognition site for hormones and neurotransmitters. Also allows cells to attach to one another to form tissues and recognize other cells.
-Glycolipid-carbohydrates covalently bonded to lipids
-Hydrophillic Head- Polar head of phospholipid molecule
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How does osmosis affect freshwater unicellular organisms such as paramecium or amoeba?
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Protists like amoeba lack a supporting cell wall and instead have a contractile vacuole that pumps out excess water that enters the cell by osmosis. These contracting vacuoles are not needed for osmoregulation in species with a cell wall or in parasitic protists inhabiting multicellular hosts with organ systems to regulate isotonic conditions for cells.
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Describe " tugor pressure" and importance to plants
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Turgor supports plants that do not have woody stems. Plants lacking in turgor visibly wilt. The process of osmosis plays an important part in maintaining the turgidity of plant cells.Water leaves and enters the cell by osmosis. If too much water leaves the cell, for example during drought or saline conditions, then turgor is lost and the cell becomes flaccid. As turgor gives the plant rigidity, loss of turgidity results in the plant wilting
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Diagram and Describe the three stages of cellar response
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[1] (Signal) Reception: The target cell's detection of a signal molecule coming from outside the cell. A chemical signal is detected when it binds to a receptor protein located at the cell's surface or inside the cell.
[2] (Signal) Transduction: A membrane protein may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. The binding of the signal molecule changes the receptor protein in some way, initiating the process of transduction. The external messenger (signal) may cause a conformational change in the protein (receptor) that relays the message to the inside of the cell. The transduction stage converts the signal to a form that can bring about a specific cellular response.
[3] (Target Cell) Response: In the third stage of cell signaling, the transduced signal finally triggers a specific cellular response. The response may be almost any imaginable cellular activity, such as catalysis by an enzyme, rearrangement of the cytoskeleton, or activation of specific genes in the nucleus
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Contrast hydrophobic and hydrophilic ligands
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-A molecule that binds specifically to a receptor site of another molecule (protein/enzyme).
- hydrophobic- Water hating but fat loving. These diffuse through the cell and bind to intracellular receptors to produce cell response
-hydrophilic- cannot cross the plasma membrane and so they bind to he cell surface receptors (such as those on the plasma membrane).
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Describe the major functions of cell communication
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Cell-to-cell communication is essential for multicellular organisms for coordinating various metabolic activities including activation of immune systems and gene expression.
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Contrast protein activity and gene activity as forms of cellular response
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...
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Contrast direct, local and long distance cell signaling
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...
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What is the role of phosphorylation in signal transduction?
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Phosphorylation will turn an inactive protein into an active one, which triggers another response in the cell.
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Do all cells respond to a ligand in the same way?
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no
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Can different ligands initiate the same cellular response?
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yes
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Describe cell signal amplification
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allows a small amount of ligand to produce a large cellular response
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How is cell communication regulated?
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-hormones
- control of cell communication may be breakdown or removal of the ligand or of the secondary messengers (chemicals in the signal transduction pathway)
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What problems can arise if cell communication is unregulated?
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When control of cell communication fails, the reactions may take place beyond the level needed by the cell or organism. Failure of cell control can lead to health problems such as cancer.
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Metabolism
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-refers to the sum of chemical reactions taking place within living cells
anabolic: synthetic putting together are endergonic
catabolic: degradative taking apart are exergonic
The released energy may be used for
-cellular respiration
- building things
- transporting
-synthesis, active trasport movement
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Metabolic Rate
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-temperature is one important factor influencing reaction rates
- increases in temperature increase reaction rate
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Activation Energy
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Energy needed to get a reaction started
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Enzyme catalyzed reaction
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induce shape change; lowers activation rate; increases rate of reaction
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Optima
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-Most Favorable Or Ideal.
- each type of enzyme has a specific temperature and pH at which it operates best- its temperature and pH optima for optimum performance
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Denatured
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... |
Homeostasis
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-Process by which organisms maintain a relatively stable internal environment.
- internal environment must be stable for an enzyme
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Enzyme inhibition
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-Process by which a substance known as an inhibitor binds to an enzyme and decreases it's activity
- The decrease in enzyme activity that results in reduced metabolism of drugs.
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Competitive inhibition
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The process of a substance reducing the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics.
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Allosteric Site
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A site on an enzyme other than the active site, to which a specific substance binds, thereby changing the shape and activity of the enzyme.
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Noncompetitive Inhibition
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A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate.
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Biochemical Pathways
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-A sequence of enzyme-catalyzed reactions where the product of one reaction is the substrate for the next.
- typically many different enzymes work together in the for nation of the final product
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Negative Feedback (feedback inhibition)
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In feedback inhibition, there is a second binding site on the enzyme where the inhibitor binds, so that the inhibitor is not necessarily similar in structure to the substrate.
The absence or presence of the inhibitor at this second binding site activates or deactivates the enzyme, presumably by changing the conformation of the enzyme so that the active site is made available or unavailable to the substrate. (Or perhaps in other ways.)
Benefits: conserves substrate, conserves energy, avoids buildup of a product
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Enzyme Functions
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- they lower the activation energy required for reactions to take place
- speed reaction rate
- self regulate the rate at which reactions take place
- not used up in the reactions
- specific to the reaction they catalyze
- require optimal conditions or they become denatured
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Contrast anabolic and catabolic reactions
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A catabolic reaction is one that breaks down large molecules to produce energy; an example is digestion. An anabolic reaction is one that involves creating large molecules out of smaller molecules.
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Contrast endergonic and exergonic reactions
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exergonic release more energy than they absorb. Endergonic reactions absorb more energy than they release.
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Contrast potential and kinetic energy
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Kinetic energy is being used, it is the energy that is in the process of being used. Potential energy is stored and is able to do the work but is not being used.
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Describe several uses of energy at a cellular level
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Cells use the energy from ATP for active transport and protein synthesis.
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What is the transition state?
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-Enzymes are typical tertiary level protein molecules specially designed to increase the rate of chemical reaction.
-The activated state of a molecule that has partly undergone a chemicalreaction.
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What is the active site of an enzyme?
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Where the substrate fits in an enzyme
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What is a substrate?
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A molecule upon which an enzyme acts, binds to the active site of an enzyme
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What is enzyme inhibition?
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The enzymes are inhibited, meaning that there are not enough enzymes to break down a drug and thus, the drug will accumulate and could produce toxicity.
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Contrast competitive and noncompetitive inhibition of an enzyme
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Competitive inhibition is where a inhibitor has a structural similarities of a substrate. Due this the inhibitor binds to the active site of the enzyme,where normally substrate binds. This binding of the inhibitor to the enzyme forms a EI complex instead of ES complex and thus inhibiting the catalytic activity of an enzyme.
Non competitive inhibition is when inhibitor possessing same structure of substrate binds to the site other than the active site of an enzyme. The substrate binds to the active site of an enzyme. This binding of the inhibitor to the site other than an active site disturbs the normal structure of an enzyme. Thereby, lowering the catalytic activity of an enzyme.
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What is the allosteric site of an enzyme?
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The place on an enzyme where a molecule that is not a substrate may bind, thus changing the shape of the enzyme and influencing its ability to be active.
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Contrast an enzyme that is too cold with an enzyme that is too hot
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-enzyme is a protein so if it is too hot or too cold it will denature and lose its structure and function.
-It will work slower and slower until it finally stops working. Enzymes are biological catalysts and are designed to work at their peak at body temperature usually, many have a poor tolernace for divations from this temperature.
-When an enzyme gets "too hot" it starts to lose it's activity. At high enough temperatures, the enzyme starts to denature (unfold) and becomes inactive.
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What is the role of ATP?
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ATP transports chemical energy within cells for metabolism. It is produced as an energy source during the processes of photosynthesis and cellular respiration and consumed by many enzymes and a multitude of cellular processes including biosynthetic reactions, motility and cell division.ATP is therefore continuously recycled in organisms
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Describe the importance and functioning of an enzyme catalyzed reactions
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- induce shape change; lowers activation rate; increases rate of reaction
-they take place in the active site of the enzyme where the substrate is bond
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What is the importance of homeostasis relative to enzyme function?
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Homeostasis have to control the temperature of the body so that no enzyme is damaged.
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What are the functions of the allosteric site of an enzyme?
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- have 2 or more binding sites which can bind the same or different molecules.
When a molecule bind one of the sites the other site changes conformation and gets a higher affinity for a ligand.
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What are the qualities of an enzyme?
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-they are catalysts
-they are specific to their functions
-they main function is to break materials down
-they are selective for their substrates and speed up only a few reactions from among many possibilities
-there are inhibitors that decrease enzyme activity
-there are activators that increase enzyme activity
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To which group of organic chemicals do most enzymes belong?
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Proteins
-enzymes can be used over and over again because even though they speed up the process, they do not take part in the process. They just help to speed things up and thats it, they don't bind or change their shape in anyway, so after helping in a process they are ready to help another batch in the same process
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What are metabolic (biochemical) pathways?
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-series of chemical reactions that occur within a cell. Within each of these pathways, one chemical is transformed into another chemical through a series of steps. These reactions are catalyzed by enzymes and will often require vitamins and minerals in order to function properly.
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Contrast cofactors, coenzymes, and prosthetic groups
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-A cofactor is any substance that is required for an enzyme to be catalytically active. These include organic and inorganic substances such as biotin and magnesium.
-Coenzymes are organic cofactors. An example of this is NAD.
-Prosthetic groups are cofactors that are tightly bound to the enzyme refers to a structural property, and is similar to coenzyme.
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How are enzymes regulated?
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-by changing their structure through temperature, pH, chemical change or with inhibitors
- Enzymes are regulated with the use of Competitive Inhibitors and Noncompetitive Inhibitors. Basicly every enzyme has an active site where the substrate binds to and what an the first kind of inhibtor does is that it blocks the substrate from joining with the enzyme by attaching to the enzyme's active site. The other kind of inhibitor joins with the enzyme at another place not the active site. This makes the enzyme change shape so it cannot fit the substrate or it somehow makes the enzyme unable to catalize the reaction.
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Laws of Thermodynamics
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1) energy can not be created or destroyed, only converted from one form to another
2) each time you convert one form of energy to another, some energy is converted to a non-usable form (more energy efficient to consume plants because they exist very close to the initial source of energy)
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Antiport
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A membrane transport process that carries one substance in one direction and another in the opposite direction.
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Tight junctions
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-stop materials from moving in between cells (extracellular spaces) hold membrane components in particular areas
-Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
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Desmosomes
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-attach cells tougher epithelial cells
-Anchoring junctions found in areas subjected to pulling forces
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Gap junctions
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-communication junction cell-to cell channel protein allowing for communication (chemical and electrical) between cells, such as muscle cells (smooth and cardiac),
-Communicating Junctions; channels that allow small molecules to flow through protein-lined pores between cells
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Diffusion Facilitated by Carrier Proteins
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Facilitated diffusion is a passive movement of solutes across the cell membrane. Specific proteins provide channels for specific solutes (like ions and polar molecules). The most important ions include Na+ and K+. Note that the facilitated diffusion goes from area of higher concentration to area of lower concentration.
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Channel Proteins
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Proteins in plasma membrane; help transport stuff in & out through a channel. |
Gated Channel Proteins
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A transport protein that opens a "gate," allowing a molecule to flow through the membrane.
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Aquaporin
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A transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane
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Describe the functioning of the structure of plant cells that is found surrounding (outside of the cell membrane. Include the name of the structure in your description.)
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cell wall - a thick, rigid membrane that surrounds a plant cell. This layer of cellulose fiber gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant.
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Describe the two parts of Cell Theory. Provide one example sentence for each.
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1. All living things are made of cells
Cells by themselves are alive, but they can also be part of a larger living things such as unicellular organisms and multicellular organisms.
2. The cell is the smallest living thing that can perform all the functions of life.
The process of production of energy from food takes place in cells of animals and the process of making of starch from CO2, water and sunlight is done inside all chlorophyll containing cells of plants.
3. All cells must come from pre-existing cells
Cells are born from older cells, in a process called cell division in which a parent cell (old cell) divides into two new daughter cells (new cells) to keep up the process of growth of an organism.
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Name the function of the green colored organelle that is found in plant cells, but is lacking in animal cells. Be sure to include the name of the organelle.
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Chloroplasts - The most important characteristic of plants is their ability to photosynthesize, in effect, to make their own food by converting light energy into chemical energy. This process is carried out in specialized organelles called chloroplasts.
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Contrast anabolic (synthetic) and catabolic (degradative) reactions. In addition, relate each to the term endergonic along with meanings.
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Catabolic and anabolic reactions are metabolic processes. A catabolic reaction is one that breaks down large molecules releasing energy and is not endergonic but instead it is exergonic ; an example is digestion. An anabolic reaction is one that involves the absorption of energy (endergonic) by creating large molecules out of smaller molecules; an example is when your body makes fat out of extra nutrients you eat.
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Provide a fully illustration of the process of negative feedback (feedback inhibition). Tell the three major benefits of this process.
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1) conserves substrate
2) conserves energy
3) avoids buildup of a product
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feedback inhibition
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If the products being produced is too fast and too plentiful, the product would inhibit the enzymes and slow the reactions down so that the products can be used up first without being mass produced.
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