BIOL 120 1st EditionExam # 2 Study Guide Lectures 8-11Lecture 8Cell Structure - Cell Theory: All organisms are composed of cells; cells are the basic unit of life; cells ariseonly from pre-existing cells- Cell size is limited by: o Surface area available o Temperatureo Concentration Gradient o Distance - Prokaryotic Cells  lack a membrane bound nucleuso All lack a membrane o Bacteria: Lack a membrane bound nucleus  Possesses a single chromosome  nucleoid- Contains a long strand of DNA with a few supportive proteins Has ribosomes A stiff cell wall  Some contain plasmids  small, supercoiled circular DNA  Has an internal photosynthetic membrane o External Structures Flagella  tail like features that spin around to move the cell Most have a cell wall Many have an additional layer outside of the cell wall called a capsule- Eukaryotic Cells  compartmentalized cellso Differences from Prokaryotic Eukaryotic chromosomes are inside the nucleus (membrane bound) Eukaryotic cells are larger Eukaryotic cells have membrane bound compartments Eukaryotic cells have a diverse and dynamic cytoskeleton o Animal Cello Plant Cello Nucleus Store genetic information  Nucleolus: region where ribosomal RNA is synthesizedNuclear envelope: a double membrane surrounding the nucleolus with nuclear pores to control what goes in and out of the nucleus  Linear chromosomes Chromatin: chromosomes and proteins which are in charge of folding o Endomembrane System  a series of membranes throughout the cytoplasm divides cell into compartments  a distinction between eukaryotes and prokaryoteso Rough ER a network of membrane bound tubes and sacs studded with ribosomes  interior is called the lumen synthesize proteins o Smooth ER Similar to rough ER but lacks ribosomes  Enzymes within the Smooth ER synthesize fatty acids and phospholipids used for membranes  Also breaks down poisonous lipids and stores calcium ionso Golgi Apparatus  a flattened stack of interconnected membranes Function  transport system- Packs molecules into package (vesicles)- Distributes molecules synthesized at one location ot be used at another o Ribosomes are non membranous and not considered organelles large and small subunits containing RNA molecules and protein made of rRNA Functions: - Protein synthesis o Microbodies Enzyme bearing membrane enclosed vesicles  Peroxisomes - contain enzymes involved in oxidation of fatty acids hydrogen peroxide produced as a by product that is broken down by catalase - in plants it is glyoxysomes  use enzymes that oxidize fats to forma compound used to store energyo Lysosomes single membrane bound structures containing about 40 different digestive enzymes Found in animal cells  Function  used for digestion and waste processing  Delivered through:- Phagocytosis  bringing in matter to the cell to be broken down- Autophagy  breaking down material inside of the cell- Receptor- mediated endocytosis  brings material into the cell through receptors  Endocytosis: a process by which the cell membrane can pinch off a vesicleto bring outside material into the cell Pinocytosis: a process that brings fluid into the cell o Vacuoles Found in plants  Functions: - Storage- Contain digestive enzymes- Most are used for water and ion storage  Types- Central, storage, contractile o Mitochondria  Inner and outer membrane  Cristae  finger like projections that give more surface area  Have their own DNA and make their own ribosomes o Chloroplast Found in plant and algae cells  double membrane and contain their own DNA Thylakoids: membrane bound flattened vesicles Grana: thylakoids stacked into piles Stroma: the solution surrounding the grana and thylakoids Function  convert light energy to chemical energy o Cell Wall Found in plants, fungi, and many protistso Cytoskeleton A network of protein fibers that support the shape of the cell and keeps organelles in fixed locations  Three types:- microfilaments (actin filaments)  two protein chains loosely twined together - microtubules  dimers of alpha and beta tubulin subunits - intermediate filaments  very stableo Centrosomes  Found in animal cells and most protist  region surrounding centrioles (help move chromosomes during cell division)o Extracellular matrix Animal cells lack a wall  secrete a mixture of glycoproteins into the areaaround them (i.e. collagen) which forms a protective layer over the cell surfaceo Connections Tight junction  Connect the plasma membrane of adjacent cells  Anchoring junction  attaches cytoskeletons of neighboring cells Communication junction  chemical or electrical signal passes directly from one cell to an adjacent cell  Plasmodesmata  specialized openings in cell walls (similar to communication junction in animal cells) - Membrane Proteinso hydrophobic interior of membrane makes it hard for molecules to pass through proteins function as transport proteinso Functions Transporters  Enzymes  Cell- surface receptors Cell- surface identity markers Cell to cell adhesion proteins  Attachments to the cytoskeleton o Types Passive transport  no energy input needed, goes with gradient  Sodium- Potassium pump  goes against gradient  Active Transport  requires energy directly or indirectly - Needs selective carrier proteins:o Uniporterso Symporterso Antiporters Carrier protein  gradient goes from high to low o Channel protein  act as gates (ion channels, and gated channels)o Endocytosis  movement of substances into the cello Exocytosis  the discharge of materials out of the cell - Cell Division/ Cell Cycleo Key facts Chromosomes are duplicated during the S phase from 46 to 92 Diploid (46 chromosomes; 2 sets) Haploid (23 chromosomes; 1 set for reproduction) o Bacterial cell division Divide through binary fission  Circular chromosomes o Meiosis and Mitosis Meiosis: leads to the production of gametes (egg and sperm) Mitosis: leads to the production of all other cell types (somatic cells)- Functions:o Growtho Wound repairo Asexual reproduction o G1, S, G2  Interphase  G1 and G2 do not have DNA synthesis  During this phase organelles replicate and additional cytoplasm is createdo Chromosomes  Chromosomes: contain a single long