Intro:Microscopy:Membranes and Proteins:Membrane Proteins:Membrane Transport:Signal Transduction:MCB 2210 1st EditionExam # 1 Study Guide Intro:- Small molecules can move into and out of the cell via DIFFUSIONo Amount of Transport Depends on: Surface Area (SA) of the cell- Increases as a square function in relation to increasing cell sizeo Cytoplasmic volume increases as a cubic function There is a limit to the size of cells, and therefore a limited amount of SAo Diffusion: the spread of molecules via RANDOM MOTION Molecules are in constant motion Random movement—Brownian motion—no directionality Rate of Diffusion Depends on:- The size of the moleculeo Larger = slower- Chemical properties- Physical properties As distance increases—time increases as a square function- The cell can move biological materials via the CYTOSKELETONo Drives cell shape changes o Motor proteins help move cargo- Cell Theory:o All living creatures are made of one or more cellso The cell is the basic structural unit of living thingso Cells can only arise from other cells (division of preexisting cells)- Cells are composed of:o Proteins, lipids, carbohydrates, and nucleic acids- Cells have a high degree of complexity that depends upon the genes that are expressed in each cello Genes contain the encoded information within the cell- Cells are separated from the external environment with membranes- Most cells can reproduce—some are locked in a nondividing state, and thus do not reproduce- Cells must be able to acquire and use energy, carry out the chemical reactions necessary for life and respond to stimuli.- Cells can also self-regulate via feedback mechanisms and can evolve over time.- The Central Dogma:o Based on the fact that eukaryotes have membrane-bound organelleso DNA----(transcription)--- RNA----(translation)-- Proteino DNA codes for RNA: mRNA codes for amino acids, which make up proteins miRNA and siRNA, small RNA species that regulate stability of mRNAo One gene codes for one protein, but genes can be alternatively spliced (spliced in multiple ways) that allow for genes to be expressed in different ways- Proteins:o Enzymes: catalyze chemical reactiono Structural: organizationo Regulatory: informationo Directly carry out cell processes o Changed as a result of changes in DNA- Genome: complete sequence of geneso Proteome: complement proteins to the genomeo All cells contain the entire genome, and thus the same DNA Different cells however, express different genes—Differential Gene Expression- Transcription Factors: proteins that bind DNA and can activate or repress the transcription of genes- Transcriptome: the genes being transcribed - So different proteins are translated- Signal Transduction: pathways of interactions between proteins, lipids, and other biochemical activated by internal or external pathways- The same cell can behave in different ways based on its environment because the environment can lead to differential gene expressiono Cells can develop complex gene regulatory networkso Transcriptional changes are often TEMPORARY and REVERSIBLE- DNA with its associated proteins (histones) can become chemically MODIFIEDo Methylation (addition of methyl group) or acetylation (addition of ethyl group)o Can be heritableo DOESN’T change the DNA sequence, just the STURCTURE o Epigeneticso Can cause genes to become activated or inactivated- Cell Structures:o Plasma Membrane: lipid bilayer that separates cell from outside environment Creates its own internal environment that’s different Special systems allow transportation through membraneo Cytoplasm: soluble contents of cell Contains organelles in eukaryotes  Ribosomes: carry out protein synthesiso Extracellular Matrix (ECM): made by cells and deposited outside the membraneo Cytoskeleton: network of filaments in cells for framework of cell and tracks for movement of moleculeso Mitochondria: makes ATP from various biomolecules and signals apoptosis in some cellso Chloroplasts: make ATP from sunlightProkaryotes (bacteria and archaea) Eukaryotes (multicellular or protest)- Less coding sequences - Less complex organisms- Can be more complex cellularly (because a single cell must perform all the necessary functions for lifethemselves)- Lack membrane-bound organelles and nucleus- Plasma Membrane- Cytoplasm- Nucleoid (area where DNA is located)- Circular DNA- Ribosomes- Flagellum (proton-driven)- ECM- Cell Wall (some have a polysaccharide capsule)- Evolved first- Grow in a vast number of environments- More coding sequences- More complex organisms- Cells can be less complex (because cells can differentiate to have specialize, specific functions)- Have membrane-bound organelles and nucleus (creating micro-environments for each organelle)- Plasma Membrane- Internal Membranes and Organelles- Cytoskeleton- Nucleus (location of DNA)- Mitochondria- ECM- Chloroplasts (plants and algae)- Cell Walls (plants and algae)- Evolved from prokaryotes via internalization and Symbiosiso Cell Walls: rigid cellulose walls (ECM) that defines shape, protects and strengthens, counters osmotic pressure and prevents movement of cells- Evolution of Cells: (based on the best evidence)o Cells all have a common ancestor b/c they share fundamental processes of lifeo The more closely related, the more similarities in genetic sequenceso First Cell arose from a soup of organic molecules that was created abiotically RNA created first because if was catalytic like proteins and could encode information like DNA- Proteins and DNA cannot do both like RNA Lipid bilayers formed boundaries than encapsulated its contents, creating the cell DNA eventually evolvedo Eukaryotes evolved from prokaryotes Symbiosis: one prokaryote engulfed another, and instead of dying, it had a symbiotic relationship- The 2 different prokaryotes combined to form a new kind of organism that could perform more functions together than they could separately- Most multicellular organisms are create through fertilization of gametes and proliferation combined with coordinated movement and reorganization of cells (morphogenesis)o Cells differentiate to become specialized in different functionso However, single-celled organisms CAN FORM MULTICELLULAR ORGANISMS Myxobacteria: prokaryote than can aggregate to form swarms and fruiting bodies through cell to cell signaling Dictyostelium: single-celled amoeboid that can become multicellular by active