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BIO132 Exam 1
| Question | Answer |
|---|---|
| Lipid function | store energy, pigment that capture/respond to sunlight, serve as signals between cells, form waterproof coatings on skin and cells, acts as vitamins in cellular processes |
| lipid fluidity | determined by length and saturation of their hydrocarbon chains |
| fatty acids | unbranched hydrocarbon chains joined to a carboxyl group |
| saturated | full of C-H bonds |
| unsaturated | non- sp3 carbons thru pi bonds |
| Steroids | family of lipids bulky, four aryl groups differ by functional groups attached to carbons in ring Hormones: estrogen and testosterone Cholesterol, component of plasma membranes |
| Steroid common structure | Polar head, nonpolar (rings), isoprenoid tail (nonpolar), |
| Fats | triacylglycerols or triglycerides; made of 3 fatty acids linked to glycerol |
| fat roles | energy storage is primary= large number of high energy bonds in fatty acid chains; bonds allow fats to store twice as much chemical energy |
| Fats form? | -dehydration rxn between hydroxyl group of glycerol and carboxyl group of a free fatty acid -glycerol and fatty acid molecules become joined by ester linkage -fatty acids are not linked in chains (polymers) |
| phospholipid | -glycerol linked to phosphate group and two hydrocarbon chains -fatty acid tails: domain Bacteria and Eukarya -isoprenoid tails: domain Archaea -primary role is to form cell membranes |
| Lipids in water | -have both hydrophobic and hydrophilic regions -hydrophilic head contains: glycerol, neg. charge phosphate group, charged or polar group -hydrocarbon tail: non polar and hydrophobic, water molecules cannot form hydrogen bonds with tail -amphipathic |
| amphipathic | -has both hydrophilic and hydrophobic regions -responsible for lipids' plasma membrane property |
| Phospholipid Biplayers | -amphipathic lipids dont dissolve in water, hydrophilic heads interact with water while tails dont -lipid micelles: ring of heads facing water and tails inside the ring -lipid bilayers: 2 layers of lipids, heads on top and bottom with tails in middle |
| vesicles | -form from phospholipids in lab -small bubble-like structers surrounded by phospholipids -artificial membrane-bound vesicles are called liposomes |
| Lipid bilayer permeability scale | Highest-> lowest 1. small, nonpolar molecules (O2,CO2, N2) 2. small, uncharged polar molecules (H2O, glycerol) 3. large, uncharged polar molecules (glucose, sucrose) 4. small ions (Cl-, K+, Na+) |
| Lipid structure effect on membrane permeability | Length of hydrocarbon tails, presence of cholesterol molecules, saturation state of hydrocarbon tails |
| Degree of saturation on permeability | lipid bilayer with short and unsaturated hydrocarbon tails=higher permeability lipid bilayer with long and saturated hydrocarbon tails= lower permeability |
| Cholesterol on membrane permeability | +cholesterol to membranes increases density of hydrophobic section -reduces membrane permeability -bulk cholesterol rings force phospholipd tails closer, increasing their packing density |
| temperature on fluidity and permeability of membranes | -phospholipids in plasma membranes move laterally within bilayer -membrane fluidity decreases as temp drops: molecules in bilayer move more slowly, hydrophobic tails pack together more tightly, decreased membrane fluidity causes decreased permeability |
| why do substance mobe between soltuions? | dissolved solutes are in constant random motion due to their thermal energy |
| Diffusion | Spontaneous movement of molecule and ions: concentration gradient created by difference in solute concentrations, net movement from high-concentration regions to low-concentration regions, |
| Equilibrium | occurs when molecules or ions are randomly distributed throughout solution: molecules are still moving randomly, no more net movement |
| Passive transport | occurs when substances diffuse across membrane in absence of an outside energy source |
| hypertonic | outside solution higher concentration than inside cell -water moves out |
| hypotonic | outside solution lower concentration than inside cell -water moves in |
| isotonic | equal concentration between outside and inside |
| Proteins can insert into membrane: | Amphipathic: side chains can be polar, charged, or nonpolar Secondary and tertiary structure allow proteins to form openings and function as passageway across lipid bilayer -hydrophobic region of an amphipathic protein can be anchored into a lipid bilay |
| Fluid Mosaic Model | Nature of cell debate resolved with new tech: -involves freezing and fractuing membrane and examining it under scanning electron microscope (SEM) -observations conflicted with sandwich model -fluid-mosaic model now widely accepted |
| Types of membrane proteins | Integral membrane proteins or transmembrane proteins Peripheral membrane proteins |
| Integral membrane proteins or transmembrane proteins | Proteins that span membrane, have segments facing both interior and exterior surfaces |
| Peripheral membrane proteins: | bind to membrane lipids without passing through, may be found on interior or exterior of cell |
| Channel proteins facilitate __- | diffusion |
| Ion channels | Specialized transmembrane proteins, form pores/openings in membrane, allow ions to cross membranes |
| Electrochemical gradients | occur when ions build up on one side of plasma membrane -estbalish both concentraiton gradient and charge gradient, ions diffuse down their electrochemical gradients |
| Central dogma | DNA is transcribed to mRNA by RNA polymerase, and the mRNA is translated to proteins by ribosomes |
| Codon | -redundant -a 3 base codon will code for a specific amino acid, 1 codon will not code for multiple amino acids -an amino acid can be coded by multiple different codons -signal where translation starts and stops |
| Mutations | random permanent changes in DNA |
| Point mutations | -singe base pair or very small sections of DNA that are mutated -can be silent, missense, nonsense, or frameshift |
| Chromosome mutation types | Deletion Inversion Duplication Translocation |
| Deletion chromosome mutation | A broken segment of a chromosome that is lost |
| Inversion chromosome mutation | segment of broken chromosome flipped and rejoined |
| Duplication chromosome mutation | Errors in crossing over or in DNA synthesis can lead ot the presence of one or more additional copies of a segment |
| Translocation chromosome mutation | broken piece of a chromosome can become attached to a different chromosome |
| Karyotype | the complete set of chromosomes in a cell |
| DNA tertiary structure | supercoil or histones (balls) ->chromosomes |
| How understood gene expression? | -process of converting information in DNA into functioning molecules within the cell -Beadle & Tatum discovered what genes do by radiating an organism and made the genes defective to see what would change in the organism= what did that gene code for |
| Metabolic pathway for arginine synthesis | 1. precurser 2. omithine 3. citruline 4. arginine all catalyzed by enzymes |
| Defective genes | Non-functional alleles= null allele |
| One-gene-one enzyme hypothesis | each gene contains information to make one enzyme, historical idea which was pretty good but isn;t as good as current |
| Srb & Haorowitz | -tested by studying metabolic pathways 1. genetic screen on N. crassa mutants by growing on deficient media 2. Identified enzymes inability to make a product in pathway showed defiicency |
| 1-gene-1 polypeptide hypothesis | current gene expression hypothesis |
| Jacob & monod | -suggested RNA links genes nucleus to protein synthesis in cytoplasm |
| reverse transcriptase | synthesizes a DNA version of the RNA genes |
| RNA polymerase | an enzyme that synthesizes mRNA by using DNA as s template for complementary nucleotides -doesn't require a primer |
| genetic screen | technique for picking particular types of mutants out of many randomly generated ones |
| mRNA | sends information to ribosome so the codons can be translated into the amino acids of proteins |
| Genotype | genetic information used (DNA) |
| Phenotype | physical traits/charachteristics (Protein) |
| Alleles of same gene ___in sequence | differ |
| Genetic code principles | -redundant -unambiguous -non-overlapping -universal -conservative |
Created by:
Slayy