Biology 102 Exam 2 Study Guide
Biology 102 Exam 2 Study Guide BY 101
Jacksonville State University
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This 5 page Study Guide was uploaded by Kimberly Burke on Friday January 22, 2016. The Study Guide belongs to BY 101 at Jacksonville State University taught by Dr. Tolley-Jordan (TJ) in Fall 2014. Since its upload, it has received 33 views. For similar materials see Introductory Biology I in Biology at Jacksonville State University.
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Date Created: 01/22/16
Bio 101 Exam 2 • Membranes are fluid mosaic( mixtures) models o Phospholipids – spinning & presence of unsaturated fats in tail § Contributes to membranes fluid nature; can drift through membrane o Glycolipids – lipids w/ sugar monomer attached o Sterols-cholesterol; phytosterols o Proteins • Internal membrane proteins – span the lipid bilayer w/ hydrophilic regions extending past membrane • Peripheral membrane proteins – positioned at the surface of the membrane (do not span bilayer) • Transport proteins – help substances move through membrane • Selective Permeability–osmosis(water)&diffusion(substance) – some substances can cross, others can’t o Can pass - Phospholipids, proteins. gas, neutral molecules o Glucose & large, polar molecules need Transport Prot eins o Critical that2O & CO2pass openly • Mechanisms needed to cross: osmosis & diffusion • Membrane crossing mechanisms o Diffusion – net movement of like molecules or ions down concentration gradient § Away from place w/ most molecule collisions (down gradie nt) § Each substance diffuses independently § Factors that affect diffusion rate • Steepness of concentration gradient • Molecular size (smaller=faster) • Temp (higher=faster) • Electrical (difference in charge) or pressure gradients § Mechanisms act to • Supply cells & organelles w/ raw materials & remove waste products • High concentration à low concentration releases energy o Passive Transport – doesn’t require energy inputs; net movement=down gradient § Solutes diffuse through channel inside protein § ENERGY YIELDING o Active Transport-requires ATP, protein is an ATPase pump § Pumps solute against its concentration gradient § ENERGY REQUIRING o Osmosis-diffusion of water molecules across a selectively permeable membrane § Higher H 2 concentration à lower H 2 concentration § Total # of molecules or ions dictates concentration of water(more=lower) § Direction of net flow is determined by water concentration gradient § Tonicity – relative solute concentration of 2 fluids • Hypotonic-fluid w/ fewer solutes • Hypertonic-fluid w/ more solutes • Isotonic-fluid w/ same amount • Photosynthesis 6CO + 6H O à C H O + 6O 2 2 6 12 6 2 o Energy from sun; splitting of water to get sugar o Pigments in photosynthesis § Bacteria(plasma membranes) & § Plants-pigments&proteins organized into photosystems embedded in thylakoid membrane system (200 -300 pigment molecules) • Electromagnetic Spectrum – shorter waves=more energetic o Different wavelengths form colors of rainbow ; blue is most powerful; infrared-heat o Photosynthesis – uses wavelengths of 380-750 nm § Stopped by shading out chlorophyll – create orange & red o Pigment-organic molecule that selectively absorbs light at specific wavelengths o Visible light-most important for plants; chlorophyll & accessory pigments absorb most o Chlorophyll a-most common photosynthetic pigment -absorbs violet&red(appears green) § Accessory pigments bounce chlorophyll a until it’s right wavelength • Noncyclic Electron Flow – light dependent reaction, requires Photosystems I & II o 2 step pathway for light absorption, produces ATP & NADPH ( battery molecules) • Photolysis – splitting of water via photon (light) energy o Provides energy for sugar occurs in thylakoid o 2 steps: energy from sun to excite electrons & split water o Reactants Products H 2 à O2 NADP à NADPH ADP à ATP • Light Dependent reactions- use NADPH & ATP; based of excitation of electrons in pigments o Only includes water & oxygen parts of equation o 12H 2 à 6O “2hoto” • Light Independent Reactions-synthesis of sug2rs; CO is IMPORTANT; ATP used for energy o 6CO à C H O “synthesis”; can occur in dark 2 6 12 6 • Carbon Fixation-extract carbon atoms from atmosphere & incorporating them into an organic molecule o CO 2 C H6O 12C6 dif2used in atmosphere o Used bond energy of molecules formed in light -independent reactions(ATP,NADPH) • Calvin Benson Cycle – enzyme mediated reactions that build sugars in stroma of plants o Goes around 12x; battery molecules=NADP & H; NADP active w/ H o Carbon recycles to make Rubsico; PRODUCT: 2 3C Sugars o Enzymes are recycled; allows cycle to keep going o ATP & NADPH – fuel reformation of RuBP(starter) o Reactants Products 6CO 2 à C6H12 6 NADPH à NADP ATP à ADP • Photosynthesis & respiration are opposites; photosynthesis & metabolism are synonyms • Respiration – exhale2CO b/c of cellular metabolism • ATP=universal energy source ; regardless of source, energy converted to ATP o Plants make ATP during photosynthesis (light dependent reactions) o Cells make ATP by breaking down organic molecules (carbs, fats, proteins) • Mitochondria- powerhouse of cell, energy made, site of cellular metabolism • Aerobic Respiration – using oxygen, yields 36 ATP; make lactic acid(glycolysis, no oxy, cramps) & alcohol (glycolysis) o Glycolysis – occurs in cytoplasm, doesn’t require oxygen, yields 2 ATP § Reactants Products C6H 12 6 à 2 3C sugars 2 ATP à ATP – lose ATP ADP à 4 ATP o Kreb’s Cycle-stroma of mitochondria-2x to get 6C sugar, Enzyme- Acetyl CoA, link molecules - 12 H, yields 2 ATP § Form battery molecules convert energy into hydrogen § Reactants Products 2 3C sugars à 3CO 2 ADP à ATP FAD à FADH NAD à NADH o Electron Transfer Phosphorylation – occurs in plasma membrane, yields 32 ATP ; like turbine on dam § Results in attachment of phosphate to ADP to form ATP § Electron transfer sets uion gradient (downhill), powers ATP formation § H’s come from enzymes ; Oxy withdraws spent electrons from transfer chain, combines w/ H to form water § Oxygen attracts Hydrogen & pulls them through tunnels § Reactants Products O 2 à H2O ADP à ATP NADH à NAD FADH à FAD Reactants Products • If bacteria do not have mitochondria, but have cells (cytoplasm) -only do glycolysis • Metabolic Pathways –any series of enzyme-mediated reactions by which a cell builds,rearranges,breaks down an organic substance o ATP, enzymes, & other molecules interact in organized pathways of metabolism(cells acquire & use energy) o Dispose of materials in cells; controls enzymes that govern metabomake cell activity fast o Anabolic pathways-build molecules (photosynthesis) o Catabolic pathways-break apart molecules (metabolism) o Cyclic pathways-regenerate a molecule from 1 step (KC & CB cycle) o DRIVE EVERY SINGLE CELLULAR PROCESS IN BODY; yield energy – downhill o Enzymes-proteins that speed up reactions; lower activation energy; Reused; specific to substance § Energy carriers- activate enzymes & other molecules by phosphorylation (ATP) § Cofactors-small molecules & metal ions that help enzymes by carrying atoms or electrons § Every action mediated by enzyme: joining substrates, orientating substrates, fitting enzyme & substrate, shutting out water molecules b/c they love oxy who love hydrog en § Reactants-products that make reactions proceed § Feedback mechanisms: adjust enzyme production, activate enzymes, & inhibit enzymes § Regulatory molecules can bind to allosteric sites to activate & inhibit enzymes • Feedback Inhibition-process that regulates enzymatic activity; can shut down during any step • External regulators of Enzymatic activity: temp, pH, salinity o Temp -Extremes in temp ranges affect food making; warmer=faster § Law of Q10-for every 10°C increase, double reaction speed o pH-measure of concentration of hydrogen ions; Log Scale; enzymes in stomach are not in intestine o Salinity-salt breaks down proteins/unfolds proteins; Shape dictates function. • Gregor Mendel – 1822, Czech Republic(Austria), monk o 1 to study inheritance patterns – combined math & breeding knowledge o BIG question: Is it the trait that is passed on to offspring or the code for the trait? • Louis Pasteur – Life Begets Life – no spontaneous generation o Nutrient broth experiment – 1856; 1 vaccine – Anthrax & rabies o Asexual-no sex, clone (mitosis) o Sexual-2 parents (meiosis & fertilization) • Mendel’s study organism – garden pea, used previously by others o Pea is good choice b/c traits could be studied in offspring, “true -breeding”, grow fast & easy, change sex o Started w/ 32; focused on 7 comparable traits o Stage 1: confirm true breeding o Stage 2: cross b/n different varieties, reciprocal crosses o Stage 3: mate offspring w/ one another, several generations. Confirm trait patterns § Mendel COUNTED, others did not o Results: blending traits is NOT the mechanism for inheritance of traits, only purple & white flowers § 705 purple & 224 white. 3:1. Consistent for 7 traits § 3:1 expected for crossing heterozygotes § Blending does not occur, traits that skip generations were latent, traits s egregated offspring, 3:1 o Conclusions: § Traits are not passed on – information coding traits is. Gene coined in 1920s § Offspring get 2 genes for any trait § Not all copies of a gene are identical • Alleles – alternative forms of a trait • Homozygous – having 2 of same alleles for a trait • Heterozygous- having 2 different alleles for a trait § 2 alleles for a trait do not influence one another • when gametes are formed – alleles segregate randomly § only dominant trait in an allele pair is expressed • phenotype-physical expression of allele • genotype-totality of alleles an individual carries (blueprint) o Inheritance Probability – patterns expressed as mathematical probability o Law of Segregation-alleles of same generation separate during mitosis – 1 gene § Different alleles of same gene segregate independently o Law of Independent Assortment - different genes segregate independently from one another § Dihybrid cross – 9:3:3:1
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