Molecular and Cellular Biology

protons, neutrons, electrons (valence shell)

ionic (cation and anion) and covalent

organic: C&H, held by covalent bonds inorganic: ionic bonds, metal and nonmetals

covalent bonds bw H20 (polar bonds) oxygen attracts more strongly, carries partial neg hydrogen bonds bw O and H

covalent bonds bw subunits, one loses OH and other loses H, this is dehydration synthesis proteins (amino acids) carbs (polymers of C,H,O atoms), store energy lipids (from fatty acids and glycerol, energy storage/ structure of cells) nucleic acids- store genetic info

diff in conc. of protons inside and outside of a cell gives membrane electrical charge -this makes potential gradient this if for cell signaling and cell to cell communication

study of energy and its transformations 1st law- energy can change from one for to another but cannot be created or destroyed, total amt of energy is constant 2nd law- direction energy flows/changes energy flows /changes till reaches equilibrium entropy inc

metabolic rxns enzymes catalyze both Anabolism- use energy to build complex from simpler molecules Catabolism- releases energy, degradation rxn (hydrolysis)-add h20 to break covalent bonds bonds of molecules broken

cell needs energy so chemical bonds broken and electrons harvested, ATP is made and stored ATP is degraded and energy released electrons lost (oxidized) and accepted by another which is reduced oxidation number: how many electrons atoms can gain/lose

specificity induced fit- site changes shape when substrate bound pH and temp influence

pH and temp alter enzyme activity pH alters shape and charge inc in temp weakens bonds, enzyme unfold or denature

Cooperative binding: enzymes bind more than one substrate substrate bound to one affects another Positive cooperativity: Inc in affinity of sites for substrate Negative cooperativity: dec affinity of sites Feedback inhibition: product of enzymatic rxn can bind to enzyme and repress action of enzyme product blocks active site therefore repressor is competitive inhibitor product binds to enzyme not at active site but forces shape change and substrate cant bind (noncompetitive inhibitor

energy for cellular work from the sun maintains membranes, builds proteins, and cell division plants, algae, photosynthetic bacteria etc use light to convert to chemical chemical rns occur when bonds forms/breaks These pathways drive metabolism: photosynthesis, cell resp, and chemosynthesis

• light penetrates mesophyll cells filled with chloroplasts • within chloroplast thylakoids are chlorophyll (light absorbing pigments) • proteins anchor chlorophyll to thylakoid membrane to form photosystems– light dependent rnxs occur • cell captures photons of energy in photosystem 2 • electrons become excited and this energy is passed bw cholorophyll molecules • excited electrons released and go to electron transport • electrons lost, and rxn splits water to form O2 • in electron transport electrons goes thru series of protein carriers in thylakoid membrane • energy of electrons pumps protons into thylakoid space • protons inc and flow down conc. gradient • they go out of thylakoid space and thru ATP synthase to make ATP • electron transport transfer e- from photosystem 2 to photosystem 1 • NADPH is produced • ATP and NADPH enter calvin cycle (in stroma) • energy of ATP and H atoms make carbs C3 Photosynthesis (Calvin Cycle) -carbon from CO2 fixed to make glucose C4 Photosynthesis- malate made in mesophyll then bundle sheath, malate degraded, and CO2 released

-glucose oxidized, electrons harvested, ATP produced -1st stage: anaerobic (glycolysis) Glycolysis: in cytoplasm, transform glucose to 2 pyruvate -2 ATP made and 2 NAD+ reduced -pyruvate reduced by fermentation -NAD+ recycled 2nd stage: aerobic (Krebs Cycle) Krebs Cycle: within mitochondria -pyruvate oxidized to 6CO2 -2 ATP & 10NADH & 2 FADH2 electron transport: series of oxidation reduction rxns electrons transferred from NADH and FADH2 to carrier molecules movement of e- drives formation of H+ gradient these protons move back across ATP synthase to make ATP

devoid of sunlight used by organisms within deep sea hydrothermal vents vents release hydrogen sulfide (H2S) bacteria and other microbes oxidize H2S and other inorganic molecules to use e- to reduce CO2 to make organic molecules these molecules serve as base of food chain for deep sea animals

smallest unit of life organelles (for specific fns)- mainly in eukaryotes

nucleus golgi- collect, packs and ditrib proteins ER- location of some ribosomes mitochondria- metabolism lysosome- degrading enzymes chloroplast vacoules- carry water, collect metabolic waste plastid- make and store sugars

prokaryotes (peptidoglycan) and certain eukaroytes like plant (cellulose) cells animal cells lack

eukaroytes have nucleus, mitochondria, golgi bodies, ER, ribosomes cell membranes around cytoplasm plants have cell wall of cellulose plant cells (rectangular) animal cells (circular mostly) animals have lysosomes plants (choloroplasts) and large central vacoule animal cells (flagella) plants (autotrophs) animals (heterotrophs)

prokaryotes or eukaryotes cytoplasm around cell membrane -2 layers of phospholipids phospholipid molecules: • polar head • chemical group with phosphate attached to 2 nonpolar hydrophobic fatty acids tails (C and H) • tails on inside, heads on outside cell membrane has proteins (selective permeability) cell membrane is semipermeable phospholipid bilayer -forms channels and bridges

attached to proteins and within plasma membrane gives cell shape (animals) certain enzymes and organelles found here built from 3 types of protein fibers • intermediate filaments: thick fibers of proteins, gives cell strength and prevent stretching • microtubules: hollow tubes, made from tubulin, aids in separating chromosomes, and component in flagells • microfilaments: long thin fibers of actin, cell shape and movement

• transmembrane proteins regulate movement of molecules in and out of cell • acquire nutrients and rid of waste diffusion: movment down conc gradient - high to low - equilibrium - passive (no energy) - movment same rate in as out

passive diffusion: simple and facilitates simple-small and or hydrophobic down conc. gradient and thru bilayer facilitated: large and or charged or hydrophilic, via carrier or channel protein active transport- molecule pushed up or against conc gradient to high conc -driven by oxidation or hydrolysis of ATP Example: Na+ K+ pump • Na+ outside of cell is higher and K+ higher inside cell • driven by ATP hydrolysis • ATP phosphorylates pump and incuces conformational change in this protein • one cycle leads to 3 Na+ outside and 2K+ inside