Bio midterm 2

Na+/k+ pump process

3 Na’s bind, ATP phosphorylates it making it change change shape and open to outside, releasing Na to outside. K will bind, P released, changes shape back to original releasing K inside

Proton pump

• ex of active transport coupled to facilitated diffusion

• Proton pump powered by ATP and creates H+ gradient

• H+ flows back down gradient using sucrose channels

Types of endocytosis

Phagocytosis: large particles

Punocytosis: small dissolved particles

Receptor-mediated: transports molecules that bind to receptor proteins, selective

Order of origin of life

1) abiotic synth of organic molecules

2) abiotic synth of macromolecules

3) formation of protocells

4) origin of self replicating, info sharing molecules

Abiotic synthesis

Of small organics

Required lots of water

• early at,sphere was reducing enviro where organics could be formed from inorganic molecules

• Miller and Urey tested hypothesis

Abiotic synthesis of macromolecules

Polymers joined by covalent bonds which are formed by enzymes

• early polypeptides may have been precursors to 1st enzymes

formation of protocells

metabolic reactions more efficient when contained

lipids spontaneoulsy form membranes then vesicles which spontaneously divide

self replicating vesicles w basic metabolism= protocell

origin of self-replicating info-storing molecules

-RNA polymers can be catalysts and can self-replicate

-RNA has variation thru nitrogenous bases, could encode info and direct protein synth

-enclosure of these in protocells= early cell

glycocalyx

external feature of prokaryotic cell, made of polysaccharides and proteisn, allows adhesion and prevents dehydration

fimbriae

protein fibers in prokaryotes, help w adhesion

dna organization in prokaryote

single, circular chromosome compressed into nucleoid region

-more genes on plasmids

-ribosomes= only true organelles

which organelles does endosimbyosis theory apply to

mitochondria and chloroplasts

evidence of endosymbiosis theory

-size of these organelles similar to prokaryotic species

-have double membrane

-produce own variety of ribosomes similar to prokaryotes

-have own circular chromosoems

-reproduce using binary fission

ribosomes

-2 subunits made of protein and rRNA

-made in nucelus, function in cytoplasm, usually attached to rough ER

-assemble aa’s into polypeptides

nucelus

-double membrane- pores connect cytoplasm and nuceloplasm

-proteins and nucleotides can enter, RNA and ribosomal subunits can exit

-contains DNA as chromatin

nucleolus

dense region of nucleus where proteins and rRNA make ribosomal subunits

rough E.R

ribosomes on surface

-continuous w outer membrane of nuclear envelope

-site for synthesis of proteisn destined for plasma membrane or export from cell

smooth E.R

no ribosomes

-site for synth of lipids (phospholipids)

-isolates toxic cmpds

-stores Ca2+ ions

golgi body

-flat membranous sacs (cisternae)

-cis face: receives transport vesicles to take in things to cisternae

-trans face: releases vesicles

-processes things made in E.R

endomembrane system

ER and golgi vesicles work together to distribute proteins in/out of cell

lysosomes

-vesicles w digestive fluids

-recycle organelles, breakdown macromolecules for nutrients

vaculoues

membranous storage centers

plant cells have large one for water

animals have multiple smaller ones

mitochondria

site of cellular respiration

inside is matrix, free ribosomes

chloroplasts

capture light E, photosynthesis

3 membranes, innermost forms thylakoids

microfilaments

-actin strands twisted around each other

-maintain cell shape, resist stretching

-muscle contraction, cell motility, cell division

intermediate filaments

-keratin (usually), multiple coiled together

-maintain cell shape

-anchor nucleus, form nuclear lamina

microtubules

hollow tubes made of alpha and beta tubulin

-maintian cell shape, resist compression

-cell motility

-move chromosmes in division

-organelle movement

centrioles

-in centromere of cytoplasm of animal cells

-made of microtubules

-each rod is 9 triplets of microtubules

cilia and flagella

movement controlled by microtubules

-made of 9+2 arrangemnt of microtubules

2nd law of thermodynamics

when E is converted, new form has less usable E than original

allosteric regulation

-regulatory molecule binds to enzyme at one site and affects fxn at another site

-can inhibit or stimulate

allosteric activation/inhibition

-allosterically regulated enzyme has active/inactive forms

-binding of activator stablizes active form

-binding inhibitor stabilizes inactive form

cooperativity

one substrate primes enzyme to act on other substrate molecuels (allosteric regulation)

general cellular respiration formula

C6H12O6 + 6O2 → 6CO2 + 6H20 + energy

glycolysis

-happens in cytosol

-requires 2 ATPs per glucose

-produces 4 ATPs (2 net), 2NADH, 2 pyruvate

citric acid cycle

-in mitochondria

-breaks down pyruvate to CO2

-generates 1 ATP, 3 NADH, 1 FADH2 per cycle, 2CO2

(cycle happens twice, once for each pyruvate)

acetate step

step right before citric acid cycle

-pyruvate from cytosol enters mt, output is 2 CO2, 2 NADH, 2 acetyl coA

total citric acid cycle inputs and outputs (including acetate step)

input: NAD+ (8), ADP (2), FAD (2)

output: NADH (8), ATP (2), FADH2 (2), CO2 (6)

oxidative phosphorylation overview

-ETC + chemiosmosis

-ETC converts energy in electron carriers to H+ gradient across inner mitochondrial membrane that powers ATP synthase

ETC

• in inner membrane of mitochondria (cristae)

• chain of proteins

• carriers alternate between oxidized and reduced states

• electrons drop in free energy as they go down chain, ending at O2

chemiosmosis

-H+ flow through ATP synthase complex

-flow around a rptor then are released, rotation activates process to make ATP

-H+ gradient= proton motive force

overall ATP production by cellular respiration

• 30-32 ATP made

• exact number unknown cuz it depends on which electron carrier brings them because it affects how many H+ are used to create gradient

what happens when no O2

-electrons remain in ETC

-proton pumping stops, no gradient to power ATP synthase

-eelctron carriers remain in reduced state

-glycolysis and krebs stop cuz NAD+/FAD supplies get used up

alcohol fermentation

pyruvate to ethanol in 2 steps, releases CO2

lactic acid fermentation

-pyruvate reduced by NADH, forms lactate, no CO2 released

-muscles use to generate ATP when O2 low

chloroplast structure

thylakoids are little pancakes that form stacks called granum

-stroma is fluid filled compartment

visible light

-380-750nm

-shorter wavelength means higher energy

-longer wavelength means lower energy

photosynthetic pigments

chlorophyll a: main photosynthetic pigment (has CH3)

chlorophyll b: accessory pigment, broadens spectrum of use for photosynthesis (has CHO)

carotenoids: accessory pigments, absorn excessive light that could damage chlorophylls

fluorescence

when adding energy to electrons they momentarily jump to excited state then back down, emiting energy as a photon

-new photon can carry on and excite nect chlorophyll molecule

photosynthesis overview

1) light reactions- light captured by pigments and energy used to create ATO, reduce NADPH

2) calvin cycle- energy from ATP and electron from NADPH used to convert CO2 to organic forms

light reaction inputs

-light, water, NADP+, ADP

light reaction outputs

-ATP, NADPH, O2

calvin cycle inputs

-CO2, NADPH, ATP

calvin cycle outputs

sugar

calvin cycle overview

-takes energy than light reactions harvested to reduce CO2 to sugar

-CO2 enters cycle and leaves as G3P

-cycle goes 3 times, fixing Co2 3 times, producing 1 G3P total

calvin cycle inputs and outputs

-co2 enters

-6 ATP used

-6 NADP+ used

6 G3P made, one released and 5 used to regenerate RuBP- req 3 ATP