Exam 2

metabolism

sum of chemical reactions in an organism

2 types of catabolic reactions

exergonic and hydrolysis

exergonic reactions

release energy (break covalent bonds)

hydrolysis reactions

use water to break macromolecules into monomers

3 types of anabolic reactions

endergonic, dehydration synthesis, biosynthetic

endergonic reactions

requires an energy input (ATP)

dehydration synthesis

release water when making covalent bonds between monomers

biosynthetic reactions

build high potential energy macromolecules

the ATP cycle is coupled to

anabolic and catabolic reactions

ATP is the useful

source of energy in cells

3 components of ATP

adenine, ribose, triphosphate (ATP)

catabolic reactions are coupled to

ATP synthesis (energy + ADP + Pi → ATP)

anabolic reactions are coupled to

ATP hydrolysis (ATP → ADP + Pi + energy)

enzymes are biological catalysts meaning

speed up chemical reactions

enzymes are highly specific

each enzyme can only facilitate one chemical reaction because 3D structure determines function

enzymes are reusable

enzyme shape is unchanged after reaction

the amount of collision energy required to start the reaction is called

activation energy

enzymes lower the

energy of activation for a chemical reaction

all metabolic reactions in cells require

enzymes

naming enzymes

• usually end is -ase

• named after what major type of reaction they assist

holoenzyme components

apoenzyme, non-protein portions - (coenzymes, cofactors)

holoenzyme components - apoenzymes

protein portion; inactive alone

non-protein portions are required

to activate

holoenzyme components - coenzymes

organic molecules like NAD+ and FAD

holoenzyme components - cofactors

inorganic ions like Mg2+

4 steps of mechanism of enzyme action

1. substrate binds to active site on enzyme due to complementary shape

2. enzyme-substrate complex forms and energy of activation in lowered

3. chemical reaction occurs

4. products are released and enzyme is back to original shape

lock and key fit in enzymes

active site shape uses orientation of substances for favorable reactions

induced fit in enzymes

enzyme changes shape (conformation) to help initiate the reaction

3 factors influencing enzyme activity

physical factors, substrate concentration, enzyme inhibition

physical factors influencing enzyme activity

temperature and pH

if the shape of protein is altered it reduces

function, potentially, non-functional

denaturation

unfolding of protein 3D shape

graph when vary physical conditions

bell shaped curve

substrate concentration in enzymes initially

increasing substrate increases enzyme products

substrate concentration in enzymes at saturation

(all enzymes at use) - no further increase produces a plateau

competitive inhibitor in enzymes - analog

similar in shape to substrate

• compete to bind the same active site and physically block other from reacting

• concentration level determines the winner

enzyme inhibition - non-competitive inhibitors in enzymes

• bind to secondary groove called allosteric site

• alters the shape of the enzyme so its unable to bind to the substrate

feedback inhibition in enzymes

• used in to control metabolic pathways

• the final end product of pathway acts as the inhibitor of one of the first enzymes

redox couple reactions

if one molecule is oxidized then the other must be reduced

acronym for redox reactions

LEO the lion says GER

LEO in redox reactions

lose electron then oxidized ex. NAD+, FAD, NADP+

GER in redox reactions

gain electrons then reduced ex. NADH, FADH2, NADPH

in redox reactions, electrons are from a

hydrogen atom: follow presence of H

in redox reactions, high energy electrons are

transferred using coenzymes

as a requirement of ATP production, an energy source

generates electrons

as a requirement of ATP production, electron energy is passed to

coenzymes - temporary carriers

cell respiration coenzymes

use NAD+ and FAD

photosynthesis coenzymes use

NADP+

coenzymes (NADH) take electrons to

electron transport chain in plasma membrane of bacteria

3 steps in electron transport chain in plasma membrane of bacteria

1. coenzyme is recycled back to oxidized form (NAD+)

2. electron transfers in chain power proton pumps and create a proton gradient

3. electron passed to final electron acceptor (o2 to water)

as a requirement of ATP production, ATP synthase generates

ATP by facilitated diffusion of protons back across the membrane

3 types of ATP production

substrate level phosphorylation (SLP), photophosphorylation, oxidative phosphorylation

substrate level phosphorylation (SLP) occurs in

enzyme reaction

photophosphorylation

occurs in light reactions - sunlight powers electron passed to ETC to generate ATP

oxidative phosphorylation

occurs in cell respiration

• coenzymes power ETC to generate ATP

• ETC and ATP synthase are common metabolisms because make lots more ATP

2 types of energy source classification

phototrophs and chemotrophs

phototrophs

use sunlight

chemotrophs

use chemical compounds

2 types of carbon source classification

autotroph and heterotroph

autotroph

use CO2 from atmosphere

heterotroph

use organic molecules

photosynthesis equation

sunlight + CO2 + H2O → sugar + oxygen + ATP

in photoautotrophs, photo means

run light dependent reactions to produce ATP

location of light reactions

chromatophore (pigments) and plasma membrane (ETC)

in photoautotrophs, chlorophyll pigment absorbs

sunlight energy and excites electrons from water

in photoautotrophs, electron passed down ETC make

proton gradient for ATP synthase to produce ATP (photophosphorylation)

in photoautotrophs, auto means

run calvin cycle to fix CO2 from atmosphere

• uses ATP and NADPH from light reactions to convert CO2 into sugars

• located in carboxysome inclusion

in photoautotrophs, oxygenic photosynthesis

produce oxygen products ex. cyanobacteria

in photoautotrophs, anoxygenic photosynthesis

produce sulfur products from using H2S instead of H2O as electron source ex. green and purple sulfur bacteria

in photoheterotrophs, photo means

run light reactions in chromatophore/plasma membrane to obtain light energy to power ETC to make ATP

in photoheterotrophs, hetero means

convert organic molecules into own macromolecules

photoheterotrophs are typically

anoxygenic ex. green and purple non sulfur bacteria

in chemoautotrophs, chemo means

redox reactions to obtain energy from inorganic chemicals like hydrogen sulfide or ammonia to power ETC and make ATP

in chemoautotrophs, auto means

runs the calvin cycle to fix CO2 and make own sugars in carboxysomes

chemoautotrophs are thought to be the 1st

metabolism used by the first cells in planet (at deep sea vents)

Chemoheterotrophs include most

gram positive and proteobacteria phyla including all human pathogens and our lab bacteria

in Chemoheterotrophs, chemo means

run redox reactions on chemical energy source, typically organic chemical

in Chemoheterotrophs, hetero means

use organic chemicals from environment as carbon source for making macromolecules

in Chemoheterotrophs, glucose is the most commonly used

organic chemical that serves as carbon, energy, and electron source

in Chemoheterotrophs, the final electron acceptor determines which

metabolic pathway the Chemoheterotroph is using

in Chemoheterotrophs, locations where respiration and fementation occur:

bacteria - cytoplasm (enzymes) and membrane (ETC)

step 1: glycolysis

1. input glucose

2. produce 2 ATP by substrate level phosphorylation (SLP), 2 NADH, and 2 pyruvate

step 2: krebs cycle and how many atp produced

1. input 2 pyruvate

2. produce 2 ATP (by SLP), coenzymes (NADH & FADH2), and CO2

step 3: electron transport chain

1. receive electrons from coenzymes and recycle them back to NAD+ and FAD

2. produce the proton gradient to power ATP synthase

3. give electron to final acceptor

aerobic respiration equation

glucose + O2 → water + CO2 + ATP

aerobic respiration final electron acceptor

oxygen

aerobic respiration final products

water and carbon dioxide gas

aerobic respiration ATP produced

38 ATP total (2 glycolysis, 2 krebs, 34 etc)

aerobic respiration growth rate

more ATP produced per glucose so faster growth than anaerobic metabolisms

anaerobic respiration

no oxygen involved

anaerobic respiration example equation

glucose + NO3 → NO2 or N2 gas

anaerobic respiration final electron acceptor

nitrates, sulfates

anaerobic respiration types of products

nitrites, nitrogen gas, hydrogen sulfide

anaerobic respiration ATP produced

more than 2 and less than 38 ATP b/c krebs and etc are only partially active

anaerobic respiration growth rate

less ATP/glucose typically means slower division rates

3 fermentation steps

1. glycolysis

2. fermentation

• Pyruvate converted into products of acid or alcohol; CO2 gas

• Recycle NADH back to NAD+, so glycolysis can continue

fermentation step

1. pyruvate converted into products of acid or alcohol; CO2 gas

2. recycle NADH back to NAD+, so glycolysis can continue

how many ATP per glucose per ATP in fermentation

2 ATP per glucose

fermentation does not require

oxygen, but may take place in oxygen

in fermentation, no electron

transport chain is used in the process (low APT totals)