glycolysis and metabolism quiz

glycolysis stage 1

• ENERGY INVESTMENT

• uses 2 atp

• trap glucose in cell and modify it to make 2 phosphorylated 3-carbon compounds

glycolysis stage 2

• ENERGY PAYOFF

• makes 4 atp and 2 nadh

• oxidizes 3-carbon compounds to pyruvate

hexokinase

• traps glucose in cell

• adds phosphate to glucose

• begins glycolysis

• turns glucose → glucose 6 phosphate

stages of cellular respiration

1. glycolysis (happens in cytoplasm)

2. pyruvate processing

3. citric acid cycle

4. electron transport chain

why is glucose an important molecule

• can form under prebiotic conditions

• its stable

• low tendency to make bad bonds with proteins

PFK

• adds another phosphate to trap glucose

• irreversible

• controls glycolysis

• 2 binding sites: active site and regulatory site

• inhibited by atp

• stimulated by amp (signal for low energy state)

start of glycolysis phase 2

• fructose 1,6 biphosphate turns into DHAP and GAP

• reversible reaction

• catalyzed by aldolase

DHAP and GAP

• GAP can be turned into pyruvate to make atp but DHAP can’t

• triose phosphate isomerase lets DHAP be converted to GAP for further metabolism

what happens when GAP is oxidized

it generates 1,3-BPG which has high phosphoryl transfer potential

what enzymes regulates glycolysis

1. hexokinase

2. phosphofructokinase

3. pyruvate kinase

the allosteric regulation of PFK

when atp is low, more PFK is made at a faster rate. when atp is high, It is able to generate and accumulate less and slower

the activation of PFK by fructose 2,6-biphosphate

• F 2,6 BP tells PFK there’s plenty glucose and glycolysis needs to happen to give energy to energy consuming processes instead of wasting energy

• PFK kickstarts glycolysis so F 2,6 BP tells PFK its okay.

regulation of glycolysis in muscle

long slow run

• co2 and h2o is made from pyruvate

• oxygen is more abundant

sprint

• lactate is made to regenerate NAD+ to keep glycolysis running

• oxygen is not abundant you need more

entry points In glycolysis for galactose and fructose

• liver and adipose tissue

• glucose 6-P

• fructose 6-P

2 types of fermentation

1. lactic acid fermentation

• pyruvate → lactate (happens in muscles)

2. alcohol fermentation

• pyruvate → ethanol

fermentation

regenerate NAD+ so glycolysis can continue

catabolism

makes atp

• breaks molecules and releases energy

anabolism

use atp to make biomolecules

common denominator between anabolic and catabolic pathways

the regulated, irreversible reactions are always distinct

2 ways organisms get energy

chemotrophs and phototrophs

basic principles for energy manipulation in cells

1. molecules are made or broken by metabolic pathways

2. atp is energy currency

3. atp can be formed by oxidation of carbon fuels

4. many reactions repeat similar patterns

5. metabolic pathways are highly regulated

criteria for constructing a metabolic pathway

1. individual reactions must be specific

2. total pathway must be thermodynamically favorable (must release energy)

ATP

• high potential energy (stores energy)

• allows cells to work

• works by transferring phosphate group

ATP hydrolysis

• breaking atp releases energy because phosphate groups repel each other with negative charges (EXERGONIC RXN)

• the energy released can be transferred to another molecule with phosphorylation

muscle atp

creatine phosphate regenerates ATP from ADP, allowing a short burst of activity (ex: a sprint)

why is phosphate important

1. they’re thermodynamically unstable but kinetically stable

2. negative charges resist hydrolysis

3. they are ideal regulatory molecules

ATP → ADP phosphates in biochemical processes

• motion

• active transport

• biosyntheses

• signal amplification

ADP → ATP phosphates in biochemical processes

• oxidation of fuel molecules

• photosynthesis

carbon oxidation

• the more reduced a carbon atom is, more free energy is released with oxidation

• more oxygens = less energy

what is a better fuel

fats are better than glucose because fats are more reduced

• they have more C-H bonds and less oxygen

activated carriers

universal, reusable currency that can do different reactions (ex: ATP is the active carrier of phosphorylation groups, NAD+ and FAD carry activated electrons)

2 characteristics of activated carriers

1. kinetically stable without specific enzymes

2. can do metabolism with less carriers

3 regulatory controls of homeostasis

1. amount of enzyme (can be regulated at gene transcription or after)

2. catalytic activity of enzyme

3. accessibility of substrate

how is catalytic activity regulated

allosterically or covalent modification

• hormones coordinate metabolic activity (allosteric)

• energy status of cell

how to assess energy status of a cell

energy charge and phosphorylation potential

the accessibility of substrates is regulated

• with opposing reactions (fatty acid synthesis and degradation)

• and regulating flux of substrates between cellular compartments

energy charge regulates metabolism

• atp generating pathway: relative rate decreases because the needs are met and doesn’t want to waste resources

• atp utilizing pathway: the relative rate increases because it needs more energy