BioChem Review 2

What is free energy change (ΔG)?

the amount of free energy released (negative ΔG) or absorbed (positive ΔG) in a reaction

If ΔG > 0 the reaction is?

unfavorable (endergonic)

If ΔG < 0 the reaction is?

favorable (exergonic)

If ΔG = 0 the reaction is?

at equilibrium

What’re the two ways a ΔG > 0 occur in cells?

by decreasing the concentration of products and increasing the concentration of reactions and couple the reaction with an exergonic reaction

How does pushing happen?

when reactants in a reaction are added or increased

How does pulling happen?

when products are removed/ reduced

One monomeric unit (glucose, fructose, ribose)

Monosaccharides

2-20 monosaccharide units (sucrose, lactose)

Oligosaccharides

> 20 monosaccharide units (starch, glycogen, cellulose)

Polysaccharides

Which carbohydrates are commonly referred to as sugars?

monosaccharides and disaccharides

When a OH group of one sugar displaces the OH group on the other sugar’s anomeric carbon the bond is called?

glycosidic bond

What is glycogen?

the animal storage form of glucose (a-1,4 glycosidic bonds with a-1,6-linked branches)

What is starch?

the plant storage form of glucose (a-1,4 glycosidic bonds, it can have a-1,6-linked branches)

What is cellulose?

the constituent of plant cell walls, it has unbranched linear chains of glucose polymers linked by B-1,4 glycosidic bonds

The degradative phase of metabolism where organic nutrients are converted into small, simpler components

Catabolism

What does catabolism produce?

ATP and reducing equivalents

The synthesis phase of metabolism where simple precursors are built into larger, more complex molecules

Anabolism

What does anabolism consume?

ATP and reducing equivalents

In Glycolysis, glucose is converted into?

2 pyruvate, 2 NADH, 2 ATP

In Gluconeogenesis What is used?

4 ATP, 2 GTP, 2 NADH

Where does gluconeogenesis occur?

in the liver

In oxidative pentose phosphate pathway, Glucose-6-P is converted into?

ribose-5-P and 2 NADPH

What is fermentation?

the process that breaks down an energy-rich molecule to 2-3 carbon compounds such as lactate or ethanol under anaerobic conditions without O2

What process converts glucose into 2 pyruvate molecules?

glycolysis

Under aerobic conditions, what happens to pyruvate?

Pyruvate → 2 Acetyl-CoA + 2 CO₂

After pyruvate becomes acetyl-CoA, what cycle does it enter?

The Citric Acid Cycle (Krebs Cycle)

What are the main products of the citric acid cycle from pyruvate?

4 CO₂ (total from 2 pyruvate)

Under anaerobic conditions in muscle cells and some bacteria, what happens to pyruvate?

Pyruvate → 2 Lactate (lactic acid fermentation)

Under anaerobic conditions in yeast, what happens to pyruvate?

Pyruvate → 2 Ethanol + 2 CO₂ (ethanol fermentation)

What happens to pyruvate in muscle cells when there’s not enough oxygen?

 It’s converted to lactic acid.

Why is pyruvate converted to lactic acid during anaerobic conditions?

to regenerate NAD+ used up in step 6 of glycolysis

What does regenerating NAD+ allow glycolysis to do?

it allows glycolysis to continue producing ATP without oxygen

What are the enzymes used in glycogen synthesis?

glycogen synthase and branching enzyme

What are the enzymes used in glycogen degradation?

glycogen phosphorylase and debranching enzyme

What does the citric acid cycle generate?

3 NADH, 1 FADH2, 1 GTP

What is reduction potential (E)?

a measure in volts of the affinity for electrons

The more positive the reduction potential value…

the more likely the molecule is to accept electrons

How do electrons flow in reduction potential?

from lower to higher

What blocks electron transfer in complex I and causes paralysis?

Rotenone

What blocks electron transfer in complex III?

Antimycin A

What blocks electron transfer in complex IV?

Cyanide or carbon monoxide

In the electron transport change for NADH complex I and III pump out?

4 H+

In the electron transport change for NADH complex IV pumps out?

2 H+

In the electron transport change for FADH2 complex III pumps out?

4 H+

In the electron transport change for FADH2 complex IV pumps out?

2 H+

What is oxidative phosphorylation?

the enzymatic phosphorylation of ADP to form ATP coupled to electron transfer from a reducing molecule (NADH/FADH2) to molecular oxygen

What is the proton gradient generated by the oxidation of NADH and FADH2 and what does it do?

it’s called the proton-motive force and it powers the synthesis of ATP

What is the P/O for NADH?

2.5

What is the P/O for FADH2?

1.5

Where does photosynthesis take place?

in the chloroplasts of plant cells

What is the light dependent reaction?

it results in the production of O2, NADPH, and ATP; O2 is released into the atmosphere and ATP and NADPH can be used for carbon assimilation reactions

What is carbon assimilation reactions?

ATP and NADPH are used to convert CO2 to hexose phosphates and takes place in the stroma

Where do light dependent reactions take place?

thylakoid membrane

The ultimate donor of electrons is _____ and the ultimate acceptor of electrons is_____.

water ; NADP+

The synthesis of ATP coupled to light-driven electron transport is called?

photophosphorylation

What are the similarities of oxidative phosphorylation and photophosphorylation?

both processes are associated with membranous elements of the cell, contain cytochromes in their electron carrier chains, and protons are pumped across a membrane to create a proton gradient

What are the differences of oxidative phosphorylation and photophosphorylation?

oxidative phosphorylation, O2 is reduced to H2O and O2 is the ultimate electron acceptor; photophosphorylation, H2O is oxidized to O2 and H2O is the ultimate electron donor while NADP+ is the ultimate electron acceptor

How can enzyme activity be regulated?

by changing the number of enzyme molecules by changing the rate of synthesis and degradation of enzyme; alteration of the activity of existing enzymes

If Glycogen synthase is inactive, glycogen phosphorylase is…

active and vise versa

What does glucagon stimulate?

glycogen breakdown and inhibits glycogen synthesis

If there are high blood glucose levels, insulin does what?

stimulates glycogen synthesis and inhibits glycogen breakdown

What energy sources are required for the calvin cycle?

ATP and NADPH

What is RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase)?

it’s the enzyme that catalyzes the first major step of the calvin cycle

When blood glucose is low ____.

glucagon is released