Ch 15 Electron Transfer and Metabolism- Biochem

Does glycolysis require oxygen?

No

What is the net ATP amount from glycolysis?

2

What does triose phosphate isomerase do?

isomerization in step 5 of glycolysis from dihydroxyacetone phosphate to glyceraldehyde-3-phosphate

What is phosphoglycerate kinase used for?

isomerization in step 8 of glycolysis for 3-phosphoglycerate to 2-phosphoglycerate

Does phosphoglycerate produce ATP?

Yes

What is a major regulatory item and irreversible step in glycolysis?

PFK-1 (Phosphofructokinase)

What are the three irreversible steps in glycolysis?

1) Hexokinase

3)Phosphofructokinase-1

10) Pyruvate kinase

What happens to an open-chained form when it is turned into the cyclic form (regarding chirality)?

Has one more chiral center (anomeric carbon) than the open-chain form

What is the importance of energy changes and electron transfer in metabolism?

cells need energy to carry out reactions and energy is made into useful chemical forms

electron transfer is important because it allows energy to be transferred during oxidation-reduction reactions

catabolism

breaks down large molecules into smaller ones, releasing energy

anabolism

builds larger molecules from smaller ones, requires energy

What are standard states?

conditions used to measure standard free energy changes

standard state/condition for liquids and solids

pure substance

standard condition/state for gas

pressure of 1 atm

standard condition state for solutions

conc of 1 M

what is free energy (delta G)

says whether a reaction is energetically favorable under specific conditions

negative delta G

spontaneous reaction (EXERGONIC), releases energy

positive delta G

nonspontaneous reaction (ENDERGONIC), absorbs energy

delta G=0

equilibrium of reaction

What is the modified standard state for biochemical applications?

Biochemical use modified standard state called delta G°’ that ssumes ion conc of 10^-7 M (pH=7)

Why is a modified standard state in biochemistry used?

because it provides a more realistic way to describe free-energy changes in biological systems

What is thermodynamics?

the study of energy changes as a system undergoes a transformation

Isolated system

no exchange of matter or energy with surroundings

closed system

exchange with only energy with surroundings

open system

exchange of both matter and energy with surroundings

What is entropy and what does an increase in it mean?

entropy (S) is the measure of randomness or disorder of a system, so an increase in S means greater disorder

Ex: heat moving from a warm object to a cold one

Ex: solute going from high conc to low (we inc the entropy of our surroundings by releasing heat)

First law of thermodynamics

conservation of energy, energy cannot be created or destroyed

second law of thermodynamics

a spontaneous process occurs only when the total entropy of a system and surroundings increases (greater than 0)

does catabolism or anabolism involve oxidation

catabolism=oxidation

anabolism=reduction

Oxidation

loss of electrons

Reduction

gain of electrons

Reducing agent

donates electrons and becomes oxidized

Oxidizing agent

accepts electrons and becomes reduced

Example of a reduced carbon and an oxidized carbon

reduced= carbon in an alkane

oxidized= carbon in CO2

What is a spontaneous reaction?

energetically favorable and can occur without a continuous input of energy (has negative delta G)

What is a coenzyme?

assist enzymes in carrying out metabolic reactions

What is an example of a coenzyme in redox reactions?

NAD+

An oxidizing agent

accepts 2 electrons

reduced to NADH

IMPORTANT ELECTRON CARRIER that transfers energy during metabolism

What is a coupled reaction?

an energy-releasing reaction connected to an energy-requiring reaction

How is energy that is released used fo rmetabolic processes

in the form of ATP (usable chemical forms)

What is the primary energy currency of cells?

ATP

What important bonds does ATP have?

high energy bonds (phosphoric anhydride bonds, hydrolyzing ATP to ADP breaks these bonds and releases energy that can be used for the cell)

Does ATP synthesis need energy?

yes, to go from ADP to ATP needs energy

Why is ATP less stable than ADP?

ATP has more negatively charged phosphate groups and creates electrostatic repulsion between them, and phosphorylation causes a loss in resonance stabilization