Introduction to Metabolism

Question 1

Definition of metabolism

Answer 1

Series of enzyme reactions within cells for converting fuel molecules into useful energy.
The enzyme reactions of synthesis/breakdown/interconversion of essential biomolecules

Question 2

Definition of catabolism

Answer 2

Breakdown of complex molecules in living organisms to form simpler ones with energy release

Question 3

Definition of anabolism

Answer 3

Synthesis of complex molecules in living organisms from simpler ones with the storage of energy

Question 4

Definition of endergonic

Answer 4

Accompanied by or required the absorption of energy

The products being of greater free energy than reactants

Question 5

Definition of exergonic

Answer 5

Accompanied by or requiring the release of energy

The reactants being of greater free energy than products

Question 6

Definition of induction

Answer 6

Up regulation of the rate of transcription of a gene

Question 7

Definition of repression

Answer 7

Down regulation of the rate of transcription of a gene

Question 8

What occurs in catabolism

Answer 8

Heat is lost

Forms the building blocks for biosynthesis

Question 9

Properties of catabolism

Answer 9

Names end in lysis
Glycolysis, lipolysis, glycogenolysis
Generate ATP, NADH
Mitochondrial

Question 10

Properties of anabolism

Answer 10

Names end in genesis
Gluconeogenesis, lipogenesis, glycogenesis
Use ATP, GTP, UTP
Mainly in cytosol

Question 11

Integration of glucose

Answer 11

Pathway of glycolysis and TCA cycle act together, convert glucose => CO2

C6H12O6 + 6O2 => 6CO2 + 6H2O + 30ATP

Through mitochondrial respiration, energy for tissue becomes available

Question 12

Catabolism of glucose, fatty acids, amino acids

Answer 12

Glucose =glycolysis=> pyruvate
Fatty acids =b oxidation=> acetate
Amino acids =transamination=> acetate

Acetate enters the TCA cycle

2H + O => H2O
ADP + Pi => ATP oxidative phosphorylation

Question 13

How do fatty acids enter the cell

Answer 13

Fatty acids bind to albumin, detach and freely diffuse through plasma membrane

Question 14

How does glucose enter the cell

Answer 14

Glucose moves by facilitated diffusion via protein channels

Question 15

Describe the structure of mitochondria

Answer 15

2 bilayers,

Inner mitochondrial bilayer has 3 transmembrane proteins and I integrated protein, forms ETC

Pyruvate converted into acetyl CoA by pyruvate dehydrogenase, enter TCA

Question 16

Describe the energy currency of the cell

Answer 16

Adenosine triphosphate
Adenine and ribose (nucleoside) allows cells and organelles to recognize ATP

Chemically stable at pH6-9

ATP + H2O => ADP + Pi + H+ + energy

Question 17

What bonds are broken in ATP

Answer 17

Phosphoanhydride bonds, v high energy (30.5kjmol-1)

Question 18

Functions of ATP

Answer 18

Used directly in cell motility and contraction (myosin, dynein)
Used in NaKATPase pumo, AT systems and metabolic control
Used in metabolism to add Pi to metabolic intermediates

Question 19

General feature of a metabolic pathway

Answer 19

Each step in a sequence of reactions needs a different enzyme

Question 20

Enzymes and how they affect reactions

Answer 20

Rate of biochemical reaction dependent on enzyme activity
Equilibrium dependent on properties of the chemical molecules themselves
Enzymes provide a pathway with a lower activation energy

Question 21

Reversible and irreversible steps in a metabolic pathway

Answer 21

Quite often different enzymes will act in opposite directions
Otherwise, many middle products will accumulate

Question 22

How is enzyme activity regulated

Answer 22

Alter availability of substrate (by increasing transport into the cell)
Increase amount of enzyme present in cell by increase rate of transcription from gene in DNA => mRNA (induction, repression)
Interconversion of active and inactive forms of key enzymes

Question 23

What enzymes are used in interconversions of active and inactive forms of an enzyme by covalent modification

Answer 23

Inactive enzyme =protein kinase ATP)=> active enzyme P

Active enzyme =(protein phosphatase)=> Inactive enzyme and Pi

Question 24

Allosteric control mechanisms

Answer 24

Enzymes have an activating site, inhibitory site and a substrate binding site
Sigmoid curve

Question 25

What do metabolic reactions need

Answer 25

Fuel molecules (substrates/intermediates)
Enzymes
Cofactors
activating ions
coenzymes/prosthetic group (ATOP for kinase enzymes)

Question 26

Role of ATP in enzymatic reactions

Answer 26

High energy cofactor in the cell for driving mechanical events

Question 27

Role of other high energy nucleotides

Answer 27

GTP, protein synthesis
UTP, drives complex sugar synthesis
CTP, lipid synthesis