6- basic bioenergetics and an overview of cellular metabolism

Question 1

2 main classes of metabolic pathways

Answer 1

Catabolic

Anabolic

Question 2

Catabolic

Answer 2

Breaking down fuel molecules to generate energy

Question 3

Anabolic

Answer 3

Using energy to build complex bio molecules required for life

Question 4

Change in Free energy ( G)

Answer 4

The energy change associated with a reaction
kJ/mol
Reaction will only proceed spontaneously if delta G is NEGATIVE

Question 5

ATP

Answer 5

Adenosine triphosphate
Key intermediate in metabolism
Hydrolysis of ATP to ADP and phosphate (Pi) is energetically favorable

Question 6

ATP hydrolysis

Answer 6

Making ADP 
Favorable 
Negative delta G 
Used for motion, active transport
free energy released

Question 7

ATP syynthesis

Answer 7

Positive delta G
Making ATP
Make using energy from food , carbs, fats, amino acids

Question 8

Oxidation of food molecules

Answer 8

Carbon based food molecules are oxidised to release energy
In aerobic respiration, electrons are eventually passed to o2 making h2o
Highly reduced carbon fuels have more energy ) more oxidation potenital

Question 9

Cellular respiration

Answer 9

glucose + oxidation —— carbon + water

ATP made
Proceeds via a series of oxidation reactions transferring electrons ( and h+) to specialised electron carriers ( coenzymes ) such as NAD+ and FAD
VERY energetically favourable so lots of energy needed

Question 10

Activated carriers ( coenzymes ) in metabolism

Answer 10

Activated carriers are biomolecules that store energy in the form of transferable chemical groups
Bound to enzymes as coenzymes
Many conenzymes are derived from vitamins
e.g. ATP carrier of phosphate group
NADH - carrier of electrons and derived from vitamin nicotiate

Question 11

NADH and NADPH

Answer 11

NAD+ can accept 2 electrons and a proton ( reduction ) to form NADH , used in catabolic pathways
Store energy when accept electrons
Nicatinimide site
NADP+ is phosphorylated on OH group , used in anabolic reactions
COENZYME

Question 12

FADH2

Answer 12

COENZYME
-FAD can accept 2 electrons and 2 protons to form reduced FADH2
FAD is covalently linked to the enzymes for which it acts as a coenzyme
Stores energy by accepting electrons

Question 13

What does NAD stand for

Answer 13

Nictoinamide adenine dinucleotie

Question 14

What does FAD stand for

Answer 14

Flabin adenine dineucleotide

Question 15

CoA

Answer 15

Coenzyme A
Carrier of acyl groups
Acyl groups form thioester bonds to CoA to form acylCOA
acylCoA is important intermediate in metabolism

Question 16

Steps of respiration

Answer 16

Glycolysis - one glucose into 2 pyruvate, 2 atp and 2 nadh
Krebs cycle - 3NADH, 1 FADH2 an 1GTP
Oxidative phosphorylation - electrons from NADH and FADH2 = energy released used to pump h+ out of matrix, h+ flows back down its conc through atp synthase, generating ATp from ADP ( energy using atp synthase)

Question 17

Control of metabolism

Answer 17

Carefully regulated to control cell needs

Question 18

Rate determining enzymes

Answer 18

The activity of 1 key enzyme determining overall flux throughout the pathway

Question 19

Catabolic and anabolic pathways - controlling metabolism

Answer 19

Often controlled reciprocally to avoid futile cycling
When catabolic is switched ON, anabolic is switched OFF
No point constantly breaking down molecules to then build them up again

Question 20

Short term control(mins/seconds) metabolism

Answer 20

• Binding of allosteric inhibitors or activators to alter enzyme activity
• Covalent modification such as phosphorylation to alter enzyme activity

Question 21

Long term control ( hours /days ) of metabolism

Answer 21

Changes in gene expression to alter the total amount of enzymes
Changes in proteolysis ( breaking down proteins ) to alter the total amount of enzymes

Question 22

Effect of adenaline of the metabolism

Answer 22

Fight or flight
Mobilizing energy molecules like glucose so the cells have energy to work muscules e.g. to runa way
Binds to GPCR, cyclic AMP

Question 23

Hormones can have long or short term effects on metabolism

Answer 23

both