Bioenergetics 2

Question 1

What can be used to drive a reaction that requires the input of free energy?

Answer 1

The free energy (/\G) released from an exergonic reaction

Question 2

Which type of /\G reactions can occur spontaneously?

Answer 2

-ve /\G

Question 3

What does ATP stand for?

Answer 3

Adenosine triphosphate

Question 4

In terms of ATP, ADP + AMP what remains constant and what varies?

Answer 4

Constant - total conc

Varies - ratios

Question 5

What type of reaction is the synthesis of ADP + P –> ATP?

Answer 5

Exergonic

cellular respiration

Question 6

What does the hydrolysis of ATP –> ADP + P produce?

Answer 6

Fuel for endergonic processes

Question 7

Define valency

Answer 7

The combining power of an element
- how well it forms bonds

No. of bonds the atoms of an element can form

Question 8

What does empty space on chemical diagram represent?

Answer 8

C bound to 2 H

Question 9

What is type of molecule is adenine?

What type of molecule is adenosine?

Answer 9

Base

Nuceloside

Question 10

What type of molecule is AMP?

What about ADP?

What about ATP?

Answer 10

Nuceleotide

Ns diP (NDP)

Ns triP (NTP)

Question 11

What is a nucleoside?

Answer 11

Base + sugar

Question 12

What are the 4 nucleoside examples?

Answer 12

Cytidine
Uridine
Adenosine
Guanosine

Question 13

What is the function of cytidine?

Answer 13

Lipid biosynthesis

Question 14

What is the function of uridine?

Answer 14

Carbohydrate

biosynthesis (e.g. glycogen)

Question 15

What is the function of adenosine?

Answer 15

Energy carrier

Question 16

What is the function of guanosine?

Answer 16

Transmembrane signalling

Some energetics

Question 17

Only which type of molecules can diffuse across plasma membranes?

Answer 17

Hydrophobic

Question 18

What is the free energy of ATP hydrolysis?

Answer 18

/\Go’ = 30.5 kJ/mol

Question 19

What does /\Go’ mean?

Answer 19

The reactants were 1M + the products were 1M + the pH is 7

Question 20

How do Na-K transporters work?

Answer 20

3Na+ exit
2K+ enter
Uses ATP

Question 21

Describe the muscle contraction process.

Answer 21

1. Ca2+ binds to troponin
   - >active site on actin exposed
2. myosin head forms crossbridge w/ actin
3. power stroke
   - myosin head bends & ADP + P released
4. new ATP attaches to myosin head –> cross bridge breaks
5. ATP hydrolysed into ADP + P
   - -> returns myosin to original position

Question 22

How does free energy vary?

Answer 22

> from 1 cell type to another
within the cell when conditions vary
between compartments within a cell

Question 23

What is the complication with ATP, ADP + Pi?

Answer 23

They can each bind tightly to some cellular proteins

–> affects conc of molecule available to react

Question 24

Is /\Gp greater or less than /\Go’?

Answer 24

greater than

Question 25

/\G of ATP –> ADP is large enough for what?

Yet small enough that…?

Answer 25

Driving many reactions for biosynthetic pathways

ATP can be synthesised ready from available nutrients

Question 26

Although /\G is large and
-ve, ATP is a relatively… what?

How is this?

Answer 26

Stable compound in aqueous solution
(doesn’t spontaneously hydrolyse)

-ve charges on P groups are balanced by Mg

Question 27

ADP phosphorylation is driven by what?

Answer 27

Energy derived from catabolism

Question 28

What does ATP hydrolysis drive?

Answer 28

Anabolic processes, mechanical + active transport

Question 29

What do the adenine + ribosyl groups of ATP, ADP + AMP do?

Answer 29

Provide structures that allow these molecules to bind to enzymes + participate in regulating enzymatic activities

Question 30

The hydrolysis of which energy carrying compound is linked to ATP synthesis?

Answer 30

Phosphoenolpyruvate

Question 31

What is the role of phosphocreatine?

Answer 31

Acts as a buffer for ATP production in muscle

Question 32

What energy-related role does acetyl-coA have?

Answer 32

Energy carrier related to lipid synthesis

Question 33

What is the name of the high energy bond in acetyl-coA?

Answer 33

Thioester