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cell biology sem2 > 8 - cell energetics > Flashcards

8 - cell energetics Flashcards

1
Q

what is energetics?

A

the flow and transformation of energy

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2
Q

what is metabolism?

A

all chemical reactions in an organism that harness energy to work

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3
Q

what is cellular metabolism?

A

all chemical reactions in a cell that harness energy to do work.

  • cell pumps and motors
  • muscular work
  • maintain homeostasis
  • heat
  • growth, maintenance and repair
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4
Q

what is kinetic energy?

A

is the energy of motion - energy that can be transferred to another object and do work

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5
Q

what is potential energy?

A

stored energy - energy that has the potential to do work

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6
Q

what is the activation energy?

A

the minimum amount of energy required to initiate a chemical reaction.

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7
Q

what are enzymes?

A

proteins that act as biological catalysts by accelerating chemical reactions

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8
Q

what do enzymes do?

A
  • lower activation energy
  • increases reaction speed
  • do not increase product
  • do not change enzymes themselves
  • specific to catalyse one type of reaction
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9
Q

what is a lock-and-key enzyme?

A

the enzyme fits exactly into the active site

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10
Q

what is an induced fit enzyme?

A

the enzyme changes shape slightly to produce catalytic state

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11
Q

how is the substrate held in the enzyme?

A

substrate held by interactions including hydrogen and ionic bonds

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12
Q

what happens after the substrate has bound to the enzyme?

A

substrate can be split into products or joined to other substrates.

the enzyme is then released.

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13
Q

what are cofactors?

A

they are non-protein substances that help enzymes work.

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14
Q

what are the two main types of cofactors?

A

prosthetic group and coenzyme

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15
Q

what is a prosthetic group?

A

they are generally bound tightly to the enzyme.

an examples are metal ions

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16
Q

what are coenzymes?

A

they are not tightly bound to the enzyme and can be released.
they carry energy for the reaction

some examples are NAD+, ATP and FAD.

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17
Q

what are the six main enzyme classification types?

A

1 - oxidoreductase
2 - transferase
3 - hydrolases
4 - lyases
5 - isomerase
6 - ligases

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18
Q

what do oxidoreductases do?

A

catalyse redox reactions.

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19
Q

what is oxidation?

A

loss of electrons or hydrogen atoms; loss of energy

20
Q

what is reduction?

A

gain of electrons or hydrogen atoms; gain of energy

21
Q

what do transferases do?

A

catalyse the transfer of chemical groups from one compound to another.

22
Q

what do hydrolases do?

A

catalyse the splitting of a large molecule into smaller products by adding water: hydrolysis

they can also catalyse the reverse condensation reactions.

23
Q

what do lyases do?

A

catalyse the breakage of a bond

splitting without water

24
Q

what do isomerases do?

A

catalyse rearrangements within molecules

25
what do ligases do?
catalyses bond formation between two compounds = joining DNA ligase joins breaks in strands of DNA
26
what are the two types of enzyme inhibitors?
competitive and non-competitive
27
how is ATP regenerated?
cell break down organic molecules to release bond energy to regenerate ATP.
28
what is stored bond energy used for?
stored bond energy is used to perform cellular work: hydrolysis of ATP-> ADP.
29
where does most energy production take place?
most energy production takes place in mitochondria.
30
why do we need a constant supply of energy?
we need a constant supply of energy for anabolism (locomotion, transport, secretion, cell division)
31
how many ATP molecules is catabolised from 1 glucose molecule?
30-32
32
explain glycolysis
1 - glucose is activated by phosphorylation to glucose 6-phosphate by Hexokinase or Glucokinase IRREVERSIBLE 2 - glucose 6-phosphate is isomerised to fructose 6-phosphate by an isomerase. REVERSABLE 3 - fructose 6-phosphate is phosphorylated to fructose 1, 6-biphosphate by the enzyme phosphofructokinase (PFK) IRREVERSIBLE 4 - fructose 1, 6-biphosphate is splits into two molecules. REVERSABLE 4a - dihydroxyacetone phosphate is isomerised to glyceraldehyde 3-phosphate by the enzyme phosphotriose isomerase REVERSABLE 5 - glyceraldehyde 3-phosphate is get dehydrogenated and phosphorylated to 1, 3-bisphosphoglycerate (1, 3-BPG) by G 3-P DH. REVERSIBLE 6 - the enrgy of (1, 3-BPG) is used for synthesis of ATP in this reaction REVERSIBLE 7 - phosphoglycerate mutase converts 3-phosphoglycerate to 2-phosphoglycerate by shifting the phosphate gr. REVERSIBLE 8 - 2-phosphoglycerate is converted into Phosphoenol pyruvate by the enzyme enolase by removing one water molecule REVERSIBLE 9 - phosphoenol pyruvate converts into pyruvate by the enzyme pyruvate kinase. IRREVERSIBLE
33
1 hexokinase
adds phosphate to glucose
34
2 phosphoglucose isomerase
rearranges glucose-6-phosphate to fructose-6-phosphate
35
3 phosphofructokinase
adds another phosphate
36
4 aldolase
splits 6 carbon into 3 carbon units
37
5 triphosphateisomerase
interconverts 3 carbon units
38
6 triosephosphate dehydrogenase
oxidises 3 carbon unit by removing H2 to NAD+ and adds a phosphate
39
7 phosohoglycerate kinase
removes a phosphate to ADP to give ATP
40
8 phosohoglycerate mutase
moves the phosphate group to another carbon
41
9 enolase
removed a molecule of water
42
10 pyruvate kinase
removes a phosphate to ADP to give ATP
43
what is regulation of glycolysis initiated by?
initiated by small ATP and high ADP, NAD+ and AMP
44
what are the advantaged of glycolysis (anaerobic)?
rapid release of energy from glucose doesn't require oxygen produces pyruvate and lactate for other pathways (TCA cycle) and tissues (skeletal and cardiac muscle)
45
what are the disadvantaged of glycolysis (anaerobic)?
not as much ATP produced reduced available NAD+, can end up with a shortage of this cofactor metabolic acidosis from proton build up due to lack of cellular buffering (pyruvate to lactate retards acidosis rather than contributes)
46
what can act as fuel if glucose is in short supply?
- lipolysis - proteins
47
what happens if O2 is in short supply?
anaerobic glycolysis regenerates NAD+

cell biology sem2 (18 decks)

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