1.6 Cell Metabolism Flashcards

1
Q

Definition of cell metabolism

A

All the enzyme controlled reactionsthat occur in a cell at the same time

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2
Q

The two groups that reactions in a cell can be categorised into

A
  • Catabolic

* Anabolic

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3
Q

Explain an anabolic pathway

A
  • Requires energy

* Involves biosynthetic processes (large molecules synthesised from small molecules)

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4
Q

Explain a catabolic pathway

A
  • Releases energy

* Involves the breakdown of large molecules into smaller molecules

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5
Q

An example of a catabolic reaction

A

Aerobic respiration

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6
Q

An example of an anabolic pathway

A

Protein synthesis

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7
Q

Definition of a metabolic pathway

A

A series of chemical reactions that follow on, one after the other

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8
Q

What each stage in a metabolic pathway is controlled by

A

Enzymes

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9
Q

Example of a reversible metabolic pathway

A

The conversion of pyruvate into lactic acid in animal cells

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10
Q

Example of an irreversible metabolic reaction

A

The conversion of pyruvate into ethanol and CO2 in plant cells

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11
Q

What alternative routes do in metabolic reactions

A

Bypass steps in a pathways

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12
Q

The two ways metabolic pathway can be controlled

A
  • the presence or absence of particular enzymes in the pathway
  • regulation of the rate of reaction of key enzymes within the pathway
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13
Q

The result of the genes for some enzymes being continuously expressed

A
  • the enzymes are always present in the cell

* their control involves the regulation of their rate of reaction

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14
Q

The two molecules regulation of rate of reaction is controlled by

A
  • intracellular

* extracellular

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15
Q

Describe the work of extracellular signal molecules

A

Secreted by a particular cell but work elsewhere in the body

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16
Q

Example of extracted signal molecules

A

Hormones which travel in the bloodstream to reach target tissues
eg. Insulin produced in the pancreas works on the liver

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17
Q

Describe the work of intracellular signal molecules

A

Work inside the cell that produces them

18
Q

Where enzymes are found

A

Every living cell

19
Q

What an enzyme is

A

Biological catalysts made of protein

20
Q

What would happen if enzymes weren’t present in cells

A

Chemical reactions would occur in cells to slowly for life to exist

21
Q

What activation energy is

A

The energy needed to start a reaction

22
Q

Basic work of enzymes

A

Enzymes lower the activation energy needed to start a chemical reaction

23
Q

Symbol for activation energy

24
Q

Define what is ment by affinity

A

The active site having a chemical attraction to the substrate

25
Explain the meaning of induced fit
* structural changes occur so that the active site fits precisely around the substrate * the substrate induces the active site to change shape
26
How enzymes reduce the activation energy required for the reaction to occur
Orientating and then holding the reactants close together
27
Why the end products are released from the enzyme
The end products have a lower affinity for the active site
28
What the direction and speed of an enzyme controlled reaction are controlled by
The concentrations of both the substrate and the end product
29
In what direction does the increase in the substrate concentration drive to the reaction in
In the direction of the end product
30
What drives a sequence of reactions in a particular direction
* presence of a substrate | * removal of a product
31
What happens when enzymes act in groups
The product of one reaction acts as a substrate for the next
32
What is ment by multi enzyme complexes
Where a number of enzymes work together at the same time on the same substrate molecule
33
An example of a multi enzyme complex
DNA polymerase and RNA polymerase both working on a strand of DNA
34
What an enzyme needs to function effectively
* suitable temperature * appropriate pH * adequate supply of substrate molecules
35
Effects of inhibitors on the rate of reactions
* slow the rate of reaction down | * bring the reaction to a halt
36
What happens when the genes responsible for the production of some enzymes are continuously expressed
The enzymes are always present in the cell
37
How enzyme activity can be controlled
Regulation of the rate of reaction that the enzymes catalyse
38
Explain the term enzyme inhibitor
* molecule that can affect the rate of reaction * does this by blocking the active site of the enzyme * or denaturing the enzyme
39
Role of a competitive inhibitor
* competes with the substrate for the active site | * resembles the shape of the substrate
40
How the effect of competitive inhibition can be reversed
By increasing the concentration of the substrate molecules so there is more of a chance that the substrate molecules occupy the active sites
41
Effect of non competitive inhibition
Changed the shape of the active site on an enzyme
42
How a non competitive inhibitor works
Binds to an area of the enzyme which is not the active site