Metabolism Flashcards

1
Q

What is Metabolism?

A

Metabolism is the sum of all biochemical reactions taking place in the cell (the sum of all anabolic and catabolic reactions)

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2
Q

Describe catabolism and its characteristics

A

Catabolism is the process by which large molecules are decomposed into smaller molecules. -It is degradative and oxidative -It liberates energy stored in the bonds of large molecules -Converging

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3
Q

Why is catabolism converging?

A

Because a great variety of different compounds re used to produce the same products.

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4
Q

Describe anabolism and its characteristics

A

Anabolism is a process by which large and complex molecules are built up from smaller components. -Biosynthetic and reductive -Energy is required to create bonds -Diverging

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5
Q

What are the three ways to describe oxidation?

A

1) Oxidation is joining with an Oxygen 2) Oxidation is losing an hydrogen 3) Oxidation is losing an electron

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6
Q

What is reduction?

A

Reduction is gain of electrons.

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7
Q

What is redox potential?

A

Reduction potential is a mesure of how readily a compound donates and electron compare do Hydrogen.

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8
Q

If reduction potential is less than zero (is negative)…

A

It means that the reduced form of the compound has lower affinity for electrons than hydrogen.

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9
Q

What are the two conditions for a spontaneous redox reaction to occur?

A

-Reduction potential has to be positive and ΔG has to be negative.

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10
Q

What are the two conditions for a non spontaneous reaction to (not) occur?

A

-Reduction potential has to be negative and ΔG has to be positive.

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11
Q

How is energy provided in cells?

A

It is provided through high energy electrons.

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12
Q

What are high energy electrons?

A

Electrons with negative redox potential that tend to flow to positive redox potential.

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13
Q

Describe photoautotrophs

A

The energy source of photoautotroph is the sun and the carbon source is CO2.

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14
Q

Describe photoheterotrophs

A

The energy source for photoheterotroph is the sun and the carbon source are organic compoounds.

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15
Q

Describe chemoautotrophs

A

The energy source of chemoautotrophs are chemical bonds and the carbon source is CO2

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16
Q

Describe chemoheterotrophs

A

The energy source of chemoheterotrophs are chemical bonds and the carbon source are organic compounds.

17
Q

Describe phototrophs in general

A

Phototrophs capture energy from the sun and use it to oxidise H2O or H2S to release high energy electrons.

18
Q

Describe chemotrophs in general:

A

Chemotrophs oxidise organic compounds to release high energy electrons.

19
Q

What are electron carriers?

A

Are intermediate of redox reaction in the metabolic pathways of the cell.

20
Q

Why do NADH and FADH2 need to be re-oxidised?

A

Because they’re present in small amount to is important to recycled them in order to keep the metabolism in function.

21
Q

What are final electron acceptors?

A

The final product of a metabolic pathway that allows the regeneration of electron carriers.

22
Q

Describe the first stage of metabolism

A

In the first stage of metabolism macromolecules are degraded to their monomeric units. It occurs outside the cell n the process of digestion.

23
Q

Describe the second stage of metabolism:

A

In the second stage of metabolism, the small molecules produced in the previous stage enter the cell and are converted into a small number of simple molecules. The products of this stager are: 2-Carbon Acetyl CoA and some ATP.

24
Q

Describe the third stage of metabolism:

A

The acetyle group of Acetyl CoA enter the Kreb’s cycle where it is completely oxidise to CO2 and H2O.

25
Q

What are the two ways to phosphorylate ATP?

A

Substrate level phosphorylation and oxidative phosphorylation

26
Q

Describe substrate level phosphorylation

A

Energy for phosphorylation is obtianed from substrate of biochemical reaction and a phosphate group is directly transfered to ADP to form ATP.

27
Q

Describe oxidative phosphorylation

A

High energy electrons are used to reduce O2 and H2O and this energy is used to create an electrochemical gradient across the membrane that then generates the energy required to synthesise ATP.

28
Q

Describe the outer membrane of mitochondria

A

The outer membrane is permeable to most molecules and this is why the intermembrane space has similar characteristics to the cytoplasm.

29
Q

Describe the inner membrane of mitochondria

A

The inner membrane is impermeable to most molecules and contain proteins for the electron transport chain

30
Q

What are the two stages of the chemiosmotic process?

A

Electron transport and ATP synthesis *Oxidative phosphorylation).

31
Q

Describe the electron transport

A

Electron from NADH enter complex I while electrons from FADH2 enter complex II. Electrons are then handed down from higher to lower redox potentials and finally they are transfere to O2 to form H2O.

32
Q

What are the two gradients formed as a result of electron transport?

A

1) Chemiosmotic gradient 2) Electrical Gradient

33
Q

Describe the chemiosmotic gradient

A

The concentration of protons is higher in the intermembrane region thus protons would flow back into the matrix but the lipid bilayer is impermeable to them. pH is lower in the intermembrane region.

34
Q

Describe the electrical gradient:

A

A difference in charge across the membrane resulting from the unbalanced presence of protons (intermembrane space is more positively charged than the matrix).

35
Q

How is energy stored in the chemiosmotic gradient used to synthesize ATP?

A

Protons flow back through ATP synthase causing the rotor to turn and such a conformation change lead to ATP synthesis.

36
Q

What effect has 2,4-Dinitrophenol on the production of ATP?

A

It forms a proton channel in the inner membrane of the mitochondrion so that the proton gradient cannot be formed and energy is release as heat instead of ATP.

37
Q

Describe the two subunits of ATP synthase

A

F1 subunit protrudes into the mitochondrial matrix while F0 subunit is hydrophobic and remain in the inner membrane (it contains the proton channel).