2.1 a Metabolism and Survival

Question 1

What is metabolism?

Answer 1

Metabolism is the sum total of all the chemical reactions in a living cell

Question 2

What is a metabolic pathway?

Answer 2

A series of stepwise chemical reactions controlled by enzymes

Question 3

What is an anabolic pathway?

Answer 3

Anabolic pathway synthesises new complex molecules from simple molecules using ATP

Question 4

example of an anabolic pathway?

Answer 4

Synthesis of protein molecules from amino acids

Question 5

What is a catabolic pathway?

Answer 5

Breakdown of large complex molecules to small simple molecules releasing ATP

Question 6

Example of a catabolic pathway?

Answer 6

Breakdown of glucose during respiration with the release of ATP

Question 7

Example of an integrated pathway?

Answer 7

Catabolic reaction of respiration supplies energy for the synthesis of protein molecules from amino acids

Question 8

What does it mean by a reversible step?

Answer 8

Metabolite A can be converted to metabolite B and B can then be converted back to A and used perhaps in an alternative pathway

Question 9

What does this give the cell? (reversible step)

Answer 9

Control over the metabolic pathway

Question 10

What is an irreversible step?

Answer 10

Irreversible step results in one metabolite fully converted into another, no alternative pathway is available

Question 11

How does an alternative route work?

Answer 11

it allows specific steps to be by passed in a pathway

Question 12

Differences between a prokaryote and a eukaryote?

Answer 12

Prokaryotes have no membrane bound organelles or nucleus. they have circular chromosomes and several smaller plasmids
Eukaryotes have membrane bound organelles and nucleus. Linear DNA in nucleus. Circular in mitochondria and chloroplasts.

Question 13

Function of mitochondria membrane?

Answer 13

Localising the enzymes for different stages of aerobic respiration. Site of proteins required for ATP production

Question 14

Function of chloroplasts membrane?

Answer 14

Localising chlorophyll and the enzymes for different stages of photosynthesis

Question 15

Function of Lysosomes membrane?

Answer 15

Localises powerful digestive enzymes required for cell defense as they would other wise destroy the cell

Question 16

Surface area to volume ratio in small structures?

Answer 16

have a larger surface area relative to its volume

Question 17

Having smaller compartments and smaller folds in the membrane means what?

Answer 17

a larger surface area upon which metabolic reactions can take place. small compartments ensure high concentration of substrates increasing reaction rates

Question 18

Fluid mosaic model membrane consists of what?

Answer 18

proteins and phospholipids

Question 19

describe the fluid mosaic model?

Answer 19

phospholipid molecules form a double layer (bilayer) and are in constant motion giving a fluid nature to the membranes making them flexible. Proteins scattered in a patchy mosaic pattern

Question 20

Why is compartmentalisation of the inner membrane of a mitochondrion important in terms of metabolic pathway?

Answer 20

Compartmentalisation isolates and brings together specific metabolites within a metabolic pathway.

Question 21

What is diffusion?

Answer 21

Diffusion is the movement of molecules from a high concentration to a low concentration down a concentration gradient through the phospholipid bilayer

Question 22

What is a concentration gradient?

Answer 22

the concentration gradient is the difference in concentration between two areas

Question 23

Shape of concentration gradient slope depends on?

Answer 23

the greater the difference in concentration gradient the steeper the slope, the faster diffusion occurs
the smaller the difference in concentration gradient the shallower the slope the slower diffusion occurs

Question 24

What is osmosis?

Answer 24

Osmosis is the movement of water molecules only from a region of high water concentration to a region of low water concentration through a selectively permeable membrane.

Question 25

What is active transport?

Answer 25

movement of molecules or ions from a region of low concentration to a high concentration against a concentration gradient.

Question 26

what does active transport require?

Answer 26

energy provided by aerobic respiration and protein pumps

Question 27

what are pores?

Answer 27

channel forming proteins have pores that control the passive diffusion of certain molecules, depending on their size.
these pores make the cell membrane selectively permeable or porous

Question 28

What are pumps?

Answer 28

active transport involves specialised protein pumps in the plasma membrane so require energy
these pumps recognise specific molecules and transfer them across the membrane

Question 29

What is ATP synthase?

Answer 29

ATP synthase is an enzyme embedded in the membrane of mitochondria and chloroplasts where it catalyses the synthesis of ATP.

Question 30

Explain the advantage of membrane bound compartments in cells?

Answer 30

Localise the metabolic activity of the cell
the larger surface to volume ratio of small compartments allow high concentrations of reactions to occur
High reaction rates are possible
Provide more favourable conditions of reactions to take place
membrane folds in organelles provide a large surface area for metabolic reactions to take place