2.1 : Metabolism

Question 1

define : metabolism

Answer 1

totality of chemical reactions and enzyme-catalysed reactions that occur within a living organism in order to maintain life.

Question 2

state the role of metabolic reactions

Answer 2

> provide a source of energy for cellular processes (growth, reproduction, etc)
enable the synthesis and accumulation of new materials for use within the cell.

Question 3

define : ion

Answer 3

an atom or molecule with an electric charge, where the number of protons is not equal to the total number of electrons.

Question 4

define : atom

Answer 4

smallest unit of matter of an element that has the chemical properties of that element

Question 5

define : molecule

Answer 5

two or more atoms bonded together to form a single chemical entity

Question 6

what are the 6 unique properties of carbon?

Answer 6

1) it has 4 single electrons
2) it’s covalent bonds are very strong
3) carbon atoms can bind to it - forming a skeleton / chains.
4) it’s 4 carbon bonds point to corners of the tetrahedron
5) double bonds can occur - unsaturated bonds.
6) chemical carbon families are made.

Question 7

What are the two different ways in which the different groups that can attach to the four carbon bonds can be arranged & briefly explain?

Answer 7

> mirror molecules : forms of molecules which are mirror images of each other.
asymmetrical molecules : certain things of the arrangement are different (e.g. a carbon atom with four different atoms/groups attached)

Question 8

what are the three functional groups?

Answer 8

> alcohol = hydroxyl group = single -O-H bond.
acid = carboxyl group = double O and single OH bond.
amino group = NH2

Question 9

what are the molecules involved in metabolism & briefly explain ?

Answer 9

metabolites : these are large molecules that are produced because carbon can construct skeletons in the form of big chains.

Question 10

what are the 6 metabolites ?

Answer 10

> a-glucose
> b-glucose
> ribose
> deoxyribose 
> fatty acid 
> amino acid

Question 11

What are anabolic reactions (anabolism)?

Answer 11

small molecules that get built up into larger molecules via condensation reactions, which requires energy so it is an endergonic reaction.
- e.g. photosynthesis

Question 12

Difference between exergonic and endergonic reactions?

Answer 12

> Exergonic reactions / “down-hill reaction” : reactions that release free energy, therefore the products have less stored energy than the reactants.
Endergonic reactions / “up-hill reactions” : reactions that require energy, therefore the products (larger molecules) have more stored energy than reactants.

Question 13

How do anabolic reactions work?

Answer 13

Anabolic reactions build up larger molecules from smaller ones, via condensation reactions - this occurs when monomers are covalently joined and water is produced as a by-product.

Question 14

Purpose of anabolic reactions?

Answer 14

To synthesise complex molecules from simpler molecules.

Question 15

What are catabolic reactions (catabolism) ?

Answer 15

The breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers.
-e.g. respiration, glycolysis

Question 16

What type of reaction is catabolism?

Answer 16

Exergonic reaction - it releases energy in the form of ATP .

Question 17

What is required for a hydrolysis reaction to take place?

Answer 17

Hydrolysis reactions requires the consumption of water molecules, to break the bonds within the polymer, to form smaller molecules.

Question 18

What happens to the ATP gained & set free in catabolism?

Answer 18

the ATP, after being gained and set free, is then used in anabolism.

Question 19

where does chemical energy exist?

Answer 19

In the structural arrangement of atoms in a molecule.

Question 20

what is free energy?

Answer 20

free energy is an amount of stored energy in a molecule that is available to conduct necessary processes.

Question 21

what are reactions that release free energy called?

Answer 21

exergonic reactions

Question 22

what are reactions that require energy called?

Answer 22

endergonic reactions

Question 23

explain the use to ATP in coupling endergonic and exergonic reactions.

Answer 23

ATP acts as a common intermediate, allowing it to link energy-requiring and energy-yielding reactions in metabolism (often endergonic reactions are possible by the energy released from exergonic reactions - so they are coupled up for this to happen)