1.5 nucleic acids and their functions

Question 1

what does a general nucleotide consists of?

Answer 1

• phosphate group
• pentose sugar
• nitrogenous base

Question 2

what is the difference between DNA and RNA?

Answer 2

DNA holds genetic information whereas RNA then transfers this genetic information from DNA to ​ribosomes​ ​made of RNA and proteins.

Question 3

DNA

Answer 3

-sugar is deoxyribose
- base pairs A C G T
- long polynucleotides
- double stranded

Question 4

RNA

Answer 4

-sugar is ribose
-base pairs A C G U
-short polynucleotides
-single stranded

Question 5

what are the two groups of nitrogenous base:

Answer 5

Pyrimidine (single ring) or purine (double ring)
Pyrimidines: Cytosine and Thymine. Purines: Adenine and Guanine.

Question 6

5 different nitrogen bases

Answer 6

adenine = DNA RNA ATP
guanine = DNA RNA
cytosine = DNA RNA
thymine =DNA
uracil = replaces thymine in RNA

Question 7

function of ATP

Answer 7

Chemical energy is stored in lipids or carbohydrates like glucose. Respiration oxidises glucose in a series of small reactions to release energy in the form of ATP. It is involved in energy changes by carrying the energy to where it is needed and releasing the energy when ATP is broken down

Question 8

Why is ATP called the universal energy currency?

Answer 8

as it is used to provide energy for all biochemical reactions in all living organisms.

Question 9

ATP as an energy supplier:

Answer 9

ATP releases energy in one hydrolysis reaction controlled by one enzyme that releases energy immediately.
ATP releases small amounts.

Question 10

role of ATP

Answer 10

metabolism, active transport, movement, nerve transmission, secretion.

Question 11

formation of ATP

Answer 11

ATP is formed in an endergonic reaction (in respiration). 30.6kJ of energy is stored in this bond and released when it is hydrolysed into ADP and an inorganic phosphate (Pi).

Question 12

DNA structure:

Answer 12

DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine ( with 2 hydrogen bonds ) or cytosine and guanine ( 3 hydrogen bonds )

Question 13

DNA replication:

Answer 13

when cells divide, the daughter cells receive an exact copy of the genetic material from the parent. Therefore, chromosomes must be able to make exact copies of themselves.

Question 14

describe the replication fork semi conservative hypothesis:

Answer 14

1. DNA helicase unwinds the hydrogen bonds between the bases in the double helix.
2. two separate strands are formed and exposes unpaired bases.
3. free nucleotides from the nucleoplasm attach themselves to the bases on the old strands by complementary base pairing
4. enzyme DNA polymerase joins the nucleotides together by condensation reactions ( strong covalent bonds ) which forms sugar phosphate backbone
5. eventually, 2 new DNA molecules are formed from 1 new and 1 old strand of the DNA. This is called semi-conservative replication.

Question 15

Conservative replication:

Answer 15

direct copying of the nucleotide sequence onto a new double stranded molecule which would give one light and one heavy molecule in generation 1.

Question 16

Dispersive replication:

Answer 16

where half the nucleotides are placed randomly in the DNA being replicated to make new molecules which would give successively lighter molecules and therefore a band between hybrid and light in generation 2.