A1.2 (Nucleic Acids)

Question 1

Nucleic Acid

Answer 1

Polymers of nucleotides such as DNA and RNA

Question 2

DNA

Answer 2

Deoxyribonucleic acid: Molecule that carries genetic information for development and functioning of an organism

Question 3

RNA

Answer 3

Ribonucleic acid: A type of nucleic acid that has riobose sugar in its structure and is used by viruses to replicate

Question 4

How was DNA discovered

Answer 4

Friedrich Miescher performed experiments with white bloodcells which led to DNA extraction as the membrane had to be disintegrated first. this was based on the solubility of DNA in certain substances

Question 5

Components of as nucleotide

Answer 5

pentose sugar, nitrogenous base, phosphate group

Question 6

How does sugar phosphate bonding work

Answer 6

nucleotides link together through a covalent bond to form the single strands of DNA/RNA
1. Bond betwen phosphate group and hydroxylgroup attached to 3C
2. releases one molecule of water
3. continuous chain
4. forms strong sugar phosphate backbone
5. forms 2 ends: 3C hydroxyl group and 5C phosphate group

Question 7

Pure As Gold

Answer 7

Purines: Adenine, Guanine
Nitrogenous bases with two rings

Question 8

Cut The Pie

Answer 8

Pyrimidines: Cytosine, Thymine, Uracil
Nitrogenous bases with only one ring

Question 9

features of RNA

Answer 9

• single stranded
  *has uracil instead of thymine
• has AGUC as nitrogenous bases
• 2C has an OH

Question 10

Features of DNA

Answer 10

• double stranded
• strands are connected by hydrogen bonds
• has AGTC as nitrogenous bases
• 2C has an H

Question 11

structure of DNA explained

Answer 11

two polynucleotide chains aree coiled around the same axis in which the bases inside are supported by the sugar phosphate backbone

Question 12

role of complementary base pairing

Answer 12

• cell division
• gene expression

Question 13

how does complemetary base pairing affect cell division

Answer 13

dna replicates: CBP maintains base sequnece during copying as it uses 1 strand as template to create a new one (semi conservative)

Question 14

how does complementary base pairing affect gene expression

Answer 14

Complemetary base pairing ensures that the same protein is produced as the same bases = same code = same protein

Question 15

Genetic Code

Answer 15

Instructions in a gene in the form of a base sequence that become translated into a functional protein

Question 16

replication

Answer 16

Copying of DNA to make a new DNA molecule

Question 17

Translation

Answer 17

Process in which the transcribed DNA is translataed by the ribosomes to produce proteins

Question 18

Transcription

Answer 18

process in which DNA is used as a template to produce RNA

Question 19

DNA Base sequences

Processes that happen in the 5’ to 3’ direction

Answer 19

Replication, Translation, Transcription

Question 20

Example of specific enzyme which replicates DNA in the 5’ to 3’ direction

Answer 20

DNA Polymerase

Question 21

How does pairing purines and pyrimidines enable DNA stabilisation

Answer 21

As the length stays consistent (around 2nm diameter) the bond specificy is higher resulting
+ hydrogen bonds between bases
= more stable & strong bond

Question 22

Eukaryotic

Answer 22

A group of organisms whose cells typically contain a nucleus & membrane bound organelles

Question 23

Prokaryotic

Answer 23

A group of organisms whose cells do not contain a nucleus or membrane bound orgnisms

Question 24

Histones

Answer 24

Proteins around which DNA strands are wrapped

Question 25

nucleosomes

Answer 25

structural unit of eukaryotic chromatin in which DNA is double wrapped around 8 histone and H1proteins
-> helps to supercoil and compact DNA

Question 26

Relationship between nucleosomes and chromosomes

Answer 26

Chromosome>chromatin fibre>Nucleosome>double helix

Question 27

Hershey Chase Experiment

Answer 27

proved that DNA, not protein, makes up the genetic material

Question 28

How does the Hershey Chase Experiment work

Answer 28

• used a T2 bacteriophage which injects DNA into a bacterial cell while its protein stays on the outside
• used radioactove phosphorus and sulfur to label the DNA and the protein viruses
• as the DNA was transferred the next generation all contained radioactive phosphor, proving that uit was DNA that was being transferred

Question 29

Chargaffs Data

Answer 29

proved that DNA is double stranded helix

Question 30

How was chargaffs data collected

Answer 30

he analysed samples of DNA using paper chromotography and discovered that the relative concentrations of the bases were equal
=> helped explain how DNA can be replicated accurately due to complementary base pairing

Question 31

hershey chase experiment in short

Answer 31

radioactive phosphorus found in pellet (bacterial sediment)

Question 32

Direction of DNA synthesis

Answer 32

5 -> 3

Question 33

Solubility of lipids in water vs sugars

Answer 33

more soluble in sugars than water

Question 34

All DNA/RNA processes in 5-> 3

Answer 34

• replication
• translation
• transcription

Question 35

DNA processes in 3 -> 5 direction

Answer 35

• DNA polymerisation (synthesizes DNA during DNA replication)

-> can only attach to ‘3 on -OH molecule

Question 36

lengths of Dna and its components

Answer 36

• Length of DNA: 2m
• Length of a gene:3.4nm
• Length between two base pairs: 0.34nm
• diameter of coil: 2nm

Question 37

What stabilises the DNA molecule

Answer 37

• bond specificity of complementary bases
• hydrogne bonds between bases

Question 38

Significance of the universal genetic code

Answer 38

• proves common ancestory
• universally allows transfer of genetic information across organisms (contributes to advancements in. biotechnology genetic engeneering)

Question 39

genome

Answer 39

collection of all the genetic information within an organism or a cell

Question 40

Key words for DNA questions

Answer 40

• double stranded double helix
• anti parallel bonding
• hydrogen bonding between bases
• complmentary base pairing
• purine- pyrimidine bonding
• polymer
• sugar phosphate backbone

Question 41

reading genetic code

Answer 41

• look at direction = has to be 5 to 3
• translate from DNA to mRNA = change all T’s to U’s
• read code and match to AA