Topic 4: Genetic information, variation and relationships between organisms

Question 1

Prokaryotic DNA

Answer 1

Short, circular, not associated with proteins

Question 2

Eukaryotic DNA

Answer 2

long, linear, associated with proteins called histones.

Question 3

Chromosome

Answer 3

DNA molecule + histone protein
- > tightly coiled to form chromosomes

Question 4

Mitochondria/chloroplast DNA

Answer 4

Similar to prokaryotic DNA: short, circular and not associated with proteins

Question 5

Gene

Answer 5

Sequence of DNA bases that codes for (the amino acid sequence of) a polypeptide / functional RNA

Question 6

A sequence of 3 DNA (a triplet) bases…

Answer 6

Codes for a specific amino acid

Question 7

The genetic code is..

Answer 7

Universal, non overlapping and degenerate

Question 8

A lot of the eukaryotic DNA does not code for polypeptides. Why is this?

Answer 8

• Non-coding multiple repeats of base sequences between genes
• Introns (non coding regions of DNA) separate exons (coding regions)

Question 9

Introns

Answer 9

Non coding regions of DNA. Do not code for amino acid sequences.

Found between exons, within genes

Question 10

Exons

Answer 10

Coding regions of DNA, Code for amino acid sequences

Question 11

What is the specific position on a DNA molecule where a gene is found called?

Answer 11

Locus

Question 12

Non-overlapping

Answer 12

Each triplet is only read once.

Question 13

Universal

Answer 13

Each triplet codes for the same amino acid in every species

Question 14

Degenerate

Answer 14

More than one triplet codes for one amino acid
(64 for 20)

Question 15

What are the three components of Nucleotides?

Answer 15

Pentose sugar
Phosphate group
Nitrogenous base

Question 16

Describe the structure of DNA

Answer 16

Made up of a deoxyribose sugar, a phosphate group and one of four nitrogenous base (A, T, C, G)
- Hydrogen bonds form between complementary base pairs
- Phosphodiester bonds between adjacent nucleotides
‘Sugar and phosphate backbone’

Double stranded, coiled into a helix.

Question 17

What is the role of DNA?

Answer 17

Carries genetic information and determines our inherited characterises.

Question 18

Describe the structure of RNA

Answer 18

Made up of a ribose sugar, a phosphate group and one of four nitrogenous bases (A, U, C, G)

Single stranded and a lot smaller than DNA.

Question 19

What is the role of RNA?

Answer 19

To transfer genetic information from DNA to ribosomes for protein synthesis.

Question 20

What bonds form between
A) complementary base pairs
B) adjacent nucleotides

Answer 20

A) Hydrogen bonds
B) phosphodiester bond

Question 21

Genome

Answer 21

The complete set of genes in a cell

Question 22

Proteome

Answer 22

The full range of proteins a cell is able to produce

Question 23

Structure of mRNA

Answer 23

Single stranded
Has codon

Question 24

Structure of tRNA

Answer 24

Single stranded
Has anticodon
Clover shaped
Hydrogen bonds

Question 25

What is transcription?

Answer 25

The production of mRNA from DNA

Question 26

What is the role of RNA polymerase in transcription?

Answer 26

Joining mRNA nucleotides

Question 27

In prokaryotic, transcription results directly in the production of mRNA from DNA. How and why is this different in eukaryotes?

Answer 27

Transcription results in the production of pre-mRNA in eukaryotes (rather than directly producing mRNA)

No introns in prokaryotic DNA / introns found in eukaryotic DNA
pre-mRNA is then spliced to remove the introns, and form mRNA

Question 28

What is translation?

Answer 28

The production of polypeptides from the sequence of codons on mRNA

Question 29

The role of tRNA in translation

Answer 29

Amino acid binding site -> carries correct amino acid to mRNA and puts it in correct sequence

Anticodon binds to complementary codon on mRNA