Genes

Question 1

What is a nucleotide made up of?

Answer 1

A phosphate group, a carbon sugar molecules and 1 of 4 nitrogenous bases.

Question 2

What is the structure of DNA?

Answer 2

2 complementary anti parallel chains of nucleotides

Question 3

What is the difference between the 5’ and 3’ end?

Answer 3

The 5’ end is the end where the 5th carbon on the sugar molecule is at the end of the chain whereas the 3’ end is where the 3rd carbon on the end sugar molecule is at the end

Question 4

Why is DNA described as universal?

Answer 4

All 4 nitrogen base pairs are found in the DNA of every living thing

Question 5

What are the 4 base pairs in DNA?

Answer 5

Cytosine, thymine, adenine and guanine

Question 6

How would you tell the difference between cytosine and adenine?

Answer 6

Adenine is a purine and hence has 2 rings where as cytosine is a pyrimidine and only has 1 ring

Question 7

How would you tell the difference between adenine and guanine

Answer 7

Guanine has an oxygen in it whereas adenine doesn’t. Guanine also forms 3 H bonds instead of adenines 2

Question 8

What bases are pyrimidines?

Answer 8

Cytosine, uracil and thymine

Question 9

What bases are purines?

Answer 9

Adenine and guanine

Question 10

What base does adenine pair with in DNA?

Answer 10

Thymine

Question 11

What base does guanine pair with?

Answer 11

Cytosine

Question 12

What are each bases complementary pairing in DNA?

Answer 12

G and C (3 H bonds)

A and T (2 H bonds)

Question 13

What base does uracil pair with?

Answer 13

Adenine

Question 14

How is RNA different to DNA?

Answer 14

It is only single stranded, contains a ribose sugar molecule and has uracil in place of thymine

Question 15

What is tRNA?

Answer 15

Transfer RNA, which brings amino acids to the ribosomes

Question 16

What is mRNA?

Answer 16

Messenger RNA, it is a copy of the template strand of DNA that codes for proteins

Question 17

What is rRNA?

Answer 17

Ribosomal RNA, structural component of a ribosome

Question 18

How are nucleotides joined together?

Answer 18

Through nucleotide polymerisation, a nucleotide triphosphate will bind to the 3’ end of a DNA chain and 2 of its phosphate molecules are posed in the process

Question 19

What is the first step of transcription?

Answer 19

RNA polymerase binds to a promoter region on gene which causes the DNA to unwind

Question 20

What does RNA polymerase do?

Answer 20

Unwinds the DNA and moves along its template strand creating an RNA strand by adding complementary bases of the template strand together.

Question 21

How is transcription terminated?

Answer 21

When the RNA polymerase reaches the terminator section on a gene

Question 22

What occurs during splicing?

Answer 22

Introns are cut out of the gene so only the Exons remain

Question 23

What are exons?

Answer 23

The part of the pre mRNA strand that carry the coding information

Question 24

What end is the poly(A) tail added to?

Answer 24

The 3’ end

Question 25

What end is the methylated cap added to?

Answer 25

The 5' end

Question 26

Why are pre mRNA strands capped?

Answer 26

So the strands can thread through ribosomes

Question 27

Why Do pre mRNA strands undergo polydenylation?

Answer 27

So they are provided with protection and to assist in movement

Question 28

What direction does RNA polymerase go in along the template strand?

Answer 28

5' to 3'

Question 29

What occurs during transcription?

Answer 29

DNA is copied to form RNA

Question 30

What occurs during translation?

Answer 30

Proteins are synthesised from RNA in ribosomes

Question 31

What end of the mRNA enters the ribosome first?

Answer 31

The 5' end (the cap)

Question 32

How are proteins synthesised in a ribosome?

Answer 32

tRNA brings in amino acids and if its has an anticodon complementary to the codon of the mRNA the amino acid will stay behind to form part of the polypeptide chain.

Question 33

How does transcription stop?

Answer 33

When the ribosome reaches a stop codon on the mRNA the polypeptide chain is released

Question 34

What is a codon?

Answer 34

A set of 3 bases that codes for a specific amino acids

Question 35

What is the genetic code?

Answer 35

The set of rules that defines info in mRNA sequences is translated into amino acids

Question 36

How many codon combinations are there?

Answer 36

64

Question 37

How many amino acids are there?

Answer 37

20

Question 38

What is the start codon?

Answer 38

AUG

Question 39

What are the three stop codons?

Answer 39

UAA, UAG, UGA

Question 40

Why the genetic code described as degenerate?

Answer 40

Because multiple codons can code for the same thing, that is there are more codon combinations then there are amino acids

Question 41

Why is the genetic code universal?

Answer 41

Because it is the same code used for all living things

Question 42

What is a structural gene?

Answer 42

A gene that codes for proteins which will assist in the structure and function of an organism

Question 43

What is a regulator gene?

Answer 43

A gene that codes for a protein that will assist in gene regulation

Question 44

What is the difference between prokaryotic and eukaryotic protein synthesis?

Answer 44

Prokaryotic transcription and translation occur almost simultaneously as they both occur in the cytosol Not post transcriptional modifications are made to mRNA

Question 45

What is an operon?

Answer 45

A group of genes that all have the same function, and are transcribed together as they share the same promoter and operator H

Question 46

Why is the lac operon important for Bacteria?

Answer 46

It allows them to rapidly adjust to their environment and not waste excess resources