1.3 RNA, Transcription & Translation

Question 1

What is a genotype determined by

Answer 1

The sequence of DNA bases in its genes

Question 2

What is a phenotype determined by

Answer 2

The proteins that are synthesised when the genes are expressed

Question 3

What are proteins made up of

Answer 3

Amino acids

Question 4

What does the sequence of amino acids determine

Answer 4

The structure and function of the protein

Question 5

What determines the sequence of amino acids

Answer 5

The order of DNA bases

Question 6

What codes for each amino acid

Answer 6

The order of DNA bases

Question 7

What is a gene

Answer 7

A section of DNA that codes for a particular protein

Question 8

What happens to genes during differentiation

Answer 8

Only a fraction of genes are expressed the other genes are switched off

Question 9

What influences which genes are expressed

Answer 9

The intra and extra cellular environmental factors eg diet, stress and activity levels

Question 10

What is gene expression controlled by

Answer 10

The regulation of transcription and translation

Question 11

What is RNA composed of

Answer 11

A phosphate, a ribose sugar and a base

Question 12

What are the bases in RNA

Answer 12

Adenine, uracil, guanine and cytosine

Question 13

What are the types of RNA

Answer 13

mRNA, rRNA and tRNA

Question 14

What is the function of mRNA

Answer 14

To carry a complementary copy of the DNA code from the nucleus to the ribosome

Question 15

What is the function of rRNA

Answer 15

To combine with proteins to form the ribosome

Question 16

What is the function of tRNA

Answer 16

Each tRNA carries a specific amino acid to a ribosome to build proteins

Question 17

How many strands does RNA have

Answer 17

One - it is single stranded

Question 18

What is transcription

Answer 18

The first stage of protein synthesis

Question 19

What is made during transcription

Answer 19

A complementary copy of the relevant section of DNA (mRNA)

Question 20

What happens during the first stage of transcription

Answer 20

Transcription of the gene begins at the promoter region ( a triplet of bases called a start codon )

Question 21

What happens in the second stage of transcription

Answer 21

Enzyme RNA polymerase attaches to the promoter region

Question 22

What happens during the third stage of transcription

Answer 22

The DNA unwinds and unzips and the hydrogen bond between bases causing the two strands to separate

Question 23

What happens in the fourth stage of transcription

Answer 23

Free RNA nucleotides line up against their complementary base on the coding DNA strand. RNA polymerase adds the nucleotides to the 3’end of the forming mRNA strand

Question 24

What happens in the fifth stage of transcription

Answer 24

Weak hydrogen bonds form between the base pairs and strong sugar phosphate bonds form between the adjacent RNA nucleotides forming a strand of mRNA called the primary transcript. The process stops when the terminator region is reached

Question 25

Before leaving the nucleus what has to happen to mRNA

Answer 25

It has to be modified to form the mature transcript

Question 26

What does modification of the primary transcript involve

Answer 26

Removing any non coding sections called introns leaving behind the coding regions called exons

Question 27

What is RNA splicing

Answer 27

The process which joins together the remaining exons to form a continuous sequence called the mature transcript

Question 28

What then happens to the mature transcript after splicing

Answer 28

It leaving the nucleus and travels to the ribosome reading for translation

Question 29

What is translation

Answer 29

The second stage of protein synthesis

Question 30

What is the mRNA used for in translation

Answer 30

To synthesise a polypeptide chain in the ribosome

Question 31

How many codons code for 1 amino acid

Answer 31

1 codon

Question 32

Where is tRNA found

Answer 32

The cytoplasm

Question 33

What is tRNA made up of

Answer 33

A single chain of RNA nucleotides

Question 34

What is the structure of tRNA like

Answer 34

Folded into a 3D structure, held together by hydrogen bonds between bases

Question 35

What is the triplet of bases of tRNA called

Answer 35

Anticodon

Question 36

What does the anticodon determine

Answer 36

the specific amino acid that tRNA will carry

Question 37

What is the first stage of translation

Answer 37

The ribosome binds to the 5' end of the mRNA at the start codon

Question 38

What is the second stage of translation

Answer 38

A tRNA carrying an amino acid lines up against its complementary codon on mRNA. Hydrogen bonds form between the codon of mRNA and the anticodon of tRNA

Question 39

What is the third stage of translation

Answer 39

Another tRNA carrying a specific amino acid lines it's anticodon against its complementary codon on mRNA. Hydrogen bonds form between the bases.

Question 40

What is the fourth stage of translation

Answer 40

A peptide bond forms between the first two amino acids

Question 41

What is the fifth stage of translation

Answer 41

The ribosome then moves along one codon exposing the next codon to an anticodon

Question 42

What is the sixth stage of translation

Answer 42

The process is repeated many times until the stop codon is reached and a complete polypeptide chain is translated.

Question 43

What does a start codon do

Answer 43

It initiates translation on mRNA

Question 44

What does a stop codon do

Answer 44

Signifies that the polypeptide chain is complete

Question 45

What are produced from the same primary transcript

Answer 45

Different mRNA molecules

Question 46

How can the same gene be used to make several different proteins

Answer 46

Alternative RNA splicing and Post translational modification

Question 47

What happens in alternative RNA splicing

Answer 47

Different RNA segments can be treated as introns and the resulting exons can be spliced together in different orders to form different proteins from the same original gene

Question 48

What is post translational modification

Answer 48

When the polypeptide chain can be modified after it has been formed in translation by one of two methods

Question 49

What are the two methods of post translational modifications

Answer 49

Cleavage and molecular addition

Question 50

What is cleavage

Answer 50

When the single polypeptide chain can be cut and or combined with polypeptide chains to form different protein structures

Question 51

What is molecular addition

Answer 51

When other molecules are added to the polypeptide chain such as carbohydrates and phosphate groups