The genetic code

Question 1

Define replication

Answer 1

DNA is copied to make more DNA

Question 2

Define transcription

Answer 2

DNA is copied to make RNA

Question 3

Define translation

Answer 3

RNA is read and proteins are made

Question 4

Where does transcription occur?

Answer 4

In the nucleus

Question 5

Where does translation occur?

Answer 5

In the cytoplasm

Question 6

What is the basic structure of an amino acid?

Answer 6

NH3 (amino group)
Central carbon
R group
Hydrogen
COOH (carboxyl group)

Question 7

What joins two amino acids?

Answer 7

A peptide bond

Question 8

Where does the peptide bond form?

Answer 8

Between the carboxylic group of one amino acid and the amino group of the next

Question 9

What kind of code is the genetic code?

Answer 9

Triplet code

Question 10

What does triplet code mean?

Answer 10

Three nucleotides specify one amino acid

Question 11

What is another name for a triplet?

Answer 11

A codon

Question 12

What is the start codon in all polypeptides?

Answer 12

Methionine

AUG

Question 13

What are the three stop codons?

Answer 13

UAA
UAG
UGA

Question 14

What does degenerate mean?

Answer 14

Usually there is more than one codon for an amino acid

Question 15

What is an open reading frame?

Answer 15

A string of sense codons that start with the codon ATG and end with a stop codon at the 3’ end

Question 16

What determines which reading frame is read?

Answer 16

The start codon

Also the largest possible protein is always made

Question 17

How many possible reading frames are there?

Answer 17

6

3 in each direction

Question 18

What does mRNA consist of?

Answer 18

Leader
Reading frame
Trailer

Question 19

How many subunits make up a ribosome?

Answer 19

Two

Question 20

What are the two subunits of a ribosome?

Answer 20

The small and large subunit

Question 21

What kind of ribosome is involved in protein synthesis and mRNA?

Answer 21

An 80s ribosome

Question 22

Describe the small subunit

Answer 22

40s
18s rRNA
30 ribosomal proteins

Question 23

Describe the large subunit

Answer 23

60s
28s + 5.8s + 5s rRNA
50 ribosomal proteins
2 binding sites

Question 24

What are the two binding sites present in the large subunit?

Answer 24

The P site

The A site

Question 25

What is the A site?

Answer 25

The aminoacetyl-tRNA binding site

Question 26

What is the P site?

Answer 26

The peptidyl-tRNA binding site

Question 27

What is the role of tRNA?

Answer 27

tRNA molecules carry the amino acids to the ribosomes to be assembled into polypeptide chains

Question 28

What features do all tRNA molecules share?

Answer 28

Similar in size and shape | CCA at the 3' end which amino acids bind to

Question 29

What is the anticodon?

Answer 29

The section of the tRNA molecule which during translation reads the matching codon on mRNA

Question 30

How is an amino acid added to a tRNA molecule?

Answer 30

The enzyme aminoacyl-tRNA synthetase

Question 31

What is the name of the process given to adding amino acids to tRNA

Answer 31

Aminoacylation

Question 32

How many aminoacyl-tRNA synthases are there?

Answer 32

As there are 20 amino acids, there are 20 aminoacyl-tRNA synthases

Question 33

Are aminoacyl-tRNA synthases dependent on the codon?

Answer 33

No | So when an amino acid has multiple codons it will still only have one aminoacyl-tRNA synthase

Question 34

Describe the role of ATP in aminoacylation

Answer 34

ATP binds to the amino acid once it has bound to the enzyme Loses to phosphate groups to become AMP AMP released tRNA binds

Question 35

What is the first step of translation?

Answer 35

A small ribosomal subunit binds to mRNA at start codon region

Question 36

What attracts the large subunit?

Answer 36

Initiation factors This completes the ribosome The start codon occupies the P site

Question 37

What is elongation dependent on?

Answer 37

The appropriate aminoacyl-tRNA binding to the codon in the A site of the ribosome

Question 38

What happens when a stop codon is reached?

Answer 38

Polypeptide synthesis ends Polypeptide released from tRNA tRNA released from the ribosome Ribosomal subunits separate

Question 39

Describe the stages of termination

Answer 39

No anticodon on tRNA matches a stop codon Nothing occupies the A site Release factor binds to the stop codon Peptidyl transferase is triggered releasing the polypeptide Ribosomal subunits separate

Question 40

How many ribosomes can be on a piece of mRNA at one time?

Answer 40

Many

Question 41

Name three things that cause DNA mutation?

Answer 41

Substitution Insertion Deletion

Question 42

Name the three kinds of mutation

Answer 42

Silent Missense Nonsense