Protein Synthesis

Question 1

What are the names of the four nitrogenous bases found in DNA?

Answer 1

• Adenine
• Thymine
• Guanine
• Cytosine

Question 2

What are the names of the four nitrogenous bases found in RNA?

Answer 2

• Adenine
• Uracil
• Guanine
• Cytosine

Question 3

Why is the nitrogenous base Thymine present in DNA but not RNA?

Answer 3

In the nucleus of a cell, Uracil is easily mutated, this means that Uracil is an unsuitable organic base for DNA, Thymine however is not easily
mutated in the cell’s nucleus therefore is a more suitable match to act as a base in DNA.

Question 4

Why is the nitrogenous base Uracil present in RNA but not DNA?

Answer 4

In the cell’s cytoplasm, Thymine is easily broken down by the chemical compounds present in the cytoplasm however Uracil is not as easily broken down therefore Uracil is a more suitable match due to RNAs role in protein synthesis.

Question 5

What is the name of the pentose sugar found in DNA?

Answer 5

Deoxyribose

Question 6

What is the name of the pentose sugar found in RNA?

Answer 6

Ribose

Question 7

What are the three major components of a nucleotide?

Answer 7

• A phosphate group
• A pentose sugar
• A nitrogenous base / Organic base

Question 8

What is the name of the reaction that joins nucleotides together?

Answer 8

A condensation reaction

Question 9

What is the name of the bond that is created between nucleotides during a condensation reaction?

Answer 9

A phosphodiester bond

Question 10

What is the function of mRNA?

Answer 10

To take DNA information from the nucleus to the ribosomes where it an be used in protein synthesis

Question 11

What are the three types of RNA present in a cell?

Answer 11

• mRNA (Messenger RNA)
• tRNA (Transfer RNA)
• rRNA (Ribosomal RNA)

Question 12

Describe the structure of mRNA.

Answer 12

mRNA is in a single stranded helix structure.

Question 13

How does the enzyme RNA Polymerase work?

Answer 13

RNA Polymerase binds to DNA and runs along it, breaking the hydrogen bonds between the complimentary base pairs.

Question 14

What is the name given to the strand of DNA that is used in the production of RNA?

Answer 14

The template strand

Question 15

Once RNA Polymerase has added two nucleotides to bases in the template strand, what is the next step in production of RNA?

Answer 15

The two nucleotides that have been added by RNA Polymerase are joined together via a condensation reaction which forms a phosphodiester bond between the two nucleotides.

Question 16

What happens to the previous DNA as the RNA Polymerase moves along the DNA.

Answer 16

The double helix structure is reintroduced to the two separated strands.

Question 17

Once the RNA strand is complete, what happens to the RNA strand and the RNA Polymerase?

Answer 17

The RNA and RNA Polymerase both detach from the DNA.

Question 18

What is the name for the process in which a strand of RNA is produced?

Answer 18

Transcription

Question 19

What is the name given to the strand of RNA that is produced by transcription?

Answer 19

Pre-mRNA

Question 20

What happens during the first stage of transcription?

Answer 20

During the first stage of transcription, RNA Polymerase breaks hydrogen bonds between complimentary DNA bases.

Question 21

What happens during the second stage of transcription?

Answer 21

During the second stage of transcription, RNA Polymerase adds RNA nucleotides to complimentary bases on one strand of DNA (the template strand). These nucleotides are joined together by a condensation reaction which forms phosphodiester bonds between the nucleotides.

Question 22

What happens during the final stage of transcription

Answer 22

Reattachment of the DNA strands into the double helix structure which leaves a strand of Pre-mRNA completed.

Question 23

What is the definition of a gene?

Answer 23

A gene is a base sequence of DNA that codes for the amino acid sequence of a polypeptide.

Question 24

What is the name given to a sequence in a gene that is non-coding?

Answer 24

An intron

Question 25

What is the name given to a sequence in a gene that is coding?

Answer 25

An exon

Question 26

What happens during splicing of Pre-mRNA?

Answer 26

During splicing, a group of proteins cluster around the Pre-mRNA which removes the introns, the remaining exons are then attached together. This is because introns are not needed in mRNA due to them being non-coding.

Question 27

What is the name given to each set of three bases in a strand of DNA and mRNA?

Answer 27

A triplet

Question 28

In DNA, each triplet codes for how many amino acids?

Answer 28

1

Question 29

In DNA and mRNA, the genetic code as a whole is…

Answer 29

• Degenerate
• Non-overlapping
• Universal

Question 30

Why is the genetic code in DNA and mRNA known as universal?

Answer 30

The genetic code in DNA is known as universal due to all organisms coding for one amino acid using a triplet.

Question 31

Why is the genetic code in DNA and mRNA known as degenerate?

Answer 31

The genetic code in DNA is known as degenerate because different triplets within the genetic code can code for the same amino acid.

Question 32

Why is the genetic code in DNA and mRNA known as non-overlapping?

Answer 32

The genetic code in DNA is known as non-overlapping because each base is only read once as to not overlap and code for too many amino acids.

Question 33

In mRNA, what is the name given to three bases that code for a specific amino acid?

Answer 33

A codon

Question 34

During transcription, each triplet in DNA results in…

Answer 34

a complimentary codon on mRNA.