Unit 1-Gene Expression

Question 1

Ways that RNA differs from DNA

Answer 1

RNA is single-stranded while DNA is double-stranded.

RNA has a sugar called ribose while DNA has a sugar called deoxyribose.

RNA has the base uracil while DNA has the base thymine.

Question 2

What does RNA stand for?

Answer 2

Ribonucleic acid

Question 3

What are the three types of RNA?

Answer 3

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA (rRNA)

Question 4

What is the function of messenger RNA?

Answer 4

Carries the genetic code from the nucleus to the ribosome.

Question 5

What is the function of transfer RNA?

Answer 5

Picks up a specific amino acid from the cytoplasm and brings it to the ribosome

Question 6

What is the function of ribosomal RNA?

Answer 6

Ribosomal RNA (rRNA) and proteins form the ribosome

Question 7

Where is mRNA made?

Answer 7

In the nucleus

Question 8

In RNA what are the four types of bases?

Answer 8

Adenine, cytosine, guanine, and uracil

Question 9

What is the complementary base pair for adenine in RNA?

Answer 9

Uracil

Question 10

How are proteins made?

Answer 10

Proteins are made by joining together amino acids in a specific sequence.

Question 11

What determines the type of protein formed?

Answer 11

The order of amino acids (which depends on the order/sequence of the bases in the DNA

Question 12

Gene expression is made up of which two processes?

Answer 12

Transcription and translation

Question 13

Synthesis of the primary RNA molecule from a DNA template

Answer 13

Transcription

Question 14

Synthesis of a polypeptide chain from a mRNA

Answer 14

Translation

Question 15

What are the stages of transcription?

Answer 15

1. DNA unwinds
2. Primary transcript of mRNA using RNA nucleotides.
3. The primary transcript of mRNA is spliced to produce a mature transcript of mRNA.
4. The mature mRNA transcript travels to the ribosome.

Question 16

What is the strand of mRNA produced by transcription called?

Answer 16

The Primary Transcript

Question 17

What does the primary transcript contain?

Answer 17

Exons and introns

Question 18

What are the introns of the primary transcript?

Answer 18

Introns are non-coding regions that have to be removed.

Question 19

What are the exons of the primary transcript?

Answer 19

Exons are coding regions and are joined together to form the mature transcript.

Question 20

What is RNA splicing?

Answer 20

RNA splicing is where introns are removed and the exons are joined together to form a mature transcript of mRNA.

Question 21

What happens once the mature transcript of mRNA is produced?

Answer 21

The mature mRNA leaves the nucleus and enters the cytoplasm.

Question 22

Where is tRNA found?

Answer 22

In a cell’s cytoplasm

Question 23

What is translation?

Answer 23

Translation is the synthesis of a protein in the form of a polypeptide chain of amino acids.

Question 24

What does each codon contain?

Answer 24

Each codon contains the code for one amino acid.

Question 25

Where does translation occur?

Answer 25

Translation occurs on the ribosome.

Question 26

What does the start codon indicate?

Answer 26

The start codon indicates to the tRNA where to add the first amino acid.

Question 27

What happens to the tRNA after the polypeptide is formed?

Answer 27

It leaves the ribosome once the polypeptide has been formed.

Question 28

What are amino acids linked by and what does this form?

Answer 28

Amino acids are linked by peptide bonds to form polypeptides.

Question 29

What does the polypeptide fold to form and how is this held together?

Answer 29

Polypeptide chains fold to form the three-dimensional shape of a protein, held together by hydrogen bonds and other interactions between individual amino acids.

Question 30

How can different proteins be expressed from one gene?

Answer 30

Different proteins can be expressed from one gene, as a result of alternative RNA splicing.