Chapter 6: 6.2 Genes and mRNA

Question 1

What is the basic structure of a gene?

Answer 1

A gene generally consists of 3 basic elements:
1. Promoter
2. Coding region
3. Terminator

Question 2

Describe:

Promoter (on a gene)

Answer 2

A region of DNA just before a gene that initiates transcription

Question 3

What counts as upstream?

Answer 3

A region of DNA just before a gene

Question 4

Where does RNA polymerase binds to DNA?

Answer 4

Promoter

Question 5

Describe:

Coding region (on a gene)

Answer 5

The part of the gene that codes for a particular RNA molecule (mRNA, rRNA, tRNA)

Question 6

Define:

Terminator (on a gene)

Answer 6

A region of DNA just after a gene that signals transcription to stop

Question 7

What counts as downstream?

Answer 7

A region of DNA just after a gene

Question 8

True or False:

All genes are orientated in the same direction on a chromosome

Answer 8

False

Question 9

Define:

Template strand

Answer 9

DNA strand that is to be transcribed

Question 10

Define:

Coding strand

Answer 10

The complementary strand to the template strand

Question 11

What is difference between the transcribed mRNA and the coding strand?

Answer 11

Thymines are Uracils in mRNA

Question 12

Which direction is DNA read?

Answer 12

3’ to 5’

Question 13

Which direction is the complementary RNA synthesized?

Answer 13

5’ to 3’

Question 14

What is the general structure of bacterial mRNA?

Answer 14

1. 5’ untranslated region (UTR)
2. Start codon
3. Stop codon
4. 3’ untranslated region (UTR)

Question 15

What does the 5’ UTR contain?

Answer 15

Ribosome binding site

Question 16

What is the start codon?

Answer 16

Codon at which the ribosome begins translation

Question 17

What is the stop codon?

Answer 17

Codon at which the ribosome stops translation

Question 18

What is the 3’ UTR?

Answer 18

Region downstream of stop condon that is not translated

Question 19

Bacterial mRNA is often polycistronic, what does this mean?

Answer 19

More than one protein can be encoded in a single strand of mRNA

Question 20

What represents a codon?

Answer 20

Three consecutive nucleotides on a strand of mRNA

Question 21

The genetic code is said to be redundant or degenerate, why?

Answer 21

More than one codon codes for each amino acid

Question 22

What does AUG code for?

Answer 22

The amino acid methionine
* Start codon

Question 23

What does the start codon set on the RNA strand?

Answer 23

The reading frame

Question 24

How many stop codons are there?

Answer 24

3 (UAG, UGA, UAA)

Question 25

Each mRNA codon is recognized by the complimentary ——— of a —- that carries the corresponding —– —-

Answer 25

1. Anticodon
2. tRNA
3. Amino acid

Question 26

What is aminoacyl tRNA synthetase?

Answer 26

The enzyme that “loads” the amino acids onto the appropriate matching tRNAs

Question 27

How do mRNA and tRNA interact?

Answer 27

Interact in an antiparallel orientation via hydrogen bonds

Question 28

Describe:

The Wobble Effect

Answer 28

There is a looser pairing between the 5’ nucleotide of the enticodon and the 3’ nucleotide of the codon

Question 29

Define:

The Reading Frame

Answer 29

The sequence between the start codon and the stop codon

Question 30

True or False:

A sequence has multiple reading frames

Answer 30

False, a sequence usually only has one reading frame

Question 31

What happens when the reading frame is changed?

Answer 31

A different polypeptide chain will be made

Question 32

If the reading frame changes and a different polypeptide chain is made, what might happen?

Answer 32

1. Mutated protein that is nonfunctional
2. Different functional protein is made

Question 33

What usually causes a mutated protein that is nonfunctional?

Answer 33

A deletion or another mutation in the mRNA or in the DNA itself