Chapter 16: Central Dogma

Question 1

What is gene expression?

Answer 1

the set of processes that convert information in DNA into a product (typically a protein)

Question 2

What does the one-gene, one-enzyme hypothesis say?

Answer 2

each gene contains the information encoded to make one (and only one) enzyme

Question 3

What is the central dogma?

Answer 3

DNA (nucleus) —–> RNA ——> protein (cytoplasm)

Question 4

Describe transcription in the central dogma.

Answer 4

uses DNA template to make an RNA molecules with a complementary sequence

Question 5

Describe translation in the central dogma.

Answer 5

uses information in mRNA to synthesize protein

Question 6

What are the two modifications of the central dogma?

Answer 6

1. RNA molecules do not code for protein
2. reverse transcriptase

Question 7

Which RNA molecules do not code for proteins?

Answer 7

1. ribozymes
2. introns with pre-mRNA
3. sequences that regulate gene expression

Question 8

What is reverse transcriptase?

Answer 8

• enzyme that makes DNA from RNA
• used by many viruses
• important tool for researchers

Question 9

What is a codon?

Answer 9

a group of three DNA bases that specifies a particular amino acid

Question 10

What is the start codon?

Answer 10

AUG (codes for Met)

Question 11

What are the 3 stop codons?

Answer 11

UAA, UAG, UGA (don not code for amino acids)

Question 12

How do you predict amino acid sequences from codons?

Answer 12

1. draw the non template DNA strand 5’ to 3’
2. draw the template strand by flipping non template 3’ to 5’
3. Transcription (A goes to U, T goes to A, etc.)
4. Translate with amino acids

Question 13

What are the 5 features of the genetic code?

Answer 13

1. redundant
2. unambiguous
3. non-overlapping
4. universal
5. conservative

Question 14

1. redundant (genetic code)

Answer 14

most amino acids coded for by multiple genes (degeneracy)

Question 15

2. unambiguous (genetic code)

Answer 15

each codon codes for only one amino acid

Question 16

3. non-overlapping (genetic code)

Answer 16

codons are read one after another (reading frame)

Question 17

4. universal (genetic code)

Answer 17

codons code for the same amino acids in (almost) all organisms

Question 18

5. conservative (genetic code)

Answer 18

when multiple codons code for the same amino acid, usually only the third base differs (wobble base)

Question 19

What are point mutations?

Answer 19

alters the sequence of one or a small number of base pairs

Question 20

What are the 4 types of point mutations?

Answer 20

1. silent
2. missense
3. nonsense
4. frameshift

Question 21

What is a silent mutation?

Answer 21

• change in nucleotide sequence that doe snot change the amino acid specified by a codon
• no change in phenotype; neutral with respect to fitness

Question 22

What is a silent mutation?

Answer 22

• change in nucleotide sequence that doe snot change the amino acid specified by a codon
• no change in phenotype; neutral with respect to fitness

Question 23

What is a missense mutation?

Answer 23

• change in nucleotide sequence that changes the amino acid coded by a codon
• change in primary structure of protein (can be beneficial, neutral, or deleterious)

Question 24

What is a nonsense mutation?

Answer 24

• change in nucleotide sequence that causes early stop codon
• leads to mRNA breakdown or a shortened polypeptide; usually deleterious

Question 25

What is a frameshift mutation?

Answer 25

• addition or deletion of a nucleotide
• reading frame is shifted altering the meaning of all subsequent codons; almost always deleterious