The Genetic Code

Question 1

What is the genetic code referring to?

Answer 1

• The code tells the cell what proteins to make

Question 2

What is Epistasis?

Answer 2

The effect of gene mutation is dependent on the presence or absence of mutations in one or more other genes

Question 3

What was Beadle and Tatum’s theory on finding mutations, and why was it false?

Answer 3

• They argued that if genes make enzymes, then you should be able to find a mutant corresponding to every enzyme in the pathway
• BUT if allele does not produce a functional enzyme, then the pathway will not create another protein, and it will not grow.

Question 4

What is an auxotroph?

Answer 4

• it is a microorganism with a mutation preventing it from producing a compound needed for growth

Question 5

What is a prototroph?

Answer 5

• it is a wild type of microorganism, capable of producing whatever it needs for growth

Question 6

Where are proteins made?

Answer 6

• In cytoplasm w/ help of ribosomes

Question 7

What are 2 major differences between RNA and DNA

Answer 7

• RNA has uracil instead of thymine

- RNA has 2’ hydroxyl that DNA is missing

Question 8

How does information get from DNA to RNA? What is this process called?

Answer 8

• This process is called transcription
• RNA polymerase “sits” on DNA and unwinds it to start creating RNA strand
• This creates mRNA

Question 9

Describe the relationship between DNA sequence and amino acid sequence, does one determine the other?

Answer 9

DNA sequence determines amino acid sequence, but amino acid sequences does not determine DNA sequence

Question 10

How does mRNA create amino acid?

Answer 10

• Once mRNA travels to the cytoplasm, it is attached to a ribosome (small unit)
• the big unit then attaches on with a start tRNA codon at P site (first site in larger unit)
• tRNA corresponds to next codon binds to A site, then moves to P site

Question 11

How can the steps in information flow vary?

Answer 11

• many ribosomes can translate a single mRNA
• ribosomes sometimes begin translation before being done transcription (prokaryotes)
• proteins somethings begin function before translation is finished

Question 12

What is a mutagen?

Answer 12

• A mutagen is any agent that causes mutation (virus, radiation, chemicals…)