Chapter 7.1

Question 1

What is the difference between mRNA in prokaryotes and eukaryotes? Pay attention to the difference between the amount of protein products they can produce.

Answer 1

Eukaryotes

• > monocistronic
• > each mRNA molecule translates into one protein product
• > different mRNA molecule for a different type of protein

Prokaryotes

• > mRNA is polycistronic
• > starts the process of translation at different locations in the mRNA
• > resulting in different proteins

Question 2

What is the role of aminoacyl-tRNA synthetase?

Answer 2

• it transfers an amino acid to the 3 prime end of the correct tRNA(each tRNA has a CCA nucleotide sequence where the amino acid binds)
• > it requires two high-energy bonds from ATP
• > therefore, the amino acid is an energy-rich bond

Question 3

What is the point of the high energy aminoacyl-tRNA bonds?

Answer 3

-it is used to supply the energy needed to create a peptide bond during translation

Question 4

Where is ribosomal RNA produced in the cell? What is its function?

Answer 4

• it is synthesized in the nucleolus
• > is integral to to the ribosomal machinery during protein assembly
• > it helps catalyze the formation of peptide bonds

-note that rRNA also splices out its own introns within the nucleus

Question 5

What is the relationship between rRNA and ribozymes

Answer 5

• many rRNA function as ribozymes

- >ribozymes are made up of RNA molecules instead of peptides

Question 6

Are there any charged tRNA molecules that recognize the three stop codons

Answer 6

• no there are not

- >therefore, when this codon is put on, the protein is released from the ribosome

Question 7

Why is the genetic code degenerate?

Answer 7

• it is degenerate

- >because more than one codon can specify a single amino acid

Question 8

What is the purpose of the wobble position in the codon?

Answer 8

• it is to protect against mutations in the coding regions of our DNA
• > therefore, mutations in the wobble position are silent or degenerate
• usually for an amino acid with multiple codons
• > the first two bases are usually the same
• > the third base is the variable one(wobble position)

Question 9

What are point mutations? What are the two different types?

Answer 9

• point mutations are when one of the nucleotides in a codon is affected
• the two types are
• > silent(wobble mutation) and expressed

Question 10

What are the two types of expressed mutations

Answer 10

Missense mutation
->mutation where one amino acid substitutes for another

Nonsense mutation
->a mutation where the codon now encodes for a premature stop codon

Question 11

What is a frameshift mutation?

Answer 11

-it is when a codon is added or deleted from the mRNA sequence