Chapter 15

Question 1

produces an RNA copy of the DNA through mRNA

Answer 1

Transcription

Question 2

converts nucleotide-based information into a protein product

Answer 2

translation

Question 3

states that genes specify the sequence of mRNAs, which in turn specify the sequence of proteins

Answer 3

Central Dogma

Question 4

three consecutive nucleotides in mRNA that specify the insertion of an amino acid or the release of a polypeptide chain during translation

Answer 4

codon

Question 5

(of the genetic code) describes that a given amino acid can be encoded by more than one nucleotide triplet; the code is degenerate, but not ambiguous

Answer 5

degenerate

Question 6

strand of DNA that specifies the complementary mRNA molecule

Answer 6

template strand

Question 7

the strand not used as a template in transcription

Answer 7

coding strand

Question 8

sequence present in protein-coding mRNA after completion of pre-mRNA splicing

Answer 8

exon

Question 9

non–protein-coding intervening sequences that are spliced from mRNA during processing

Answer 9

intron

Question 10

three-nucleotide sequence in a tRNA molecule that corresponds to an mRNA codon

Answer 10

anti-codon

Question 11

What are the two main sequences in the assembly of proteins from DNA?

Answer 11

Translation and Transcription

Question 12

What is mRNA? What is its function?

Answer 12

messenger RNA that copies genes and decodes to amino acids

Question 13

Understand what is meant by the central dogma of molecular biology.

Answer 13

flow of genetic information DNA-mRNA-proteins

Question 14

How many possible nucleotide triplets are there? How many amino acids? How is this discrepancy used to an advantage?

Answer 14

64
20
Gives more variation in genes that are produced

Question 15

What does the term degenerate mean in this sense?

Answer 15

a given amino acid can be encoded by more than one codon that can protect against mutation

Question 16

Four of the codons do not strictly code for amino acids. Which four are unique and what are their special functions?

Answer 16

AUG=start
UAA, UGA, and UAG=stop

Question 17

What does it mean to say the genetic code is universal?

Answer 17

virtually all species use the same genetic code for protein synthesis
the same codons code for same amino acids in all

Question 18

Transcription occurs from which strand of the double-stranded DNA?

Answer 18

template strand

Question 19

What is the term used to describe the strand of DNA that does not function as the template during transcription? What is its relationship with mRNA?

Answer 19

coding strand the mRNA is the same but with U not T

Question 20

Name the enzyme that performs transcription in prokaryotes and eukaryotes.

Answer 20

RNA polymerase 5’-3’ direction

Question 21

What are the 4 cellular components responsible for actual protein synthesis?

Answer 21

mRNA template
ribosomes (rRNA)
tRNA
Enzymes

Question 22

What is tRNA? Where does it perform its job?

Answer 22

transfer RNA
ribosomes

Question 23

What is the anti-codon region of tRNA and why is this region so important in translation?

Answer 23

complement to the mRNA code being read

Question 24

How is the genetic code physically turned into a chain of amino acids?

Answer 24

tRNA brings amino acids corresponding to codon and adds it to growing polypeptide chain

Question 25

Which amino acid does the first tRNA bring to position #1?

Answer 25

Methionine (Met)

Question 26

How does elongation of the polypeptide chain occur? What are the three binding sites or compartments on the large ribosomal unit that advance the growing amino acid chain?

Answer 26

assembly line Aminoacyl site Peptidyl site Exit site

Question 27

The stop codons signal for termination of translation. How does this occur?

Answer 27

nonsense codons UAA, UGA, UAG ribosome subunits dissociate from mRNA and each other

Question 28

What happens to the cellular components when translation is finished? What happens to the mRNA?

Answer 28

mRNA is degraded, amino acids are modified, and the nucleotides are reused

Question 29

How does the rate of transcription in prokaryotes compare to eukaryotes?

Answer 29

prokaryotes=translation + transcription occur at the same time eukaryotes= asynchronous because you must move the mRNA to the ribosomes

Question 30

Why are transcription and translation able to be coupled in prokaryotes, but must be performed independently in eukaryotes?

Answer 30

no membrane bound organelles so you don't have to move the mRNA

Question 31

What are the two main ways listed in your notes that transcription/translation differ between prokaryotes and eukaryotes?

Answer 31

Eukaryote need to process the RNA before translation it is also asynchronous

Question 32

What are exons and introns?

Answer 32

exons-coding sequences that remain introns-sequences that don't code for functional proteins and are removed