Chapter 14

Question 1

Considering DNA and genes

Answer 1

DNA is the carrier of genetic information
DNA is replicated prior to cell division
DNA has a role in gene expression
Proteins are the major products of gene expression

Question 2

Mutation

Answer 2

A change in the genetic material not caused by recombination

Question 3

Mutagen

Answer 3

Any agent that increases the mutation rate.

Question 4

One-gene polypeptide relationship

Answer 4

Scientists previously hypothesized that only one gene coded for a protein.

Question 5

How many proteins have several polypeptide chains and subunits

Answer 5

Many

Question 6

Do all genes code for proteins?

Answer 6

no, they have other functions

Question 7

Transcription

Answer 7

The information in a DNA sequence. A gene is copied into a complementary RNA sequence

Question 8

Translation

Answer 8

This RNA sequence is used as a template to create an amino acid sequence of a polypeptide

Question 9

mRNA

Answer 9

one of the two DNA strands in the gene is transcribed to produce a complementary RNA strand which is then processed to produce mRNA. This travels from the nucleus to the cytoplasm where it is translated into a polypeptide. Th nucleotide sequence of amino acids in the polypeptide chain, which is synthesized by the ribosome.

Question 10

ribosomal RNA

Answer 10

part of the ribosome, catalyzes peptide bond formation between amino acids to form a polypeptide.

Question 11

transfer RNA

Answer 11

can bind a specific amino acid and recognize specific sequences of nucleotides in mRNA. the tRNA recognizes which amino acid should be next to the growing polypeptide chain.

Question 12

The synthesis of RNA is directed by what?

Answer 12

DNA

Question 13

Is the information preserved?

Answer 13

Yes, the message from DNA is used as a template that creates a complimentary strand with the exception of uracil replacing thymine in association with adenine.

Question 14

Transcription

Answer 14

formation of a specific RNA sequence from a specific DNA sequence.

Question 15

What are the 4 ribonucleosides triphosphates

Answer 15

ATP, GTP, CTP, AND UTP

Question 16

What does the RNA polymerase enzyme do?

Answer 16

catalyzes the synthesis of RNA from the DNA template.
catalyzes the addition of nucleotides in the 5’ to 3’ direction
they do not add a primer.

Question 17

Promoter

Answer 17

a special sequence of DNA to which RNA polymerase binds to initiate transcription.

Question 18

Promoters are what

Answer 18

control sequences. meaning they tell RNA polymerase where to start (the initiation site)
and they also tell which strand to transcribe.

Question 19

Termination is determined by

Answer 19

as specific DNA sequence. Termination site

Question 20

What happens when RNA polymerase reaches the termination site.

Answer 20

The RNA transcript and polymerase are released from the template.

Question 21

Precursor mRNA

Answer 21

initial gene transcript before it is modified to produce functional mRNA. the primary transcript.

Question 22

What are the non-coding regions of DNA

Answer 22

introns get transcribed but are spliced out of the pre-mRNA. IN THE nucleus

Question 23

What remaining sequence makes up the mRNA before it reaches the ribosome.

Answer 23

Exons

Question 24

pre-mRNA processing

Answer 24

modification of the primary transcript before it leaves the nucleus, both ends are modified and the introns are removed.

Question 25

5' cap

Answer 25

is added to the 5'end facilitates the binding of mRNA to the ribosome for translation. avoids the nucleases destroying the strand.

Question 26

poly A tail

Answer 26

is added to the 3' end assists in the export of the mature mRNA from the nucleus. Important for stability and recognition.

Question 27

Intron

Answer 27

Portion of a gene within the coding region that is transcribed, it is spliced out during mRNA processing, due to translation interrupts but does not scramble the DNA sequence.

Question 28

Exon

Answer 28

a portion of a gene that is present in mature mRNA encode for polypeptide sequences.

Question 29

RNA splicing

Answer 29

last stage of RNA processing, removed introns.

Question 30

How is mRNA led out of the nucleus?

Answer 30

a nuclear pore

Question 31

genetic code

Answer 31

the informational key by which a sequence of mRNA nucleotides correspond to a gene which is translated into a sequence of amino acids.

Question 32

what does the genetic code specify?

Answer 32

specifies which amino acids will be used to build a protein -non-overlapping three letter words

Question 33

codon

Answer 33

A sequence that codes for an amino acid, direct the placement of a particular amino acid into a polypeptide chain, corresponding to the specific triplet of bases in the DNA molecule from which it is transcribed.

Question 34

start codon

Answer 34

AUG, initiation signal for translation to start

Question 35

stop codon

Answer 35

termination signals for translation UAA, UAG

Question 36

sense codons

Answer 36

61 different codons that code for 20 amino acids.

Question 37

Is there only one corresponding sequence of sense codons that code for an amino acid

Answer 37

no, there are multiple combinations.

Question 38

Common genetic code

Answer 38

nearly universal, common language for evolution, and genetic engineering.

Question 39

Translation

Answer 39

the process by which the information in mRNA is used to specify and link a specific sequence of amino acids to produce a polypeptide chain.

Question 40

tRNA

Answer 40

transfer RNA, reads codons and provides the correct anticodon, brings the correlating amino acid to the ribosome. Must be the right message or it is released.

Question 41

3 roles of tRNA

Answer 41

bind to a particular amino acid bind to mRNA interact with the ribosome.

Question 42

How do the codon and anticodon bind?

Answer 42

via hydrogen bonds

Question 43

How does tRNA bind to the specific enzyme to create a charged tRNA?

Answer 43

via covalent attachment, high energy bond provides ATP for the peptide bond in the polypeptide

Question 44

how is tRNA bound to the ribosome

Answer 44

via noncovalent interactions.

Question 45

what is the ribosome classified as in relation to translation?

Answer 45

the work bench

Question 46

Ribosome structure

Answer 46

large and small subunits, holds mRNA and the charged tRNAs in the correct position which allows for polypeptide bond formation

Question 47

A site

Answer 47

the charged tRNA anticodon binds to the mRNA codon, this lines up the correct amino acid to be added to the growing polypeptide chain (initiation)

Question 48

P site

Answer 48

the tRNA adds the correct amino acid to the growing polypeptide chain. (elongation)

Question 49

E site

Answer 49

once the amino acid is attached to polypeptide chain the uncharged tRNA moves to the E site (termination) and out back into the cytoplasm to start the process again.

Question 50

What type of function to ribosomes have?

Answer 50

they have a fidelity function.

Question 51

Why is precision important in protein synthesis?

Answer 51

Precision is important because if the incorrect amino acid is added to the growing polypeptide chain the functional group interactions located in the amino acids can be altered affecting the way the protein folds and twists. Therefore altering the proteins function.

Question 52

signal sequence

Answer 52

a signal sequence is added to the polypeptide chain to indicate where in or out of the cell it belongs. If proteins do not have a signal sequence then they do not leave where it was synthesized.

Question 53

What modifies polypeptides?

Answer 53

the rough er

Question 54

proteolysis

Answer 54

polypeptide cutting, signal sequence is removed.

Question 55

glycosylation

Answer 55

addition of sugars to from glycoproteins

Question 56

phosphorylation

Answer 56

addition of phosphate groups, the charged groups change the conformation.

Question 57

5' -CATCGAACGAA- 3' mRNA, anticodon, codon, amino acid