Chapter 14 Gene Expression Gene To Protein

Question 1

Proteins are the link between

Answer 1

Genotype and phenotype

Question 2

Gene Expression

Answer 2

The process by which DNA directs protein synthesis: includes two stages

Transcription

Translation

Question 3

_______ is the bridge between DNA and protein synthesis

Answer 3

RNA

Question 4

RNA is similar to DNA but RNA has a ________ sugar and the base ______ rather than thymine

Answer 4

Ribose, uracil

Question 5

Transcription

Answer 5

The synthesis of RNA using information in DNA

Question 6

Transcription produces

Answer 6

Messenger RNA mRNA

Question 7

Translation

Answer 7

Is the synthesis of a polypeptide using information in the mRNA

Question 8

_________ are the sites of translation

Answer 8

Ribosomes

Question 9

In _______, translation of _______ can begin before transcription has finished

Answer 9

Bacteria, mRNA

Question 10

In eukaryotes, the __________separates transcription from translation

Answer 10

Nuclear envelope

Question 11

Eukaryotic mRNA must be _________ our of the __________ to be translated

Answer 11

Transported, translated

Question 12

Primary transcript

Answer 12

Is the initial RNA transcript from any gene prior to processing

Question 13

Central Dogma

Answer 13

Is the concept that cells are governed by a cellular chain of command

Question 14

The flow of information from gene to protein is based on a

Answer 14

Triplet code- a series of non overlapping three nucleotide words

Question 15

A chain of amino acids

Answer 15

Polypeptide

Question 16

During transcription, one of two DNA strands called the ________, provides a template for ordering the sequence of complementary nucleotides in an RNA transcript

Answer 16

Template strand

Question 17

During translation, the mRNA base triplets called, _______ are read in the ________ direction

Answer 17

Codons, 5’ to 3’ direction

Question 18

Of the 64 triplets, ______code for amino acids_______ triplets are stop signals to end translation

Answer 18

61, 3

Question 19

The genetic code is _______: more than one codon may specify a particular __________

Answer 19

Redundant, amino acid

Question 20

No codon specifies more than

Answer 20

One amino acid

Question 21

Codons must be read in the correct __________

Answer 21

Reading frame

Question 22

The genetic code is nearly ________, shared by the simplest bacteria and the most complex animals

Answer 22

Universal

Question 23

_________ is the first stage of gene expressions

Answer 23

Transcription

Question 24

RNA synthesis is catalyzes by ________ which pries the DNA strands apart and joins together the _________

Answer 24

RNA polymerase, RNA nucleotides

Question 25

RNA polymerase assembles polynucleotides in the

Answer 25

5’ to 3’ direction

Question 26

Unlike DNA polymerase, RNA polymerase can

Answer 26

Start a chain without a primer

Question 27

Promoter

Answer 27

The DNA sequence where RNA polymerase attaches

Question 28

The sequence signaling the end of transcription is called

Answer 28

The terminator

Question 29

Transcription Unit

Answer 29

The stretch of DNA that is transcribed

Question 30

Three stages of transcription

Answer 30

Initiation Elongation Termination

Question 31

________ signal the transcriptional start point

Answer 31

Promoters

Question 32

Transcription Factors

Answer 32

Mediate the binding of RNA polymerase and the initiation of transcription

Question 33

As RNA polymerase moves along the DNA, it _______

Answer 33

Untwists the double helix

Question 34

Transcription progresses at rate of _______ nucleotides per second in eukaryotes

Answer 34

40

Question 35

Mechanisms of termination for bacteria and eukaryotes

Answer 35

Bacteria- the polymerase stops transcription at the end of the terminator and the mRNA can be translated without further modification Eukaryotes- RNA polymerase II transcribes the polydenylation signal sequence

Question 36

RNA Processing

Answer 36

Enzymes in the eukaryotic nucleus modify pre mRNA before the genetic messages are dispatched to the cytoplasm

Question 37

Modification of mRNA ends

Answer 37

5’ end receives a modified G nucleotide 5’ cap The 3’ end gets a poly-A-tail

Question 38

Introns

Answer 38

The non coding regions are called intervening sequences

Question 39

Exons

Answer 39

Coded regions of mRNA

Question 40

RNA Splicing

Answer 40

Removes introns and joins exons creating an mRNA molecule with a continuous coding sequence

Question 41

Alternative RNA splicing

Answer 41

Genes give rise to two or more different polypeptides depending on which segments are used as exons

Question 42

RNA splicing is carried out by __________, consisting of ________and _________

Answer 42

Spliceosomes, Proteins, small RNA

Question 43

Ribozymes

Answer 43

Are RNA molecules that function as enzymes

Question 44

A cell translates an mRNA message into protein with the help of

Answer 44

Transfer RNA tRNA

Question 45

TRNA transfer ________ to the growing polypeptide in a ribosome

Answer 45

Amino acids

Question 46

Each tRNA can translate a particular ______into a given amino acid

Answer 46

mRNA codon

Question 47

The tRNA contains an ______at one end and at the other end has a ___________ that can base pair with the complementary codon on mRNA

Answer 47

Amino acid, nucleotide triplet

Question 48

A tRNA molecule consist of a single ________ strand that is about _______ nucleotides long

Answer 48

RNA , 80

Question 49

tRNA molecules can base pair with

Answer 49

Themselves

Question 50

Accurate translation requires two steps

Answer 50

First, a correct match between a tRNA and an amino acid, done by the enzyme aminoacyl-tRNA synthetase Second, a correct match between the tRNA anticodon and an mRNA codon

Question 51

Flexible pairing at the third base of a codon

Answer 51

Wobble

Question 52

Wobble allows some tRNA to bind more than one

Answer 52

Codon

Question 53

A ribosome has three binding sites for tRNA

Answer 53

Psite A site Esite

Question 54

P Site

Answer 54

Holds the tRNA that carries the growing polypeptide chain

Question 55

A Site

Answer 55

Holds the tRNA that carries the next amino acid to be added to the chain

Question 56

E Site

Answer 56

Is the exit site where discharged tRNA leave the ribosome

Question 57

Energy for translation is provided by

Answer 57

GTP

Question 58

The initiation stage of translation

Answer 58

mRNA, a tRNA with the first amino acid, and the two ribosomal subunits A small ribosomal subunit binds with mRNA and a special initiator tRNA Then the small subunit moves along the mRNA until it reaches the start codon

Question 59

Steps in elongation

Answer 59

Amino acids are added one by one to the previous amino acid at the c-terminus of the growing chain Each addition involves proteins called elongation factors and occurs in three steps: codon recognition, peptide bond formation, translocation Translocation proceeds along the mRNA in a 5’ to 3’ direction

Question 60

Termination

Answer 60

Occurs when a stop codon in the mRNA reaches the A site of the ribosome The A site accepts a protein called a release factor The release factor causes the addition of a water molecule instead of an amino acid This reaction releases the polypeptide and the translation assembly then comes apart

Question 61

Two populations of ribosomes in cells

Answer 61

Free ribosomes Bound ribosomes

Question 62

Free ribosomes

Answer 62

Mostly synthesize proteins that function in the cytosol

Question 63

Bound ribosomes

Answer 63

Make proteins of the endomembrane system and proteins that are secreted from the cell

Question 64

Polypeptide synthesis always begins in the

Answer 64

Cytosol

Question 65

Synthesis finishes in the _______ unless the polytsignals the ribosome to attach to the _______

Answer 65

Cytosol, ER

Question 66

Polypeptides destined for the ER or for secretion are marked by a

Answer 66

Signal peptide

Question 67

Mutations

Answer 67

Changes in the genetic material of a cell or virus

Question 68

Chemical changes in just one nucleotide pair of a gene

Answer 68

Point mutations

Question 69

If a point mutation occurs in a gamete it may be transmitted to

Answer 69

Offspring

Question 70

Two categories of point mutations

Answer 70

Single nucleotide pair substations Nucleotide pair insertions or deletions

Question 71

A nucleotide pair substitution

Answer 71

Replaces one nucleotide and its partner with another pair of nucleotides

Question 72

Silent mutations

Answer 72

Have no effect on the amino acid produced by a codon because of redundancy in the genetic code

Question 73

Missense Mutations

Answer 73

Still code for an amino acid, but not the correct amino acid

Question 74

Nonsense mutations

Answer 74

Change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein

Question 75

_________ and ______ are additions or losses of nucleotide pairs in a gene

Answer 75

Insertions, deletions

Question 76

Frameshift mutation

Answer 76

Altering of the reading frame of the genetic message

Question 77

Mutagens

Answer 77

Physical or chemical agents that can cause mutations

Question 78

A gene can be defined as

Answer 78

A region of DNA that can be expressed to produce a final functional product, either a polypeptide an RNA molecule

Question 79

The template strand is always the _______ strand for any given gene.

Answer 79

Same