Chapter 7: RNA and the Genetic Code

Question 1

DNA coding strand is identical to the ________.

Answer 1

mRNA

Question 2

The DNA template strand is ________________ and ____________ to the mRNA.

Answer 2

complementary; antiparallel

Question 3

____________ RNA carries information specifying the amino acid sequence of the protein to the ribosome.

Answer 3

messenger

Question 4

mRNA may undergo a host of ________________ modifications prior to its release from the nucleus.

Answer 4

posttranscriptional

Question 5

mRNA is transcribed from template DNA strands by ____ ____________ in the ________ of cells.

Answer 5

RNA polymerase; nucleus

Question 6

mRNA is the only type of RNA that contains information that is translated into ________.

Answer 6

proteins

Question 7

In eukaryotes, mRNA is ____________, meaning each mRNA molecule translates into only one protein product.

Answer 7

monocistronic

Question 8

In prokaryotes, mRNA may be ____________, and starting the process of translation at different locations in the mRNA can result in different proteins.

Answer 8

polycistronic

Question 9

____________ RNA is responsible for converting the language of nucleic acids to to the language of amino acids and peptides.

Answer 9

transfer

Question 10

Each tRNA molecule contains a folded strand of RNA that includes a 3-nucleotide ____________.

Answer 10

anticodon

Question 11

To become part of a nascent polypeptide in the ribosome, amino acids are connected to a specific tRNA molecule; such tRNA molecules are said to be ________ or ________ with an amino acid.

Answer 11

charged, actiavated

Question 12

Each type of amino acid is activated by a different ____________-________ ____________ that requires 2 high-energy bonds from ____, implying that the attachment of the amino acid is an energy rich bond.

Answer 12

aminoacyl-tRNA synthetase; ATP

Question 13

Aminoacyl-tRNA synthetase transfers the activated amino acid to the ____ end of the correct tRNA.

Answer 13

3’

Question 14

Each tRNA has a ____ nucleotide sequence where the amino acid binds.

Answer 14

CCA

Question 15

The high-energy aminoacyl-tRNA bond is used to supply the energy needed to create a ________ bond during translation.

Answer 15

peptide

Question 16

____________ RNA is synthesized in the ________ and functions as an integral part of the ribosomal machinery used during protein assembly in the cytoplasm.

Answer 16

ribosomal; nucleolus

Question 17

Many rRNA molecules function as ____________, that is, enzymes made of RNA molecules instead of peptides.

Answer 17

ribozymes

Question 18

rRNA helps catalyze the formation of peptide bonds and is also important in splicing out its own ________ within the nucleus.

Answer 18

introns

Question 19

Every preprocessed eukaryotic protein starts with the exact same amino acid: ________________.

Answer 19

methionine

Question 20

The codon for methionine (____) is considered the ________ codon for tranlation of the mRNA into protein.

Answer 20

AUG; start

Question 21

What are the 3 stop codons?

Answer 21

UAA, UGA, UAG

U Are Annoying, U Go Away, U Are Gone

Question 22

The genetic code is ____________ because more than 1 codon can spcify a single amino acid.

Answer 22

degenerate

Question 23

A ____________ mutation is where one amino acid substitutes for another.

Answer 23

missense

Question 24

A ____________ mutation is where the codon now encodes for a premature stop codon.

Answer 24

nonsense

Question 25

The creation of mRNA from DNA is ____________.

Answer 25

transcription

Question 26

RNA polymerase locates genes by searching for specialized DNA regions known as ____________ regions.

Answer 26

promoter

Question 27

In eukaryotes, ____ ____________ ____ is the main player in transcribing mRNA, and its binding site in the promoter region is known as the ________ ____.

Answer 27

RNA polymerase II; TATA box

Question 28

____________ ________ help RNA polymerase locate and bind to this promoter region of the DNA, helping to establish where transcription will start.

Answer 28

Transcription factors

Question 29

RNA polymerase does not require a ________ to gstart generating a transcript.

Answer 29

primer

Question 30

RNA polymerase I is located in the ____________ and synthesizes ________.

Answer 30

nucleolus; rRNA

Question 31

RNA polymerase III is located in the nucleus and synthesizes ________ and some ________.

Answer 31

tRNA and some rRNA

Question 32

Does RNA polymerase proofread?

Answer 32

No!

Question 33

RNA polymerase travels along the ____________ strand, and RNA is thus identical to the ________________ strand.

Answer 33

template, coding

Question 34

The first base transcribed from DNA to RNA is defined as the ____ base of that gene region.

Answer 34

+1

Question 35

Bases to the left of the first transcribed base (+1) are known as being ____________ and are given ____________ numbers.

Answer 35

upstream; negative

Question 36

Bases to the right of the first transcribed base are ____________ and are given ____________ numbers.

Answer 36

downstream; positive

Question 37

The TATA box usually falls around position ____.

Answer 37

-25

Question 38

After a stop sequence is reached, transcription is terminated, the DNA helix reforms, and the primary transcript formed is termed ________________ ____________ RNA (hnRNA).

Answer 38

heterogeneous nuclear

Question 39

Before hnRNA can leave the nucleus to be translated, it must undergo what 3 processes?

Answer 39

1. intron/exon splicing 2. addition of 5' cap 3. addition of 3' poly-A tail

Question 40

Splicing removes noncoding sequences called ____________ and ligates coding sequences called ____________.

Answer 40

introns, exons

Question 41

Splicing is accomplished by the ________________.

Answer 41

spliceosome

Question 42

In the spliceosome, ________ ________ RNA molecules couple with proteins known as ________ ________ ________________.

Answer 42

small nuclear; small nuclear ribonucleoproteins

Question 43

At the 5' end of the hnRNA molecule, a ____ is added during transcription. What does this do?

Answer 43

cap; it is recognized by the ribosome as the binding site and protects the mRNA from degrading in the cytoplasm

Question 44

A ________-____ tail is added to the ____ end of the mRNA transcript and protects the message against rapid degrdation.

Answer 44

poly-A, 3'

Question 45

As soon as the mRNA leaves the nucleus, it will start to ________ from the 3' end. The longer the poly-A tail, the longer the mRNA can survive before this happens.

Answer 45

degrade

Question 46

When only exons remain and the cap and tail have been added, the cell has created the ________ mRNA.

Answer 46

mature

Question 47

____________ regions of the MRNA will still exist at the 5' and 3' edges of the transcript because the ribosome initiates translation at the start codon and will end at a s top codon.

Answer 47

untranslated

Question 48

For some genes, the primary transcript can be spliced together in different ways to produce different protein variants. This is called ____________ ____________.

Answer 48

alternative splicing

Question 49

Once the mRNA transcript exits into the cytoplasm, it begins ____________.

Answer 49

translation

Question 50

The ____________ is composed of proteins and rRNA. It brings the mRNA message together with the charged aminoacyl-tRNA complex to generate the protein.

Answer 50

ribosome

Question 51

What are the 3 stages of translation?

Answer 51

1. initiation 2. elongation 3. termination

Question 52

In prokaryotes, the small ribosomal unit binds to the ________-____________ sequence in the 5' ________________ region of the mRNA.

Answer 52

Shine-Dalgarno; untranslated

Question 53

In eukaryotes, the small subunit binds to the ____ ____ structure.

Answer 53

5' cap

Question 54

The charged ________ ________ binds to the AUG ________ ________ through base-pairing with its anti-codon within the P site of the ribosome.

Answer 54

initiator tRNA, start codon

Question 55

After the small subunit binds, the ________ subunit then binds, forming the completed initiation complex. This is assisted by ____________ ________ that are not permanently associated with the ribosome.

Answer 55

large; initiation factors

Question 56

What are the 3 main binding sites of ribosomes?

Answer 56

1. A site 2. P site 3. E site

Question 57

The A site holds the incoming ____________-________ complex.

Answer 57

aminoacyl-tRNA

Question 58

What determines the A site?

Answer 58

the mRNA codon

Question 59

The P site holds the ________ that carries the growing polypeptide chain. A ____________ bond is formed as the polypeptide is passed from the tRNA in the P site to the tRNA in the A site.

Answer 59

tRNA; peptide

Question 60

This requires ____________ ____________, an enzyme that is part of the large subunit.

Answer 60

peptidyl transferase

Question 61

____ is used for energy during the formation of peptide bonds.

Answer 61

GTP

Question 62

The E site is where the now inactivated ________ pauses transiently before exiting the ribosome.

Answer 62

tRNA

Question 63

As the now-uncharged tRNA enters the E site, it quickly ________ from the mRNA and is ready to be recharged.

Answer 63

unbinds

Question 64

____________ ________ assist by locating and recruiting aminoacyl-tRNA along with ____, while helping to remove ____ once the energy has been used.

Answer 64

elongation factors; GTP, GDP

Question 65

When any of the three stop codons moves into the A site, a protein called ________ ________ binds to the termination codon, causing a water molecule to be added to the polypeptide chain.

Answer 65

release factor

Question 66

The addition of a water molecule to the polypeptide chain allows ________ ____________ and ____________ ____________ to hydrolyze the completed polypeptide chain from the final tRNA.

Answer 66

peptidyl transferase; termination factors

Question 67

A specialized class of proteins called ____________ assist in the protein-folding process.

Answer 67

chaperones

Question 68

____________ is the addition of a phosphate group by protein ________ to activate or deactivate proteins.

Answer 68

phosphorylation; kinase

Question 69

Phosphorylation in eukaryotes is most commonly seen with which 3 amino acids?

Answer 69

1. serine 2. threonine 3. tyrosine

Question 70

____________ is the addition of carboxylic acid groups, usually to serve as ________-binding sites.

Answer 70

carboxylation; calcium

Question 71

________________ is the addition of oligosaccharides as proteins pass through the ____ and ________ ________ to determine cellular destination.

Answer 71

glycosylation; ER, Golgi apparatus

Question 72

____________ is the addition of lipid groups to certain membrane-bound enzymes.

Answer 72

prenylation

Question 73

This type of structure is called an ____________ - a cluster of genes transcribed as a single mRNA.

Answer 73

operon

Question 74

The ____________ gene codes for the protein of interest.

Answer 74

structural

Question 75

Upstream of the structural gene is the ____________ site, a nontranscribable region of DNA that is capable of binding a ________ protein.

Answer 75

operator; repressor

Question 76

Further upstream is the ____________ site, which is similar in function to promoters in eukaryotes; it provides a place for ________ ____________ to bind.

Answer 76

promoter; RNA polymerase

Question 77

Further upstream is the ____________ gene, which codes for a protein known as the ____________.

Answer 77

regulator; repressor

Question 78

In ____________ systems, the repressor is bonded tightly to the operator system and thereby acts as a roadblock. RNA polymerase is unable to get from the promoter to the structural gene because the ________ is in the way.

Answer 78

inducible; repressor

Question 79

____________ systems allow constant production of a protein product.

Answer 79

repressible

Question 80

In contrast to the inducible system, the repressor made by the ____________ gene is inactive until it binds to a ____________.

Answer 80

regulator; corepressor

Question 81

____________ ________ are transcription-activating proteins that search the DNA looking for specific DNA-binding motifs.

Answer 81

Transcription factors

Question 82

The ____-________ domain binds to a specific nucleotide sequence in the promoter region or to a DNA ____________ ____________.

Answer 82

DNA-binding; response element

Question 83

The ____________ ________ allows for the binding of several transcription factors and other important regulatory proteins.

Answer 83

activation domain

Question 84

Several response elemnts may be grouped together to form an ____________, which allows for the control of one gene's expression by multiple signals.

Answer 84

enhancer

Question 85

________________ is tightly coiled DNA that appears dark under the microscope. It is ____________.

Answer 85

heterochromatin; inactive

Question 86

____________, on the other hand, is looser and appears light. These genes are ________.

Answer 86

euchromatin; active

Question 87

________ ____________ are involved in chromatin remodeling and acetylate lysine residues found in the ________ terminal tail regions of histone proteins.

Answer 87

histone acetylases

Question 88

____________ of histone proteins decreases the positive charge on lysine residues and weakens the interaction of the ________ with DNA, resulting in an open ____________ conformation that allows easy access.

Answer 88

acetylation; histone; chromatin

Question 89

____________ ____________ are proteins that function to remove acetyl groups from histones, which results in a closed chromatin conformation.

Answer 89

histone deacetylases

Question 90

____ ____________ is also involved in chromatin remodeling and regulation of gene expression levels. Methylation is often linked with ____________ of gene expression.

Answer 90

DNA metyhlation; silencing