Chapter 7 - Gene Expression

Select all of the following that are true about the genetic code.

-AUG encodes methionine and "start." -The same genetic code is used by nearly all species. -There are three codons that act as "stop" codons.

Select all of the following that are utilized in the process of translation.

-mRNA -tRNA -amino acids -ribosome

Select three types of RNA.

-mRNA -tRNA -rRNA

Select all of the following that are components of nucleotides.

-phosphorus-containing groups -sugar -nitrogen-containing base

Select all of the following that are genes.

-sequence of DNA nucleotides that codes for a specific RNA molecule -sequence of DNA nucleotides that codes for a specific protein

Select all of the following agents or processes that can cause mutations.

-some forms of radiation -chemical mutagens -errors in DNA replication

Select all of the following that are methods of gene regulation found in eukaryotes but not prokaryotes.

-splicing exons in alternative ways -adding methyl groups to silence genes -blocking mRNA exit from the nucleus

Select all the ways that cells can make DNA less available for transcription.

-tag DNA with methyl groups -wind DNA more tightly

Select all of the reasons why eukaryotic cells regulate gene expression.

-to express different subsets of genes in different types of cells -to coordinate early development -to activate different genes at different times in the life of an organism

In a frameshift mutation, nucleotides are added or deleted in any number other than a multiple of

3

During transcription, RNA polymerase moves along the DNA template strand, adding RNA nucleotides to the growing ______ end of the RNA molecule.

3'

If a DNA sequence underwent a missense mutation, what would be the result?

A codon would code for a different amino acid.

If an mRNA was blocked from exiting the nucleus, what would happen to expression of the gene from which the RNA transcript was made?

The gene would be silenced.

Bacterial genomes normally consist of ______ chromosome(s), whereas eukaryotic genomes are normally made up of ______ chromosome(s).

a single circular; multiple linear

Most of the epigenetic markers present in a multicellular organism are placed onto its DNA

after the sperm and egg cell unite in fertilization.

What describes a ribosome?

an rRNA-protein structure that is the site of translation

The regulation of gene expression in eukaryotic cells allows for

cell specialization in multicellular eukaryotes.

During the elongation phase of translation, a _______ bond is formed between the incoming _______ acid and the growing polypeptide chain, and empty tRNAs are released from the ribosome to be reused.

covalent; amino

What are coding regions of eukaryotic mRNA that are translated?

exons

A(n) _______ mutation is one that occurs in the cells that give rise to sperm or egg.

germline

A ribosome is composed of

rRNA and protein

What role does DNA play in the cell?

store genetic information

A(n) ______ mutation is caused by the replacement of one nucleotide with another.

substitution

During translation elongation, what molecule brings amino acids to the ribosome, as dictated by the sequence of codons on the mRNA?

tRNA

The DNA strand that is "read" during transcription is called the ______ strand.

template

The promoter is a sequence on the ______ that signals the start of a gene.

template strand of DNA

In the 1950s, the biochemist Erwin Chargaff found that in DNA, the amount of the nucleotide base adenine always equals the amount of the nucleotide base _____, and the amount of the nucleotide base cytosine always equals the amount of the nucleotide base _____.

thymine; guanine

True or false: Unlike DNA, RNA can catalyze chemical reactions.

true

Shortly after transcription in eukaryotic cells, a string of 100-200 adenines is added to the 3' end of the mRNA molecule, producing what is known as a poly _____, and a short sequence of nucleotides called the 5' _____ is added to the 5' end of the mRNA molecule.

A; cap

Which scientist showed that the amount of the base guanine in a DNA molecule equals the amount of the base cytosine in a DNA molecule?

Chargaff

During transcription, RNA nucleotide bases bind with the exposed complementary bases on the template strand of

DNA

Hershey and Chase showed that the part of a virus that could enter bacterial cells and cause the production of more viruses was

DNA

The information that each cell needs to produce proteins is stored in a molecule called

DNA

Match the following scientists with their contribution to the discovery of the structure of DNA.

Erwin Chargaff -> Determined that DNA contains equal amounts of adenine and thymine and of guanine and cytosine Maurice Wilkins and Rosalind Franklin -> Used X-ray diffraction to determine that DNA has a regular, repeating structure of building blocks James Watson and Francis Crick -> Used the known ratios of nucleotides along with the X-ray diffraction data to build a ball-and-stick model of the DNA double helix

During transcription, what enzyme attaches to the promoter, unzips the DNA double helix, and adds complementary RNA nucleotides?

RNA polymerase

During production of a protein, the information encoded in a DNA base sequence is transcribed to produce a molecule of _____, which is then processed and translated to produce the sequence of _____ acids in a protein.

RNA; amino

What scientists worked out the double helical structure of DNA using a ball-and-stick model?

Watson and Crick

On one half of a DNA double helix, a single strand of nucleotides has

a 3' end on one side, and a 5' end at the opposite end.

Protein processing and degradation is a method of regulating gene expression that occurs

after translation

The term genome refers to

all the genetic material in an organism's cell.

Mutations can lead to genetic variability because they create new _____, or variants of genes.

alleles

What represents Chargaff's discovery about the amounts of the nitrogenous bases A, G, C, and T in the DNA molecule?

amount of A = amount of T; amount of G = amount of C

On a tRNA molecule, the _____ is a three-base sequence that is complementary to and binds to an mRNA codon during translation.

anticodon

What 3-base site of a tRNA molecule is complementary to an mRNA codon?

anticodon

In eukaryotic cells, the mRNA is altered before it leaves the nucleus. A short sequence of modified nucleotides, known as a ______ is added to the 5' end and a string of adenines called a ______ is added to the 3' end.

cap; poly-A tail

Epigenetics is the study of changes in gene expression due to

chemical modifications of histones or DNA bases.

In an RNA molecule, a(n) ______ is a genetic "code word" that corresponds to one amino acid.

codon

The genetic code specifies what amino acid is matched to each three-nucleotide ______ in the mRNA.

codon

A mutation that causes a single codon to be removed such that a protein lacks one amino acid is a ______ mutation.

deletion

DNA has a ______ helical structure consisting of two intertwining strands of ______.

double; nucleotides

A eukaryotic transcription factor may bind to a promoter or to a(n) _____, a regulatory region on the DNA that lies outside the promoter and regulates transcription.

enhancer

Modifications to DNA, such as methylation, that do not change the nucleotide sequence but do affect gene expression are called ______ modifications.

epigenetic

______ are portions of mRNA that get spliced together to form mature mRNA prior to translation.

exons

After translation is complete, the newly synthesized polypeptide must ______, as determined by some regions of the amino acid chain.

fold into its functional shape

The ______ describes the correspondence of three-nucleotide codons to specific amino acids or directions for starting and stopping translation.

genetic code

All of the genetic material that is within a cell is called its

genome

The DNA double _____, resembles a twisted ladder, where each rail of the "ladder" (each backbone) is composed of alternating deoxyribose sugars and _____ groups joined together by _____ bonds.

helix; phosphate; covalent

Match the following steps of transcription with their descriptions.

initiation -> RNA polymerase moves down the template strand, adding nucleotides and producing a complementary RNA molecule. elongation -> RNA polymerase binds to the gene's promoter. termination -> RNA polymerase separates from the DNA and the newly synthesized RNA is released.

An _____ is a portion of RNA that averages about 1,000 nucleotides long and that is removed before translation.

intron

As described by Jacob and Monod, what E. coli genes and regulatory sequences are only produced when the bacteria need to break down lactose in the immediate environment?

lac operon

When Griffith mixed together live strain R bacteria and heat-killed S bacteria and injected them into mice, the mice died, and ______ bacteria were isolated from the mice, indicating that something could pass between cells and transform them.

live S strain

In transcription, the genetic information in DNA is copied into a(n) ______ molecule, and in translation, the "message" in an mRNA molecule is translated into a(n) ______ sequence.

mRNA; amino acid

During the elongation stage of translation, the ribosome exposes codons on the ______ one at a time; each codon determines what ______ will bring its attached amino acid to the ribosome to be added to the polypeptide chain.

mRNA; tRNA

A(n) _____ is any external agent, such as X-rays or chemicals, that induces mutations.

mutagen

A change in a protein-encoding DNA sequence or a regulatory DNA sequence, such as an enhancer, is called a(n)

mutation

A(n) _____ is a change in a cell's DNA sequence.

mutation

_____ in DNA may arise spontaneously as errors in replication, or they can be induced by external agents, like chemicals and radiation.

mutations

A substitution mutation that changes an amino acid into a "stop" codon is called a(n) ______ mutation and shortens the protein product.

nonsense

Subunits called ______ are the building blocks of nucleic acids, as determined by scientists by about 1930.

nucleotides

In the synthesis of RNA from DNA, the enzyme RNA polymerase adds ______ to the ______ end of the growing RNA molecule.

nucleotides; 3 prime

What describes a substitution mutation?

one DNA base is replaced with another

RNA ______ is the enzyme that builds the RNA chain during transcription.

polymerase

Enzymes and chaperone proteins assist in ______ that takes place after translation is complete.

polypeptide folding

Splicing of different exons together from the same mRNA molecules can result in

production of different proteins.

In the "central dogma," information flows from DNA to RNA to

proteins

The sugar in RNA nucleotides is called ______, whereas the sugar in DNA nucleotides is called ______.

ribose; deoxyribose

A substitution mutation is said to be ______ if the mutated gene encodes the same protein as the original gene version.

silent

In his experiments with S. pneumoniae bacteria and mice, Frederich Griffith found that

something in heat-killed S bacteria could transform type R bacteria.

In the DNA double helix, the two backbones are composed of alternating

sugar and phosphate groups.

At the beginning of transcription, RNA polymerase binds to

the promotor

Wilkins and Franklin performed X-ray diffraction that revealed details about

the three-dimensional shape of the DNA molecule.

In eukaryotic cells, proteins called ______ factors bind at specific DNA sequences, which allows RNA polymerase to initiate transcription.

transcription

In eukaryotes, what regulatory proteins are required for RNA polymerase to bind to the promoter and initiate transcription?

transcription factors

In the "central dogma" describing the flow of genetic information from DNA to protein, DNA is copied to RNA in a process called _____, and the information in RNA is used to direct the synthesis of a protein in a process called _____.

transcription; translation

The ______ pattern generated by Wilkins and Franklin revealed that DNA was comprised of a regular repeating structure of building blocks.

x-ray diffraction

Select all of the following that occur during the elongation stage of translation.

-Amino acids are transferred from tRNAs to a polypeptide chain. -Anticodons bind to their complementary codons. -Bonds between amino acids are formed. -Proteins called elongation factors assist in translation elongation.

Match each eukaryotic regulatory mechanism with where it would act within the "central dogma."

-DNA availability -> occurs before transcription -mRNA processing, mRNA exit from the nucleus -> occurs after transcription but before translation -protein degradation -> occurs after translation -transcription factors -> occurs at initiation of transcription

Select all of the following that are true about prokaryotic versus eukaryotic gene expression.

-In eukaryotes, mRNA is altered before it leaves the nucleus. -In eukaryotes, the nuclear membrane separates transcription from translation.

Select all of the following that are true with respect to genomes.

-In eukaryotic cells, the genome is usually divided up into multiple chromosomes. -In prokaryotic cells, the genome usually consists of just one circular DNA molecule.

Select all of the following that are ways to control gene expression after translation.

-degrading the protein -blocking addition of a necessary sugar to a newly synthesized protein -preventing the protein from reaching its correct destination

Select all of the following that are true about frameshift mutations.

-disrupts the codon reading frame -likely to change the amino acid sequence -can be caused by the addition of one nucleotide -can be caused by the deletion of two nucleotides

Select all of the following that describe the nitrogenous bases adenine and guanine.

-double-ring structure -purines

Select all of the following organisms that have introns in their primary mRNA transcripts.

-eukaryotes -archaea -animals

Select all the reasons a cell regulates gene expression.

-to respond to changing conditions -to have a specialized function

In what process does the cell make a complementary RNA molecule from a DNA sequence?

transcription