Biology - Chapter 7

What role does DNA play in the cell?

store instructions for making proteins

The replacement of one DNA base with another is called a(n)

substitution mutation.

In eukaryotic cells, proteins called ______ factors bind at specific DNA sequences and form a pocket that allows RNA polymerase to initiate transcription.

transcription

Select all of the following that are true regarding mutations.

Mutations can occur in a promoter region. Mutations are alterations in DNA sequences.

Where would you find a transcriptional terminator sequence?

On a DNA sequence

Gene expression is the production of

an RNA molecule or protein.

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

anticodon

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

anticodon

Messenger RNA contains ________, which are triplets of bases that act as "code-words" corresponding to the _______ acid monomers that make up a polypeptide.

codon; amino

UV rays, X-rays, some chemicals found in tobacco, and radioactive fallout are all examples of _____, agents that can damage DNA and cause mutations.

mutagens

A change in a gene sequence or a regulatory DNA sequence is called a(n) ______.

mutation

Subunits called ______ are the building blocks of DNA.

nucleotides

Messenger RNA carries information that specifies the amino acid sequence of a

protein

What is produced during translation?

protein

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

protein folding

In eukaryotes, RNA polymerase cannot bind to the promoter and initiate transcription without the presence of regulatory proteins called

transcription factors.

What sequence of nucleotides has undergone a deletion mutation compared to the original DNA sequence shown here: C G T C C C A A C T C G

C G T C C C A A C C G

Epigenetics is the study of ______ that affect gene expression but do not change the DNA sequence.

DNA modifications

Select all of the reasons that gene regulation is advantageous in multicellular eukaryotic organisms.

It saves energy. Not all cells need all proteins encoded in the genome.

The modern definition of gene is any sequence of DNA that is transcribed into

RNA

True or false: Gene regulation allows cells to produce only the proteins that they need.

TRUE

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

Three codons are "stop" codons. AUG encodes methionine and "start."

_________ RNA is a type of RNA that serves as a "connector" between the mRNA codon and a particular amino acid.

Transfer

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

codon

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

covalent; amino

Select all of the bases that can be present in DNA nucleotides.

cytosine guanine adenine thymine

Within the DNA double helix, the so-called backbone is composed of ______ sugars alternating with phosphate groups.

deoxyribose

Whereas ______ wipes away most epigenetic markers on the genome, ______ does not; therefore, identical twins may accumulate epigenetic differences throughout life.

fertilization; cell division

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

fold into its functional shape

A(n) _______________ is a portion of mRNA that is about 1,000 nucleotides long and that is removed before translation.

intron

Select all of the following that can be a direct product of transcription.

mRNA tRNA rRNA

What method of gene expression regulation allows one gene to code for multiple proteins due to different combinations of exons spliced together?

mRNA processing

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

What describes a substitution mutation?

one DNA base is replaced with another

Select all of the following that are present in a bacterial operon.

operator group of genes promoter

In bacteria, a(n) ______ is a group of genes under control of a single promoter.

operon

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

polymerase

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

proteins

Proteins combine with ______ to form a ribosome.

rRNA

Eukaryotic cells can compact their DNA or add methyl groups to make their DNA unavailable for

transcription.

During ________ , Incorrect Unavailable, the information that is encoded in the DNA base sequence is copied into the complementary language of mRNA. Then, once the mRNA is produced and modified, a process called ________ uses that information to assemble a sequence of amino acids.

transcription; translation

In a process called ______, an RNA molecule is used to produce a protein.

translation

What sequence of nucleotides has undergone an insertion mutation compared to the original DNA sequence shown here: A G G T C T A G A G C C

A G G T T C T C T A G A G C C

During translation initiation, the first codon to specify a particular amino acid is usually ______, which encodes the amino acid ______.

AUG; methionine

During transcription, the template strand of ______ contains the nucleotide sequence that is transcribed into RNA.

DNA

The instructions in ______ encode the information that a cell needs to produce proteins, which are vital to living things.

DNA

True or false: Complementary base pairing rules state that in DNA, A pairs with G and T pairs with C.

False

What type of mutation is most likely to alter many amino acids in a protein?

Frameshift mutation

In 1953, James Watson and ______ built a ball-and-stick model of the DNA double helix using two lines of evidence to deduce the structure.

Francis Crick

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

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

During transcription, what reads the template strand within a gene and adds complementary bases?

RNA polymerase

Select all of the following that are involved in transcription initiation in eukaryotes.

TATA box RNA polymerase transcription factors promoter

True or false: Although mutations often cause changes that are harmful, they are also the source of genetic variation for evolution.

TRUE

Two strands of DNA within the double helix are said to be complementary to each other _________ because on one strand always pairs with thymine on the opposite strand, and cytosine on one strand always pairs with ________ on the opposite strand.

adenine; guanine

Stabilization of a protein or the alteration of its structure are examples of controlling gene expression

after translation.

A(n) ________ is a three-base sequence on the tRNA that binds to the three-base _________ on the mRNA.

anticodon; codon

During transcription, a gene's DNA sequence is transcribed into a

complementary RNA molecule.

As RNA is synthesized in transcription, it can curl into a three-dimensional shape that is dictated by ______ within the molecule.

complementary base pairing

A DNA molecule consists of two intertwining strands of nucleotides that form a

double helix.

Transcription, translation, nucleotide synthesis, and modification of mRNA are all processes that require

energy

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

epigenetic

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

errors in DNA replication some forms of radiation chemical mutagens

What are coding regions of eukaryotic mRNA that are translated?

exons

_____ are portions of mRNA that get spliced together to form mature mRNA before translation occurs in eukaryotes.

exons

Epigenetic modifications to the DNA are removed at

fertilization

In ______ mutations, nucleotides are added or deleted by a number other than a multiple of three, such that the reading frame of the gene is disrupted.

frameshift

A(n) ______ is a sequence of DNA nucleotides that codes for a specific protein or RNA molecule.

gene

In the 1960s, researchers deciphered the ______, which determines what amino acid is specified by each three-nucleotide ______.

genetic code; mRNA codon

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

genome.

In archaea and eukaryotes, a part of an mRNA molecule that is removed before translation is called a(n)

intron

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

The start codon AUG of translation corresponds to ______.

methionine

The DNA double helix is made up of two strands of ______ monomers oriented in opposite directions.

nucleotide

Select all that apply Select all of the following that describe RNA.

nucleotides contain the sugar ribose can catalyze chemical reactions the nitrogenous base uracil is used instead of thymine can be single-stranded

The DNA double helix resembles a twisted ladder, where the rails of the "ladder" (also called the "backbones") are composed of alternating deoxyribose sugars ___________ and groups joined by covalent bonds, while the rungs of the ladder are composed of A-T and G-C base pairs joined by _________ bonds.

phosphate; hydrogen

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

preventing a protein from reaching its correct destination degrading proteins block modifications or alterations to proteins

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

production of different proteins.

At the beginning of transcription, RNA polymerase binds to the ______ on the DNA.

promoter

The ______ is a sequence of DNA that signals the start of a gene and also which of the two strands of DNA is the template for transcription.

promoter

Select all of the following that can be components of RNA nucleotides.

ribose guanine adenine uracil

Ribosomal RNA (rRNA) combines with proteins to form a protein-synthesizing structure called a

ribosome.

Only producing proteins that are needed allows a cell to

save energy

A mutation that causes an mRNA nucleotide to change from GGC to GGA is a ______ mutation.

silent

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

silent

In the first step of translation initiation, the "cap" end of the mRNA binds to the

small ribosomal subunit.

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

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

Sometimes a substitution mutation changes a base triplet into a ______ codon, such as UAA or UGA, which shortens the protein product.

stop

Sickle cell disease results from a(n) ______ mutation in which a single codon is changed and specifies a different amino acid.

substitution

What molecule binds to both an amino acid and an mRNA codon, bringing the amino acid to the correct spot on the mRNA?

tRNA

An anticodon is a sequence found on a(n) ______ molecule, whereas a codon is a sequence found on a(n) ______ molecule.

tRNA; mRNA

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

template

A specific sequence on the DNA called a(n) ______ sequence signals the end of a gene during transcription.

terminator

In a process called ______, an RNA copy of a gene sequence on the DNA molecule is made.

transcription

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

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

wind or fold DNA in a way that makes it unavailable tag DNA with methyl groups