Biology Module 3: Smartbook Chapter 7

Place these translation initiation and elongation events in order from the first step at the top to the last step at the bottom.

1. The small ribosomal subunit binds to the 5' "cap" at the end of the mRNA molecule. 2. A tRNA carrying the amino acid methionine binds to the start codon on the mRNA molecule. 3. The large ribosomal subunit binds to the small ribosomal subunit. 4. A tRNA molecule carrying the second amino acid binds to the second codon on the mRNA molecule. 5. A covalent bond is formed between the two amino acids. 6. The ribosome releases an empty tRNA.

What is an allele?

A similar but slightly different form of the same gene.

Select all of the following that are true about codons.

The corresponds to one amino acid. They are composed of three mRNA bases.

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

Watson anf Crick

What is a mutation?

a change in the nucleotide sequence of a gene

What describes a ribosome?

an rRNA-protein structure that is the site of translation

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

animals archaea eukaryotes

Select all of the following that are actions of the enzyme RNA polymerase.

attach to the promoter on DNA unzip the DNA to expose the template strand build an mRNA chain

In ______, the lac operon is a group of genes and their regulatory elements that increase production of lactose-digesting enzymes only when ______ is present in the environment, which maximizes efficiency.

bacteria; lactose

Select all of the following that are reactions of the enzyme RNA polymerase.

build an mRNA chain attach to the promoter of DNA unzip the DNA to expose the template strand

Select all of the following that are affected by epigenetic modifications in eukaryotes.

cell division gene expression developmental patterns

The regulation of gene expression in eukaryotic cells allows for

cell specialization in multicellular eukaryotes

A germline mutation is a DNA sequence change that occurs in

cells that give rise to sperm and eggs.

The flow of information from DNA to RNA to proteins is called the ______, as first described by Francis Crick.

central dogma

Regulating gene expression allows cells to produce

certain proteins only when they are needed.

In the Hershey and Chase experiment, ______ was found inside the infected bacteria, indicating that the labeled viral ______ had entered the bacterial cells to direct new virus production.

radioactive phosphorus; DNA

Transcription factors can bind to ______ called enhancers, which can be located thousands of base pairs away from genes.

regulatory DNA sequences

What role does DNA play in the cell?

store genetic information

An anticodon is a three-base loop found in _______ that is complementary to the codon on mRNA.

tRNA

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

to coordinate early development to express different subset of genes in different types of cells to activate different genes at different time in the life of an organism

Select all the reasons a cell regulates gene expression.

to respond to changing conditions to have a specialized function

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

transcription

Watson and Crick were able to use ______ about proportions of bases in DNA and the pattern revealed by Franklin's ______ to deduce and build a model showing the double helical structure of DNA.

"Chargaff's rule"; X-ray diffraction

Put the following steps in the order that they occur during transcription initiation in eukaryotes, beginning with the first step at the top.

1. A transcription factor binds to the TATA box of the promoter. 2. The TATA-binding protein attracts other transcription factors, including transcription factors bound at enhancers. 3. RNA polymerase is able to bind to the promoter at the start of the gene and begin transcription.

Arrange the events of transcription in the order that they occur, beginning with the first event at the top.

1. RNA polymerase bind to the gene's promoter. 2. RNA polymerase moves down the DNA template strand, producing a complementary RNA molecule. 3. RNA polymerase separates from the DNA and the newly synthesized RNA is released.

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

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

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

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 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

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

Exons

Select all of the correct statements regarding the results of Frederick Griffith's 1928 experiment involving Streptococcus pneumoniae.

Heat-killed S strains mixed with live R strains caused pneumonia in mice. Live S strains caused pneumonia in mice.

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

Mutations

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

RNA polymerase

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.

What takes place after translation is complete?

The newly synthesized protein folds into its final shape.

Select all of the statements about nucleotides that are accurate.

They are composed of a sugar, a nitrogen-containing base, and one or more phosphorus-containing groups. DNA always contains the same sugar in its nucleotides.

Select all the statements about nucleotides that are accurate.

They are composed of a sugar, a nitrogen-containing base, and one or more phosphorus-containing groups. DNA always contains the same sugar in its nucleotides.

A mutation that occurs in a sperm cell has the potential of being passed on to the next generation. True or False

True

What scientists built a model revealing that the structure of DNA is a double helix?

Watson and Crick

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

X-ray diffraction

The term genome refers to

all the genetic material in an organism's cell.

A variant of a gene is referred to as a(n)

allele

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

alleles or allele

What gene regulation mechanism allows for the production of different proteins from the same mRNA?

alternative splicing of exons

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

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

In humans, the production of the protein keratin in hair follicle cells and the protein of hemoglobin in red blood cells is made possible by expressing

different subsets of genes in different cells.

In eukaryotes, transcription factors can bind at near or distant regulatory DNA sequences called

enhancers.

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

epigenetic

Mutations caused by ______ are example of spontaneous mutations, which occur without outside causes, such as mutagens.

errors in DNA replication or meiosis

While cells constantly produce proteins ______, cells regulate the production of many proteins due to the high costs gene expression.

essential to basic functions

In eukaryotic mRNA processing, the ______ of mRNA can be spliced together in different combinations to regulate gene expression and produce different proteins.

exons

In the Hershey and Chase experiment, radioactively-labeled sulfur was found in the ______within one test tube, while radioactively-labeled phosphorus was found in the ______ within the other test tube, indicating that ______ was the genetic material.

fluid; bacterial cells; DNA

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

fold into its functional shape

Some of the mutations that cause cystic fibrosis are ______ mutations resulting from the addition or deletion of just one or two nucleotides.

frameshift

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

genetic code

An organism's genome is all of the ______ in one of its cell.

genetic material

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

gremlin

In eukaryotic cells, chemical modifications added to ______ proteins can unwind and expose ______, making it more available for transcription.

histone; DNA

Match the following steps of transcription with their descriptions.

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

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

intron or introns

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

intron.

The lac operon in E. coli bacteria includes three genes that produce

lactose-degrading proteins.

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

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

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

Codons are three consecutive bases that are found in ______ and that correspond to one amino acid.

mRNA

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

mRNA tRNA amino acids ribosome

During production of a protein, the information encoded in a DNA base sequence is transcribed to produce a molecule of ______, which is processed and tranalsted to produce the sequence of _______ acids in a protein.

mRNA, RNA or messenger RNA amino

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 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 or genetic mutation

A silent mutation is a mutation that results in

no change to the amino acid sequence of the polypeptide

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

nucleotides

Select all the true statements about blocking the exit of mRNA from the nucleus as a method of regulating gene expression.

occurs in eukaryotes is a post-transcriptional mechanism

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

What describes exons?

portions of mRNA that leave the nucleus and are expressed

What mechanism of regulating gene expression acts after RNA processing but before translation?

preventing mRNA exit from the nucleus

The ______ is a sequence of DNA that signals the start of a gene and is the site where RNA polymerase binds to begin transcription.

promoter

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

promoter RNA polymerase enhancers transcription factors TATA box

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

proteins.

In a substitution mutation, a DNA base is

replaced with another.

A complex of rRNA and proteins called a(n) ______ is the physical location of protein synthesis.

ribosome

A mutation that causes an mRNA nucleotide to change from GGC to GGA is a ______ mutation. Refer to the genetic code table, which is shown larger in the text.

silent

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.

Select all of the following that are components of nucleotides.

sugar nitrogen-containing base phosphorus-containing groups

At the beginning of transcription, RNA polymerase binds to

the promoter

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

the three-dimensional shape of the DNA molecule.

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

three.

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 nucleotide base cytosine always equals the amount of the nucleotide base ____.

thymine or T guanine or G

In protein synthesis, a DNA base sequence is ______ into a complementary mRNA sequence, which is then ______ into a sequence of amino acids.

transcribed; translated

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

In eukaryotes, what regulatory proteins bind to specific DNA sequences, form a pocket for RNA polymerase, and help initiate transcription?

transcription factors

The image is showing what process in eukaryotes?

transcription initiation

Transcription factors are eukaryotic proteins that bind to a promoter or enhancer, attract RNA polymerase, and help initiate

transcription of genes

A DNA molecule consists of ______ of repeating ______ subunits that form a double helix structure resembling a twisted ladder.

two strands; nucleotide

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

wind DNA more tightly tag DNA with methyl groups