bio ch 7
_________: an infecting virus would enter via the mouthparts of an herbivores insect
plant cell
tobacco mosaic virus (TMV) infects many species of
plants
a ________ is an infectious protein and is simpler than a virus
prion
______: structural component of the ribosome
rRNA
ribosomal RNA (rRNA) combines with proteins to form a protein-synthesizing structure Called a ___
ribosome
select all of the following that are true of HIV in a latent infection. -HIV responded more easily to HIV drug therapy -HIV genes are integrated into the host cell's DNA -HIV has entered the body by does not infect cells -Hiv's genetic information remains dominant
-HIV genes are integrated into the host cells DNA -HIV's genetic information remains dominant
select all of the following that are used during translation -mRNA -DNA -nucleosome -ribosome -rRNA
-mRNA -ribosome -tRNA
select all of the following that are true regarding mutation. -mutations can occur in a promoter region -all mutations are harmful -mutations are alterations in DNA sequence
-mutations can occur in a promoter region -mutations are alterations in DNA sequence
select the two plant defenses that must be overcome for a virus to infect a plant -deactivate the various plant defense chemicals and used them for DNA production -penetrate the thick plant cell wall -penetrate the chloroplasts to take over photosynthetic activities -penetrate waxy outer leaf layers
-penetrate the thick plant cell wall -penetrate waxy outer leaf layers
ribosomes consists of
a small and large subunit
_______: viral nucleic acid released inside host cell
penetration
some proteins are composed of multiple _______ that join together after translation
polypeptides
splicing of different exons together from the same mRNA molecule can result in
production of different proteins
true or false: insertions or deletions of large parts of chromosomes are considered mutations
true
select all of the following that are true about the human immunodeficiency virus (HIV). -can cause latent infections -its genetic material remains separate from the host cell genome -has an RNA genome -infects B cells of the immune system -is an enveloped virus -contains the enzyme reverse transcriptase
-can cause latent infections -has an RNA genome -is an enveloped virus -contains the enzyme reverse transcriptase
select all the conditions in a host cell that can cause bacteriophages to switch from the lysogenic pathway to the lytic pathway -cell starvation -DNA damage -prophage formation -cell division
-cell starvation -DNA damage
what disease results when HIV causes such an immense loss of T cells that the body's imbue system is defenseless against infections and cancer?
AIDS
epigenetic is he study of ________ that affect gene expression but do not change the DNA sequence
DNA modifications
________: includes many genes
DNA molecule
All viruses contain genetic material, which is either RNA or ________, and _______ coat that surrounds the genetic material
DNA; protein
during transcription, what reads the template strand within a gene and adds complementary bases
RNA polymerase
_____: viral genes are expressed, new HIV particles are produced and released
active HIV infection
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
a variant of a gene is referred to as an ______
allele
_________: an infecting virus would be engulfed by endocytosis into cytoplasm of cell
animal cell
in the _____ infection cycle, a bacteriophage causes the host cell the burst, thus killing it and releasing the new viral particles
lytic
_______: carries the information that specifies a protein
mRNA
a codon consists of three _______ that correspond to one _______
mRNA bases; amino acid
what method of gene expression regulation allows one gene to code for mutiple proteins due to different combinations of exons spliced togehter?
mRNA processing
___________: used xray diffraction to determine that DNA has a regular, repeating structure of building blocks
maurice Wilkins and Rosalind franklin
the first codon in initiation of translation corresponds to
methionine
___________: new viruses depart from the host cell
release
______: viral enzyme that synthesizes DNA from an RNA template
reverse transcriptase
a _____________ is composed of rRNA and proteins and is the site of protein synthesis
ribosome
select all the statements about nucleotides that are accurate. -they are composed of three fatty acids bonded to a three-carbon molecule of glycerol -they are composed of sugar, a nitrogen-containing group, and one or more phosphorus-containing groups -they are the building blocks of proteins -RNA contains the the sugar deoxyribose in its nucleotides -DNA always contains the same sugar in its nucleotides
-they are composed of a sugar, a nitrogen-containing group, and one or more phosphorus-containing groups -DNA always contains the same sugar in its nucleotides
select all of the following that are true about the genetic code. -AUG is usually the last codon in a strand of mRNA -each amino acid is specified by only one codon -three codons are "stop" codons -AUG encodes methionine and "start"
-three codons are "stop codons" -AUG encodes methionine and "start"
select all of the following that can be components of RNA molecules. -deoxyribose -thymine -uracil -adenine -ribose -guanine
-uracil -adenine -ribose -guanine
on a tRNA molecule, the _______ is a three-base sequence that is complementary to and binds to an mRNA codon during translation
anticodon
________: new viruses are put together from newly produced protein coats and nucleic acids
assembly
_________: virus binds to cell surface
attachment
antibiotics are targeted to the cell walls and enzymes of _______, and they are not effective against _______
bacteria, viruses
viruses that infect bacteria are called _______
bacteriophages
_______: an infecting virus would inject genetic material directly into cell through a hole in the cell wall
bacterium
in a lytic infection of bacteriophage, the host cell ____, whereas in a lysogenic infection of a bacteriophage, the host cell _______.
bursts when new viruses leave the cell; is not destroyed immediately
_________: discrete package of DNA copied around proteins
chromosome
a DNA molecule consists of two intertwining strands of nucleotides that form a ___
double helix
____________: determined that DNA contains equal amounts of adenine and thymine and of guanine and cytosine
erwin chargaff
________ are portions of mRNA that get spliced together to form mature mRNA before translation occurs in eukaryotes
exons
what are coding regions of eukaryotic mRNA that are translated?
exons
_____: a sequence of nucleotides that codes for a specific protein or RNA molecule
gene
the human genome contains 20,000-25,000 ______ scattered on its 23 pairs of _______-
genes; chromosomes
all of the genetic material that is within a cell is called its ______
genome
________: interacts with envelope protein on HIV during viral attachment
host cell receptor
_________: 10 microns _________: 1 micron (1,000 nanometers) _________: 80 nanometers
human cell bacterium virus
steps of the process of translation
initiation elongation termination
an _________ is a portion of mRNA that is about 1,000 nucleotides long and this is removed before translation
intron
in eukaryotic cells, the mRNA is altered before it leaves the nucleus. after transcription, the _____ are removed from mRNA, and _____ are spliced together to form the mature mRNA
introns; exons
_________: used the known ratios of nucleotides along with the X-ray diffraction data to build a ball-and-stink model of the DNA double helix
james Watson and Francis crick
______: viral genome is integrated into host genome but no new virus particles are produced
latent HIV infection
what features do some viruses have
lipid-rich envelope enzymes
a _______ is any external agent, such as X-rays or chemicals, that induces mutations
mutagen
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
vaccines work by causing
the immune system to recognize molecular components of the virus without the person having the disease
a latent viral infection is one in which
the viral genetic information remains inside the cell but does not cause disease symptoms
in a process called _____, an RNA copy of a gene sequence on the DNA molecule is made.
transcription
in a process called _______, an RNA copy of a gene sequence on the DNA molecule is made
transcription
____RNA is a type of RNA that serves as a "connector" between the mRNA codon and a particular amino acid
transfer (t)
in a process called ________, an RNA molecule is uses to produce a protein
translation
preventative treatments for viruses called ______ cause the immune system to recognize molecular components of a virus without exposing the person to the disease, conferring future immunity to the target virus
vaccines
a ________ is a small, infectious agent that is genetic information enclosed in only a protein coat
virus
select all of the reasons that gene regulation is advantageous in multicellular organisms. -it allows cells to delete unneeded genes and recycle the nucleotides for other processes -it saves energy -not all cells need all proteins encoded in the genome
-it saves energy -not all cells need all proteins encoded in the genome
select all the types of protein modification that can occur after translation to produce a functional protein. -addition of poly A tails -joining with other polypeptides -cutting of the protein by enzymes -removal of introns
-joining with other polypeptides -cutting of the protein by enzymes
select all of the following that can be a direct product of transcription -lipid -glucose -tRNA -mRNA -rRNA -DNA
-rRNA -mRNA -rRNA
select all of the symptoms of viral infection in plants -early flowering -streaked flower petals -blotchy, mottled leaves -bent stems
-streaked flower petals -blotchy, mottled leaves
select all the reasons why the protein product of translation may be nonfunctional -only one ribosome binds to an mRNA during translation -the DNA sequence is altered due to mutation -the amino acid sequence of the protein is altered -the polypeptide misfiles or clumps
-the DNA sequence is altered due to mutation -the amino acid sequence of the protein is altered -the polypeptide misfiles or clumps
select all of the ways that a cell can maximize the efficiency of protein synthesis -proteins may initiate their own replication at ribosomes -the cell may produce multiple copies of each mRNA -RNA polymerase may read amino acid sequences and transcribe new proteins directly -many ribosomes may simultaneously translate the same mRNA molecule
-the cell may produce multiple copies of each mRNA -many ribosomes may simultaneously translate the same mRNA molecule
select all the ways that newly made viruses can exit host cells. -budding out of the cell by exocytosis -forming prophages -moving through transmembrane channels -making holes in the cell wall and killing the cell
-budding out of the cell by exocytosis -making holes in the cell wall and killing the cell
select all of the following that are true about the Epstein-barr virus -can cause a latent infection of B cells. -can lead to cancer -can lead to mononucleosis -carried by more than 80% of the human population -carried by only 10% of the human population -infects helper T cells
-can cause a latent infection of B cells. -can lead to cancer -can lead to mononucleosis -carried by more than 80% of the human population
select the two characteristics that all viruses share. -ribosomes -several cell organelles, such as a cell membrane and a nucleus -genetic material, either RNA or DNA -a protein coat that surrounds the genetic material -outer envelope composed of lipids
-genetic material, either RNA or DNA -a protein coat that surrounds the genetic material
select all of the following that can be components of RNA nucleotides -deoxyribose -guanine -ribose -adenine -uracil -thymine
-guanine -ribose -adenine -uracil
select all of the following that are true about the termination stage of translation. -the polypeptide is released -a release factor protein prompts the release of the last tRNA from the ribosome -the stop codon attracts a stop tRNA molecule -the large and small ribosomal subunits separate
-the polypeptide is released -a release factor protein prompts the release of the last tRNA from the ribosome -the large and small ribosomal subunits separate
latent viruses, such as human papilloma virus and Epstein-barr virus, can induce a cell division disorder called ______ because they are signaling the host cell to continue to divide
cancer
after transcription in eukaryotes, a short sequence of modified nucleotides called the _________ is added to one end of the mRNA molecule, and a string of 100 to 200 adenines called the ____ is added to the opposite end of the mRNA molecule
cap; poly A tail
after a virus attached to and penetrates a host cell, a virus can enter a phase where symptoms of the infection are delayed or it can
cause immediate cell death
select the viruses that contain DNA as their genetic material -chickenpox virus -smallpox virus -rabies virus -polio virus -papilloomavirus -hepatitus B virus
chickenpox virus small pox virus papillomavirus hepatitis b virus
in an RNA molecule, a ______ is a genetic "code word" that corresponds to one amino acid
codon
how does an abnormal prion protein (PrP) form?
contact with an abnormal PrP
HIV infects ____ cells, and the Epstein Barr virus infects _____ cells
T B
sickle cell disease results from a _______ mutation
substitution
the DNA strand that is read during transcription is called the _____ strand
template
a specific sequence on the DNA called a _____ sequence signals the end of a gene during transcription
terminator
when is a substitution mutation "Silent"
when the replaced DNA base does not change the protein encoded by the gene
select all of the following that occur during the synthesis and assembly stages of a viral infection. -the viral genetic material is used by the host cell to synthesize viral proteins -the genetic material of the virus enters the host cell -proteins needed to form the viral capsid diffuse into the cell through special channels -capsid subunits join and surrounded viral genetic material -multiple copies of the viral genetic material are sydnthazised by the host cell
-the viral genetic material is used by the host cell to synthesize viral proteins -capsid subunits join and surrounded viral genetic material -multiple copies of the viral genetic material are synthesized by the host cell
select the two ways that viral infections can spread through plant tissue. -water uptake through the roots -windblown pollen -vascular tissue that distribute sap -bridges of cytoplasm between cells
-vascular tissue that distribute sap -bridges of cytoplasm between cells
the modern definition of gene is any sequence of DNA that is transcribed into
RNA
_______ viruses -rhinovirus -measles virus -hepatitis a virus -Ebola virus -influenza virus
RNA viruses
genes that control the formation of an organism's body parts and therefore profoundly influence animal evolution are called _______ genes
homeotic
one major difference between eukaryotes and prokaryotes with respect to translation is that
in prokaryotes, both transcription and translation occur in the cytoplasm
the genetic variability of viruses complicates the development of ________ drugs
antiviral
________ into a host cell may not cause immediate death of the host cell
viral penetration
what type of infectious agent is a naked RNA molecule that can prevent plants from producing one or more essential proteins
viroid
in ________, mRNA is altered before it is translated
eukaryotic cells
epigenetic modifications to the DNA are removed at
fertilization
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
what type of mutation if most likely to alter many amino acids in a protein
frameshift mutation
the development of antiviral drugs is difficult due to the _________ of many viruses
genetic variability
the outer envelope present in some viruses, such as the influenza virus and HIV, is composed of ____, which maybe derived from the host cell's membrane
lipids and proteins
An ______ molecule may persist long enough to be translated many time and may be degraded before it is translated
mRNA
in eukaryotes, gene expression can be blocked by preventing ______ from leaving the nucleus
mRNA
what mechanism of regulating gene expression acts after RNA processing but before translation
mRNA degradation
what method of gene expression regulation allows one gene to code for multiple proteins due to different combinations of exons spliced together?
mRNA processing
________: lead to anitbiotic resistance in bacteria, allow scientists to learn the normal functions of genes, and agricultural scientists use them to create new varieties of crops
mutations
in ______, translation of an mRNA can begin before transcription of the mRNA is complete
prokaryotic cells
the DNA of a lysogenic bacteriophage that is inserted into a host's chromosome is called a
prophage
what is produced during translation
protein
enzymes and chaperone proteins assist in _____ that takes place after translation is complete
protein folding
in eukaryotes, the car and poly A tail on the mature mRNA ensures that
ribosomes attach to the correct end of the mRNA for translation
only producing proteins that are needed allows a cell to
save energy
how does a fever help fight a viral infection
speeds immune responses
when the ribosome reaches a UGA, UAG, or UAA codon on the mRNA, it halts because none of these codons has a corresponding tRNA. these three sequences are called ______ codons
stop
defects in _______ can effect the production of proteins that regulate cell division and can lead to cancer
transcription factors
select all of the following that occur during lysogenic infection of a bacterial cell. -new viruses are produced -genetic material of virus is replicated -host cell is killed -prophage may be formed
-genetic material of virus is replicated -prophage may be formed
select all of the following that are true with respect to genomes. -in eukaryotic cells, the genome usually consists of just one circular DNA molecule -in prokaryotic cells, the genome is usually divided up into multiple chromosomes -in eukaryotic cells, the genome is usually divided up into multiple chromosomes -in prokaryotic cells, the genome usually consists oj just one circular DNA molecule
-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. -preventing a protein from reaching its correct destination -degrading proteins -blocking the exit of mRNA from the nucleus -degrading mRNA -block modifications or alterations to proteins
-preventing a protein from reaching its correct destination -degrading proteins -block modifications or alterations to proteins
select all of the following that are present in a bacterial operon. -enhancer -promoter -operator -group of genes -TATA box
-promoter -operator -group of genes
which of the following are true with respect to mutations? -some mutations can increase an organism's reproductive success -some mutations produce detrimental alleles -all mutations that are passed from parent to offspring are harmful -mutations can cause drug resistance in bacteria -mutations provide the raw material for evolution
-some mutations can increase an organism's reproductive success -some mutations produce detrimental alleles -mutations can cause drug resistance in bacteria -mutations provide the raw material for evolution
select all of the following that are components of chromosomes -specialized proteins -DNA -RNA -ribosomes
-specialized proteins -DNA
select all the ways that cells can make DNA less available for transcription -tag DNA with methyl groups -wind of fold DNA in a way that makes in unavailable -unwind DN -remove introns and split exons together
-tag DNA with methyl groups -wind or fold DNA in a way that makes in unavailable
select all of the following that describe RNA. -the nitrogenous base trail is used instead of thymine -nucleotides contain the sugar ribose -can catalyze chemical reactions -always occur as a double stranded helix -nucleotides contain the sugar deoxyribose -can be single stranded -the nitrogenous base thymine is used instead of guanine
-the nitrogenous base uracil is used instead of thymine -nucleotides contain the sugar ribose -can catalyze chemical reactions -can be single stranded
select all of the following that are true about E. coli bacteria in an environment lacking lactose -the three genes of the lac operon are not transcribed -the repressor is bound to lactose -the lac operon makes lactose-degrading enzymes -the repressor binds to the operator of the lac operon
-the three genes of the lac operon are not transcribed -the repressor binds to the operator of the lac operon
select all the ways that plants can fight off viral infections. -viral mRNA is destroyed before it is translated -infected cells commit suicide -lysosomes ingest infected cells -pollen incompatibility mechanisms are activated
-viral mRNA is destroyed before it is translated -infected cells commit suicide
list from smallest at top to largest on bottom -bacterium -virus -human cell
-virus -bacterium -human cell
what describes a substitution mutation
one DNA base if replaced with another
in bacterial operons, a DNA sequence that exists between the promoter and the protein coding region is called the ______ and is where a repressor protein can bind
operator
in bacterial operons, a DNA sequence that exists between the promoter and the protein coding region is called the ________ and is where a repressor protein can bind
operator
in bacteria, an ______ is a group of genes under control of a single promoter
operon
messenger RNA contains ______, which are triplets of bases that act as "code-words" corresponding to the ______ acid monomers that make up a polypeptide
codons, amino
during transcription, a gene's DNA sequence is transcribed into a -sequence of amino acids -complementary RNA molecule -complementary DNA molecule -protein
complementary RNA molecule
during a __________ infection, a bacteriophage's genetic material is replicated along with the host cell's DNA, but the host cell is not immediately destroyed
lysogenic
a _______ 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 chemicals called mutagens
mutations
_________: building block of nucleic acids
nucleotide
a single strand of DNA consists of a polymer of _________ monomers
nucleotide
where would you find a transcriptional terminator sequence
on a DNA sequence
_____: host cell produces viral nucleic acids and proteins
synthesis
_______: connector molecule that binds to an mRNA codon and to an amino acid
tRNA
during transcription, RNA nucleotide bases are added to the growing mRNA strand as dictated by the complementary bases on the ___ strand of the DNA
template
a homeotic gene encodes a
transcription factor that affects embryo development
in eukaryotes, RNA polymerase cannot bind to the promoter and initiate transcription without the presence of regulatory proteins called ______
transcription factors
During _______, 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 the "central dogma" describing the glow 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