Exam 3 Review
Select all of the following that are true about growth factors triggering cell division. - Growth factors are only found in animal cells. - Growth factors normally act to block exit of the cell from the G1 phase of the cell cycle, thereby suppressing cell division. - In response to a signal, a cascade of chemical reactions inside the cell initiates cell division. - Growth factors bind to receptors on the cell membrane. - Growth factors "walk" along microtubules to receptors on the nuclear membrane. - A growth factor stimulates the production of new skin cells at a wound site.
- In response to a signal, a cascade of chemical reactions inside the cell initiates cell division. - Growth factors bind to receptors on the cell membrane. - A growth factor stimulates the production of new skin cells at a wound site.
Select all of the following that are true about proto-oncogenes. - When they are overactive because of mutation, the cell cycle may become accelerated. - They encode proteins that stimulate cell division. - Proto-oncogenes encode proteins that normally block cancer development.
- When they are overactive because of mutation, the cell cycle may become accelerated. - They encode proteins that stimulate cell division.
Select all of the following that are methods of gene regulation found in eukaryotes but not prokaryotes. - proteins that bind to regulatory sequences within DNA - blocking mRNA exit from the nucleus - splicing exons in alternative ways - controlling access of RNA polymerase to the promoter - adding methyl groups to silence genes
- blocking mRNA exit from the nucleus - splicing exons in alternative ways - adding methyl groups to silence genes
Select all the functions of ribosomal RNA. - catalyze the formation of bonds between amino acids in the developing protein - bind to mRNA on one end and carry an amino acid on the other end - help align the ribosome with the mRNA to prepare for translation - carry the message encoded by the DNA to the cell's cytoplasm so it can be translated
- catalyze the formation of bonds between amino acids in the developing protein - help align the ribosome with the mRNA to prepare for translation
Select all of the following that are true about frameshift mutations. - is caused by replacement of one nucleotide with another - disrupts the codon reading frame - can be caused by the deletion of two nucleotides - can be caused by a change in a codon from CAC to CAU - likely to change the amino acid sequence - can be caused by the addition of one nucleotide
- disrupts the codon reading frame - can be caused by the deletion of two nucleotides - likely to change the amino acid sequence - can be caused by the addition of one nucleotide
Select all of the following that describe newer cancer treatments with fewer side effects. - gene therapy - angiogenesis inhibitors - chemotherapy - tissue-specific antibiotics - drugs that target specific molecules
- gene therapy - angiogenesis inhibitors - drugs that target specific molecules
Select all of the following that describe the two chromatids of a single replicated chromosome. - called nonsister chromatids - called homologous chromosomes - joined to each other at the centromere - separated during cell division - identical copies
- joined to each other at the centromere - separated during cell division - identical copies
Select all of the following that occur during interphase. - protein production - DNA replication - attachment of spindle fibers to kinetochores - separation of sister chromatids
- protein production - DNA replication
Select all of the following that are components of chromatin. - proteins for replication - actin microtubules - proteins for scaffolding - proteins for transcription - DNA
- proteins for replication - proteins for scaffolding - proteins for transcription - DNA
Select all of the following that are genes. - sequence of DNA nucleotides that codes for a specific protein - sequence of DNA nucleotides where a regulatory protein binds - 5' cap and poly-A tail attached to RNA - sequence of DNA nucleotides that codes for a specific RNA molecule
- sequence of DNA nucleotides that codes for a specific protein - sequence of DNA nucleotides that codes for a specific RNA molecule
Select all the ways that cells can make DNA less available for transcription. - tag DNA with methyl groups - wind DNA more tightly - unwind DNA - remove introns and splice exons together
- tag DNA with methyl groups - wind DNA more tightly
Select all of the following that are affected by epigenetic modifications in eukaryotes. - ability of the repressor to bind to the operator - developmental patterns - the sequence of nucleotides in the genome - cell division - gene expression
-developmental patterns - cell division - gene expression
What describes the S phase checkpoint?
-ensures that DNA replication occurs properly
In DNA replication, DNA polymerase can only add new nucleotides to an exposed _____' end
3
What are codons composed of?
3 mRNA bases
DNA polymerase can only add nucleotides to the ______
3' end
start codon
AUG (methionine)
Block the recruitment of blood vessels by a tumor.
Angiogenesis Inhibitors
The enzyme called ______________ adds new complementary DNA nucleotides to a single-stranded DNA template.
DNA polymerase
What enzyme adds complementary bases to exposed single strands of DNA during DNA replication?
DNA polymerase
Why does an RNA primer need to be added to the DNA template for DNA replication?
DNA polymerase can only add nucleotides to an existing strand.
A eukaryotic chromosome consists of
DNA wrapped around histones and other proteins
Choice, Target unique molecules in cancer cells. Target unique molecules in cancer cells.
Drug Therapy
______ are portions of mRNA that get spliced together to form mature mRNA prior to translation.
Exons
In the ______ phase of the cell cycle, the cell grows, carries out basic functions, and produces new organelles.
G1
The checkpoint that regulates the cell cycle by screening for DNA damage prior to the start of DNA replication during the S phase is called the
G1 checkpoint
The initiation of chromosome condensation and the production of proteins that will coordinate the movements of chromosomes during mitosis occur during what phase of the cell cycle?
G2
What checkpoint ensures that DNA has been completely replicated and that the spindle-making machinery is in place?
G2
Add functional genes to cells with disabled genes.
Gene Therapy
Stimulate the immune system to attack cancer cells.
Immunotherapy
A(n) ________ is a portion of RNA that averages about 1,000 nucleotides long and that is removed before translation.
Intron
In eukaryotes, a part of an mRNA molecule that is removed before translation is called a(n)
Intron
What checkpoint monitors the cell's supply of DNA nucleotides during DNA replication?
S
Why do chemotherapy and radiation therapy cause hair loss, fatigue, and nausea?
They target all rapidly dividing cells.
Malignant tumors invade adjacent tissue (T/F)
True
When the requirements of a checkpoint are not met, then the cell will not progress to the next stage of the cell cycle. (T/F)
True
stop codons
UGA, UAA, UAG
In prokaryotes, DNA is contained in ______ (how many chromosomes)
a single chromosome
mRNA processing, mRNA exit from the nucleus occurs when
after transcription but before translation
protein degradation occurs
after translation
A variant of a gene is referred to as a(n)
allele
What gene regulation mechanism allows for the production of different proteins from the same mRNA?
alternative splicing of exons
Cancer cells are able to stimulate the development of new blood vessels, a process called
angiogenesis
What 3-base site of a tRNA molecule is complementary to an mRNA codon?
anticodon
DNA availability occurs
before transcription
A tough capsule surrounds a __________ tumor
benign
Usually, warts and moles are ______ tumors of the skin, meaning they do not invade surrounding tissues or metastasize.
benign
Type of prokaryotic asexual reproduction in which replicated DNA and other cell parts are distributed into two new daughter cells.
binary fission
place where two sister chromatids attach in a replicated chromosome
centromere
The cell cycle has ________ that regulate the transitioning of one phase of the cell cycle into the next.
checkpoints
The cell cycle has internal ______ that do not let the cell proceed to the next stage of the cell cycle until the previous stage is complete.
checkpoints
Epigenetics is the study of changes in gene expression due to
chemical modifications of histones or DNA bases
The goal of ______ is to stop cell division in cancer cells anywhere in the body
chemotherapy
replicated copy of a chromosome
chromatid
Eukaryotic chromosomes consist of _______, which is composed of uncondensed DNA and associated proteins.
chromatin
A single molecule of DNA and its associated proteins is called a(n)
chromosome
What describes chromosomes at the end of the S phase of interphase?
consist of two chromatids
In eukaryotic cells, translation occurs in the ______
cytoplasm
New DNA is synthesized ________________ on the lagging strand
discontinuously
Cancer is caused by ______ that cause cells to divide uncontrollably.
genetic mutations
All the cell's genetic material (DNA) and consists of one or more chromosomes containing the DNA.
genome
body and cell processes that require cell division to function
growth and development, reproduction, replacement of dead cells
Proteins called ______ are chemical signals that bind to receptors on a cell membrane and trigger cell division.
growth factors
Unlike normal cells, many cancer cells can divide even in the absence of
growth factors
What enzyme unwinds DNA to separate the strands for DNA replication?
helicase
Functions of the 5' cap and 3' poly A tail added to mRNA after transcription in eukaryotes
help ribosomes attach to 5' end of mRNA and protect RNA from degradation
Many cancer cells send signals to stimulate angiogenesis, which results in
increased exchange of nutrients and wastes in the area of the tumor.
During prometaphase, spindle fibers attach to proteins called ______ that assemble at each centromere of a chromosome.
kinetochores
Okazaki fragments are formed on the
lagging strand
On one strand of DNA, called the ______ strand, the 3' end is exposed, and DNA replication can proceed ______.
leading, continuously
In DNA replication, gaps between newly synthesized segments of DNA and existing segments of DNA are sealed by enzymes called ______, which form covalent bonds between the two segments.
ligase
The type of RNA that carries the information to specify a protein is called
mRNA
__________ tumors are likely to metastisize
malignant
The checkpoint that ensures that all chromosomes are aligned and that the spindle fibers are attached correctly is the
metaphase checkpoint
When a mutation changes the sequence of amino acids
missense
type of mutation represented by sickle cell mutation
missense substitution mutation
In eukaryotes, DNA is contained in _____________
multiple chromosomes
A _________ is a change in a cell's DNA sequence.
mutation
when a mutations causes premature stop codons
nonsense
stretch of DNA wrapped around proteins; become tightly arrayed during chromatin condensation
nucleosome
In eukaryotic cells, transcription occurs in the ______
nucleus
transcription factors
occurs at initiation of transcription
Codons correspond to
one amino acid
What RNA modification in eukaryotes decreases the chances that the mRNA will be degraded before translation?
poly A tail
What mechanism of regulating gene expression acts after RNA processing but before translation?
preventing mRNA exit from the nucleus
What enzyme adds an RNA primer to the template strand of a DNA segment to be replicated?
primase
Splicing of different exons together from the same mRNA molecules can result in
production of different proteins
Apoptosis is ______________ cell death
programmed
The p53 protein acts at the G1 checkpoint to
promote DNA repair
During translation, a(n) ______ is produced from the information that is encoded in a(n) ______.
protein, RNA molecule
What is a ribosome made of?
rRNA and proteins
The goal of ______ is to kill cancer cells in limited areas
radiation therapy
DNA replication is said to be a ______________ process because it keeps an original template
semiconservative
Nonsense mutations results in a
shortened product
A substitution mutation is said to be ______ if the mutated gene encodes the same protein as the original gene version.
silent
After DNA replication, chromosomes consist of two
sister chromatids
Proteins encoded by proto-oncogenes normally act to
stimulate cell division
A(n) ______ mutation is caused by the replacement of one nucleotide with another.
substttution
What type of RNA binds to an mRNA codon at one end and a specific amino acid at the other end?
tRNA (transfer RNA)
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
In DNA replication, continuously synthesis occurs on the leading strand
toward the origin of replication.
Eukaryotic cells can compact their DNA or add methyl groups to make their DNA unavailable for
transcription
Process where a cell copies a gene's DNA sequence to a complementary RNA molecule
transcription
Eukaryotic proteins that are often required for RNA polymerase to bind to a promoter and initiate
transcription factors
In what process does the cell use the information in an RNA molecule to assemble a protein?
translation
Process where the information in RNA is used to manufacture a protein by joining a specific sequence of amino acids into a polypeptide chain.
translation
What type of genes normally encode proteins that prevent cell division or promote apoptosis?
tumor-suppressor genes
At the G2 checkpoint, the cell checks if
two full sets of identical DNA are present after DNA replication.
2 reasons a tumor can form:
uncontrolled cell division, lack of programmed cell death
The type of cell division that separates chromosomes and produces two daughter cells with identical nuclei
Mitosis
What occurs in a deletion mutation?
One or more nucleotides are removed from the DNA.
