Bio 184 - Exam 2
Stretches of DNA of 1000-2000 bp in length containing a high number of CpG sites and found near gene promoters are called
CpG islands
A breakpoint refers to the region
Where two chromosome pieces break and rejoin with other chromosome pieces
In a natural population, a ____-____ genotype is the most common one.
Wild type
The gametes (sperm and egg cells or their precursors) are called ____ cells.
Germ
True or false: The function of regulatory transcription factors is modulated.
True
Activator proteins often increase transcription through an interaction with
Coactivators
The restoration of protein function by a second mutation in a different gene is known as a(n)
Intergenic suppressor
Place these steps in a simplified model for transcriptional activation of a eukaryotic gene in order from first to last.
1. Binding of activator to an enhancer in the NFR. 2. Recruitment of a chromatin-remodeling complex and history- modifying enzyme 3. Recruitment of general transcription factors and RNA Pol II to the core promoter, allowing the formation of a preinitiation complex 4. Eviction or destabilization of histone octamers, allowing RNA pol II to pass, and elongation to occur.
Which of the following best describes asexual reproduction?
A mother cell divides to produce two identical daughter cells.
An organelle is
A structure within the cytoplasm with a specific function
Which of the following base changes are transversion mutations?
A to C, G to C, A to T
Unicellular organisms proliferate by _______ reproduction, in which a preexisting cell divided to produce two new cells.
Asexual
Most bacterial cells divide by
Binary fission
What effect can ATP- dependent chromatin remodeling have on transcription?
Both activation and repression.
The region where two chromosome pieces break and re-attach to other chromosome pieces is called a chromosomal
Breakpoint
Mediator phosphorylates the _______-terminus of RNA polymerase II, stimulating progression to the __________ stage of transcription.
Carboxy; elongation
The two chromatids of a chromosome are joined together at a region of DNA called the
Centromere
After replication, each chromosome consists of two copies called
Chromatids
What is the term that can refer to either a dyad (pair of sister chromatids) or a monad (single chromatid)?
Chromosome
The structures within all living cells that contain the genetic material are called
Chromosomes
The phenomenon is which the combination of many factors determines the expression of a given gene is known as
Combinatorial control
Mutations that affect the phenotype only under certain circumstances are called
Conditional mutations
Select common factors that contribute to combinatorial control.
DNA methylation inhibits transcription; Repressor proteins inhibit the ability of RNA polymerase to initiate transcription; Activator proteins stimulate the ability of RNA polymerase to initiate transcription; Regulatory proteins alter the composition or arrangement of nucleosomes in the vicinity of a promoter; Activator and repressor activity is modulated by small effector molecules, protein-protein interactions, and covalent modifications.
The methylation of DNA that was previously unmethylated is called __ ____ methylation.
De novo
Transcription factors contain protein regions called _______ that have specific functions.
Domains
You are studying a transcription factor that binds to DNA near a gene of interest. You discover that once the transcription factor binds, transcription of your gene of interest becomes undetectable. This is an example of
Down regulation
Activators bind to
Enhancers
A position effect can alter gene expression in cases when the gene is moved from a less condensed, or ___________ chromosome, where it is active, to a very highly condensed, or _______________ chromosome, where it's expression may be turned off.
Euchromatic; heterochromatic
Organisms, such as protists and fungi, that have a true nucleus are called
Eukaryotes
True or false: Most eukaryotic species are haploid or have such a phase to their life cycle.
False
The eukaryotic cell cycle is composed of
Four phases called: G1, G2, S, and M
Gene regulation means that
Gene expression can be controlled so that genes can be expressed at high or low levels
If fully methylated DNA is introduced into a plant or animal cell, in subsequent generations the DNA will be __________. If the same sequence of nonmethylated DNA is introduced into a cell, it will be _____________ in daughter cells.
Methylated; nonmethylated
A base substitution in DNA that ultimately leads to a change in the encoded amino acid is called a(n) ________ mutation.
Missense
An individual that has somatic regions with different genotypes is known as a genetic
Mosaic
Which of the following statements about eukaryotes is true?
Most eukaryotic species are diploid or have a diploid phase to their life cycle.
An allele that has a DNA sequence different from that one or the wild-type is called a(n) ______ allele.
Mutant
A heritable change in the genetic material is called a(n)
Mutation
A(n) ______ mutation is a missense mutation that has no detectable effect in protein function.
Neutral
A silent mutation is a mutation that results in
No change to the amino acid sequence of the polypeptide
What type of mutations involve a change from a normal codon to a stop codon?
Nonsense mutations
A(n) _____ mutation refers to a mutation in which just one base is changed within the DNA sequence.
Point
Muscle cells, nerve cells, skin cells are examples of
Somatic cells
DNA sequences that are analogous to the operator sites found near bacterial promoters are called ______ elements or __________ sequences.
Control; regulatory
Mutations that occur in a promoter sequence can be divided into two types: __ promoter mutations increase the transcription rate, while ____ promoter mutations decrease it.
Up; down
Which of the following base changes is a transition mutation?
A to G
Which of the following are eukaryotes?
Plants, protests, fungi
The function of TFIID is to
Bind to the TATA box and recruit RNA polymerase II to the core promoter
When chromatin is accessible to transcription factors and RNA polymerase, it is referred to as being in the
Open confirmation
Mutations in body cells that do not go on to form gametes are known as
Somatic mutations
Errors in DNA replication are examples of ___________ mutations, while mutations caused by ultraviolet light are _______ mutations.
Spontaneous; induced
An enhancer is a DNA element that is bound by a regulatory transcription factor, which leads to
Up regulation
Select the organism with the highest amount of DNA methylation.
Vertebrates
The _______ of a eukaryote is the organelle that contains most of the genetic material found in the cell.
Nucleus
Prokaryotes usually have a single type of circular chromosome in a region of the cytoplasm called the
Nucleoid
Some errors create bulky distortions of the double helix. These errors are removed primarily by a DNA repair system called NER, which stands for _________ ________ repair.
Nucleotide excision
In Drosophila melanogaster, 2n = 8. A triploid fly would have __ chromosomes, while a tetraploid fly would contain __ chromosomes.
12; 16
The house mouse Mus musculus has a diploid chromosome number of 40. Suppose that the first meiotic division of a germ cell is normal, but a single dyad one one of the two daughter cells undergoes nondisjunction in meiosis II. How many chromosomes would be present in each of the four gametes that result from meiosis?
20,20,21,19
A normal human cell carries __ pairs of chromosomes for a total of __.
23; 46
In organisms that are normally diploid, a trisomic individual is designated
2n + 1
_______ are different variations of the same gene.
Alleles
__________ is the gain or loss of individual chromosomes that is not an exact multiple of a set.
Aneuploidy
The interchange of corresponding chromatid segments of homologous chromosomes during prophase I of meiosis is called
Crossing over
In a _______ cell, each type of chromosome is a member of a pair.
Diploid
The transactivation domain of coactivators promotes the activation of RNA polymerase, often by interacting with
General transcription factors
A mutation that occurs directly in a sperm or egg cell, or in one of their precursors, is referred to as a(n) ____-____ mutation.
Germ line
Cells that give rise to eggs and sperm are called
Germ line
Copy number variation (CNV) described DNA segments of at least ________ in size which exhibit copy number differences among members of ________________.
1,000 bp; the same species
Order the steps in chromatin immunoprecipitation (ChIP-Seq) from first to last.
1. Living cells are treated with formaldehyde, broken open, and treated with micrococcal nuclease. 2. Heavy beads attached to antibodies that recognize specific histones are added the nucleosome mixture. 3. The mixture is centrifuged to separate the immunoprecipitated material, crosslinks are reversed, and proteases partially digest core histones. 4. The remaining DNA is subject to gel electrophoresis. Fragments of 150 bp are saved. 5. Linkers are added to the DNA, then they are PCR amplified and subjected to DNA sequencing, DNA sequences are analyzed.
Place the steps in glucocorticoid hormone and receptor action in order from first to last.
1. The glucocorticoid hormone diffuses through the plasma membrane. 2. The glucocorticoid hormone binds to the glucocorticoid receptors. 3. HSP90 is released from the glucocorticoid receptor. 4. Two glucocorticoid receptors form a homodimer and travel through a nuclear pore into the nucleus.
DNA methyltransferase is an enzyme that attaches a methyl group to the _ position of the ________ base.
5; cytosine
A frameshift mutation is caused by what?
A base addition, a base deletion
What is chromatin?
A complex between DNA and proteins that are found in eukaryotic cells.
A motif
A domain that has a very similar structure in many different proteins
A haploid cell is represented by 1n and a diploid cell is represented by 2n. The n refers to
A set of chromosomes
What does a haploid cell contain?
A single set of chromosomes
A piece of a chromosome that has lost its centromere is called a(n) ________ fragment.
Acentric
A duplication is best defined as the
Addition of a chromosome segment
The term _______ variation refers to differences in specific genes.
Allelic
When does nondisjunction typically occur?
Anaphase of meiosis I; anaphase of meiosis II
An individual that has multiple sets of chromosomes from the same specifies is best describes as a(n)
Autopolyploid
Prokaryotes, which include the ________ and the _______, are organisms that lack a membrane-bound nucleus.
Bacteria; archaea
A mutation that enhances the survival and/of reproduction success of an individual is referred to as a(n) __________ mutation.
Beneficial
In metaphase I of meiosis, the _________ (which are also termed tetrads) re aligned along the metaphase plate.
Bivalents
Which of the the following statements about synapsis and crossing over is true?
Both synapsis and crossing over occur in prophase I of meiosis
The two microtubule-organizing centers (MTOCs) that form the mitotic spindle of animal cells are called
Centrosomes
Select ways that nucleosomes can change.
Change in location; change in histones to variants with specialized roles; covalent modification to the amino-terminal tails of histones
The three most common autosomal trisomies in humans are those involving what chromosome?
Chromosome 21; Chromosome 18; Chromosome 13
A technique called _________________________________ (CGH) can be used to determine whether a cancer cell has changes in chromosome structure, such as duplications or deletions.
Comparative genomic hybridization
In meiosis, if all of the chromosomes fail to separate normally, and end up migrating to one of the two daughter cells, the result is that all four cells are abnormal. This event is known as _______________________.
Complete nondisjunction
Transcription factors that affect the ability of RNA polymerase to begin the transcription process may work by
Controlling the switch from the initiation to the elongation stage of transcription; regulating the binding of the transcriptional complex to the core promoter
Which of the following can cause reciprocal translocations to occur?
Crossover between nonhomologous chromosomes; chromosomal breakage and DNA repair
A scientist who examines the chromosomal composition of a particular cell is called a(n) ______________.
Cytogeneticist
Which of the following are examples of base pair mismatches?
Cytosine on parent strand and adenine on daughter strand; adenine in parent strand and cytosine on daughter strand; cytosine on parent strand and thymine on daughter strand
What are the major components of a chromosome?
DNA; proteins
A change in chromosome structure where a portion of the chromosome is missing is called a(n)
Deletion
Comparative genomic hybridization is a method that can be used to detect what changes in chromosome structure?
Deletion; duplications
The primary purpose of mitosis is to
Distribute the replicated chromosomes equally into two daughter cells
Nondisjunction occurs when chromosomes
Do not separate properly during meiosis
Copy number variations may involve which of the following?
Duplications; deletions
Which of the following best describes the events of anaphase I of meiosis?
Each homologous pair of sister chromatids migrate to opposite poles
What affect does acetylation have on lysine in core histone proteins?
Eliminates the positive charge on lysine, disrupting the electrostatic attraction between the histone and the negatively charged DNA backbone.
Liver cells of humans may be triploid (3n), tetraploid (4n), or even octaploid (8n). This phenomenon is best described as
Endopolyploidy
A(n) _______ organism is one with a chromosome number that is an exact multiple of a chromosome set.
Euploid
In a particular plant species, individuals can be diploid, triploid, or tetraploid. All of these organisms are said to be
Euploid
True or false: Gametogenesis is the process by which gametes fuse to produce a new individual.
False
A collection of two or more genes in a particular species that are similar to each other is known as a gene ______.
Family
Sexual reproduction involves the fusion of two _______ in the process of _____________.
Gametes; fertilization
Select the histones in which variants have been identified.
H1; H2A; H2B; H3
A _______ cell has a single set of chromosomes.
Haploid
A genetic mosaic is an individual that
Has regions of the body that are genotypically different from each other
An individual that carries one copy of a normal chromosome and one copy that contains an inverted segment is described by the term _______________________.
Heterozygotes inversion
The dimerization of two identical proteins results in a
Homodimer
Each type of chromosome in a diploid cell is found in a homologous pair. Each chromosome in such a pair is referred to as a(n)
Homolog
Two or more genes that are derived from the same ancestral gene are referred to as __________ genes.
Homologous
Synapsis is the process by which
Homologous chromosomes recognize each other and begin to align themselves in prophase I
The DNA from one source forms a double stranded region with the DNA from another source during what process?
Hybridization
The restoration of function by a second mutation at a different site in the same gene is known as a(n)
Intragenic suppressor
A chromosomal change in structure in which came a segment of DNA is rotated 180 degrees is referred to as a(n)
Inversion
If a segment of DNA changes orientation along the chromosome, a(n) _________ is said to have taken place.
Inversion
In general, the chromosome number of a particular species
Is the same for all individuals of the species
What is the effect of a suppressor mutation?
It suppresses the phenotypic effect of another mutation.
An organized representation of the chromosomes of a cell is called a
Karyotype
A mutation that results in the death of an organism is known as a(n) ______ mutation.
Lethal
A(n) _____ refers to the physical location of a gene.
Locus
If chromatin is in a closed confirmation, nucleosome position and histone composition
Make it difficult for transcription factors to gain access to and bind their target sequences in the promoter DNA
Most eukaryotic genes are regulated by
Many facitrs
The protein complex that mediates the interaction between RNA polymerase II and regulatory transcription factors is called
Mediator
Eukaryotic cells that are diploid can divide by ______ to produce haploid sex cells.
Meiosis
During which of the following phases are tetrads organized at random along a plate in the center of the cell?
Metaphase of meiosis I
An organism that has only one copy of a particular chromosome instead of the normal two copies is said to be _________.
Monosomic
The term meiotic ______________ refers to the failure of chromosomes to separate normally during meiosis. This results in haploid cells that have too many or too few chromosomes.
Nondisjunction
A Robertsonian translocation occurs when two _________________________ chromosomes lose their short arms and fuse to form a large single chromosome.
Nonhomologous chromosomes
Which of the following events occurs during metaphase of mitosis?
Pairs of sister chromatids become organized in a single row
Polyploidy is commonly found in species of
Plants
A(n) _________ organism is one that contains three or more sets of chromosomes.
Polyploid
The expression of an intact gene may be altered when it is moved to a new location. That is due to a(n)
Positive effect
During ____________, pairs of sister chromatids become attached to kinetochore microtubules which emanate from opposite poles of the cell.
Prometaphase
Rank the phases of mitosis in order, starting with the earliest at the top.
Prophase; prometaphase; metaphase; anaphase; telophase
If gene regulation acts to prevent translation, which molecule will not be produced?
Protein
DNA sequences in eukaryotes that can be bound by regulatory transcription factors, which then affect the ability of RNA polymerase to transcribe a particular gene are called
Regulatory sequences; regulatory elements; control elements
Identical or similar DNA sequences that occur multiple times on a chromosome are called __________ sequences.
Repetitive
Regulatory transcription factors that prevent transcription from occurring are called __________.
Repressors
A _______ mutation is one that converts a mutant allele back to the wild-type form.
Reverse
Consider a homologous pair of chromosomes if a particular individual, where one homolog carries a single copy of gene A while the other carries two copies of the same gene. The latter chromosome is said to have undergone a(n)
Segmental duplication
Repressors bind to
Silencers
Which of the following events occurs during anaphase of mitosis?
Sister chromatids separate from each other and head to opposite poles
During prophase of mitosis, the nuclear membrane breaks down into small vesicles and the nucleolus becomes less visible. Furthermore, the two ___________ move apart from each other and the mitotic _______ begins to form.
Spindle
A second mutation that occurs in a different site than the first mutation, and which converts the mutant back to the wild-type phenotype, is best referred to as a(n) _______ mutation.
Suppressor
During prophase I of meiosis I, homologous chromosomes recognize and begins to align with each other via a process called ________.
Synapsis
The ends of a eukaryotic chromosome are called _________.
Telomeres
All the following events occur during prometaphase except:
The chromosomes become visible with the light microscope
Select all the events that occur during prophase.
The nuclear membrane begins to dissociate into small vesicles; the mitosis spindle begins to form; the nucleolus becomes less visible, the chromatids become condensed
Select all of these that are events of telophase I in meiosis.
The nuclear membrane reforms in most species; sister chromatids have reached their respective pole; sister chromatids decondense in most species
The majority of inversions do not cause phenotypic consequences because
The total amount of genetic material does not change in a given chromosome
Coactivators often contain a _______________ domain that promotes the activation of RNA polymerase.
Transactivation
A _____________ ______ is a protein that influences the ability of RNA polymerase to transcribe a given gene.
Transcription factor
The movement of a DNA segment from one chromosome to another is an example of a(n)
Translocation
An organism that has three sets of chromosomes is called a(n) ________, while one with four sets is called a(n) __________.
Triploid; tetraploid
An organism that has three copies of a particular chromosome instead of the normal two copies is said to be ________.
Trisomic
If the original diploid mother cell has eight chromosomes, a cell in telophase of mitosis would have
Two nuclei, each with eight chromosomes
The cytosines in CpG islands near housekeeping genes are
Unmethylated
When a fully methylated DNA segment of DNA is replicated, the newly made daughter strand contains ____________ cytosines. This DNA is said to be ______________.
Unmethylated; hemimethylated
Which of the following statements about promoter mutations is true?
Up promoter mutations cause the promoter sequence to be more like the consensus sequence; down promoter mutations decrease the affinity of transcription factors to the promoter
Genetic differences within individuals of the same species or between different species is referred to as genetic _________.
Variation
