BIO 211 Exam 2
All humans have 46 chromosomes in every cell (except gametes)
-1 pair of sex chromosomes -22 pairs of autosomes
If nondisjunction occurs in meiosis I
-2 gametes will have an extra copy of a chromosome causing a condition called TRISOMY -2 gametes will lack that chromosome (causing a condition called MONOSOMY)
Damaged DNA
-DNA can be broken or altered (various chemicals and types of radiation are the cause of such damage) -UV light can cause thymine dimers to form (these dimers produce a KINK in the DNA strand)
Meiosis II
-Daughter cells are haploid (n) and contain just one homolog -Sister chromatids separate -Four daughter cells contain one chromosome each (n) In animals, these cells become gametes.
How does DNA Replication work?
-Enzyme DNA HELICASE breaks the hydrogen bonds between base pairs, to separate strands. -Single-strand DNA-binding proteins (SSBPs) attach to the separated strands and prevent them from snapping back into a double helix -Topoisomerase relieves twisting forces -Sliding clamp holds DNA polymerase in place -DNA polymerase works in a 5-3 direction, synthesizing the leading strand.
Consequences of Meiosis
-Independent shuffling of maternal and paternal chromosomes and crossing over during meiosis I result in 4 gametes, with a chromosome composition different from the parent cells. -The changes in chromosomes produced by meiosis and fertilization are significant because chromosomes contain the hereditary material.
Meiosis I
-Parent cell is diploid (2n) and contains a homologous pair of replicated chromosomes -Homologs separate
Linked genes
-are predicted to always be transmitted together during gamete formation -should violate the principle of independent assortment -are inherited together unless crossing over occurs
Social control
-cells respond to signals from other cells -divide only when their growth benefits the whole organism
Somtic cells normally LACK telomerase
-chromosomes of somatic cells progressively shorten -this occurs as the individual ages Telomere shortening may have a role in limiting the amount of time cells remain in an actively growing state
Why did Mendel chose the common garden pea as his model organism?
-easy to grow -reproductive cycle is short -produces large numbers of seeds -matings are easy to control -traits are easily recognizable
If the DNA is physically damaged in G1 phase, the p53 protein does what?
-either pauses the cell cycle -or initiates apoptosis = programmed cell death
Repair enzymes remove defective bases and repair them
-if mistakes remain after synthesis is complete or if DNA is damaged
Meiosis
-is the nuclear division that precedes the formation of gametes (egg/sperm) -results in a halving of chromosome number -is usually accompanied by cytokinesis
DNA polymerase proofreading
-it can correct mismatched bases when they do occur -if the enzyme finds a mismatch, it pauses and removes the mismatched base that was just added -DNA POLYMERASE III can do this because it has an EPSILON subunit that acts as an exonuclease and removes deoxyribonucleotides from DNA
Replication of telomeres can be problematic
-leading strand synthesis results in a normal copy of the DNA molecule -telomere on the lagging strand shortens during DNA replication -There is no way to replace the RNA primer from the lagging strand with DNA
Diploid cells have:
-one paternal chromosome -one maternal chromosome
X-linked dominant traits
-rarely skip generations -are indicated in a pedigree where an affected male has all affected daughters but no affected sons -Hypophosphatemia is an example
Social control is based on growth factors
-small proteins released by cells that stimulate division in other cells -cell cultures will not grow unless growth factors are present
Repairing Damaged DNA
-the nucleotide excision repair system recognizes such types of damage. -Enzymes then remove the single stranded DNA in the damaged section -the presence of a DNA strand complementary to the damaged strand provides a template for re-synthesis of the defective sequences
Cancerous cells have two types of defects:
1. Defects that make the proteins required or cell growth active when they should not be 2. Defects that prevent tumor suppressor genes from shutting down the cell cycle.
Meiosis I is a continuous process with five distinct phases
1. Early Prophase I 2. Late Prophase II 3. Metaphase I 4. Anaphase I 5. Telophase I
Meiosis II has 4 distinct phases
1. Prophase II 2. Metaphase II 3. Anaphase II 4. Telophase II
Nondisjunction may occur in as many as what percent of meiotic divisions?
10% of meiotic divisions
DNA synthesis always adds on to which side of the DNA
3' it goes 5' --> 3'
Blood type dominance
A is codominant with B A is dominant to O B is dominant to O
Nondisjunction
A mistake in Meiosis, if both homologs or both sister chromatids move to the same pole of the parent cell. Results in ANEUPLOIDY. All gametes have too many or too few chromosomes
Chromosome
A structure composed of a DNA molecule and associated proteins
Principal of independent assortment
Alleles of different genes are transmitted independently of one another
DNA synthesis works which way
BIDIRECTIONALLY occurs in both directions at the same time.
Cancer cells and social control
Cancer cells divide without growth factors and are no longer subject to social control at the g1 checkpoint
Prophase I
Centrasomes go their sides of the cell, unspooling the microtubules. Each chromosome gets matched up with a chromatid and its homologous chromosome. Crossing over/Homologous recombination -Each double chromosome lines up to homolog. total of 4 chromatids. they tangle up and switch genetic code. -Creates variation
Quantitative traits
Characteristics that are not discrete but fall into a continuum, like height.
Discrete traits
Characteristics that are qualitatively different. Like colors of eyes
Metaphase I
Chromosomes lined up with crossed over pair
Homologous chromosomes aka Homologs
Chromosomes of the same type. Not identical but similar. Carry the same genes in the same order, but may be different alleles.
The secondary structure is stabilized by
Complementary Base Pairing Adenine bonds with Thymine Guanine bonds with Cytosine
Centrioles
Cylindrical structures that comprise microtubules, located inside animal centrosomes
Genetic map
Diagram showing the relative positions of genes along a particular chromosome
Anaphase I
Each chromosome gets pulled apart from homolog
Telomerase
Enzyme - adds more repeating bases to the end of the lagging strand -catalyzing the synthesis of DNA from an RNA template carried with it
During sexual reproduction, a sperm and an egg unite to form a new individual. This process is called
Fertilization
Cell-cycle can vary greatly among cell types thanks to:
G1 phase. It can be essentially eliminated in rapidly dividing cells Nondividing cells get permanently stuck in G1 phase (this arrested stage is called the G0 state)
Fission
How bacteria divides, since it doesnt undergo cytokinesis. It is a process similar to animal cytokinesis
What group is exposed on the 3' end of a deoxyribose?
Hydroxyl group is exposed on 3' end
Cytokinesis in bacteria occur:
IT DOESNT OCCUR Bacteria instead divide via FISSION
DNA replication is SEMICONSERVATIVE
If the old parental strands of DNA separated, each could then be used as a template for the synthesis of a new, daughter strand. This hypothesis is called semiconservative because each new daughter DNA would consist of one old strand and one new strand
Outcrossing
In many sexually reproducing species, gametes from different individuals combine to form offspring Outcrossing increases genetic diversity of the offspring because chromosomes from two different parents are combined
Meiosis is two cell divisions
Meiosis I & Meiosis II The two divisions occur consecutively but differ sharply
What is the leading cause of spontaneous abortion?
Mistakes in meiosis
Benign tumors are
Noninvasive and noncancerous
Telophase I
Nuclear envelope forms around each new bundle of chromosomes
Chromotid
One strand of replicated chromosome, with its associated proteins
Sex Chromosomes
Pair during meiosis I Segregate during Meiosis II Results in gametes with either an X or Y chromosome
What group is exposed on 5' end of DNA?
Phosphate group is exposed on 5' end
Telomere
Region at the end of a linear chromosome does not contain genes consists of short, repeating stretches of bases
Meiosis II
Separates the sister chromatids into single separate single chromosome strands
What is the backbone of DNA made of
Sugar-phosphate
Chromosome Theory of Inheritance
The genes for different traits must assort independently of one another at meiosis I because: - they are located on different nonhomologous chromosomes and they assort independently of one another
Chromotin
The material that makes up eukaryotic chromosomes; consists of a DNA molecule complexted with histone proteins
Centrosome
The microtubule-organizing center in animals and some plants
Linkage
The physical association of two or more genes found on the same chromosome
lagging strand
The strand of DNA that extends in the direction away from the replication fork
Centromere
The structure that joins sister chromatides
Kinetochores
The structures on sister chromatids where microtubules attach
Principal of Segregation
The two members of each gene pair must segregate into different gamete cells during the formation of eggs and sperm in the parents
Sister chromatids
Two strands of a replicated chromosome. When chromosomes are replicated, they consist of two sister chromatids. The genetic material in sister chromatids is identical. When sister chromatids separate during mitosis, they become independent chromosomes.
Antiparallel fashion
Watson and Crick proposed that 2 DNA strands line up in the opposite direction to each other
Metastasis
When cancer cells detach from the original tumor and invade other tissues
Pleiotropic
When genes influence many traits
If males are much more likely to have a trait it is usually:
X-linked
A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in A) G1 B) G2. C) prophase. D) metaphase. E) anaphase.
a
Cells that are in a nondividing state are in which phase? A) G0 B) G2 C) G1 D) S E) M
a
Fibroblasts have receptors for this substance on their plasma membranes: A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
a
G1 is represented by which number(s)? A) I and V B) II and IV C) III D) IV E) V
a
If there are 20 chromatids in a cell at metaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80
a
If there are 20 chromatids in a cell, how many centromeres are there? A) 10 B) 20 C) 30 D) 40 E) 80
a
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in A) cells with more than one nucleus. B) cells that are unusually small. C) cells lacking nuclei. D) destruction of chromosomes. E) cell cycles lacking an S phase.
a
Nerve and muscle cells are in this phase: A) G0 B) G1 C) S D) G2 E) M
a
Of the following, the best conclusion concerning the difference between the S phases for beta and gamma is that A) gamma contains more DNA than beta. B) beta and gamma contain the same amount of DNA. C) beta contains more RNA than gamma. D) gamma contains 48 times more DNA and RNA than beta. E) beta is a plant cell and gamma is an animal cell.
a
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, taxol must affect A) the fibers of the mitotic spindle. B) anaphase. C) formation of the centrioles. D) chromatid assembly. E) the S phase of the cell cycle.
a
The MPF protein complex turns itself off by A) activating a process that destroys cyclin component. B) activating an enzyme that stimulates cyclin. C) binding to chromatin. D) exiting the cell. E) activating the anaphase-promoting complex.
a
The centromere is a region in which A) chromatids remain attached to one another until anaphase. B) metaphase chromosomes become aligned at the metaphase plate. C) chromosomes are grouped during telophase. D) the nucleus is located prior to mitosis. E) new spindle microtubules form at either end.
a
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to A) disruption of mitotic spindle formation. B) inhibition of regulatory protein phosphorylation. C) suppression of cyclin production. D) myosin denaturation and inhibition of cleavage furrow formation. E) inhibition of DNA synthesis.
a
Which of the following is released by platelets in the vicinity of an injury? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
a
Antiparallel strands twist to form
a double helix
Primer
a strand a few nucleotides long that is bonded to the template strand-- provides DNA polymerase with a free 3' hydroxyl (-OH) group that can combine with an incoming deoxyribonucleotide to form a phosphodiester bond.
DNA replication is very:
accurate average error rate of less than one mistake per billion bases
Females produce _____gametes
all X gametes
Trait
any characteristic of an individual
Cytokinesis in plants occurs :
as vesicles are transported from Golgi apparatus to middle of the dividing cell These vesicles fuse to form a CELL PLATE
If a trait appears equally often in males and females, it is likely to be
autosomal
all other types of chromosomes besides sex chromosomes are called
autosomes
Density-dependent inhibition is explained by which of the following? A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors. B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing. C) As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor. D) As cells become more numerous, more and more of them enter the S phase of the cell cycle. E) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.
b
For a newly evolving protist, what would be the advantage of using eukaryote -like cell division rather than binary fission? A) Binary fission would not allow for the formation of new organisms. B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes. C) Cell division would be faster than binary fission. D) Cell division allows for lower rates of error per chromosome replication. E) Binary fission would not allow the organism to have complex cells.
b
If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will A) move directly into telophase. B) complete the cycle and divide. C) exit the cycle and switch to a nondividing state. D) show a drop in MPF concentration. E) complete cytokinesis and form new cell walls.
b
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80
b
The research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long -term bacterial infections, and elderly volunteers. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the women teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples but got the same results. What might be among their conclusions? A) The young women showed these results because they have poorer nutrition. B) The elderly personsʹ samples demonstrated their lowered immune responses. C) The young men had higher response because they are generally healthier. D) The patient samples should have had the lowest response but did not, so the experiment is invalid. E) The elderly donor samples represent cells no longer capable of any cell division.
b
The somatic cells derived from a single-celled zygote divide by which process? A) meiosis B) mitosis C) replication D) cytokinesis alone E) binary fission
b
The ʺrestriction pointʺ occurs here: A) G0 B) G1 C) S D) G2 E) M
b
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei re-forming on either side of the cell plate. This cell is most likely A) an animal cell in the process of cytokinesis. B) a plant cell in the process of cytokinesis. C) an animal cell in the S phase of the cell cycle. D) a bacterial cell dividing. E) a plant cell in metaphase.
b
What is a chromatid? A) a chromosome in G1 of the cell cycle B) a replicate chromosome C) a chromosome found outside the nucleus D) a special region that holds two centromeres together E) another name for the chromosomes found in genetics
b
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? A) centromere B) centrosome C) centriole D) chromatid E) kinetochore
b
Which number represents DNA synthesis? A) I B) II C) III D) IV E) V
b
Which number represents the point in the cell cycle during which the chromosomes are replicated? A) I B) II C) III D) IV E) V
b
Which of the following are primarily responsible for cytokinesis in plant cells? A) kinetochores B) Golgi-derived vesicles C) actin and myosin D) centrioles and basal bodies E) cyclin-dependent kinases
b
Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis? A) The chromosomes are ʺreeled inʺ by the contraction of spindle microtubules. B) Motor proteins of the kinetochores move the chromosomes along the spindle microtubules. C) Non-kinetochore spindle fibers serve to push chromosomes in the direction of the poles. D) both A and B E) A, B, and C
b
Which of the following does not occur during mitosis? A) condensation of the chromosomes B) replication of the DNA C) separation of sister chromatids D) spindle formation E) separation of the spindle poles
b
Which of the following questions might be answered by such a method? A) How many cells are produced by the culture per hour? B) What is the length of the S phase of the cell cycle? C) When is the S chromosome synthesized? D) How many picograms of DNA are made per cell cycle? E) When do spindle fibers attach to chromosomes?
b
Which of the following triggers the cellʹs passage past the G2 checkpoint into mitosis? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
b
Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase
b
Why do chromosomes coil during mitosis? A) to increase their potential energy B) to allow the chromosomes to move without becoming entangled and breaking C) to allow the chromosomes to fit within the nuclear envelope D) to allow the sister chromatids to remain attached E) to provide for the structure of the centromere
b
A particular cyclin called cyclin E forms a complex with a cyclin-dependent kinase called Cdk 2. This complex is important for the progression of the cell from G1 into the S phase of the cell cycle. Which of the following statements is correct? A) The amount of cyclin E is greatest during the S phase. B) The amount of Cdk 2 is greater during G1 compared to the S phase. C) The amount of cyclin E is highest during G1. D) The amount of Cdk 2 is greatest during G1. E) The activity of the cyclin E/Cdk 2 complex is highest during G2.
c
An enzyme that attaches a phosphate group to another molecule is called a A) phosphatase. B) phosphorylase. C) kinase. D) cyclase. E) ATPase.
c
Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor? A) metastasis B) changes in the order of cell cycle stages C) lack of appropriate cell death D) inability to form spindles E) inability of chromosomes to meet at the metaphase plate
c
Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur? A) Cancer cells are no longer density dependent. B) Cancer cells are no longer anchorage dependent. C) Chromosomally abnormal cells can still go through cell cycle checkpoints. D) Chromosomally abnormal cells still have normal metabolism. E) Transformation introduces new chromosomes into cells.
c
Chromosomes first become visible during which phase of mitosis? A) prometaphase B) telophase C) prophase D) metaphase E) anaphase
c
DNA is replicated at this time of the cell cycle: A) G0 B) G1 C) S D) G2 E) M
c
In order for anaphase to begin, which of the following must occur? A) Chromatids must lose their kinetochores. B) Cohesin must attach the sister chromatids to each other. C) Cohesin must be cleaved enzymatically. D) Kinetochores must attach to the metaphase plate. E) Spindle microtubules must begin to depolymerize.
c
MPF reaches its threshold concentration at the end of this stage. A) I B) II C) III D) IV E) V
c
One difference between cancer cells and normal cells is that cancer cells A) are unable to synthesize DNA. B) are arrested at the S phase of the cell cycle. C) continue to divide even when they are tightly packed together. D) cannot function properly because they are affected by density-dependent inhibition. E) are always in the M phase of the cell cycle.
c
Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants A) the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils. B) sister chromatids are identical, but they differ from one another in animals. C) a cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage. D) chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase. E) spindle poles contain centrioles, whereas spindle poles in animals do not.
c
The decline of MPF activity at the end of mitosis is due to A) the destruction of the protein kinase Cdk. B) decreased synthesis of cyclin. C) the degradation of cyclin. D) synthesis of DNA. E) an increase in the cellʹs volume-to-genome ratio.
c
The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that A) the presence of the pathogen made the experiment too contaminated to trust the results. B) their tissue culture methods needed to be relearned. C) infection causes lymphocytes to divide more rapidly. D) infection causes cell cultures in general to reproduce more rapidly. E) infection causes lymphocyte cultures to skip some parts of the cell cycle.
c
Which is a general term for enzymes that activate or inactivate other proteins by phosphorylating them? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
c
Which term describes two centrosomes arranged at opposite poles of the cell? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase
c
All cancers arise from cells in which:
cell-cycle checkpoints have failed
each of the DNA copies in a replicated chromosome is called a
chromatid
Cross-pollination
collect pollen from one individual and transfer it to the female organs of an individual whose male organs have been removed
Genetic Recombination occurs when
crossing over takes place in meiosis I
A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes? A) 12 B) 16 C) 23 D) 46 E) 92
d
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. Those cells would have __________ picograms at the end of the S phase and __________ picograms at the end of G2. A) 8; 8 B) 8; 16 C) 16; 8 D) 16; 16 E) 12; 16
d
Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with A) a single large nucleus. B) high concentrations of actin and myosin. C) two abnormally small nuclei. D) two nuclei. E) two nuclei but with half the amount of DNA.
d
How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle? A) The daughter cells have half the amount of cytoplasm and half the amount of DNA. B) The daughter cells have half the number of chromosomes and half the amount of DNA. C) The daughter cells have the same number of chromosomes and half the amount of DNA. D) The daughter cells have the same number of chromosomes and the same amount of DNA. E) The daughter cells have the same number of chromosomes and twice the amount of DNA.
d
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested? A) anaphase B) prophase C) telophase D) metaphase E) interphase
d
If the cell whose nuclear material is shown in Figure 12.2 continues toward completion of mitosis, which of the following events would occur next? A) cell membrane synthesis B) spindle fiber formation C) nuclear envelope breakdown D) formation of telophase nuclei E) synthesis of chromatids
d
Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis? A) telophase B) prophase C) anaphase D) metaphase E) prometaphase
d
In the figure above, mitosis is represented by which number? A) I B) II C) III D) IV E) V
d
In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis? A) seedless plants B) dinoflagellates C) diatoms D) B and C only E) A, B, and C
d
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle was the nucleus with 6 picograms of DNA? A) G0 B) G1 C) S D) G2 E) M
d
Movement of the chromosomes during anaphase would be most affected by a drug that A) reduces cyclin concentrations. B) increases cyclin concentrations. C) prevents elongation of microtubules. D) prevents shortening of microtubules. E) prevents attachment of the microtubules to the kinetochore.
d
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A) 4 B) 8 C) 16 D) 32 E) 64
d
The best conclusion concerning delta is that the cells A) contain no DNA. B) contain no RNA. C) contain only one chromosome that is very short. D) are actually in the G0 phase. E) divide in the G1 phase.
d
These Protists are intermediate in what sense? A) They reproduce by binary fission in their early stages of development and by mitosis when they are mature. B) They never coil up their chromosomes when they are dividing. C) They use mitotic division but only have circular chromosomes. D) They maintain a nuclear envelope during division. E) None of them form spindles.
d
What causes the decrease in the amount of cyclin at a specific point in the cell cycle? A) an increase in production once the restriction point is passed B) the cascade of increased production once its protein is phosphorylated by Cdk C) the changing ratio of cytoplasm to genome D) its destruction by a process initiated by the activity of its complex with a cyclin E) the binding of PDGF to receptors on the cell surface
d
Which is the longest of the mitotic stages? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase
d
Which of the following is a function of those spindle microtubules that do not attach to kinetochores? A) maintaining an appropriate spacing among the moving chromosomes B) producing a cleavage furrow when telophase is complete C) providing the ATP needed by the fibers attached to kinetochores D) maintaining the region of overlap of fibers in the cellʹs center E) pulling the poles of the spindles closer to one another
d
Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
d
sex chromosome
determine the sex of the individuals
Allele
different versions of a specific gene
Organisms with two of each type of chromosome are termed:
diploid (2n) (plants/animals)
An example of trisomy is
down syndrom. Caused by an extra copy of chromosome 21.
A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation? A) The cell would prematurely enter anaphase. B) The cell would never leave metaphase. C) The cell would never enter metaphase. D) The cell would never enter prophase. E) The cell would undergo normal mitosis, but fail to enter the next G1 phase.
e
During which phases of mitosis are chromosomes composed of two chromatids? A) from interphase through anaphase B) from G1 of interphase through metaphase C) from metaphase through telophase D) from anaphase through telophase E) from G2 of interphase through metaphase
e
If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase? A) 1 B) 2 C) 4 D) 8 E) 16
e
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called A) ATPases. B) kinetochores. C) centrioles. D) proton pumps. E) cyclins.
e
The cyclin component of MPF is destroyed toward the end of this phase: A) G0 B) G1 C) S D) G2 E) M
e
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B? A) spindle formation B) spindle attachment to kinetochores C) DNA synthesis D) cell elongation during anaphase E) cleavage furrow formation
e
The formation of a cell plate is beginning across the middle of a cell and nuclei are re -forming at opposite ends of the cell. What kind of cell is this? A) an animal cell in metaphase B) an animal cell in telophase C) an animal cell undergoing cytokinesis D) a plant cell in metaphase E) a plant cell undergoing cytokinesis
e
This is the shortest part of the cell cycle: A) G0 B) G1 C) S D) G2 E) M
e
What is the most probable hypothesis about these intermediate forms of cell division? A) They represent a form of cell reproduction which must have evolved completely separately from those of other organisms. B) They demonstrate that these species are not closely related to any of the other Protists and may well be a different Kingdom. C) They rely on totally different proteins for the processes they undergo. D) They may be more closely related to plant forms that also have unusual mitosis. E) They show some of the evolutionary steps toward complete mitosis but not all.
e
Which of the following describe(s) cyclin-dependent kinase (Cdk)? A) Cdk is inactive, or ʺturned off,ʺ in the presence of cyclin. B) Cdk is present throughout the cell cycle. C) Cdk is an enzyme that attaches phosphate groups to other proteins. D) Both A and B are true. E) Both B and C are true.
e
Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
e
Which of the following is true concerning cancer cells? A) They do not exhibit density-dependent inhibition when growing in culture. B) When they stop dividing, they do so at random points in the cell cycle. C) They are not subject to cell cycle controls. D) B and C only E) A, B, and C
e
Which term describes centrioles beginning to move apart in animal cells? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase
e
primase
enzyme that synthesizes a short stretch of RNA that acs as a primer for DNA polymerase.
Morgan proposed that genes are more likely to cross over when they are:
far apart
Phenylketonuria (PKU) is an example of
gene-by-environment interaction
Multiple allelism
genes that have more than two alleles when more than two distinct phenotypes are present in a population due to multiple allelism the trait is called POLYMORPHIC
Males produce __________ gametes
half X gametes, half Y gametes
Organisms with just one of each type of chromosome are called:
haploid (n) (bacteria/archea, many algae, and plant/animal gametes)
bivalent
homologous replicated chromosomes that are joined together during prophase I and metaphase I of meiosis
Pure-line individuals are
homozygous
Malignant tumors are
invasive, cancerous, can spread through the body via blood or lymph, and initiate secondary tumors
A gene
is a section of DNA that influences one or more hereditary traits
Karyotype
is the number and types of chromosomes present in an organism
Lagging strand synthesis cannot be continuous.
it moves away from the replication fork. In bacteria, enzymes called primase, DNA polymerase III,, DNA polymerase I, and ligase work in sequence to synthesize Okazaki fragments and link them into a continuous whole.
Self-pollination
male organ of plant produces pollen, and female organ of same plant receives pollen
Codominance
neither allele is dominant or recessive to the other. a heteryozygous organism that displays the phenotype of BOTH alleles of a single gene
Organisms with three or more versions of each type of chromosome are called
polyploid (3n, 4n, etc)
Before mitosis each chromosome is
replicated
Chromatids from the same chromosome are referred to as
sister chromatids a replicated chromosome consists of TWO chromatids, but is still considered a single chromosome
leading strand
the enzymes product
replisome
the enzymes responsible for DNA synthesis around the replication fork joined into one large, multi-enzyme machine
Incomplete dominance
the heterozygotes have an intermediate phenotype
Wild type
the most common phenotype for each trait
haploid number
the number of DISTINCT TYPES of chromosomes present
A cell's ploidy (n, 2n,3n, etc...)
the number of EACH TYPE of chromosome present
Critical characteristic of DNA polymerases
they can only work in one direction
p53 is an example of a
tumor supressor. damage to the p53 gene can lead to uncontrolled cell division (cancer)
X-linked recessive traits
usually skip generations in a pedigree Hemophilia is an example
Cytokinesis in animals, fungi, and slime molds occurs:
when a ring of actin and myosin filaments contracts inside the cell membrane causing it to pinch inward into a CLEAVAGE FURROW
