BIO 134 Exam 2 Practice
True or False: You can find sister chromatids in the cell nucleus at any point during the life of the cell
False
True or false: Cell division requires the function of all three components of the cytoskeleton: microtubules, microfilaments, and intermediate filaments.
False
ID the phases of the cell cycle. what happens in each phase? what is the goal of the cell cycle?
G1- cell makes components to duplicate DNA S- duplication of DNA G2- organelles, nucleotides, and centrosomes duplicate and the cell prepares for division M- cell divides the goal of the cell cycle is to prepare the cell for mitosis
During which phase of the cell cycle would you expect to see an increase in the number of ribosomes in the cell
G2
If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents? A) It has half the amount of DNA as the cell that began meiosis. B) It has the same number of chromosomes but different alleles than another cell from the same meiosis. C) It has half the chromosomes but twice the DNA of the originating cell. D) It has one-fourth the DNA and one-half the chromosomes as the originating cell. E) It is identical in content to another cell from the same meiosis.
A
If there are 20 chromatids in a cell in prophase, how many chromosomes will there be in the daughter cells at the end of mitosis? A) 10 B) 20 C) 30 D) 40 E) 80
A
Which is the smallest unit containing the entire human genome? A) one human somatic cell B) one human chromosome C) all of the DNA of one human D) the entire human population E) one human gene
A
Which of these is a way that the sexual life cycle increases genetic variation in a species? A) by allowing crossing over B) by allowing an increase in cell number C) by increasing gene stability D) by conserving chromosomal gene order E) by decreasing mutation frequency
A
Humans have a total of 46 chromosomes, organized into 23 pairs. Which of the following statements is/are true of human cells? A. Human somatic cells have 23 chromosomes and gametes have 46. B. Human somatic cells have 46 chromosomes and gametes have 23. C. Human somatic cells have 92 chromosomes, 46 pairs; human gametes have 23 pairs of chromosomes. D. Human gametes have 23 random chromosomes.
B
Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white? A) red × white B) roan × roan C) white × roan D) red × roan E) none of the above
B
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
B
A genome can best be described as: A. all of the DNA that codes for a protein. B. the DNA in the chromosomes of a cell. C. all of the DNA in a cell. D. all of the DNA in the nucleus.
C
Genome
a cell's endowment of DNA (its genetic information)
chromosome
a cellular structure consisting of one DNA molecule and a protein
compare and contrast gene and allele
a gene is a stretch of DNA on a chromosome that carries information on synthesis of a protein, while an allele is different versions of the same gene
centromere
a region of the chromosomal DNA where the chromatid is attached most closely to its sister chromatid
cleavage furrow
a shallow groove in the cell surface near the old metaphase plate
at the end of G2, what must happen in order for mitosis to proceed correctly?
centrosomes must replicate and the cell makes copies of everything except DNA in the cell
distinguish between a chromatid and a chromosome. at what points in the cell cycle/mitosis do we see chromatids vs chromosomes?
chromatid is a pair of identical chromosomes 8 chromatid is the chromosome put together 88 *chromosomes are visible during prophase and metaphase *chromatids are visible during anaphase and telophase *sister chromatids are seen during pro metaphase, metaphase, and anaphase
how does cytokinesis occur?
cleavage
what is the first sign of cleavage?
cleavage furrow
compare and contrast dominant and recessive
dominant only needs one allele to show the phenotype while recessive needs both alleles to show the phenotype
phases of mitosis
prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis
gametes
reproductive cells (23 chromosomes)
Each duplicated chromosome has two ___________________.
sister chromatids
compare somatic cell vs gamete
somatic cell refers to all cells that contain the full number of chromosomes for an organism (most cells in the body) gametes, or sex cells, have half the amount of DNA because two sex cells join to share the formation of offspring (sperm or egg)
cytokinesis
the division of the cytoplasm
mitosis
the division of the genetic material in the nucleus
chromatin
the entire complex of DNA and proteins that is the building material of chromosomes
sister chromatids
two copies of a duplicated chromosome attached to each other by proteins at the centromere, and sometimes along the arms
what happens during cytokinesis?
two daughter cells appear shortly after end of mitosis
meiosis
yields daughter cells with only one set of chromosomes
A plant-derived protein known as colchicine can be used to poison cells by blocking the formation of the spindle. Which of the following would result if colchicine is added to a sample of cells in G2? A) The cells would immediately die. B) The cells would be unable to begin M and stay in G2. C) The chromosomes would coil and shorten but have no spindle to which to attach. D) The chromosomes would segregate but in a disorderly pattern. E) Each resultant daughter cell would also be unable to form a spindle.
C
Cells from advanced malignant tumors often have very abnormal chromosomes as well as an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities? A) Cancer cells are no longer density dependent. B) Cancer cells are no longer anchorage dependent. C) Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities. D) Chromosomally abnormal cells still have normal metabolism. E) Transformation introduces new chromosomes into cells.
C
Crosses that would produce offspring in the ratio of 1 red:2 roan:1 white is an example of what type of inheritance? A) incomplete dominance B) complete dominance C) codominance D) epistasis E) sex-linked
C
In a single-celled organism, the main function of cell division is: A. growth B. wound healing C. reproduction D. development
C
SRY is best described in which of the following ways? A) a gene present on the X chromosome that triggers female development B) an autosomal gene that is required for the expression of genes on the Y chromosome C) a gene region present on the Y chromosome that triggers male development D) an autosomal gene that is required for the expression of genes on the X chromosome E) a gene required for development, and males or females lacking the gene do not survive past early childhood
C
What is the name given to the complex of proteins that assemble on the centromere during cell division? A. centromere B. aster C. kinetochore D. chromatid
C
When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? A) 0% B) 25% C) 50% D) 75% E) 100%
C
Where do the microtubules of the spindle attach to chromosomes during mitosis in animal cells? A) centromere B) centrosome C) centriole D) chromatid E) kinetochore
E
True or False: The process of splitting the two new cells apart is known as cytokinesis.
True
what happens during prophase?
*DNA condenses into chromosomes *centrosomes dictate direction of cell division *microtubules formed from centrosomes
what happens during metaphase?
*centrosomes are at opposite ends of the cell *chromosomes are all lined up on metaphase plate *microtubules connected to kinetochore
binary fission
*means "division in half" *when prokaryotes undergo a type of reproduction in which the cell grows to roughly double its size and then divides to form two cells
what happens during pro metaphase?
*microtubules extending from each centrosome can now invade the nuclear area *chromosomes even more condensed *each of the two chromatids of each chromosome now has a kinetochore *some microtubules connect to kinetochore *nonkinetochore microtubules interact with those from the opposite pole of the spindle
what happens during anaphase?
*shortest stage of mitosis *anaphase begins when the cohesin proteins are cleaved. this allows the two sister chromatids of each pair to part. each chromatid becomes a chromosome *two daughter chromosomes begin to move towards opposite ends of the cell when the microtubules shorten *cell elongates when nonkinetochore microtubules lengthen
what is a cell checkpoint? what places in the cell cycle do these occur? how does a cell "push" itself through these checkpoints?
*these checkpoints occur at G1, G2, and M (metaphase). *cell cycle checkpoints are restriction points that make sure cell has proper condition to divide. *platelet- derived growth factors is required for cell division and pushes the cell past the G1 checkpoint. *The cell will either enter Go if it can not push through and fix itself or it will die *cyclin- CDK complex
what happens during telophase?
*two daughter nuclei form in the cell *nucleoli reappear *chromosomes become less condensed *remaining microtubules become depolymerized *mitosis, the division of one nucleus into two genetically identical nuclei, is now complete
Taxol is an anticancer drug extracted from the Pacific yew tree. in animal cells, taxol disrupts microtubule formation by binding to microtubules and affecting their assembly from the protein precurson rebuild. surprisingly this stops mitosis. specifically, Taxol must affect: A. the formation of the mitotic spindle B. anaphase C. formation of the centrioles D. chromatid assembly E. the S phase of the cell
A.
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. How many picograms would be found at the end of S and the end of G2? A) 8; 8 B) 8; 16 C) 16; 8 D) 16; 16 E) 12; 16
D
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the offspring of crosses BbTt × BBtt will be expected to have black fur and long tails? A) 1/16 B) 3/16 C) 3/8 D) ½ E) 9/16
D
Males are more often affected by sex-linked traits than females because A) male hormones such as testerone often alter the effects of mutations on the X chromosome. B) female hormones such as estrogen often compensate for the effects of mutations on the X chromosome. C) X chromosomes in males generally have more mutations than X chromosomes in females. D) males are hemizygous for the X chromosome. E) mutations on the Y chromosome often worsen the effects of X-linked mutations.
D
What is produced if a cell divides by mitosis but does not undergo cytokinesis? A) two cells, one cell containing two nuclei and a second cell without a nucleus B) two cells, each cell with half of the genetic material of the parent cell C) one cell with one nucleus containing half of the genetic material of the parent cell D) one cell with two nuclei, each identical to the nucleus of the parent cell
D
A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following? A) It must be human. B) It must be a primate. C) It must be an animal. D) It must be sexually reproducing. E) Its gametes must have 23 chromosomes.
E
A sexually reproducing animal has two genes on separate chromosomes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? A) tt B) Hh C) HhTt D) T E) HT
E
Chromatids are separated from each other. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II.
E
In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC? A) ¼ B) 1/8 C) 1/16 D) 1/32 E) 1/64
E
Several organisms, primarily protists, have what are called intermediate mitotic organization. What is the most probable hypothesis about these intermediate forms of cell division? A) They represent a form of cell reproduction that 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 but not all of the evolutionary steps toward complete mitosis.
E
The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following? A) mitosis in her ovary B) metaphase I of meiosis C) telophase II of meiosis D) telophase I of meiosis E) either anaphase I or II
E
compare and contrast the processes of mitosis and meiosis. how are they similar and different?
Mitosis: *Identical daughter cells *cytokinesis separates cell into two cells *makes diploid cells Meiosis: *Two processes (Meiosis 1 and Meiosis 2) *Daughter cells (gametes) that are different from parent cell *Meiosis 1, cytokinesis does not separate the cell *Homologous pairs separate in Meiosis Metaphase 1 *Makes haploid cells Both: *uses prophase, metaphase, anaphase, and telophase *chromosomes replicate in S phase
In order, the phases of mitosis are
Prophase, Prometaphase, Metaphase, Anaphase, and Telophase
What must happen before the cell can divide to form genetically identical daughter cells?
The DNA must be copied (or replicated), then the two copies must be separated so that each daughter cell ends up with a complete genome
Define Mendel's 2 Laws of Inheritance.. Explain where in meiosis we see these laws take place and why they are important for determining gametes in genetic crosses
The Law of Independent Assortment *each pair of alleles segregate from other pairs of alleles during gamete formation. *Metaphase 1 *gives different traits equal opportunity of occurring together The Law of Segregation *homologous pairs separate to form new gametes *one allele per gamete *Anaphase 1 *important because you can not have 2 alleles for the same gene in one gamete
somatic cells
all body cells except the reproductive cells (contain 46 chromosomes)
what are asexual and sexual reproduction and how do they differ? what are the benefits to sexual reproduction?
asexual reproduction is when an individual reproduces by itself (offspring are "clones" of parents) sexual reproduction is when an individual reproduces with another individual (offspring different from parents) benefits: genetic variation for entire organism.
compare autosome vs sex chromosome
autosomes are other chromosomes that are not sex chromosomes. they contain genes that code for characteristics of an organism. sex chromosomes are the chromosomes that determine what sex an organism will be (in humans: female: xx male: xy)
compare and contrast genotype vs phenotype
genotype refers to the alleles, while phenotype refers to the outward appearance of the individual
compare and contrast haploid vs diploid
haploid is half the number of chromosomes (1 homologous pair) N, gametes diploid is full number of chromosomes, 2N, somatic
compare and contrast homozygous vs heterozygous
homozygous is having two of the same dominant alleles or two of the same recessive alleles, while heterozygous is having one dominant and one recessive allele
what are sister chromatids considered once they separate?
individual chromosomes (this step doubles the amount of chromosomes in the cell)
why is meiosis 1 considered a "reductional" division? why is it important for gametes to be formed by meiosis?
it is considered "reductional' division because homologous chromosomes separate into two daughter cells. this separates the DNA and reduces it by half. it is important for gametes to be formed by meiosis because it cuts down the DNA by half, so there will not be too much or too little of DNA in the offspring.
explain how mitosis evolved from bacteria---> dinoflagellates ---> yeast ---> animals
mitosis came from binary fission in prokaryotes. eukaryotes with nuclear envelopes and larger genomes developed the process of mitosis. dinoflagellates and yeast go through "intermediate mitosis"; their nuclear envelopes do not fragment, unlike mitosis. chromosomes divide and separate within the nucleus and use microtubules Evolution of Mitosis - We can hypothesize that mitosis evolved from simpler prokaryotic cell reproduction since some proteins involved in bacterial binary fission are similar to eukaryotic proteins in mitosis. - Possible intermediate stages in the evolution of mitosis might be found in dinoflagellates, diatoms and some yeasts. - In these types of nuclear division, the nuclear envelope remains intact in contrast to what happens in most eukaryotic cells.
