Chapter 3 both
What would be the sex of a human with each of the following sets of sex chromosomes? XXY
Male; the Y chromosome determines maleness.
What would be the sex of a human with each of the following sets of sex chromosomes? XYY
Male; the Y chromosome determines maleness.
With regard to sister chromatids, which phase of mitosis is the organization phase, and which is the separation phase?
Metaphase, anaphase
Which of the following does not occur during prophase of meiosis I?
Separation of the homologous chromosomes
_________ is when two _______ fuse with each other in the process of fertilization to begin the life of a new organism.
Sexual reproduction; gametes
A ring of the protein FtsZ forms at the future site of the septum.
T
After binary fission is completed, two identical cells result.
T
Binary fission is a form of asexual division.
T
Homologous chromosomes are 99% identical.
T
Homologous chromosomes carry the same types of genes.
T
Homologous chromosomes may contain different alleles of a gene.
T
T or F: In animals sperm production can be continuous or seasonal.
T
T or F: In animals spermatogenesis usually produces four viable products.
T
T or F: Mitosis and cytoplasmic division result in the formation of two genetically identical cells.
T
The daughter cells are separated by formation of a septum.
T
Assuming that such a fly would be viable, what would be the sex of a fruit fly with the following chromosomal composition? One X chromosome and two sets of autosomes
The fly is a male because the ratio of X chromosomes to sets of autosomes is 1/2, or 0.5.
What would be the sex of a human with each of the following sets of sex chromosomes? XXX
Female; there are no Y chromosomes.
A cell has four pairs of chromosomes. Assuming that crossing over does not occur, what is the probability that a gamete will contain all of the paternal chromosomes? If n equals the number of chromosomes in a set, which of the following expressions can be used to calculate the probability that a gamete will receive all of the paternal chromosomes: (1/2)^n, (1/2)^n-1, or n^1/2?
(1/2)^n = (1/2)^4 = 1/16 or 6.25%
Morgan knew that female flies have 2 X chromosomes and male flies have one X. He used reciprocal crosses to demonstrate that inheritance of X-linked traits was consistent with these differences. Given the following reciprocal crosses what are the expected phenotypic ratios for the progeny? Xw is the allele for white eyes. Xw+ is the wild type allele for red eyes. Xw+ is dominant to Xw. XwXw crossed with Xw+Y 1/2 white males
1/2 red females
How many chromosomes will each cell have after mitosis?
10
A red-eyed female is mated to a white-eyed male. What percentage of the male progeny have red eyes if the parental female was homozygous?
100%
How many centromeres are in the cell at metaphase?
14
How many centromeres are in the cell at prophase?
14
Describe chromosome number in meiosis II in humans.
1N -> 1N
Following mitosis how many cells will be produced?
2
How many centrosomes are in the cell at metaphase?
2
How many centrosomes are in the cell at prophase?
2
Arrange the following events in the proper order in which they occur during meiosis I. 1 = Separation of homologous chromosomes 2 = Synapsis 3 = Crossing-over 4 = Independent assortment
2, 3, 4, 1
If a diploid cell contains six chromosomes (i.e. three per set), how many possible random arrangements of homologs could occur during metaphase of meiosis I?
2^3, which is 8.
How many centrioles are in the cell at metaphase?
4
How many centrioles are in the cell at prophase?
4
The arctic fox has 50 chromosomes (25 per set), and the common red fox has 38 chromosomes (19 per set). These species can interbreed to produce viable but infertile offspring. How many chromosomes would the offspring have? What problems do you think may occur during meiosis that would explain the offspring's infertility?
44 chromosomes (i.e. 25+19). each chromosome does not have a homologous partner.
How many chromosomes are present in a human primary oocyte? How many chromatids?
46; 92
How many chromosome pairs are in the cell?
5
A red-eyed female is mated to a white-eyed male. What percentage of the male progeny have red eyes if the parental female was heterozygous (XW+XW)?
50%
Three genes (A,B, and C) are found on three different chromosomes. For the following diploid genotypes, describe all of the possible gamete combinations. Aa Bb Cc
A B C, A B c, A b C, A b c, a B C, a b C, a B c, a b c
Three genes (A,B, and C) are found on three different chromosomes. For the following diploid genotypes, describe all of the possible gamete combinations. Aa BB Cc
A B C, A B c, a B C, a B c
Three genes (A,B, and C) are found on three different chromosomes. For the following diploid genotypes, describe all of the possible gamete combinations. AA Bb CC
A B C, A b C
Three genes (A,B, and C) are found on three different chromosomes. For the following diploid genotypes, describe all of the possible gamete combinations. Aa bb cc
A b c, a b c
u have set up a mating between white-eyed male and wild-type female flies. The F1 progeny consist entirely of red-eyed males and red-eyed females, which are allowed to mate with each other. Predict the phenotype(s) of the F2 progeny.
All red-eyed females; white and red-eyed males in equal proportions.
Eukaryotic cells must sort their chromosomes during mitosis so each daughter cell receives the correct number of chromosomes. Why don't bacteria need to sort their chromosomes?
Bacteria do not need to sort their chromosomes because they only have one type of chromosome.
Which principles are part of the chromosome theory of inheritance?
Chromosomes contain genetic material that is transmitted from parent to offspring. The nuclei of most eukaryotic cells contain chromosomes that are found in homologous pairs. Each parent contributes one set of chromosomes to its offspring.
For the following events, specify whether they occur during mitosis, meiosis I, or meiosis II: Alignment of chromatids along the metaphase plate.
During all
With regard to thickness and length, what do you think chromosomes would look like if you microscopically examined them during interphase? How would that compare with their appearance during metaphase?
During interphase, the chromosomes are longer, thinner, and much harder to see. In metaphase, they are highly condensed, which makes them thicker and shorter.
For the following events, specify whether they occur during mitosis, meiosis I, or meiosis II: Pairing of homologous chromosomes.
During meiosis I
Choose the scenario that is best explained by Mendel's law of segregation.
During meiosis, a rose plant containing a dominant red petal allele and a recessive white petal allele creates gametes in which these alleles are separate.
For the following events, specify whether they occur during mitosis, meiosis I, or meiosis II: Attachment of sister chromatids to both poles.
During mitosis and meiosis II
For the following events, specify whether they occur during mitosis, meiosis I, or meiosis II: Separation of conjoined chromatids within a pair of sister chromatids.
During mitosis and meiosis II
You have crossed a red-eyed female to a red-eyed male. What outcome from your cross would indicate that the female was heterozygous?
Equal proportions of white-eyed males and red-eyed males.
Chromosomes that are heterozygous for an allele are not homologous.
F
Each cell has two copies of the chromosome following division.
F
Haploid organisms can have homologous chromosomes.
F
Most eukaryotes divide by binary fission.
F
T or F: Independent assortment occurs in prophase I
F
The physical location of a gene on the chromosome is called its allele.
F
T or F: DNA replication occurs in mitosis
False
T or F: Germ-line cells are haploid but gametes are diploid.
False
What would be the sex of a human with each of the following sets of sex chromosomes? X(also described as Xo)
Female; there are no Y chromosomes.
What is the correct order of the phases of the cell cycle?
G1 -> S -> G2 -> M
A eukaryotic cell is diploid containing 10 chromosomes (5 in each set). For mitosis and meiosis, how many daughter cells would be produced, and how many chromosomes would each one contain?
Mitosis--two diploid cells containing 10 chromosomes each (two complete sets). Meiosis--four haploid cells containing 5 chromosomes each (one complete set)
Assuming that such a fly would be viable, what would be the sex of a fruit fly with the following chromosomal composition? Four X chromosomes, two Y chromosomes, and four sets of autosomes
The fly is female because the ratio of X chromosomes to sets of autosomes is 1.0.
Assuming that such a fly would be viable, what would be the sex of a fruit fly with the following chromosomal composition? Two X chromosomes, one Y chromosome, and two sets of autosomes
The fly is female because the ratio of X chromosomes to sets of autosomes is 1.0.
Assuming that such a fly would be viable, what would be the sex of a fruit fly with the following chromosomal composition? Two X chromosomes and four sets of autosomes
The fly is male because the ratio of X chromosomes to sets of autosomes is 0.5.
With regard to question c13, how would the phenomenon of crossing over affect the results? In other words, would the probability of a gamete inheriting only paternal chromosomes be higher or lower?
The probability of inheriting only paternal chromosomes would be much lower because pieces of maternal chromosomes would be mixed with the paternal chromosomes. Therefore, inheriting a chromosome that was completely paternally derived would be unlikely.
Explain why the products of meiosis ay not be genetically identical, whereas the products of mitosis are.
The products of meiosis have only one copy of each type of chromosome. In contrast, mitosis produces genetically identical daughter cells that have both copies of all the pairs of homologous chromosomes.
Select the true statements about chromosomes
The term chromosome means colored body. Each chromosome contains a very long segment of DNA.
You have a diploid cell with 6 chromosomes. Which of the following would be true for this cell?
There are 6 chromosomes present at metaphase I.
T or F: Egg production in animals and plants is similar because in both cases only one viable product is made
True
T or F: In human females all primary oocytes are produced before birth.
True
T or F: Meiosis in both plants and animals produces haploid products.
True
Discuss why crosses (ie the experiments of Mendel) and the microscopic observations of chromosomes during mitosis and meiosis were both needed to deduce the chromosome theory of inheritance.
You need to make crosses to understand the pattern of inheritance of traits (determined by genes) from parents to offspring. And you need to microscopically examine cells to understand the pattern of transmission of chromosomes. The correlation between the pattern of transmission of chromosomes during meiosis, and Mendel's laws of segregation and independent assortment, is what led to the chromosome theory of inheritance.
Describe the key events during meiosis that result in a 50% reduction in the amount of genetic material per cell.
a single DNA replication event but two cell divisions.
In Morgan's experiments which result do you think is the most convincing piece of evidence pointing to x-linkage of the eye color gene?
all of the white-eyed flies of the F2 generation were males.
Morgan knew that female flies have 2 X chromosomes and male flies have one X. He used reciprocal crosses to demonstrate that inheritance of X-linked traits was consistent with these differences. Given the following reciprocal crosses what are the expected phenotypic ratios for the progeny? Xw is the allele for white eyes. Xw+ is the wild type allele for red eyes. Xw+ is dominant to Xw. Xw+ Xw+ crossed with XwY
all red progeny
Environmental conditions determine sex.
alligators
Prokaryotic chromosomes
are usually circular pieces of DNA. contain many genes.
Males are haploid, females are diploid.
bees
The female is the heterogametic sex.
birds
The division of the cytoplasm is called
cytokinesis
T or F: Both plants and animals have sporophytic and gametophytic portions of their life cycle.
false
Nine-banded armadillos almost always give birth to four offspring that are genetically identical quadruplets. Explain how you think this happens
fertilization begins with one sperm and one egg cell. This fertilized egg then could divide twice by mitosis to produce four genetically identical cells. These four cells could then separate from each other to begin the lives of four distinct individuals.
The X to autosome ratio determines sex.
flies
The process of binary fission begins with a single mother cell and ends with two daughter cells. Would you expect the mother and daughter cells to be genetically identical? Explain why or why not.
genetically identical
The male is the heterogametic sex and Y determines maleness.
humans
What is a sister chromatid? Are sister chromatids genetically similar or identical? Explain.
identical copies derived from the replication of a parental chromosome. genetically identical
Stages of mitosis
interphase --> prophase --> prometaphase --> metaphase --> anaphase --> telophase --> cytokinesis
cytokinesis:
is a division of the cytoplasm and organelles. Correct involves a cleavage furrow in animals. Correct yields two cells with nuclei
Stages of meisosis 1 Prophase
leptotene --> zygotene --> pachytene --> diplotene --> diakenesis
How does the attachment of the kinetochore microtubules to the kinetochore differ in metaphase of meiosis I and metaphase of mitosis? Discuss what you think would happen if a sister chromatid was not attached to a kinetochore microtubule.
metaphase I: one pole via the kinetochore microtubules. metaphase: two attachments (i.e. to both poles). If the attachment was lost, a chromosome would not migrate to a pole
Centromeres divide in
mitosis and meiosis II.
The period between meiosis I and meiosis II is called interphase II. Does DNA replication take place during interphase II?
no
Egg cell formation
primary oocyte --> secondary oocyte and first polar body --> second polar body --> egg cell
What is the correct order of the phases of mitosis?
prophase -> metaphase -> anaphase -> telophase
The arrangement of homologs during metaphase of meiosis I is a random process. In your own words, explain what this means.
the maternally derived and paternally derived chromosomes are randomly aligned along the metaphase plate during metaphase I.
What is a homolog? With regard to genes and alleles, how are homologs similar to and different from each other?
the members of a chromosome pair. same size and carry the same types and order of genes. differ in that the genes they carry may be different alleles.
Why is it necessary for the chromosomes to condense during mitosis and meiosis? What do you think might happen if the chromosomes were not condensed?
they might get tangled up with each other and not sort properly during meiosis and mitosis. T easily align along the metaphase plate
T or F: Pollen grains are made up of a single cell.
true