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BIOL 100: Ch. 8

Terms in this set (88)

Amanda's parents realized that her body was not developing properly about the time she was 12 years old. She was shorter than most of her friends and was not going through changes normally associated with female puberty. They took her to a doctor who initially diagnosed Amanda with Turner Syndrome because of her physical features. The doctor ordered a karyotype that confirmed his diagnosis. Amanda was born with only one X chromosome. Although there is no specific cure, the doctor was able to treat her and correct some of the problems associated with the condition. For example, she received growth hormone to improve her growth and estrogen to help her develop the physical changes of puberty.

Amanda's abnormal number of sex chromosomes resulted from ________.
Non-disjunction
How many chromosomes does an individual with Turner syndrome have?
2n-1
A karyotype would be unable to determine
eye-color
A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. What is the most probable cause of the child's condition?
One of the gametes in the mother most likely underwent nondisjunction during meiosis.
T/F: A zygote is haploid.
True
The above figure shows that ________.
meiosis results in the formation of four haploid daughter cells
A(n) ________ is an example of an organism that can sometimes reproduce asexually by parthenogenesis.
zebra shark
Nondisjunction might result in gametes with the chromosome numbers ________.
n+1 or n-1
T/F: Sex chromosomes are present in gametes but not somatic cells.
False
Homologous chromosomes ________.
separate at meiosis I
are a set of chromosomes received from one parent during sexual reproduction
G1 phase of the cell cycle is associated with which cellular events?
Normal growth and cell function
T/F: G1 phase of the cell cycle is associated with which cellular events?
False
Bdelloid rotifers appear to reproduce only asexually. Which outcome, if found in this group, would demonstrate that sexual reproduction may occur?
Cells in which meiosis occurs
Which of the following statements describes a major difference between mitosis and meiosis in a diploid organism?
Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I
What happens during prophase?
The mitotic spindle begins to form.
The karyotype above shows ________.
trisomy 21, a cause of Down syndrome
Of the following human genetic disorders due to nondisjunction, which one generally has the most severe impact on the health of the individual?
47, trisomy 21
The drug cytochalasin B blocks the function of microfilaments. Which aspects of the animal cell cycle would be most disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
How much genetic material is present in a cell during prophase I compared to a cell that has completed meiosis II?
four times as much
For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes?
about 8 million
Chromatin consists of ________.
DNA and protein
When in mitosis are there twice as many chromatids compared to the original cell's chromosomes?
Prophase
T/F: In humans, somatic cells are diploid and gametes are haploid.
True
T/F: Nondisjunction is the main cause of miscarriages.
True
Eukaryotic cells have their chromosomes packaged in the ________.
Nucleus
Amanda's parents realized that her body was not developing properly about the time she was 12 years old. She was shorter than most of her friends and was not going through changes normally associated with female puberty. They took her to a doctor who initially diagnosed Amanda with Turner Syndrome because of her physical features. The doctor ordered a karyotype that confirmed his diagnosis. Amanda was born with only one X chromosome. Although there is no specific cure, the doctor was able to treat her and correct some of the problems associated with the condition. For example, she received growth hormone to improve her growth and estrogen to help her develop the physical changes of puberty.

With respect to her sex chromosomes, Amanda would be designated as ________.
XO
Sister chromatids are joined at the ________.
centromere
During metaphase, ________.
Chromosomes line up in the middle of the cell
T/F: Somatic cells in the human body contain 46 autosomes.
False
During anaphase I ________.
homologous chromosomes randomly separate and migrate to opposite poles
In meiosis, how does prophase I differ from prophase II?
During prophase I there is one diploid cell; during prophase II there are two haploid cells.
A cleavage furrow is ________.
a groove in the plasma membrane between daughter nuclei
Taxol is an anticancer drug that works by preventing microtubule disassembly. Thus, Taxol stops mitosis by interfering with ________.
cytokinesis (wrong)
mitotic spindle
If organisms reproduced sexually but without meiosis, what would result?
The chromosome number would double each generation.
A cell in prophase II of meiosis _______.
has half the amount of DNA present in the parent cell that began meiosis
Scientists obtain cells in various phases of the cell cycle. They obtain a group of cells that have 1½ times more DNA than G1 phase cells. The cells are most likely ________.
between the G1 and S phases of the cell cycle (wrong)
S phase
Starting with a fertilized egg (zygote), a series of six cell divisions would result in how many cells?
64
Which event occurs during anaphase?
Sister chromatids become separate chromosomes.
What is the chromosome number found in humans cells if meiosis I is completed normally?
22 autosomes and a sex chromosome
How does natural selection apply to sexual reproduction as opposed to asexual reproduction?
Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction.
What is a syndrome?
a characteristic group of symptoms typically associated with a particular chromosomal aberration or gene mutation
This diagram of the human life cycle shows that ________.
meiosis produces haploid sperm and egg cells
It has been proposed that miscarriages due to genetic defects occur in _____ of all pregnancies.
1/4
Examine the figure below. Nucleosomes are made of ________.
DNA and histone proteins
The 2n number for the cell depicted here is ________.
two
Most _______ and _______ cells of the body are in a permanently non-dividing state.
Skin; liver (wrong)
nerve;muscle
Which of the following processes occur during meiosis but not mitosis?
Diploid cells form haploid cells.
A major function of the mitotic spindle during M phase of the cell cycle is ________.
Separation of sister chromatids
Which characteristic seen in prophase I does NOT occur in prophase II?
Crossing over occurs.
T/F: Nucleosomes consist of DNA and histones.
True
Eukaryotic chromosomes are composed of ________.
DNA and proteins
Which does NOT occur in the life cycle of an organism that reproduces by sexual reproduction?
Exchange of chromosomes between organisms of different species
Which of the following processes occurs in meiosis but not in mitosis?
Synapsis of chromosomes
The CORRECT sequence of stages of mitosis is ________.
prophase, metaphase, anaphase, telophase
One difference between mitosis and meiosis is that mitosis ________.
produces cells genetically identical to the parent cell, but meiosis does not
T/F: During prophase I of meiosis, synapsis of homologous chromosomes leads to formation of tetrads.
True
Immunotherapy is a promising new type of cancer treatment. Which treatment below is not a type of immunotherapy?
creating proteins that kill cancer cells and giving them to a cancer patient (wrong)
Upon completion of telophase I and cytokinesis in meiosis, there is(are) ________ cell(s).
two haploid
What is the chromosome composition of a normal human male?
44 autosomes, 1 X chromosome, and 1 Y chromosome
When chiasmata are seen in cells using a microscope, the cells are most likely in which stage of meiosis?
prophase I
T/F: In humans, meiosis occurs in both somatic cells and gametes.
False
During metaphase I ________.
homologous chromosomes line up in the middle of the cell
Which activity will help prevent cancer and increase survival?
Seek early detection of tumors.
A cell that completed the cell cycle without undergoing cytokinesis would ________.
have two nuclei
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell during metaphase I of meiosis will be ________.
2x
During cell division in eukaryotic cells, the nuclear envelope has to disappear to permit ________.
separation of the centrosomes (wrong)
________ is the only known condition in humans where having 45 chromosomes is not fatal.
Turner syndrome
The cell cycle normally halts within the ______ phase of interphase unless specific proteins of the cell cycle control system are present.
G1
A karyotype ________.
is an organized picture of a cell's chromosomes.
T/F: Meiosis occurs in both eukaryotes and prokaryotes.
False
Anaphase II is essentially the same as mitotic anaphase except that in anaphase II ________ and in mitotic anaphase ________.
the cells are haploid and sister chromatids separate; the cells have the same number of chromosomes as the original cell and sister chromatids separate
Genetic variation is accomplished by all but one of the following. Choose the EXCEPTION.
the events of meiosis II
Which statement is TRUE of a cell at the conclusion of meiosis I?
The daughter cells no longer have pairs of homologous chromosomes.
Which of the following processes occurs when homologous chromosomes cross over in meiosis I?
Corresponding segments of non-sister chromatids are exchanged.
A correct comparison between a benign and a malignant tumor is that ________.
Benign tumors do not metastasize; malignant tumors do.
Which of the following is an example of monosomy in humans?
Turner syndrome
Which statement accurately describes the structure of a eukaryotic chromosome?
It is a single linear molecule of double-stranded DNA plus proteins.
Tetrads normally occur during which stage(s) of meiosis?
prophase I
Crossing over of chromosomes normally takes place during ________.
meiosis I
What happens during interphase?
Chromosome duplication occurs.
How do cells at the completion of meiosis II compare with cells that are in prophase of meiosis I?
The cells have half the number of chromosomes and one-fourth the amount of DNA.
Karyotypes are usually prepared from cells in which stage of mitosis?
metaphase
T/F: Mitosis occurs in both eukaryotes and prokaryotes.
False
How is plant cell cytokinesis different from animal cell cytokinesis?
Plant cells form a cell plate between the two daughter cells; animal cells form a cleavage furrow.
T/F: Chromosomes can be seen with a light microscope during all phases of the cell cycle.
False
As shown in the accompanying figure, plant cell cytokinesis differs from animal cell cytokinesis because ________.
plant cells form a cell plate and animal cells do not
Using a microscope, you see a cell plate developing across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely ________.
a plant cell in the process of cytokinesis
A duplicated chromosome consists of two ________.
sister chromatids
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