Bio: Ch. 8 - EXAM 3
Meiosis I produces ____ haploid cells?
2
What is the chromosome number found in humans cells after meiosis I is completed?
22 autosomes and a sex chromosome
Meiosis is typically accomplished in _____ many steps.
3 - all of the chromosomes are duplicated in a diploid cell, and then there are two cell divisions to produce a total of four haploid gametes.
Meiosis II produces ___ haploid cells?
4
What chromosomes belong to a typical human female?
44 autosomes and 2 X chromosomes
What chromosomes belong to a typical human male?
44 autosomes, 1 X chromosome and 1 Y chromosome
With the exception of gametes, a human cell contains, how many chromosomes?
46 total. 22 pairs of autosome chromosomes + 2 sex chromosomes.
Sexual reproduction in humans allows what to happen?
A haploid sperm cell to fertilize a haploid egg cell
Homologous chromosomes migrate to opposite poles during_______?
Anaphase I
During Meiosis in the ______ phase, the sister chromatids separate?
Anaphase II
The sister chromatids separate and begin moving toward opposite poles of the cell, during which phase of Mitosis?
Anaphase; sisters separate
What is the difference between a Benign and a Malignant Tumor?
Benign Tumors do not metastasize; Malignant Tumors do.
Mitosis produces?
Cells genetically identical to the parent cell
Most of an organisms DNA is carried by its?
Chromosomes
At the end of the Mitotic (M) phase, the cytoplasm divides in a process called____?
Cytokinesis which occurs in-conjuction with Telophase; last phase in Mitosis
Nucleosomes are made of what?
DNA and histone proteins make
Chromatin consists of?
DNA and protein
Meiosis starts with ______ cells and produces _____ gametes?
Diploid & haploid
Asexual reproduction _________?
Does not happen often, but can produce offspring genetically identical to the one single parent
Karyotype Trisomy 21 is a cause of?
Down Syndrome, triploid for chromosome 21
What is the difference of Prophase I and Prophase II during Meiosis?
During Prophase I there is one diploid cell; during Prophase II there are two haploid cells.
Crossing over during Prophase I, results in?
Genetic recombination
What term is used to describe the way homologous pairs of chromosomes line up at random orientation during Metaphase I?
Independent assortment; daughter cell randomly inherits either the maternal or paternal chromosome from each pair.
Chromosome duplication occurs during what phase?
Interphase
Nucleoli are present during?
Interphase
Chromosomes line up in the middle of the cell, during what phase?
Metaphase
Homologous chromosomes line up in the middle of the cell, during what phase?
Metaphase I (middle phase)
During _____ chromosomes align single file along the equator of a haploid cell?
Metaphase II
The chromosomes line up in the center of the cell during which phase of Mitosis?
Metaphase; the middle phase of Mitosis.
The mitotic phase encompasses both?
Mitosis and Cytokinesis
Accidents can occur in Meiosis wherein members of a chromosome pair fail to separate at Anaphase. This is called ?
Non-disjunction; when gametes have too few and/or many chromosomes
Spindle fibers attach to kinetochores during what phase?
Pro-metaphase; spindle fibers attach
The mitotic spindle begins to form in which phase?
Prophase
Synapsis occurs during______?
Prophase I; pairing of homologous chromosomes.
During ____ a spindle forms in a haploid cells.
Prophase II
Name the correct sequence of stages in Mitosis:
Prophase, Metaphase, Anaphase, Telophase
Chromosomes become visible during______?
Prophase; the chromatin fibers become discrete chromosomes
The centrosomes move away from each other and the nuclear envelope breaks up during which phase of Mitosis?
Prophase; the first phase of Mitosis, when the centrosomes begin moving toward opposite poles and the nuclear envelope breaks up.
The function of Meiosis is/are _________?
Reproduction (production of gametes)
What happens during Anaphase?
Sister chromatids become separate chromosomes.
What happens to the sister chromatids during Anaphase?
Sister chromatids separate and migrate to opposite poles
Cytokinesis often, but not always, accompanies_______?
Telophase
The events of Prophase are revered, during what phase?
Telophase
At the end of _______ and cytokinesis, haploids cells contain chromosomes that each consist of two sister chromatids.
Telophase I
At the end of _____ and Cytokinesis there are four haploid cells.
Telophase II
The chromosomes arrive at the poles and nuclear envelopes form, during which phase of Mitosis?
Telophase; the final phase of Mitosis.
What must happen before a cell can begin Mitosis?
The chromosomes must be duplicated (which occurs during Interphase)
Upon completion of Telophase I and Cytokinesis, there is(are) _______ cell(s).
Two haploid
A cell that completed the cell cycle without undergoing Cytokinesis would have?
Two nuclei
What combination of sex chromosomes results in Turner syndrome?
XO; individuals are females but have only one X chromosome.
During Prophase a homologous pair of chromosomes consists of _____?
at this point, each of the chromosomes consists of two chromosomes and four chromatids
Chromosomes that do not determine the sex of an individual are called _________?
autosomes
Trisomy 21 is the condition of?
being triploid for chromosome 21 (instead of the usual diploid condition), they have 47 chromosomes in total.
Homologous Chromosomes_____?
carry genes controlling the same inherited characteristics
In Mitosis a cell has ?
doubled its genetic material, divides into two diploid daughter cells.
In Meiosis a cell has ?
doubled its genetic material, undergoes two rounds of division, resulting in four haploid cells.
Anaphase II is essentially the same as Mitotic Anaphase,
except that the cell is haploid
Metaphase II is essentially the same as Mitotic Metaphase,
except that the cell is haploid
Prophase II is essentially the same as Mitotic Prophase,
except that the cells are haploid
Meiosis and cytokinesis result in the formation of ______?
four haploid cells
The __________ separate in Meiosis I; the ______ separate in Meiosis II.
homologous chromosomes ; sister chromatids
During ________ the cell grows & replicates both its organelles & its chromosomes.
interphase
Sexual reproduction requires the cellular process of ______ followed by fertilization.
meiosis; produces gametes, and a gamete from one individual unites with a gamete from another individual during fertilization.
Chromosomes of eukaryotic cells are found in the?
nucleus
How many genes are contributed genetically?
only one identical gene from the parent to the offspring.
A duplicated chromosomes consists of two ___?
sister chromatids
Crossing over is ______ ?
the exchange of corresponding portions of homologous chromosomes.
During ______ both the contents of the nucleus and the cytoplasm are divided.
the mitotic phase
The process of Meiosis accomplishes what?
the producing of four haploid cells & allows exchange of genetic material between homologous chromosomes.
Genetic recombination
the result of new combinations of genetic material
The mitotic cell cycle results in the production of?
two cells, each with the same amount of genetic material and the same genetic information
