Terms in this set (58)
a diploid zygote
(the union of haploid gametes at fertilization produces the zygote, or fertilized egg, which marks the beginning of the diploid phase of the life cycle)
Which of the following contributes to genetic variation in sexually reproducing species?
random fertilization, independent assortment, crossing over
involved or an outcome of crossing over?
The DNA in two nonsister chromatids is broken by specific proteins at exact points.
Chiasmata indicate where crossing over is occurring between homologs.
formation of chromosomes containing paternal and maternal alleles
number of each distinct type of chromosomes present
n, 2n, 3n, etc
cells have a single set of chromosomes
(somatic) cells (in interphase) have two sets of chromosomes
Which, if any, of the following statements is true?
Diploid cells can divide by mitosis.
Diploid cells can divide by meiosis.
Haploid cells can divide by mitosis.
Haploid cells cannot divide by meiosis.
All of the above responses are correct.
All of the above
What is the result when a diploid cell undergoes meiosis?
4 haploid cells
In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing _____ different types of gametes.
For each gamete there are two possibilities for each chromosome (the paternal or the maternal chromosome), and there are 23 different chromosomes per gamete.
purpose of Meiosis
halving of parental chromosome number
precedes formation of gametes
a photograph of all of an individual's chromosomes
46 autosomes (non sex chromosomes)
1 sex chromosome (determine sex of individual)
A human cell containing 22 autosomes and a Y chromosome is
section of DNA that influences hereditary trait(s)
How many genes in the human genome?
versions of specific genes
the precise location of a gene on a chromosome
same genes at same locations (loci)
but different alleles
sister and nonsister chromatids
are identical copies of each other formed during DNA synthesis,
participate in meiosis and mitosis
The egg of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?
In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes
chromosome on diploid parent is duplicated
Cell Divisions in Meiosis
Phases of Meiosis I
1. Early Prophase I
2. Late Prophase I
3. Metaphase I
4. Anaphase I
5. Telophase I
Early Prophase I
pairing of homologous chromosomes during prophase I.
Late Prophase I
crossing over (exchange) between
lining up at metaphase plate
separation of homologs to opposite ends of cell
Cytokinesis after Meiosis I result
two haploid cells
Homologous chromosomes move toward opposite poles of a dividing cell during
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 at metaphase of meiosis I would be
Meiosis II phases
1. Prophase II
2. Metaphase II
3. Anaphase II
4. Telophase II
spindles form and attach to each sister chromatid at centromere
holds the sister chromatids together at the centromeres prior to their separation at metaphase II
Sister chromatids separate and migrate toward opposite poles.
after arrive at different edns
nuclear envelope froms around each haploid set of chromosomes
Cytokiness after Meiosis II result
two daughter cells become four haploid cells
Meiosis II is similar to mitosis in that
sister chromatids separate during anaphase.
If we continued to follow the cell lineage from before (answer: 2x), then the DNA content of a single cell at metaphase of meiosis II would be
Asexual vs Sexual Reproduction
Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment.
Sexual and asexual reproduction are alike in that _____.
they can both occur in multicellular organisms
In sexually reproducing species, the chromosome number remains stable over time because _____ and _____ always alternate.
A clone is the product of
asexual reproduction and mitosis
Which event occurs only during prophase I of the first meiotic division?
Synapsis of homologous pairs occurs
Mitosis vs Meiosis (# of cell division)
Mitosis vs Meiosis (# of chromosomes)
Mitosis vs Meiosis (synapsis of homologs)
Mitosis vs Meiosis (crossing over events)
Meiosis: one or more per pair of homologous chromosomes
Mitosis vs Meiosis (make up of chromosomes in daughter cells)
Mitosis vs Meiosis (role in organism life)
Mitosis: asexual reproduction, cell division for growth
Meiosis: halving of chromosome number for gametogenesis
Which of the following occurs in meiosis, but not mitosis?
Homologous chromosomes separate.
Which function makes meiosis lengthier and more complex than mitosis?
decreasing the chromosome number to haploid
introducing genetic variation among the daughter cells
ensuring that each daughter cell gets a single, complete set of chromosomes
undergoing two rounds of cytokinesis
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