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49 Cards in this Set
- Front
- Back
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What is meiosis |
A two stage cell division in which the chromosome number of the parental cell is reduced by half |
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What does haploid mean |
It refers to the number of chromosomes in a gamete |
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What does diploid mean |
Refers to twice the number of chromosomes in a gamete |
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What is a homologous chromosomes |
Paired chromosomes similar in shape, size, gene arrangement, and gene information |
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What is a tetrad |
A pair of homologous chromosomes each with two chromatids |
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What is synapsis |
The pairing of homologous chromosomes |
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What is crossing over |
The exchange of genetic material between two homologous chromosomes |
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During meiosis 1 what occurs in prophase 1 |
The replicated chromosomes condense. Homologous chromosomes come together (called a tetrad) in synapsis and crossing over occurs. Chromosomes attach to the spindle |
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During meiosis 1 what occurs in metaphase 1 |
The chromosomes line up at the equatorial (metaphase/cell) plate. Independent assortment has already occurred. |
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During meiosis 1 what occurs in anaphase 1 |
Segregation: homologous chromosomes separate and move to opposite poles.
Reduction division: from diploid to haploid |
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During meiosis 1 what occurs in telophase 1 |
The nucleus reforms. Cytokinesis occurs (splitting of cell organelles and cytoplasm). And the mitotic spindle forms. |
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The act of reduction division occurs in which stage of meiosis (1 or 2) |
1 at anaphase |
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When does mitotic division occur |
During meiosis 2 |
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During meiosis 2 what occurs in prophase 2 |
The nuclear membrane disappears. The centrioles in the 2 new cells move to opposite poles and new mitotic spindle fibres form. The chromosomes become visible and become attached to the spindle. |
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During meiosis 2 what occurs in metaphase 2 |
Chromosomes align on plate |
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During meiosis 2 what occurs in anaphase 2 |
The sister chromatids of each chromosome separates and move to opposite poles |
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During meiosis 2 what occurs in telophase 2 |
The nuclear membrane reforms. Cytokinesis occcurs. And 4 haploid sperm cells or 1 haploid egg cell is produced. |
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What is gametogenesis |
It is the formation of gametes through meiosis. This forms germ cells (2n): spermatogonia or oogonia |
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What is gametogenesis in males |
It is spermatogenesis occurring in puberty that results in 4 viable sperm cells produced |
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Describe spermatogenesis in males |
Spermatogonia (mitosis)=> primary spermatocyte (meiosis)=> secondary spermatocytes (meiosis)=> spermatid=> mature sperm cells (through cell differentiation) |
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What is gametogenesis in females |
It’s called oogenesis. Before birth the oogonia begin meiosis but stop at prophase 1. During puberty each month 1 oocyte continues meiosis stopping at metaphase 2. Unequal division results in 1 large egg. If fertilization: oocyte finishes meiosis then sperm DNA unites with egg DNA to form zygote. |
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What does oogenesis look like |
Oogonium => primary oocyte (&polar body) (meiosis)=> secondary oocyte (&polar body) (meiosis)=> ovum (cell growth)=> mature egg cell |
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What is meiosis non disjunction |
It is the major cause of chromosomal abnormalities |
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When does meiosis non disjunction occur |
In oogenesis due to maternal age. |
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In meiosis 1 how does non disjunction work |
In anaphase 1 homologous chromosomes (tetrad) fail to separate. Most chromosomal abnormalities occur here |
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In meiosis 2 when does non disjunction occur |
In anaphase 2 because sister chromatids fail to separate. |
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What results from non disjunction |
Monosomy and trisomy |
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What is monosomy |
It is when a chromosome is missing (2n=45). This is lethal for just the Y chromosome and all other autos ones. |
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What is a monosomy disorder |
Turner syndrome (XO) |
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What is trisomy |
It is when there is an extra chromosome (2n=47) |
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What are the lethal trisomy disorders |
Edwards syndrome (18) Patau syndrome (13) |
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What are other trisomy disorders |
Down syndrome(21) Klinefelter syndrome(XXX) Supermales(XYY) Trisomy X (XXX) |
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What is an ootid |
An unfertilized ovum |
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What is polyploidy |
A condition in which an organism has more than two complete sets of chromosomes |
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Interphase occurs ______ meiosis |
Before |
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What is a karyotype chart |
A picture of chromosomes arranged in homologous pairs |
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If a diploid cell (2n=8) of an organism goes through meiosis 1 then the daughter cells chromosome number is |
N=4 |
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If a diploid cell (2n=8) of an organism goes through meiosis 1 then the daughter cells chromosome number is |
N=4 |
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Polar bodies contain how many chromosomes |
23 |
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If a diploid cell (2n=8) of an organism goes through meiosis 1 then the daughter cells chromosome number is |
N=4 |
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Polar bodies contain how many chromosomes |
23 |
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During reduction division cells become haploid when |
At anaphase 1 of meiosis 1 |
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How many chromosomes does a Red blood cell contain |
None because they are enucleated (have no nucleus) to contain chromosomes |
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In meiosis when do the chromosomes (chromatin) duplicate |
At interphase (S) |
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In meiosis when do the chromosomes (chromatin) duplicate |
At interphase (S) |
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When are haploid cells visible in meiosis |
Telophase 1 |
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In meiosis when do the chromosomes (chromatin) duplicate |
At interphase (S) |
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When are haploid cells visible in meiosis |
Telophase 1 |
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When does independent assortment occur |
Prophase 1 |
