BIOL 2040 Lecture Notes - Lecture 25: Sister Chromatids, Chromosome Segregation, Oogenesis

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tanminnow712

19 Apr 2016

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Disjunction: the pulling apart of homologous chromosomes in meiosis 1, or sister chromatids in meiosis 2. Non-disjunction: failure of homologous chromosomes to separate during or after meiosis. Failure of sister chromatids to separate during or after mitosis/meiosis 2. Meiosis: the formation of 4 haploid gametes from a diploid cell. M i: where homologous pairs of chromosomes replicate and then divide into 2 diploid cells each with 46 chromosomes. Crossing over and segregation occur randomizing the process. M ii: where replicated, crossed over, and segregated chromosomes divide ( sister chromatids are pulled apart) to create 4 haploid gametes. Synapse (synapsis): pairing of two homologous chromosomes during meiosis . Tetrad (do not bother with the term bivalent ): 4 chromatids formed during meiosis 1. Monad: a sister chromatid that has detached from it"s sister, and is now it"s own chromosome. Polar bodies: during meiosis i, during formation of the cells, the sharing of cytoplasm is unequal.

Related Questions

1. How does meiosis generate genetic diversity?

a) crossing over

b) random alignment at metaphase I

c) synapsis

d) both crossing over and random alignment at metaphase I

2. What would happen if crossing over occurred between sister chromatids?

a) Genetic diversity would decrease due to the loss of gene combinations.

b) Genetic diversity would increase due to the addition of gene combinations.

c) Gene rearrangement would lead to changes in gene expression.

d) Nothing would happen becasue sister chromatids are genetically identical or nearly identical.

3. Animals that sexually reproduce are _____ and produce _____ gametes. (haploid, diploid; haploid, haploid; diploid, diploid; diploid, haploid)

4. The F1 generation of a cross between two individuals, one that is homozygous dominant for a trait and the other that is homozygous recessive for the trait, will yield progeny with the same phenotype. (true or false)

5. Homologous chromosomes separate from each other in:

a) mitosis

b) meiosis I

c) meiosis II

d) They never separate from each other during any form of cell division

chocolatealpaca651

Consider each of the following statements.

In meiosis, the chromosomal material doubles during the lastpremeiotic interphase.

The greater the number of chromosome pairs, the greater is theeffect of meiosis in producing genetically distinct gametes.

The diploid number of chromosomes is half the haploidnumber.

A cell that will not divide again remains in the GÂ2 stage ofinterphase.

The correct sequence of events during meiosis is: synapsis ?dyad formation ? chiasma formation

In an organism with n = 3, there is a 1 in 8 probability of agamete with all maternally derived chromosomes contributing to theproduction of a zygote.

An organism with n = 3 can produce 8 different kinds of gametesin relation to combinations of maternal and paternalchromosomes.

Separation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis for the law of independentassortment.

A single diploid cell that undergoes meiosis in the male testiswill produce 4 genetically different gametes if crossing-over isignored.

The independent alignment of different tetrads at metaphase I ofmeiosis is the physical basis of the law of independentassortment.

If a diploid cell has 20 pairs of chromosomes, there will be 10tetrads during prophase I of meiosis.

If a diploid cell has 20 pairs of chromosomes, there will be 20bivalents during prophase I of meiosis.

If a diploid cell has 20 pairs of chromosomes, there will be 80chromatids present during metaphase of mitosis.

If a diploid cell has 20 pairs of chromosmes, the organism canmake 20² types of gametes if crossing-over isignored.

Segregation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis of the law of segregation.

For an individual with a diploid number of 30 chromosomes, therewill be 60 chromatids at metaphase I of meiosis.

For an individual with a diploid number of 30 chromosomes, therewill be 15 tetrads at metaphase II of meiosis.

yellowpig507

Which of the following statements are true. CHALLENGEQUESTION:

a. In meiosis, the chromosomal material doubles during the lastpremeiotic interphase.

b. The greater the number of chromosome pairs, the greater isthe effect of meiosis in producing genetically distinctgametes.

c. The diploid number of chromosomes is half the haploidnumber.

d. A cell that will not divide again remains in the GÂ2 stage ofinterphase.

e. The correct sequence of events during meiosis is: synapsis âdyad formation â chiasma formation

f. In an organism with n = 3, there is a 1 in 8 probability of agamete with all maternally derived chromosomes contributing to theproduction of a zygote.

g. An organism with n = 3 can produce 8 different kinds ofgametes in relation to combinations of maternal and paternalchromosomes.

h. Separation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis for the law of independentassortment.

i. A single diploid cell that undergoes meiosis in the maletestis will produce 4 genetically different gametes ifcrossing-over is ignored.

j. The independent alignment of different tetrads at metaphase Iof meiosis is the physical basis of the law of independentassortment.

k. If a diploid cell has 20 pairs of chromosomes, there will be10 tetrads during prophase I of meiosis.

l. If a diploid cell has 20 pairs of chromosomes, there will be20 bivalents during prophase I of meiosis.

m. If a diploid cell has 20 pairs of chromosomes, there will be80 chromatids present during metaphase of mitosis.

n. If a diploid cell has 20 pairs of chromosmes, the organismcan make 20² types of gametes if crossing-over isignored.

o. Segregation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis of the law of segregation.

p. For an individual with a diploid number of 30 chromosomes,there will be 60 chromatids at metaphase I of meiosis.

q. For an individual with a diploid number of 30 chromosomes,there will be 15 tetrads at metaphase II of meiosis.

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BIOL 2040 Lecture Notes - Lecture 25: Sister Chromatids, Chromosome Segregation, Oogenesis

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