BIOL 2040 Lecture Notes - Lecture 8: Synapsis, Mendelian Inheritance, Metaphase

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1 Feb 2013

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Somatic cell with 6 chromosomes (this means 3 from mom, 3 from dad: this relates to 12 chromatids, pairs of homologues have alleles in the same places, when chromatids are together, they are one chromosome. Reduces from diploid to haploid: two phases, meiosis i and ii. There are the same number of chromosomes, duplication occurs, but there are now 2 chromatids per chromosome. Prophase i: pairing of homologues (synapsis, crossover sights are chiasma, crossing over. Metaphase i: homologues line up on opposite pole ends at equatorial plate. Anaphase i: migration to the poles. Two haploid daughter cells (n chromosomes, 2 chromatids per chromosome) If nuclear envelope was formed, it will be broken apart. Metaphase ii: chromosomes line up so chromatids may be split. Anaphase ii: sister chromatids are separated. Telophase ii: chromosomes are moved to opposite sides of the cell, nuclear envelope forms. Each cell divides, 4 haploid cells are produced. Natural selection: total fitness by effects.

Related Questions

PLEASE HELP

Which of the following statements are true?

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 theGÂ₂ stage of interphase.

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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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.