BIO 201LLB Lecture 29: Bio 201 Lecture 29

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violetantelope451

1 Nov 2018

School

University at Buffalo

Department

Biological Sciences

Course

BIO 201LLB

Professor

Todd Hennessey

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Document Summary

There is an s-phase in between the next mitosis. The goal of meiosis is reduction division, haploidization. The goal of sexual reproduction is a return to the diploid state. Sperm: haploid male gamete (1n) (2n) Meiosis is 2 nuclear divisions with no s-phase in between (reduction division) Signals received in pre-meiotic cells trigger them (in g1) to start pre-meiotic s-phase. In other words, the decision about whether to go into mitosis or meiosis is made in the g1. Cells that have just come out of pre-meiotic g2 and have entered prophase i of meiosis. Meiotic prophase nuclei differ from mitotic prophase nuclei due to formation of synaptonemal complexes and bivalents (tetrads) in meiotic prophase i. Need to find partner: ex: maternal chromosome 1 with paternal chromosome 1. It is bivalent because it is two meiotic chromosomes: tetrad because it has four chromatids. It is syntelic because both sister chromatids face the same pole.

Related Questions

6.A) If one follows 120 primary oocytes in an animal through their various stages of oogenesis, how many secondary oocytes would be formed?

B) How many first polar bodies would be formed?

C) How many ootids would be formed?

D) If one follows 120 primary spermatocytes in an animal through their various stages of spermatogenesis, how many secondary spermatocytes would be formed?

E) How many spermatids would be formed?

14. From which phase of the cell cycle does a cell enter G0 phase

21. Which of the following is true about the second meiotic division?

-The products are four identical gametes.

-Homologous chromosomes are pulling apart.

-Nondisjunction would lead to extra bivalents forming.

-Synapsis occurring in the second meiotic division.

-Sister chromatids are pulling apart.

23.Which if the following is true?

-Cells are 4n after S phase.

-Sister chromatids in mitosis are not identical.

-Cells are considered to be 2n after meiosis I.

-A chromosome always contains the same number of chromatids, regardless of phase of the mitotic or meiotic cell cycle.

-A chromosome may contain one or two chromatids in different phases of the mitotic or meiotic cell cycle.

Question 1 (2 points)

In which phase of cell division is marked by the dissolution of the nuclear membrane, the condensation of chromosomes, and the formation of the mitotic spindle?

Question 1 options:

	prophase
	metaphase
	telophase
	anaphase

Question 2 (2 points)

The physical separation of cells during cell division is called:

Question 2 options:

	Cytokinesis
	Telophase
	Interphase
	Chromosome
	Cell plate

Question 3 (2 points)

Meiosis is necessary for sexual reproduction; the gametes formed during this process before fertilization are _______________.

Question 3 options:

	Haploid
	Diploid
	Zygote
	Homologous
	Tetrads

Question 4 (2 points)

Mitosis is the process by which a ___________ cell separates the chromosomes in its nucleus into two identical sets of nuclei.

Question 4 options:

	eukaryotic
	prokaryotic
	bacterial
	all of these are correct

Question 5 (2 points)

Which of the following statements about crossing over is INCORRECT?

Question 5 options:

	It occurs between homologous chromosomes
	It allows for two parents to produce many different types of offspring
	It contributes to genetic diversity in a population
	It occurs during prophase I of mitosis

-Complete the following sentences: metaphase of mitosis, prophase II of meiosis, crossing over, anaphase I of meiosis, variable, random fertilization, identical, random orientation, metaphase I of meiosis, prophase I of meiosis, metaphase II of meiosis, reduction division

Two processes that occur during meiosis produce genetically ____________ cells.

In a process called ____________ , paired homologous chromosomes align randomly at the cell equator. This occurs during this stage of cell division: ____________ .

In a process called ____________ , genetic material is exchanged between homologous chromosomes. This occurs during this stage of cell division: ____________ .

-Complete the following paragraph to describe nondisjunction and the resulting effects on chromosome number.

words: euploidy, primary nondisjunction, nomal, nondisjunction, secondary nondisjunction, homologous chromosomes, abnormal, trisomy, monosomy, sister chromatids, aneuploid

1.During meiosis I, ____________ separate and move towards opposite ends of the poles.

2.During meiosis II, ____________ separate and move towards opposite ends of the poles.

3.During meiosis I, if both members of a homologous pair go into the same daughter cell, ____________ is said to occur and no normal gametes are produced.

4.During meiosis II, if the sister chromatids fail to separate and both daughter chromosomes go into the same gamete, ____________ is said to occur. Half the gametes are aneuploid while the other half are euploid.

5.If an egg that contains 24 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

6.If an egg that contains 22 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

BIO 201LLB Lecture 29: Bio 201 Lecture 29

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