L41 BIOL 2970 Lecture Notes - Lecture 3: Y Chromosome, Consanguinity, Wild Type

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salmonyak403

30 Sep 2016

School

WUSTL

Department

Biology And Biomedical Sciences

Course

L41 BIOL 2970

Professor

Duncan Ian

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Document Summary

In early divisions of germ cells, two sets of homologs present. End of prophase i: chiasma (pl): variable in number and position. Physical association of 2 homologs called a bivalent. Homologs align in the center of the cell. Meiosis ii: essentially a mitotic division except no replication occurs between meiosis i and ii. Chromosomes line up in the center of the cell. One diploid cell, each chromosome composed of 2 chromatids. Mendel i: each trait controlled by particular factors that occur in pairs. Members of a pair separate during gamete formation. Chromosomes occur in pairs in cells of higher organisms. Homologs separate from one another during meiosis i. 2 haploid gametes fuse to produce diploid zygote. Elinor carothers: grasshopper: found a strain that had a chromosome that was shorter than the normal. In grasshoppers, mae has a chromosome with no homolog called the x chromosome. Anaphase i carrying the short variant and the normal length homologs.

Related Questions

What is the purpose of meiosis?

To enable an organism to produce gametes

To allow for growth

To allow an organism to replace damaged cells

Question 2

Select one answer.

10 points

Mitosis results in ________ and meiosis results in ________.

gametes, somatic cells

gametes, gametes

somatic cells, somatic cells

somatic cells, gametes

Question 3

Select one answer.

10 points

Which of the following tasks is accomplished through the processof meiosis?

Cell growth

Production of sperm or eggs

Replacement of dysfunctional cells

Question 4

Select one answer.

10 points

What advantage does sexual reproduction have over asexualreproduction?

All other selections are true.

Sexual reproduction provides more genetic variability

Sexual reproduction doubles the number of chromosomes in aspecies

Sexual reproduction is more efficient

Question 5

Select one answer.

10 points

Crossing over occurs between homologous chromosomes during whatstage of cell division? (Read each option carefully.)

Prophase I of meiosis

Prophase of mitosis

Prophase II of meiosis

Interphase

Question 6

Select one answer.

10 points

Corn has 20 chromosomes. When corn undergoes meiosis how manychromosomes are found in the gametes?

Question 7

Select one answer.

10 points

Homologous chromosomes separate and are pulled to opposite sidesof the cell during what stage of cell division? (Read each optioncarefully.)

Metaphase I of meiosis

Anaphase II of meiosis

Anaphase I of meiosis

Anaphase of mitosis

Question 8

Select one answer.

10 points

Mitosis results in ______ cells and meiosis results in _______cells.

diploid, haploid

haploid, diploid

diploid, diploid

haploid, haploid

jadepug655

-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.

Which of the following is correctly matched?

		Prophase I - Nuclear envelope reforms,nucleolus reappears, spindle apparatus disappears
		Metaphase II - Homologous chromosomes align atthe equator (center) of the cell forming tetrads
		Anaphase II - Sister chromatids are pulled toopposite poles of the cell by contraction of spindle apparatusmicrotubules
		Cytokinesis - Division of the nucleus
		Telophase I - Nuclear envelope fragments,nucleolus disappears, spindle apparatus forms

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L41 BIOL 2970 Lecture Notes - Lecture 3: Y Chromosome, Consanguinity, Wild Type

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