CAS BI 107 Lecture Notes - Lecture 2: Sister Chromatids, Meiosis, Centromere

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harlequinsardine165

30 Oct 2018

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State that meiosis is a reduction division of a diploid nucleus to form haploid nuclei. Meiosis is the process by which sex cells (gametes) are made in the reproductive organs: Most sexually reproducing animals are diploid - meaning they have two copies of every chromosome (one of maternal origin, one of paternal origin) In order to reproduce, these organisms need to make gametes that are haploid (have only one copy of each chromosome) Fertilisation of two haploid gametes (egg + sperm) will result in the formation of a diploid zygote that will grow into a new organism. The first division is a reduction division of the diploid nucleus to form haploid. The second division separates sister chromatids (this division is necessary because meiosis is preceded by interphase, wherein dna is replicated) homologous chromosomes. The same structural features (e. g. same size, same banding pattern, same centromere position) may be different)

Related Questions

Match the terms to the definitions provided.

Question 1 options:

	gamete
	somatic cells
	zygote
	sexual reproduction

1.	Reproductive life cycle that involves an alternation between haploid and diploid cells
2.	A single cell with a diploid number of chromosomes resulting from the fusion of an egg and a sperm.
3.	Cells (egg or sperm) resulting from a meiotic division of germ-line cells
4.	The non-reproductive cells found in embryos and mature individuals

Question 2 (5 points)

Match the terms to the definitions provided.

Question 2 options:

	syngamy
	haploid
	meiosis
	diploid
	germ-line cells

1.	The cells that will eventually undergo meiosis to produce gametes.
2.	The number of chromosomes found in gametes (eggs or sperm).
3.	The process by which two haploid gametes fuse to form a new diploid cell.
4.	A specialized reduction division that produces cells with half the normal number of chromosomes.
5.	Two sets of chromosomes present in the somatic cells of adult individuals.

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

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

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CAS BI 107 Lecture Notes - Lecture 2: Sister Chromatids, Meiosis, Centromere

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