BIOL 242 Lecture Notes - Lecture 18: Spindle Apparatus, Y Chromosome, Meiosis

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azuremole431

2 May 2019

School

University of San Diego

Department

Biology Courses

Course

BIOL 242

Professor

Paul Bradley

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Document Summary

Gametes are the only types of human cells produced by meiosis, rather than mitosis. Meiosis results in one set of chromosomes in each gamete. Fertilization and meiosis alternate in sexual life cycles to maintain chromosome number. In humans the sex chromosomes are called x and y. Human females have a homologous pair of chromosomes. Human males have one x and one y chromosome. The remaining 22 pairs of chromosomes are called autosomes. Each pair of homologous chromosomes includes one chromosome from each parent. A diploid cell (2n) has 2 sets of chromosomes. For humans, the diploid number is 46. A gamete (sperm or egg) contains a single set of chromosomes and is haploid (n) For humans, the haploid number is 23. Chromosomes are duplicated only during the s phase. Meiosis reduces the number of chromosome sets from diploid to haploid. The two cell divisions (meiosis i and meiosis ii) The two cell divisions result in 4 daughter cells.

Related Questions

Meiosis and Sexual Reproduction Lab Report

Homologous Chromosomes

Give an example of a cell that is diploid and one that ishaploid.

On a pair of homologous chromosomes, one allele for hair colorcodes for brown hair and one codes for red hair. Is this conditionconsidered homozygous or heterozygous?

What does homozygous mean?

Meiosis in Eukaryotes

At the end of meiosis, how does the number of chromosomes ineach cell compare to the parent cell?

draw the beads as they appear at the end of each stage ofmeiosis I and meiosis II.

Oogenesis and Spermatogenesis

Where does meiosis occur in human males and females?

What type of cells undergo meiosis?

After fertilization occurs, are the resulting cells diploid orhaploid in chromosome number?

Summary Questions

If a garden pea has 14 chromosomes before meiosis, how manychromosomes would exist in each nucleus after meiosis I? Aftermeiosis II?

Summarize the process of gametogenesis.

Give an example of homologous and heterozygous traits.

redmacaw611

Which processes contribute directly to genetic variaion?

? What is meant by ploidy? Diploid? Haploid?

? Know the phases of meiosis?

? Know the differences between meiosis and mitosis.

? What is the major difference between metaphase of mitosis and metaphase I of meiosis?

? What is the major difference between meiosis II & mitosis?

? What is crossing over? ? What is synapsis?

? What are chiasmata?

? What are autosomes?

? What are sex chromosomes? What are the sex chromosomes in human male? Human female?

? What are homologous chromosomes?

? What is genetic recombination?

? What is fertilization? What are gametes?

? What are histones? What is chromatin?

? How many autosomes do humans have? Have many pairs of autosomes? How many pairs of sex chromosomes? What is the total number of chromosomes that human have? ? What are the sites of crossing over called?

? What is a karyotype?

? What is Down syndrome?

? What is polyploidy?

? What is nondisjunction?

? What is trisomy and monosomy

pucecat917

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

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BIOL 242 Lecture Notes - Lecture 18: Spindle Apparatus, Y Chromosome, Meiosis

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