BIOL 190 Lecture Notes - Lecture 6: Sister Chromatids, Centromere, Meiosis

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lemonherring444

26 Sep 2016

School

University of San Diego

Department

Biology Courses

Course

BIOL 190

Professor

Meier Deanna

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Document Summary

Bio 190- lecture 6 (meiosis and crossing over) Random orientation of tetrad at metaphase i. In human cells, somatic cells have: 23 pairs of homologous chromosomes. Matched in their length and the genes that they have. One member of each pair came from each parent. The human sex chromosomes x and y differ in size and genetic composition. The other 22 pairs of chromosomes are autosomes with the same size and genetic composition. Homologous chromosomes are matched in: length, centromere position, gene location (locus) top orange=loci. An organism"s life cycle is the sequence of the stages leading: from the adults of one generation, to the adults of the next. Human and many animals and plants are diploid (2n), with body cells that have: two sets of chromosomes, haploid (1n) Meiosis is a process that converts diploid nuclei to haploid nuclei: occurs in the sex organs, producing gametes- sperm and eggs. Fertilization is the union of sperm and egg.

Related Questions

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

-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 statements pertaining to genetic variability are correct? Check all that apply (note that wrong answers will be deducted from right answers)!

Crossing over is defined by the exchange of chromosome pieces during metaphase one of meiosis.

If a germ cell (i.e. parent cell before meiosis) had only two pairs of homologous chromosomes (i.e. 4 chromosomes total) there are 2 possible combinations of maternal and paternal chromosomes in gametes.

Siblings produced by sexual reproduction are different because sperms are different from one another and eggs are different from one another, and the combination of an egg and sperm is basically unique.

Random fertilization means that all possible combinations of eggs and sperm are equally likely, i.e. it is pure chance which sperm fuses with which egg.

Individual chromosomes contain thousands of genes. This means that during each crossing over event, more than one gene is exchanged between paternal and maternal chromosomes.

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BIOL 190 Lecture Notes - Lecture 6: Sister Chromatids, Centromere, Meiosis

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