Meiosis Book Notes

Question 1

What happens during meiosis?

Answer 1

Consists of two nuclear divisions that together reduce the # of chromosomes to the haploid # in preparation for sexual reproduction

Question 2

Products in meiosis are

Answer 2

Genetically different

Question 3

Functions of meiosis

Answer 3

1) reduce chromosome # from diploid to haploid
2) ensure that each of the haploid products has a complete set of chromosomes
3) generate genetic diversity among products

Question 4

Meiotic division reduces

Answer 4

The chromosome #

Question 5

Homologous chromosomes come together to pair and homologous chromosome pairs separate

Answer 5

Meiosis I

Question 6

No DNA replication, product = 4 cells each containing haploid # of chromosomes but not genetically identical

Answer 6

Meiosis II

Question 7

Chromatid exchanges during Meiosis I generate

Answer 7

Genetic diversity

Question 8

Homologous chromosomes pair by adhering along their lengths

Answer 8

Synopsis

Question 9

Chromosomes appear to repel each other but (blank) keep them together

Answer 9

Cohesins

Question 10

Regions having attachments take on x-shaped appearance

Answer 10

Chiasmata

Question 11

Chiasma reflects an exchange of genetic material between nonsister chromatids on homologous chromosomes

Answer 11

Crossing over

Question 12

Result of crossing over- increases genetic variation

Answer 12

Recombinant chromatids

Question 13

During meiosis homologous chromosomes separate by

Answer 13

Independent assortment

Question 14

Explain independent assortment during meiosis

Answer 14

• diploid organism has two sets of chromosomes (2n)

- meiosis I (synopsis) maternal chromosomes pair with paternal homólogas

Question 15

Result of independent assortment

Answer 15

Each newly formed cell receives 1 member of each homologous pair so chromosome # is decreased from diploid to haploid

Question 16

Steps in meiosis I

Answer 16

Early prophase I 
Mid-prophase I 
Late-prophase I 
Metaphase I 
Anaphase I 
Telophase I

Question 17

Early prophase I

Answer 17

Chromatin begins to condense following interphase

Question 18

Mid-prophase I

Answer 18

Sysnapsis aligns homóloga and chromosomes condense further

Question 19

Late-prophase I to prometaphase

Answer 19

Chromosomes continue to coil and shorten. The chiasmata reflect crossing over. The exchange of genetic material between nonsister chromatids in a homologous pair

Nuclear envelope breaks

Question 20

Metaphase I

Answer 20

The homologous pairs line up on equatorial metaphase plate

Question 21

Anaphase I

Answer 21

The homologous chromosomes (each with 2 chromatids) move to opposite poles

Question 22

Telophase I

Answer 22

The chromosomes gather into nuclei and the original cell divides

Question 23

Steps in meiosis II

Answer 23

Prophase II
Metaphase II
Anaphase II
Telophase II

Question 24

Products of meiosis II

Answer 24

Each of the 4 cells has a nucleus with a haploid # of chromosomes

Question 25

Prophase II

Answer 25

Chromosomes condense again, following a brief interphase with no DNA replication

Question 26

Metaphase II

Answer 26

Centromeres of the paired chromatids line up across the equatorial plates of each cell

Question 27

Anaphase II

Answer 27

Chromatids finally separate, becoming chromosomes in their own right, and move to opposite poles

Question 28

Why do cells have different genetic makeup after meiosis

Answer 28

Crossing over and independent assortment

Question 29

Telophase II

Answer 29

The chromosomes gather into nuclei and the cells divide

Question 30

Meiosis II =separation of sister chromatids into

Answer 30

Daughter nuclei

Question 31

Homologous chromosomes fail to separate or remain together and migrate the the same pole which results in the production of andhploid cells

Answer 31

Nondisjunction

Question 32

Condition in which 1 or more chromosomes are either lacking or present in excess

Answer 32

Aneuploidy

Question 33

Occurs when gamete has 2 copies of chromosome 21

Answer 33

Down syndrome

Question 34

3 copies of chromosome

Answer 34

Trisomic Recognition may lead to miscarriage in humans

Question 35

A piece of a chromosome may break away and become attached to another chromosome

Answer 35

Translocation

Question 36

Pictograph of chromosomes made- image of individual chromosomes manipulated to pair them and place in an orderly arrangement

Answer 36

Karotype

Question 37

``` #, shapes, and sizes of chronometer in cell Aid in diagnosis of chromosomal abnormalities ```

Answer 37

Karyotype

Question 38

Have more than 2 complete sets of chromosomes

Answer 38

Polyploid

Question 39

Use of polyploid plants in nature because larger example

Answer 39

Wheat