Meiosis

Question 1

What is the goal of meiosis?

Answer 1

To make genetically diverse gametes-1 copy of each chromosomes-leads to a possible of 4 gametes

Question 2

______ are separated in Meiosis 1

Answer 2

homologous chromosomes

Question 3

______ are separated in Meiosis 2

Answer 3

sister chromatids

Question 4

Overview of meiosis in 3 sentences

Answer 4

• two rounds of meiosis
• chromosomes duplicate once
• nuclei divide twice
• homologous chromosomes pair up
• homologies undergo crossing over

Question 5

Prophase 1

Answer 5

homologous chromosomes pair and are held together by synaptonemal complex
crossing-over (recombination) occurs during prophase 1

Question 6

Metaphase 1

Answer 6

Centromeres do not divide and sister chromatids are not separated, but chromosomes are still pulled to opposite ends

Question 7

Telophase 1

Answer 7

only 1 homologous chromosome in each cell after meiosis

Question 8

Meiosis 2

Answer 8

Separation of sister chromatids

this is where the gametes are made and are genetically different than parents

Question 9

Haploid cells carry….

Answer 9

half of the genetic information

Question 10

Meiosis leads to….

Answer 10

4 haploid cells that are not genetically the same

Question 11

How does Meiosis 1 ensure genetic diversity?

Answer 11

Independent assortment of homologous chromosomes

Recombination

Question 12

Law of Segregation

Answer 12

Movement of homologous chromosomes to opposite poles at anaphase 1 of meiosis

Question 13

Law of Independent Assortment

Answer 13

Independent alignment of different homologous pairs on the metaphase 1 spindle

Question 14

Compare and contrast mitosis and meiosis

Answer 14

Mitosis-
homologous chromosomes do not pair do not exchange genetic material (very rare).
Occurs in somatic cellls
Haploid and diploid cells can undergo mitosis
One round of division
Mitosis is preceded by S phase (chromosome duplication)
sister chromatids attach to spindle fibers from opposite poles during metphase
the centromete splits at the beginning of anaphase
At the end of mitosis you get 2 identical cells that are both diploid

Meiosis-
Get 2 phases of division
Occurs in germ cells as part of the sexual cycle
Only diploid cells undergo meiosis
chromosomes duplicate prior to meiosis 1 but not before meiosis 2
Crossing over occurs between homologous chromosomes during prophase of meiosis
Homologous chromosomes (NOT SISTER CHROMATIDS) attach to spindle fibers from opposite poles
the centromere does not split during meiosis 1
sister chromatids attach to spindle fibers during metaphase 1
the centromere splits at the beginning of anapahse 2
At the end you have genetically diverse haploid cells that become gametes

Question 15

Germ line

Answer 15

specialized germ cells set aside during embryogenesis

Question 16

Gametogenesis

Answer 16

the formation of gametes

Question 17

In humans, oogenesis produces….

Answer 17

one ovum from each primary oocyte

Question 18

In humans, spermatogenesis produces…

Answer 18

four sperm from each primary spermatocyte

Question 19

Egg formation

Answer 19

asymmetrical meiosis, long meiotic arrest because meiosis 2 doesn’t start until puberty, may contribute to chromosome segregation errors

Question 20

asymmetrical v symmetrical meiosis

Answer 20

you know this

Question 21

Sperm formation

Answer 21

symmetrical meiosis

mitosis and meiosis occur throughout lifetime

Question 22

fertilization

Answer 22

equals zygote formation, the sperm are introduced to the egg and insert its nuclei

Question 23

Non-disjunction

Answer 23

mistakes in chromosome segregation during meiosis 1 or 2

Question 24

Non-disjunction may result in inviable…

Answer 24

gametes or embryos

Question 25

Non-disjunction can also result in abnormal characteristics like

Answer 25

trisomy 21 down syndrome

Question 26

Aneuploids

Answer 26

an abnormal number of chromosomes in the cell