Meiosis

Question 1

What type of organs are the cells that enter meiosis 1

Answer 1

Sex organs (ovaries and testes)

Question 2

What event must take place during interphase before a cell proceeds to division

Answer 2

DNA replication

Question 3

What two structures make up a single replicated chromosome

Answer 3

Sister chromatids

Question 4

How many replicated chromosomes does the cell contain during prophase

Answer 4

4

Question 5

At which stage in meiosis 1 do the pairs of homologous chromosomes come together

Answer 5

Late prophase 1

Question 6

Once chromosomes have formed a pair, what are they called?

Answer 6

Tetrads

Question 7

At the end of meiosis 1 two cells have been produced. How many replicated chromosomes are in each of these cells

Answer 7

Two

Question 8

Diploid

Answer 8

Full set of chromosomes

Question 9

Haploid

Answer 9

Half the chromosomes

Question 10

Which stage of meiosis 1 are the cells diploid and haploid

Answer 10

Diploid- prophase, metaphase, and anaphase

Haploid- telophase after the cell has split

Question 11

What is the relationship between the cells at the end of telophase 1 and the original cell?

Answer 11

The new cells have two copies of half of the genetic information in the original cell

Question 12

Will the cells at the end of telophase 1 be genetically identical to each other?

Answer 12

No because the homologous pairs are separated and the alleles on each homologous pair are not necessarily identical

Question 13

In meiosis 1 during anaphase 1, which structures separated

Answer 13

Homologous chromosomes

Question 14

In meiosis 2 during anaphase 2 which structures seperared

Answer 14

Sister chromatids

Question 15

At the end of meiosis 2 are four daughter cells. Are they haploid or diploid

Answer 15

The cells are haploid. They each contain one chromosome (sister chromatids) from each homologous pair. Each chromosome contains a complete set of genes

Question 16

What is the relationship between the cells at the end of meiosis 2 and the original cell

Answer 16

The new cells have one copy of half of the genetic information in the original cell

Question 17

What is the name given to the cells produced at the end of meiosis 1 in males

Answer 17

Secondary spermatocyte

Question 18

What is the name given to the cells produced at the end of meiosis 1 in females

Answer 18

Secondary oocyte

Question 19

At the end of meiosis 2 in males, what cells are produced

Answer 19

Spermatids

Question 20

What do spermatids eventually become

Answer 20

Mature sperm

Question 21

Before fertilization what happens to the secondary oocyte

Answer 21

Proceed to meiosis 2

Question 22

During fertilization which two cells come together

Answer 22

Mature sperm and secondary oocyte

Question 23

During meiosis 2 the secondary oocyte divides unevenly with one cell (the ovum) receiving half of the chromosomes and nearly all the cytoplasm and organelles while the other cell, the polar body, is much smaller and eventually degenerates. Why does the secondary oocyte divide this way?

Answer 23

The ovum will receive more organelles, such as mitochondria for making energy, which will provide the zygote with all of its cytoplasm and organelles( Sperm contains only scant cytoplasm, a few mitochondria and haploid chromosomes) but nuclear division is necessary to produce the correct number of chromosomes in the oocyte

Question 24

What is the ploidy of the zygote produced by fertilization haploid or diploid

Answer 24

Diploid

Question 25

What would the Ploidy of the zygote be if egg and sperm were produced by mitosis rather than meiosis. How would this affect the ploidy of each successive generations

Answer 25

The egg and sperm would Each would be diploid. So the zygote would be tetraploid. If the tetraploid organisms produced tetraploid eggs the next generation would be octoploid This doubling would Continue

Question 26

What is the origin of the chromosomes found in the zygote

Answer 26

The homologous pair of chromosomes found in the zygote have come from each parent. One half of each pair is maternal and the other half is paternal

Question 27

What are the points where the sister chromatids cross over

Answer 27

Chiasma

Question 28

What happens to the chromatids during crossover

Answer 28

Sections of the homologous pair switch places on the chromatids

Question 29

What phrase is used to describe the chromatids after crossing over takes place and the homologous chromosomes separate

Answer 29

Recombinant chromatids

Question 30

Are the genes of the recombinant chromatid the same as the original chromatids

Answer 30

Yes each chromosome in the homologous pair contains the same genes in the same spot

Question 31

Are the alleles on a recombinant chromatid the same as the original

Answer 31

No the homologous pair can have a different alleles for each gene

Question 32

Is either arrangement egually likely during the formations of tetrads in late prophase 1

Answer 32

DNA replication occurs randomly within the nucleus of the cell. When the homologous chromosomes come together as tetrads they are equally likely to line up on one side

Question 33

If there was 3 sets of homologous chromosomes. How many possible arrangements would there be for the tetrads in late prophase 1

Answer 33

2•2•2=8

Question 34

What is the possible genetic combination due to independent assortment

Answer 34

2^23= 8,388,608

Question 35

Meiosis and sexual reproduction each lead to variation in the genetic makeup of every person. With your group, explain how meiotic event as well as random fertilization of eggs and sorry together lead to this genetic variation

Answer 35

Independent assortment leads to multiple different maternal and paternal gene combinations being produced in the cells at the end of meiosis 1. Chiasma formation between homologous pairs of chromosomes leads to blocks of genes being swapped between nonsister chromatids during separation at anaphase 1. This leads to alleles combinations on the chromosomes being shuffled and further varies the chromosomes that end up in Egg and Sperm after meiosis 2 random fertilization of eggs and sperm means that when zygote are formed the gene combination will be different each time, even if they come from the same two parents

Question 36

When homologous chromosomes pairs align on the spindle during metaphase 1 the orientation of one pair is independent of the orientation of any pair

Answer 36

independent assortment