Chapter 13: Meiosis and the Sexual Cycle

Question 1

The study of heredity and hereditary variation

Answer 1

genetics

Question 2

coded information

Answer 2

genes

Question 3

segments of DNA

Answer 3

genes

Question 4

similar to our
written language and passes specific information
from parent to child

Answer 4

sequence of nucleotides

Question 5

how many genes are in chromosome?

Answer 5

100’s – 1000’s

Question 6

The specific location of a gene on a
chromosome is known as its

Answer 6

locus

Question 7

are the cells which transmit genes from one generation to the next

Answer 7

The gametes (sperm and ova)

Question 8

characteristic of Asexual Reproduction

Answer 8

• Only 1 parent produces offspring
• Offspring are genetically identical to the
  parent
• Cloning via Mitosis

Question 9

what type of cells use Asexual Reproduction

Answer 9

• Single-celled eukaryotes
• Multicellular organisms = budding

Question 10

when an egg cell develops as an embryo without the need for any genetic material from a sperm cell

Answer 10

parthenogenesis

Question 11

characteristic of Sexual Reproduction

Answer 11

• Meiosis
• fertilization
• Increases genetic diversity
• Creates unique individuals

Question 12

what type of cells use Sexual Reproduction

Answer 12

most eukaryotic organisms.

Question 13

Chromosomes that look alike , they
have the same length and shape

Answer 13

Homologous chromosomes

Question 14

the shared genes that homologous chromosomes have that control the same inherited traits

Answer 14

alleles

Question 15

the sex chromosomes

Answer 15

X and Y

Question 16

determine the sex of an individual

Answer 16

the sex chromosomes

Question 17

what chromosomes do females have?

Answer 17

homologous X sex chromosomes

Question 18

what chromosomes do males have?

Answer 18

1 X and 1 Y chromosome
pair up

Question 19

non homologous chromosomes

Answer 19

autosomes

Question 20

how many autosomes and sex chromosomes not including sex chromosomes do gametes have?

Answer 20

22 = autosomes
1 = sex chromosome

Question 21

how many chromosomes are in haploids?

Answer 21

23(only one set)

Question 22

cells with only one set of chromosomes

Answer 22

haploid

Question 23

cells with two sets of chromosomes

Answer 23

diploid

Question 24

what is the fused gametes called?

Answer 24

zygote

Question 25

The process in which the nucleus of a cell completes 2 successive divisions that produce 4 nuclei, each with a chromosome number that has been reduced by half.

Answer 25

meiosis

Question 26

the formation of gametes

Answer 26

meiosis

Question 27

fusing of the nuclei of 2 gametes

Answer 27

fertilization

Question 28

two divisions of meiosis

Answer 28

– Meiosis I – Meiosis II

Question 29

at stages are in Meiosis I and Meiosis II

Answer 29

PROPHASE METAPHASE ANAPHASE TELOPHASE

Question 30

what happens in meiosis I

Answer 30

homologous pairs separate

Question 31

what happens in meiosis II

Answer 31

The 2 sister chromatids of each chromosome are separated from each other

Question 32

what happens in prophase I

Answer 32

– chromosomes condense – nuclear envelope breaks down – homologous chromosomes pair up = Synapsis and form a tetrad

Question 33

what happens in Metaphase I

Answer 33

- Pairs of homologous chromosomes are moved to the equator of the cell. - The homologues, each made of 2 chromatids s stay together.

Question 34

what happens in Anaphase I

Answer 34

* Homologues separate * The chromosomes of each pair are “pulled” to opposite ends of the cell. * BUT (unlike in mitosis) chromatids DO NOT separate at their centromeres. Each chromosome is still composed of 2 chromatids joined by the centromere * Non-disjunction could occur

Question 35

An accident in chromosome separation when one daughter cell receives both pairs of chromosomes and the other daughter cell receives none.

Answer 35

Non-disjunction

Question 36

what happens in Telophase I

Answer 36

- Individual chromosomes gather at each pole of the cell (2). In most cases, cytoplasm then divides (cytokinesis) forming 2 new cells. -reductive division.

Question 37

Each of the cells produced contain half the number of chromosomes as the original cell. this is known as what?

Answer 37

reductive division.

Question 38

what happens in Prophase II

Answer 38

- Each chromosome becomes attached to the microtubules and starts moving toward its equator

Question 39

what happens at Metaphase II

Answer 39

All chromosomes are now positioned at the equator

Question 40

what happens in Anaphase II

Answer 40

Centromeres divide and the chromatids NOW called chromosomes move to opposite poles of the cell

Question 41

what happens in Telophase II

Answer 41

* Four daughter nuclei form. When the cytoplasm divides each new cell is haploid (n). The original chromosome number has been reduced by half. * One or all of these cells may become gametes.

Question 42

3 sources of genetic variation

Answer 42

1. Independent Assortment 2. Crossing-Over 3. Random Fertilization

Question 43

when is independent assortment done?

Answer 43

Metaphase I

Question 44

the homologous pairs of chromosomes line up at the metaphase plate -orientation random

Answer 44

Independent Assortment

Question 45

when is crossing over (homologous chromosomes) happening

Answer 45

Meiosis (Prophase I)

Question 46

segments of the chromosomes can exchange segments of DNA. -recombinant chromosomes

Answer 46

crossing over (homologous chromosomes)

Question 47

genes inherited from both parents combined onto one chromosome

Answer 47

recombinant chromosomes

Question 48

Area where crossover occurs is known as the

Answer 48

chiasmata

Question 49

how many possible chromosome combinations are possible for a human ovum and sperm?

Answer 49

8.4 million

Question 50

how many diploid combinations for the resulting zygote is possible

Answer 50

70 trillion