Chapter 18

Question 1

very long DNA molecule in association with protein

Answer 1

chromosome

Question 2

segment of DNA in a chromosome

Answer 2

Gene

Question 3

DNA and protein combined

Answer 3

chromatin

Question 4

How many chromosomes do humans get from each parent; for a total of how many?

Answer 4

23;46

Question 5

(2n) two sets of chromosomes

Answer 5

Diploid

Question 6

chromosome pairs 1-22

Answer 6

autosomes

Question 7

Female sex chromosome

Answer 7

XX

Question 8

Male sex chromosome

Answer 8

XY

Question 9

paired corresponding chromosomes

Answer 9

homologous chromosomes

Question 10

genetic and phenotypic characteristics

Answer 10

sex

Question 11

shared genetic background

Answer 11

ancestry

Question 12

produces a new generation of cells

Answer 12

reproduction

Question 13

*Division of Somatic cells
*maintains diploid chromosome number

Answer 13

Mitosis

Question 14

Purpose of Mitosis

Answer 14

growth, replace worn out or dead cells, repair tissue

Question 15

*Division of germ cells
*Halve the diploid number to haploid

Answer 15

Meiosis

Question 16

The purpose of Meiosis

Answer 16

first stage in sexual reprodcution

Question 17

“lifetime” of a somatic cell

Answer 17

Cell Cycle

Question 18

*3/4 of the cell cycle
*involves G1, S, G2

Answer 18

Interphase

Question 19

What does G1, S, and G2 stand for in Interphase?

Answer 19

G1: cell growth
S: DNA chromosomes are copied through replication
G2: preparation for mitosis

Question 20

1/4 of the cell cycle

Answer 20

Mitosis

Question 21

four phases; chromosomes are sorted into two sets

Answer 21

Mitosis

Question 22

cytoplasm divides

Answer 22

cytokinesis

Question 23

chromosome and its copy

Answer 23

sister chromatids

Question 24

region of attachment to the microtubule

Answer 24

centromere

Question 25

Once coiling is completed a chromosome has it typical ______ & _________.

Answer 25

size & shape

Question 26

What are the four stages of Mitosis?

Answer 26

Prophase, Metaphase, Anaphase, Telophase

Question 27

*Coiling and condensing of the chromosome *microtubules form into spindle formation *nuclear membrane begins breaking up *Microtubules move centrioles to the opposite poles

Answer 27

Prophase

Question 28

*Nuclear membrane breaks apart *microtubules penetrate nuclear region *microtubules interact w/ chromosomes at centromere

Answer 28

prometaphase

Question 29

Duplicated chromosomes align midway between the poles of the cell

Answer 29

metaphase

Question 30

These attach to chromosomes and move them?

Answer 30

Spindles

Question 31

*sister chromatids split; become independent chromosomes *pulled by microtubules toward the pole region *spindle elongates, pushing the poles farther apart

Answer 31

Anaphase

Question 32

*chromosomes no longer connected to the spindle *chromosomes begin to decondense - again form chromatin *nuclear envelope forms around each cluster

Answer 32

Telophase

Question 33

*begins toward end of anaphase *cleavage furrow forms

Answer 33

Cytokinesis

Question 34

*microfilaments (actin) pull the plasma membrane inward all around the cell *pinches the cell in two

Answer 34

cleavage furrow

Question 35

What do males contribute during sexual reproduction and what do females contribute?

Answer 35

Male = sperm Female = egg

Question 36

combines a sperm and an egg to produce the first cell of the new individual (Zygote)

Answer 36

fertilization

Question 37

In meiosis the parent cell of the nucleus divides how many times?

Answer 37

twice

Question 38

How meiosis divide the nuclei of germ cells in a way that halves the number of chromosomes in daughter cells; reduces the number to haploid number

Answer 38

Reductional Division

Question 39

In meiosis what step cause the germ cell to copy its DNA

Answer 39

Interphase

Question 40

two consecutive divisions of the chromosomes

Answer 40

Meiosis

Question 41

homologues pair up and then seperate

Answer 41

Meiosis I

Question 42

Sister chromatids split; four haploid cells formed

Answer 42

Meiosis II

Question 43

*Chromosomes condense *each chromosome has two sister chromatids *crossing over occurs

Answer 43

Prophase I

Question 44

*Homologous chromosomes move to central plane in pairs *spindle fibers attach to centromere *nuclear envelope fragments

Answer 44

Late Prophase to Prometaphase

Question 45

These are not genetically identical

Answer 45

Daughter Cells

Question 46

Paired chromosomes are oriented toward opposite poles

Answer 46

Metaphase I

Question 47

Chromosome disjunction Independent assortment

Answer 47

Anaphase I

Question 48

separation of paired chromosomes

Answer 48

chromosome disjunction

Question 49

separated homologues move toward opposite poles

Answer 49

independent assortment

Question 50

*reduced chromosomes to 23 in each nucleus *daughter cells separated by membranes *chromosomes reach the poles; nuclei forms

Answer 50

Telophase I

Question 51

*chromosomes attach to a new spindle apparatus *sister chromatids are attached to spindle fibers from opposite poles

Answer 51

Prophase II

Question 52

chromosomes align at equatorial plane

Answer 52

Metaphase II

Question 53

*centromeres split *chromatid disjunction - sister chromatids move toward opposite poles

Answer 53

Anaphase II

Question 54

*each chromatid is now called a chromosome *separated chromatids gather at poles; daughter nuclei (each one contains a haploid set of chromosomes) form

Answer 54

Telophase II

Question 55

homologous pairs of chromosomes line up at random during what phase?

Answer 55

Metaphase I

Question 56

disjunction and independent assortment happen when?

Answer 56

Anaphase I

Question 57

*consists chromatids break at same places along their length *exchange corresponding segments

Answer 57

Crossing Over

Question 58

genes may have different chemical forms

Answer 58

Genetic recombination

Question 59

Where does Mitosis occur?

Answer 59

Somatic Cells

Question 60

Where does meiosis occur?

Answer 60

germ cells