Chapter 4: The Chromosome Theory Of Inheritance

Question 1

How can extra chromosome cause a wide range of phenotypic effects?

Answer 1

Chromosomes transmit genetic information.

The type and amount of genetic material is important for normal development.

Question 2

In 1667 what did Anton Van Leeuwenhoek hypothesis?

Answer 2

He hypothesized that sperm may enter egg to achieve fertilization.

Question 3

What is Mitosis?

Answer 3

Nuclear division that generates two daughter cells containing the same number and type of chromosomes as parent cell.

Question 4

What is meiosis?

Answer 4

Nuclear division that generates gametes containing half the number of chromosomes found in other cells

Question 5

Most body cells are diploid or haploid?

Answer 5

Diploid

Question 6

Meiosis generates haploid gametes that?

Answer 6

Carry only a single set of chromosomes

Question 7

Two gametes fuse during fertilization to form a __________

Answer 7

Zygote

Question 8

Zygotes are diploid meaning?

Answer 8

They carry two matching sets of chromosomes

Question 9

In metacentric chromosome where is the centromere located?

Answer 9

The centromere is in the middle.

Question 10

In Acrocentric chromosome the centromere is located where?

Answer 10

Centromere is near one end.

Question 11

What are sister chromatids?

Answer 11

Identical copies of a replicated chromosome

Question 12

What are homologs?

Answer 12

They contain the same set of genes but can have different alleles for some genes

Question 13

Nonhomologs carry what?

Answer 13

Completely unrelated sets of genes

Question 14

What are autosomes?

Answer 14

All chromosomes except X and Y

Question 15

What are sex chromosomes?

Answer 15

Unpaired X and Y

Question 16

W. S. Sutton studied meiosis in what?

Answer 16

Great lubber grasshoppers

Question 17

Before meiosis, testes cells had how many chromosomes?

Answer 17

24

Question 18

After meiosis, two types of what were formed?

Answer 18

Two types of sperm were formed

1/2 of the sperm had 11 chromosomes and an X
1/2 of the sperm had 11 chromosomes and a Y

Question 19

After meiosis what was produced?

Answer 19

Only one type of egg was produced

Question 20

What did Sutton conclude at the end of his experiment with the great lubber grasshopper?

Answer 20

He concluded that the X and Y chromosomes determine sex

Question 21

What is the primary determinant of maleness in a single gene called?

Answer 21

SRY

Question 22

SRY is alway present in _______ males

Answer 22

XX

Question 23

SRY is always nonfunctional in ________ females

Answer 23

XY

Question 24

In drosophila, the ratio of X chromosomes to autosomes determines what?

Answer 24

Gender

Question 25

In humans, what determines gender?

Answer 25

The presences or absences of Y chromosomes.

Question 26

In Drosophila what determines gender?

Answer 26

The ratio of X chromosomes to autosomes

Question 27

What is heterogametic sex?

Answer 27

Gender with two different kinds of gametes males in humans

Question 28

What is homogametic sex?

Answer 28

Gender with one type of gamete

Question 29

In some species gender is determine by what?

Answer 29

Environment

Question 30

Interphase has three parts:

Answer 30

Gap 1 phase, synthesis phase, and gap 2 phase

Question 31

What is centrosome?

Answer 31

Microtubule organizing center near the nuclear envelope.

Question 32

What are centrioles?

Answer 32

Core of centrosome, not found in plant cells

Question 33

Most of cell growth occur during which phases of interphase?

Answer 33

G1 and G2

Question 34

Chromosomes replicate to form sister chromatids during which phase in the interphase?

Answer 34

S phase

Question 35

What happens during the G1 phase?

Answer 35

Chromosomes are not duplicating or dividing.

Question 36

What happens during S phase?

Answer 36

Duplication of chromosomes into sister chromatids

Question 37

What happens during G2 phase?

Answer 37

Synthesis of proteins required for mitosis

Question 38

What are the five stages of mitosis?

Answer 38

``` Prophase Prometaphase Metaphase Anaphase Telophase ```

Question 39

What happens during prophase?

Answer 39

Chromosomes condense and become visible

Question 40

What happens in prometaphase?

Answer 40

Spindle forms and sister chromatids attach to microtubules from opposite centrosomes

Question 41

What happens in metaphase?

Answer 41

Chromosome align at the cell equator

Question 42

What happens in anaphase?

Answer 42

Sister chromatids separate and move to opposite poles

Question 43

What happens during telophase?

Answer 43

Chromosomes Decondense and are enclosed in two nuclei.

Question 44

Mitotic spindle forms from what three kinds of microtubules?

Answer 44

Astral, kinetochore, and polar

Question 45

What is cytokinesis?

Answer 45

The cytoplasm divides, splitting the elongated parent cell into two daughter cells with identical nuclei

Question 46

Somatic cells make up what?

Answer 46

Vast majority of cells in the organisms

Question 47

Germ cells are what?

Answer 47

Precursors to gametes

Question 48

What are the two rounds of cell division in meiosis?

Answer 48

Chromosomes duplicate once; nuclei divide twice Meiosis 1 reduces the chromoses from 2n to n

Question 49

What happens in meiosis 1?

Answer 49

Homologs pair, cross over, and then segregate

Question 50

What are the first three sub stages of prophase 1?

Answer 50

Leptotene, zygotene, and pachytene

Question 51

What happens in prophase 1: leptotene

Answer 51

Chromosomes thicken and become visible, but the chromatids remain invisible. Centrosomes begin to move toward opposite poles.

Question 52

What happens in prophase 1: Zygotene?

Answer 52

Homologous chromosomes Exeter synapsids The synaptonemal complex forms

Question 53

What happens in prophase 1: Pachytene

Answer 53

1. Synapsids is complete | 2. Crossing-over, genetic exchange between no sister chromatids of a homologous pair, occurs.

Question 54

What is nondisjunction?

Answer 54

Mistakes in chromosome segregation during meiosis 1 or