Biology I H - Chapter 8

Front 1

___________ are tightly coiled DNA molecules and their associated proteins

Back 1

Chromosomes

Front 2

In eukaryotes, proteins called ________ help to maintain the compact structure of chromosomes

Back 2

histones

Front 3

Proteins called ___________ control the activity of specific regions of DNA

Back 3

nonhistones

Front 4

In cells that divide, chromosomes are composed of identical __________ constructed together at a centromere

Back 4

chromatids

Front 5

___________ help chromosomes to move during cell division

Back 5

Centromeres

Front 6

Most prokaryotes contain one chromosome that coils into a ________ shape

Back 6

circular

Front 7

2 types of chromosomes:

Back 7

- Sex chromosomes
- other chromosomes are called autosomes

Front 8

determine the sex of an organism and may carry genes for certain traits

Back 8

Sex chromosomes

Front 9

Humans have ___ sex chromosomes

Back 9

two

Front 10

Each cell of an organism produced by sexual reproduction has 2 copies of each ________ - one from each parent

Back 10

autosome

Front 11

The two copies of each autosome are called __________ ___________ or __________

Back 11

homologous chromosomes or homologues

Front 12

photomicrograph of the chromosomes in a dividing cell

Back 12

Karyotype

Front 13

the number of chromosomes in cells that have homologous pairs of autosomes and two sex chromosomes

Back 13

Diploid

Front 14

_______ (n) cells have half of the number of chromosomes that are present in diploid cells

Back 14

Haploid

Front 15

Human diploid cells have __ chromosomes

Back 15

46

Front 16

Human haploid cells have __ chromosomes

Back 16

23

Front 17

division of a prokaryotic cell into 2 offspring cells

Back 17

Binary fission

Front 18

Three stages of binary fission:

Back 18

- The chromosome makes a copy of itself, resulting in 2 identical chromosomes.
- The cell grows until it reaches approximately twice the cell’s original size.
- A cell wall forms between the chromosomes and the cell splits into two new cells.

Front 19

As a result of binary fission, each new cell has an _________ __________

Back 19

identical chromosome

Front 20

Two types of cell division:

Back 20

- Mitosis
- Meiosis

Front 21

results in new cells with genetic material that is identical to the original cell

Back 21

Mitosis

Front 22

reduces the chromosome number by half in the new cell

Back 22

Meiosis

Front 23

repeating set of events that make up the life of a cell

Back 23

Cell Cycle

Front 24

The cell cycle consists of __________ and ____ ________

Back 24

interphase and cell division

Front 25

Cells can exit the cell cycle and enter into a state called __ phase

Back 25

G0

Front 26

During __ phase, cells do not copy DNA and do not prepare for division

Back 26

G0

Front 27

Cell division is divided into 2 phases:

Back 27

- During mitosis or meiosis, or the M phase, the nucleus divides.
- During cytokinesis, the cytoplasm divides

Front 28

_______ is a continuous process divided into 4 phases

Back 28

Mitosis

Front 29

The four phases in mitosis are ________, _________, ________, and _________

Back 29

prophase, metaphase, anaphase, and telophase.

Front 30

During Prophase in mitosis, DNA changes into _________ chromosomes

Back 30

rod-shaped

Front 31

During Prophase in mitosis, the two copies of each chromosome called _________ stayed connected to each other by the centromere

Back 31

chromatid

Front 32

During Prophase in mitosis, _______ ________ breaks down and disappears

Back 32

nuclear membrane

Front 33

During metaphase in mitosis, Chromosomes move to the ______

Back 33

center

Front 34

During anaphase in mitosis, the chromatids of each chromosome separate at the centromere and slowly move toward ________ _____

Back 34

opposite poles

Front 35

During telophase in mitosis, spindle fibers ___________ and chromosomes return to a less tightly coiled chromatin state

Back 35

disassemble

Front 36

During telophase in mitosis, _______ ________ forms around each set of chromosomes

Back 36

nuclear envelope

Front 37

In animal cells, ___________ begins with a pinching inward of the cell membrane

Back 37

cytokinesis

Front 38

The area of the cell membrane that pinches in and eventually separates the dividing cell into two cells

Back 38

cleavage furrow

Front 39

Dueing Cytokinesis in plant cells, a ____ _____ forms and divides the cell

Back 39

cell plate

Front 40

Process of nuclear division that reduces the number of chromosomes in new cells to half the number of chromosomes in the original cell

Back 40

Meiosis

Front 41

In humans, meiosis produces _______ (egg or sperm) with __ chromosomes

Back 41

gametes; 23

Front 42

Before undergoing meiosis, cells go through __________. During this phase the number of chromosomes double

Back 42

interphase

Front 43

In meiosis, cells undergo division _____

Back 43

twice

Front 44

The cell then goes through prophase, metaphase, anaphase, telophase, and cytokinesis

Back 44

Meiosis I

Front 45

During meiosis I in prophase I, ________ ____ occurs

Back 45

crossing over

Front 46

In ________ ____, the tip of one chromatid of a chromosome replaces the tip of the other chromatid of the chromosome

Back 46

crossing over

Front 47

The two cells formed during meiosis I ______

Back 47

divide

Front 48

Result: _ cells with half of the number of chromosomes as the original cell. (Called haploid b/c they have ½ of what original cell had)

Back 48

4

Front 49

Cells are called _______

Back 49

gametes

Front 50

Humans have __ chromosomes

Back 50

46

Front 51

At the end of interphase, there are __ chromosomes

Back 51

92

Front 52

In meiosis I, there are __ chromosomes

Back 52

46

Front 53

In meiosis II, there are __ chromosomes

Back 53

23

Front 54

Meiosis occurs in the ____________ ______

Back 54

reproductive organs

Front 55

Production of eggs

Back 55

oogenesis

Front 56

Production of sperm

Back 56

spermatogenesis

Front 57

Sometimes, chromosomes do not separate properly during _______

Back 57

meiosis

Front 58

The failure to separate is called ______________

Back 58

nondisjunction

Front 59

In nondisjunction, the _______ have an abnormal number of chromosomes

Back 59

gametes