Ch. 8 Cell Reproduction

Question 1

Why do cells divide (three reasons)?

Answer 1

1. growth of an organism
2. repairing damage, such as cuts and broken bones
3. small cells are more efficient than large cells

Question 2

Why are small cells more efficient?

Answer 2

the large surface area to volume ratio allows materials to be transported well throughout the cell

Question 3

What does every living organism start out as?

Answer 3

one cell containing one set of DNA

Question 4

What must every newly reproduced cell contain?

Answer 4

an identical set of the DNA found in the original cell

Question 5

When must cells divide?

Answer 5

when their increase n size has reached a maximum

Question 6

How is DNA packed between cell divisions?

Answer 6

loosely in the nucleus

Question 7

Why would DNA need to be loose and uncoiled?

Answer 7

instructions coded by the sequence of DNA bases can be “read” and used by the cell

Question 8

What is the uncoiled form of DNA called?

Answer 8

chromatin

Question 9

What happens to the chromatin during cell division?

Answer 9

it coils and condenses into chromosomes

Question 10

What are chromosomes?

Answer 10

rod-shaped structures made of DNA wrapped around histone (protein molecules)

Question 11

What do chromosomes consist of in dividing eukaryotic cells?

Answer 11

two identical halves

Question 12

What is each half called?

Answer 12

a chromatid

Question 13

When do chromatids form?

Answer 13

as the DNA makes a copy of itself before cell division

Question 14

What are sister chromatids?

Answer 14

identical chromatids attached to each other at the centromere point

Question 15

What does each species have?

Answer 15

a characteristic number of chromosomes in each cell

Question 16

What are human sex chromosomes called?

Answer 16

X & Y

Question 17

What are autosomes?

Answer 17

all the other chromosomes in an organism besides the sex ones

Question 18

How many chromosomes do humans have?

Answer 18

46

Question 19

How many of those chromosomes are pairs of autosomes & how many are pairs of sex chromosomes?

Answer 19

22 pairs are autosomes, one pair are sex chromosomes

Question 20

How many copies of each autosome does every cell produced by sexual reproduction have? Where does each copy come from?

Answer 20

two, one copy came from each parent

Question 21

What are homologous chromosomes?

Answer 21

the two copies of each autosome that are the same size, & shape and carry genetic information for the same traits

Question 22

What does a karyotype show?

Answer 22

the 22 pairs of homologous chromosomes lined up in order of size and the one pair of sex chromosomes

Question 23

What are diploids (2n)?

Answer 23

cells that have two sets (pairs) of chromosomes, all somatic/body cells are 2n

Question 24

What are haploid cells (1n)?

Answer 24

cells that have one set of chromosomes es: sex cells (sperm & egg cells)

Question 25

What is cell division in prokaryotes called?

Answer 25

binary fission

Question 26

How do prokaryotes divide themselves through binary fission?

Answer 26

they copy their circular piece of DNA, form a piece of cell membrane between the two copies, and pinch off to form two cells that have identical DNA

Question 27

What are the two processes of cell division for eukaryotic cells?

Answer 27

mitosis and meiosis

Question 28

How do mitosis and meiosis differ?

Answer 28

mitosis divides somatic cells, meiosis divides sex cells mitosis results in 2 cells w/ identical DNA to the original meiosis results in cells that are not identical to original

Question 29

What type of cells are produced through meiosis?

Answer 29

gametes which are haploid reproductive cells genetically different from the original cell

Question 30

What is the cell cycle and it's two major stages?

Answer 30

the repeating life cycle of a cell consisting of two major stages: interphase & cell division

Question 31

When does interphase happen?

Answer 31

between cell divisions

Question 32

What happens during interphase?

Answer 32

growth G1, DNA replication S, and prep for cell division G2

Question 33

What is cell division divided into?

Answer 33

mitosis & cytokinesis

Question 34

What does mitosis divide and what does cytokinesis divide?

Answer 34

mitosis - division of nucleus | cytokinesis - division of cytoplasm

Question 35

What are the four stages of mitosis?

Answer 35

PMAT - prophase, metaphase, anaphase, and telophase

Question 36

What results from mitosis?

Answer 36

two offspring cells that are genetically identical to the original cell

Question 37

P : Prophase

Answer 37

``` cell is preparing to divide chromatin condenses into chromosomes centrioles separate spindle fibers form nuclear membrane disappears ```

Question 38

M : Metaphase

Answer 38

chromosomes attach to spindle fibers and align in the middle

Question 39

A : Anaphase

Answer 39

sister chromatids separate into individual chromosomes

Question 40

T : Telephase

Answer 40

two separate nuclei form chromosomes return to chromatin form nuclear membrane reappears

Question 41

What is cytokinesis?

Answer 41

the last step of cell division (telephase blends into it)

Question 42

What happens during cytokinesis in animal cells?

Answer 42

a cleavage furrow pinches in and eventually separates the dividing cell into two cells

Question 43

What happens during cytokinesis in plant cells?

Answer 43

a cell plate separates the dividing cells into two cells

Question 44

How is cell division in eukaryotes controlled?

Answer 44

some proteins trigger a cell to leave interphase and begin dividing while other proteins trigger the cell to halt the cycle of division and enter interphase

Question 45

Why does cancer happen when control of cell division is lost?

Answer 45

the proteins that control the cell cycle are coded for by DNA, so if a mutation occurs in this coded area, the proteins that triggers a cell to stop dividing may be defective

Question 46

How is cancer caused?

Answer 46

by a defect in the cell cycle when cells do not stop dividing and produce tumors

Question 47

What are stem cells?

Answer 47

unspecialized cells that give rise to the different types of cells that make up the human body