Chapter 12

Question 1

cell division

Answer 1

the continuity of life…the reproduction of cells

Question 2

what type of cell division happens in unicellular organisms?

Answer 2

division of one cell reproduces the entire organism

Question 3

multi cellular organisms depend on cell division for… (3 things)

Answer 3

• development from a fertilized cell
• growth
• repair

Question 4

most cell division results in ______ cells with identical ___…. and what is the exception?

Answer 4

• daughter
• DNA
• the exception is meiosis, a special type of division that can produce sperm and egg cells

Question 5

genome

Answer 5

all of the DNA in a cell

• can consist of a single DNA molecule (prokaryotic cells)
• can consist of a number of DNA molecules (eukaryotic cells)

Question 6

Chromosomes

Answer 6

DNA molecules in a cell are packaged in the chromosome
-remember a chromosome can look like an x but it can also look like an / because it is the same chromosome just a replica so you say it is still one chromosome

Question 7

chromatin (definition and where do you find chromatin)

Answer 7

• a complex of DNA and protein that condenses during cell division
• found in eukaryotic cells

Question 8

somatic cells

Answer 8

(nonreproductive cells) have two sets of chromosomes

Question 9

Gametes

Answer 9

(reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells

Question 10

in preparation for cell division, ___ is replicated and the ___ condense

Answer 10

• DNA

- Chromosomes

Question 11

sister chromatids

Answer 11

joined copies of the original chromosome which separate during cell division

Question 12

centromere

Answer 12

the narrow “waist” of the duplicated chromosome, where the two chromatids are mostly attached

Question 13

During cell division, the two sister chromatids ____ and ____ into two nuclei

Answer 13

• separate

- move

Question 14

once sister chromatids are separated into two nuclei what are they called?

Answer 14

chromosomes

Question 15

eukaryotic cells consist of what type of cell division?

Answer 15

• mitosis
• cytokinesis
• meiosis

Question 16

mitosis

Answer 16

the division of the genetic material in the nucleus

Question 17

cytokinesis

Answer 17

the division of the cytoplasm

Question 18

meiosis

Answer 18

gametes being produced

Question 19

What does the cell cycle consist of ?

Answer 19

• mitotic phase (M)

- interphase

Question 20

mitotic phase (M)

Answer 20

-mitosis and cytokinesis

Question 21

interphase

Answer 21

• cell growth and copying of chromosomes in preparation for cell division
• is about 90% of the cell cycle
• G1 phase (first gap/growth)
• S Phase (synthesis)
• G2 phase (2nd gap/growth)
• **the cell grows in all 3 phases, but chromosomes are duplicated only during the S phase

Question 22

mitosis is divided into what 5 phases?

Answer 22

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. Telophase
   * **cytokinesis overlaps the latter stages of mitosis (telophase)

Question 23

what happens in G1 phase?

Answer 23

the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis.

Question 24

what happens in S Phase?

Answer 24

To produce two similar daughter cells, the complete DNA instructions in the cell must be duplicated. DNA replication occurs during this S (synthesis) phase.

Question 25

what happens in G2 phase?

Answer 25

a safety gap during which a cell can check to make sure that the entirety of its DNA and other intracellular components have been properly duplicated. In addition to acting as a checkpoint along the cell cycle, G2 also represents the cell's final chance to grow before it is split into two independent cells during mitosis.

Question 26

what happens in prophase?

Answer 26

Chromosomes become visible, the nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears. Chromosomes become more coiled

Question 27

what happens in prometaphase?

Answer 27

phosphorylation of nuclear lamins causes the nuclear membrane to break down into numerous small vesicles. As a result, the spindle microtubules now have direct access to the genetic material of the cell.

Question 28

what happens in metaphase?

Answer 28

the alignment of chromosomes at the center of the cell

Question 29

what happens in anaphase?

Answer 29

separation of sister chromatids to opposite mitotic spindle poles.

Question 30

what happens in telophase?

Answer 30

the sister chromatids reach opposite poles. The small nuclear vesicles in the cell begin to re-form around the group of chromosomes at each end.

Question 31

mitotic spindle

Answer 31

a structure made of microtubules that controls chromosome movement during mitosis

Question 32

what begins in the centrosome?

Answer 32

the assembly of spindle microtubules...the centrosome is the microtubule organizing center.

Question 33

when do cetrosomes replicate?

Answer 33

during interphase, which forms two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase

Question 34

aster

Answer 34

- a radial array of short microtubules | - extends from each centrosome

Question 35

the spindle includes what 3 things?

Answer 35

1. centrosomes 2. the spindle microtubules 3. asters

Question 36

kinetochores

Answer 36

protein complexes associated with centromeres

Question 37

what do spindle microtubules do during prometaphase?

Answer 37

attach themselves to the kinetochores of chromosomes and begin to move the chromosomes

Question 38

how do microtubules pull chromatids to opposite parts of the cell?

Answer 38

the microtubules shorten by depolymerizing at their kinetochrome ends

Question 39

nonkinetochore microtubules

Answer 39

nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell

Question 40

cytokinesis occurs by a process known as _____, forming a _____ _____ (IN ANIMAL CELLS)

Answer 40

- Cleavage | - Cleavage furrow

Question 41

cytokinesis IN PLANTS forms a ______

Answer 41

cell plate

Question 42

binary fission

Answer 42

- for prokaryotes - the chromosome replicates (beginning at the origin or replication), and the two daughter chromosomes actively move apart - plasma membrane pinches inward, dividing the cell into two * *much simpler than mitosis

Question 43

mitosis evolved from ____ _____

Answer 43

binary fission

Question 44

the cell cycle appears to be driven by specific ____ _____ present int the cytoplasm

Answer 44

-chemical signals

Question 45

cell cycle control system

Answer 45

the sequential events of the cell cycle are directed by a distinct cell cycle control system

Question 46

how many checkpoints are there? and what are their names?

Answer 46

1. G1 checkpoint 2. G2 checkpoint 3. M checkpoint

Question 47

what does the G1 checkpoint do?

Answer 47

- if it is not needed or does not have the necessities to duplicate then it exits the cycle and destroys itself - or it goes into a resting phase called the G0 phase (nondividing state)

Question 48

what two types of regulatory proteins are involved in cell cycle control?

Answer 48

1. cyclins | 2. cyclin-dependent kinases (Cdks)

Question 49

maturation-promoting factor (MPF)

Answer 49

a cyclin-Cdk complex that triggers a cell's passage past the G2 checkpoint into the M phase

Question 50

growth factors (what is an example)

Answer 50

proteins released by certain cells that stimulate other cells to divide -PDGF

Question 51

density dependent inhibition (an external signal)

Answer 51

crowded cells stop dividing

Question 52

what is an example of an internal signal?

Answer 52

when kinetochores are not attached to spindle microtubules send a molecular signal that delays anaphase

Question 53

anchorage dependence (an external signal)

Answer 53

animal cells must be attached to a substratum (an underlying layer or substance) in order to divide

Question 54

true or false: cancer cells exhibit neither density-dependent inhibition nor anchorage dependence

Answer 54

TRUE

Question 55

cancer cells do not need ____ ____ to grow and divide and why

Answer 55

growth factors - they make their own growth factors - they convey (transport or carry to a place) a growth factor's signal without the presence of the growth factor - they have an abnormal cell cycle control system

Question 56

transformation

Answer 56

a normal cell being converted to a cancerous cell

Question 57

benign tumor

Answer 57

abnormal cells remain at the original site

Question 58

malignant tumors

Answer 58

invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form addition tumors