Chapter 12 Flashcards Preview

AP Biology Semester 1 > Chapter 12 > Flashcards

Flashcards in Chapter 12 Deck (58):
1

cell division

the continuity of life...the reproduction of cells

2

what type of cell division happens in unicellular organisms?

division of one cell reproduces the entire organism

3

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

-development from a fertilized cell
-growth
-repair

4

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

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

5

genome

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)

6

Chromosomes

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

7

chromatin (definition and where do you find chromatin)

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

8

somatic cells

(nonreproductive cells) have two sets of chromosomes

9

Gametes

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

10

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

-DNA
-Chromosomes

11

sister chromatids

joined copies of the original chromosome which separate during cell division

12

centromere

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

13

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

-separate
-move

14

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

chromosomes

15

eukaryotic cells consist of what type of cell division?

-mitosis
-cytokinesis
-meiosis

16

mitosis

the division of the genetic material in the nucleus

17

cytokinesis

the division of the cytoplasm

18

meiosis

gametes being produced

19

What does the cell cycle consist of ?

-mitotic phase (M)
-interphase

20

mitotic phase (M)

-mitosis and cytokinesis

21

interphase

-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

22

mitosis is divided into what 5 phases?

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

23

what happens in G1 phase?

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

24

what happens in S Phase?

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

25

what happens in G2 phase?

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.

26

what happens in prophase?

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

27

what happens in prometaphase?

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.

28

what happens in metaphase?

the alignment of chromosomes at the center of the cell

29

what happens in anaphase?

separation of sister chromatids to opposite mitotic spindle poles.

30

what happens in telophase?

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.

31

mitotic spindle

a structure made of microtubules that controls chromosome movement during mitosis

32

what begins in the centrosome?

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

33

when do cetrosomes replicate?

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

34

aster

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

35

the spindle includes what 3 things?

1. centrosomes
2. the spindle microtubules
3. asters

36

kinetochores

protein complexes associated with centromeres

37

what do spindle microtubules do during prometaphase?

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

38

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

the microtubules shorten by depolymerizing at their kinetochrome ends

39

nonkinetochore microtubules

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

40

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

-Cleavage
-Cleavage furrow

41

cytokinesis IN PLANTS forms a ______

cell plate

42

binary fission

-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

43

mitosis evolved from ____ _____

binary fission

44

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

-chemical signals

45

cell cycle control system

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

46

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

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

47

what does the G1 checkpoint do?

-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)

48

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

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

49

maturation-promoting factor (MPF)

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

50

growth factors (what is an example)

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

51

density dependent inhibition (an external signal)

crowded cells stop dividing

52

what is an example of an internal signal?

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

53

anchorage dependence (an external signal)

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

54

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

TRUE

55

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

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

56

transformation

a normal cell being converted to a cancerous cell

57

benign tumor

abnormal cells remain at the original site

58

malignant tumors

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