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AP Bio > Chapter 12: Cell Cycle > Flashcards

Chapter 12: Cell Cycle Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the 2 types of reproduction for cells?

A

Asexual and Sexual

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2
Q

Asexual Reproduction

A

Purpose is to create genetically identical offspring

Single parent

Can replace cells or an entire organism

Replace an entire organism
Growth of multicellular organisms
Growth of organism from fertilized egg
Repair and replacement of cells

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3
Q

Sexual Reproduction

A

Involves 2 parents

Results in genetically different organisms

Many chances for variation promoted by nature

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4
Q

How does prokaryotes reproduce?

A

Binary fission

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5
Q

Binary Fission

A
  1. Duplication of chromosome & separation of copies
  2. Continued elongation of the cell & movement of copies
  3. Division into 2 daughter cells
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6
Q

What is division is used for multicellular organisms?

A

Growth
Repair
Reproduction of an organism

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7
Q

What is passed into daughter cell’s ?

A

Exact copy of genetic material = DNA
Mitosis

Organelles, cytoplasm, cell membrane, enzymes

cytokinesis

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8
Q

What are the stages of mitosis?

A

Interphase, prophase, pro-metaphase,
Metaphase, anaphase, cytokinesis, telophase

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9
Q

Interphase

A

About 90% of cell life cycle

Cell doing its “everyday job”
Produce RNA, synthesis proteins/enzymes

Prepares for duplication of triggered

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10
Q

What cells grow and matures and never divide again ?

A

Brain, nerve and muscle cells

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11
Q

How many phases is interphase divided into ?

A

3

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12
Q

G1

A

1st Gap (Growth)
Cell doing its everyday job
Cell grows

1st phase of Interphase

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13
Q

S

A

DNA Synthesis
Copies chromosomes
Dividing cell replicates DNA
Must separate DNA copies correctly to 2 daughter cells
Human cell duplicate ~ 3 m DNA

Error rate: ~ 1 per 100 million bases

2nd phase of Interphase

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14
Q

G2

A

2nd Gap Growth

Prepares for division
Cell grows (more)
Produces organelles, proteins, membranes

3rd phase of interphase

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15
Q

How is the nucleus during interphase?

A

Well defined, DNA loosely packed in long chromatin fibers

Prepares for mitosis
Replicates chromosome
DNA & proteins

Produces proteins & organelles

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16
Q

How is DNA organized?

A

DNA is organized in chromosomes
Double Helix DNA molecule
Wrapped around histone proteins
like thread on spools

DNA- proteins complex= chromatin
organized into long thin fiber
Condensed further during mitosis

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17
Q

What happens after DNA duplicates?

A

Chromatin condenses
Coiling & folding to make a smaller package

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18
Q

The Cell Cycle is an ordered sequence events for cell division & consists of what 2 stages ?

A

Interphase : duplication of cell contents
G1– growth, increase in cytoplasm
S - duplication of chromosomes
G2 - growth, preparation for division

Mitotic Phase : division
Mitosis— division of the nucleus
Cytokinesis— division of cytoplasm

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19
Q

What are the 5 phases of Mitosis

A

Prophase
Pro metaphase
Metaphase
Anaphase
Telophase
Cytokinesis is well underway by late telophase

20
Q

Prophase

A

Chromatin condenses
- visible chromosomes
Chromatids

Centrioles move to opposite poles of cell

Protein fibers cross cell to form mitotics spindle
- microtubules
Actin, myosin
- coordinates movement of chromosomes

Nucleus disappears
Nuclear membrane breaks down

21
Q

Transition into metaphase

A

Spindle fibers attach to centromeres
creating kinetochores

microtubules attach at kinetochores
Connect centromeres to centrioles

Chromosomes begin to moving

22
Q

Metaphase

A

Chromosomes align along middle of cell

Metaphase plate
Meta= middle

Spindles fibers coordinate movement

Helps to ensure chromosomes separate properly

(So each new nucleus receives only 1 copy of each chromosome)

23
Q

Anaphase

A

Sister chromatids separate at kinetochores

Move to opposite poles

Pulled at centromeres
— pulled by motor proteins “walking” along microtubules
actin myosin
Increased production of ATP by mitochondria

Poles move farther apart

24
Q

Separation of Chromatids

A

In anaphase, proteins holding together sister chromatids are inactivated

separate to become individual chromosomes

25
Q

What causes the movement alone the chromosome?

A

Kinetochores use motor proteins that “walk” chromosome along attached microtubules

Microtubules shortens by dismantling at kinetochore (chromosome) end

26
Q

Telophase

A

Chromosomes arrive at poles
Daughter nuclei form
Nucleoli form
Chromosomes disperse
No longer visible under light microscope

Spindle fibers disperse

Cytokinesis begins
— cell division

27
Q

Cytokinesis in Animals

A

constriction belt of actin micro filaments around equator of cell

Cleavage furrow forms

Splits cell in two

Like tightening a draw string

28
Q

Cytokinesis in Plants

A

Cell plate forms
Vesicles line up at equator
Derived from Golgi

Vesicles fuse to form 2 cell membranes
New cell wall laid down b/tw membranes
New cell wall fuses with existing cell wall

29
Q

What is the eukaryotic cell cycle regulated by?

A

Molecular control system, the frequency of cell division varies w/ the type of cell

The cell cycle differences result from regulation at molecular level

30
Q

How is the control of cell signaling communicated

A

Cell signaling

31
Q

Coordination of Cell Division

A

A multicellular organism needs to coordinate cell division across different tissues & organs

Critical for normal growth, development & maintenance

Coordinate timing of cell division 

Coordinate rates of cell division 

Not all cells can have the cell cycle
32
Q

Frequency of Cell Division

A

Embryo
Cell cycle< 20 minutes
Skin Cells
Divide frequently throughout life
12-24 hours

Liver cells
Retain ability to divide, but keep it in reserves
Divide once every year or two

Mature nerve & muscle cells
Do not divide at all after maturity
Permanently in G0

33
Q

Cell Cycle Control System

A

The sequential events of the cell cycle are direct by cell cycle control system

Regulated by internal and external controls

The clock has specific checkpoints where the cell cycle stops until the go-ahead signal is received

34
Q

Checkpoint Control System

A

G1/S
Can DNA synthesis begin?

G2/M
Has DNA synthesis been completed correctly?

Spindle Checkout
Are all chromosomes attached to spindle

Can sister chromatids separate correctly

35
Q

G1/S checkpoint

A

Most critical
Primary decision point
“Restriction point”

If cell receives “Go” signal it divides
Internal signals: cell growth (size), cell nutrient
External signals: “growth factors”

If cell does not receive signal, it exits cycle & switches to G0 phase
non/dividing, working state

36
Q

G0 phase

A

Non-dividing, differentiated state

Most human cells in G0 phase

37
Q

Go- Ahead Signals

A

Protein signals that promote cell growth & division

—internal signals
“Promoting factors”

—external signals
“growth factors”

Primary mechanism of control
— phosphorylation
Kinase enzymes
either activates or inactivates cell signals

38
Q

Cell Cycle Signals

A

Cell Cycle controls

cyclins
Regulatory proteins
Levels cycle in the cell

Cdks
Cyclin-dependent kinase
Phosphorylates cellular proteins
activates or inactivates proteins

Cdk- cyclin complex (MPF maturation promoting factor)
Triggers passage through different stages of cell cycle
The activity of cyclins and Cdks fluctuates during cell cycle

39
Q

External Signals

A

Growth factors
Coordination b/tw cells
Proteins signals released by body cells that stimulate other cells to divide

Density- dependent inhibition
Crowed cells stop dividing
Each cells binds a bit of growth factor
Not enough activator left to trigger division in any one cell.

Anchorage dependence
To divide cells must attached to a substrate
“Touch sensor” receptors

40
Q

Platelet Derived Growth Factor

A

made by platelets in blood clots

Binding of PDGF to cell receptors stimulates cell division in connective tissue
heal wounds

41
Q

Growth Factors & Cancer

A

Growth factor can create cancers

—Porto-oncogenes
Normally activates cell division
growth factor genes
becomes oncogenes (cancer/causing) when mutated

If switched “On “ can cause cancer
Ex: RAS(Activates. Cyclins).

Tumor-Suppressor Genes
Normally inhibits cell division
If switched “OFF” can cause cancer
Ex: p53

42
Q

Cancer & Cell Growth

A

Cancer is essentially a failure of cell division control
— unrestrained, uncontrolled cell growth

What control is lost
Lose checkpoint stops
Gene p53 plays key role in G1/S restriction point
p53 proteins halts cell division if it detects damaged DNA

4 options
stimulates repair enzymes to fix DNA
Forces cell into G0 resting stage
Keeps cell in G1 arrest
Cause apoptosis of damaged cell

All cancers have to shut down p53 activity

43
Q

What are the 6 key mutations that have to occur for a cell to develop cancer

A

Unlimited growth
— turn on growth promoter genes

Ignore Checkpoint
— turn off tumor suppressor genes (p53)

Escape Apoptosis
— turn off suicide genes

Immortality = unlimited divisions
— turn on chromosomes maintenance genes

Promotes blood vessels growth
— turn on blood vessels growth genes

Overcome anchor & density dependence
— turn off touch-sensor gene

44
Q

What can trigger mutations in cells ?

A

UV radiation

Chemical exposure

Radiation exposure.

Heat

Cigarette smoke

Pollution

Age

Genetics

45
Q

Tumors

A

Mass of abnormal cells

46
Q

Benign Tumor

A

Abnormal cells remain at original site as a lump.
— p53 has halted cell divisions

Most do not cause serious problems & can be removed by surgery

Malignant Tumor

Cells leave original site

Lose attachment to nearby cells 
Carried by blood & lymph system to other tissues 
 Starts more rumors= metastasis

Metastasis: development of secondary malignants growth away from primary site

Impair functions of organs throughout body

AP Bio (19 decks)

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