Ch. 12 Mitosis F12

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Ch.12 Warm up

1. Define: genome, gametes, chromatin,

chromosome, centromere, kinetochore, checkpoint, Cdk, MPF

2. What is the longest part of the cell cycle?

Why?

1. If the diploid number is 46, the haploid

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Ch. 12 Warm up

1. At the end of mitosis and cytokinesis, how

do daughter cells compare with their parent cell when it was in G₁?

2. A cell’s DNA was measured at 5 picograms.

DNA levels range from 3-6 pgms in the cell cycle . What stage of the cell cycle is this cell in. How do you know?

3. At metaphase, if the haploid number is 3,

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Ch. 12 Warm up

What is the correct phase of the cell cycle/mitosis for the following:

A.Most cells that no longer divide or rarely divide

are in this phase

B.Sister chromatids separate and move apart C.Mitotic spindle begins to form

D.Cell plate or cleavage furrow form E.Chromosomes replicate

F.Chromosomes line up on equatorial plate G.Nuclear membrane forms

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Ch. 12 Warm up

1.

Describe the difference between plant

and animal cell division.

2.

Measurements of the DNA amount per

nucleus were taken. DNA levels ranged

from 3-6 picograms per nucleus, what

stage of the cell cycle are these cells in?

a)

One nucleus has 3 pgrms

b)

One with 6 pgrms

c)

5 pgrms

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Ch. 12 Warm up

1.

How do we know the cell uses chemical

signals?

2.

Summarize the cell control system.

3.

Compare a cancer cell to a normal cell.

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Ch. 13 Warm up

1.

Compare sexual to asexual reproduction.

2.

Compare/contrast mitosis to meiosis.

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Ch. 13 Warm up

1. Describe and compare the 3 sexual life

cycles

1. How does random assortment, crossing over

and random fertilization contribute to genetic variation?

2. Define: locus, karyotype, alternation of

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What you must know:



The structure of the duplicated

chromosome.



The cell cycle and stages of mitosis.



The role of kinases and cyclin in the

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Cell Cycle

: life of a cell from its formation

until it divides

Functions of Cell

Division

:

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Genome

= all of a cell’s genetic info (DNA)



Prokaryote

: single, circular chromosome



Eukaryote

: more than one linear

chromosomes



Eg. Human:46 chromosomes, mouse:

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Each chromosome must be duplicated

before cell division



Duplicated chromosome = 2 sister

sister

chromatids

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Somatic Cells

Gametes



Body cells



Diploid (2n): 2 of

each type of

chromosome



Divide by mitosis



Humans: 2n = 46



Sex cells

(sperm/egg)



Haploid (n): 1 of

each type of

chromosome



Divide by meiosis

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Phases of the Cell Cycle



The

mitotic

phase alternates with

interphase

:

G

₁



S



G

₂



mitosis



cytokinesis



Interphase (90% of cell cycle)



G

₁

Phase

: cell grows and carries out normal

functions



S Phase

: duplicates chromosomes



G

₂

Phase

: prepares for cell division



M Phase (mitotic)



Mitosis

: nucleus divides

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Mitosis

:

Prophase



Metaphase



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Mitosis

 Continuous process with observable structural

features:

 Chromosomes become visible (prophase)  Alignment at the equator (metaphase)

 Separation of sister chromatids (anaphase)  Form two daughter cells (telophase &

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Cytokinesis



Cytoplasm of cell divided

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Cell Cycle Control System



Checkpoint

= control point where

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Major Checkpoints

1.

1. GG₁₁ checkpoint checkpoint (Most important!)

 Controlled by cell size, growth factors, environment  “Go” _ completes whole cell cycle

 “Stop”  cell enters nondividing state (G₀ Phase)

 Nerve, muscle cells stay at G₀; liver cells called back from G₀

2.

2. GG₂₂ checkpoint checkpoint

 Controlled by DNA replication completion, DNA _{Controlled by DNA replication completion, DNA}

mutations, cell size mutations, cell size

3.

3. M-spindle (Metaphase) checkpointM-spindle (Metaphase) checkpoint

1. Check spindle fiber (microtubule) attachment to

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G

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M-spindle Checkpoint:

Mitotic spindle at metaphase

Kinetochore =

proteins

associated with DNA at

centromere

Kinetochore = proteins

associated with DNA at

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Internal Regulatory Molecules

• Kinases (cyclin-dependent kinase, Cdk): protein enzyme controls cell cycle; active when connected to cyclin

• _Cyclins_{: proteins which attach to kinases to activate them;}

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Internal Regulatory Molecules

MPF

= maturation-promoting factor

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

Growth Factor:

proteins released by other cells

to stimulate cell division



Density-Dependent Inhibition:

crowded cells

normally stop dividing; cell-surface protein binds

to adjoining cell to inhibit growth



Anchorage Dependence:

cells must be attached

to another cell or ECM to divide

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Cancer Cells

Cancer: disorder in which cells lose the ability to control growth by not responding to regulation.

 multistep process of about 5-7 genetic changes

(for a human) for a cell to transform

 loses anchorage dependency and

density-dependency regulation

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Tumors = mass of abnormal cells

 Benign tumor: lump of cells remain at

original site

 Malignant tumor: invasive - impairs

functions of 1+ organs (called cancer)

 Metastasis: cells separate from tumor and

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Cancer Prevention

Anyone can get cancer but there are ways to

minimize risk:

 Don’t smoke, legal or illegal (includes

hookahs, chew, 2nd-hand smoke)

 Use sun protection

 Exercise and keep weight at ideal level

 Eat 5-7 servings of fruit and veggies a day

 Use screening/preventative

measures-breast/testicle/mole checks