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 number is?
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
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
Ch. 12 Warm up
1.
How do we know the cell uses chemical
signals?
2.
Summarize the cell control system.
Ch. 13 Warm up
1.
Compare sexual to asexual reproduction.
2.
Compare/contrast mitosis to meiosis.
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?
Chapter 12: The Cell Cycle
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
Cell Cycle
: life of a cell from its formation
until it divides
Functions of Cell
Functions of Cell
Division
Division
:
Genome
= all of a cell’s genetic info (DNA)
Prokaryote
Prokaryote
: single, circular chromosome
Eukaryote
Eukaryote
: more than one linear
chromosomes
Each chromosome must be duplicated
before cell division
Duplicated chromosome = 2 sister
sister
chromatids
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
Phases of the Cell Cycle
The
mitotic
phase alternates with
interphase
:
G
1
S
G
2
mitosis
cytokinesis
Interphase (90% of cell cycle)
G
1Phase: cell grows and carries out normal
functions
S Phase: duplicates chromosomes
G
2Phase: prepares for cell division
M Phase (mitotic)
Mitosis: nucleus divides
Mitosis
:
Prophase
Prometaphase
Mitosis
1. Prophase
Chromatin fibers condense and coil
Nucleoli disappear
Spindle (microtubules) begins to form
Centrosomes begin to move to opposite
ends
2. Prometaphase
Nuclear envelope fragments
Microtubules invade nucleus
Mitotic spindle at metaphase
Kinetochore = proteins
associated with DNA at
centromere
Kinetochore = proteins
associated with DNA at
3.
Metaphase
Chromosomes line up on metaphase plate
at equator
Centrioles are at opposite poles (ends)
4.
Anaphase
(shortest phase)
Chromatids separate and pulled apart by
motor proteins toward opposite ends of cell
5. Telophase
Nuclear membrane re-forms around
chromosomes
Chromosomes less condensed
Cytokinesis
Cytoplasm of cell divided
During anaphase
Chromosomes walked
to poles by motor proteins
Kinetochore
microtubules shorten at ends as they
Cell Cycle Control System
Checkpoint
= control point where
Major Checkpoints
1.
1.
G
G
11checkpoint
checkpoint
(Most important!)
“Go”
completes whole cell cycle
“Stop”
cell enters nondividing state (G
0Phase)
Nerve, muscle cells stay at G0; liver cells called back from G0
2.
2.
G
G
22checkpoint
checkpoint
3.
3.
M Phase checkpoint
M Phase checkpoint
Anaphase does not begin unless chromatids are
G
Internal Regulatory Molecules
1. Kinases (cyclin-dependent kinase, Cdk): protein enzyme controls cell cycle; active
when connected to cyclin
2. Cyclins: proteins which attach to kinases (Cdk) to activate
them; levels fluctuate in the cell cycle
3. MPF: maturation-promoting factor; specific Cdk which
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
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
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
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
