Download Chapter 5: Cell Growth and Division

Chapter 5:
Cell Growth and Division
PART ONE
Sections 1, 2, & 4
5.1 The Cell Cycle
KEY CONCEPT : Cells have distinct phases of growth, reproduction, and normal
functions.
Cell Reproduction


“All cells come from pre-existing cells”
Two main types of cell reproduction:
◦ Asexual: (MITOSIS) – offspring is identical to the
parent cell
◦ Sexual: (MEIOSIS) – offspring is not identical to either
parent
◦ produces gametes (sperm and egg cells)
The Cell Cycle

The complete series of events from one cell
division to the next.

Why Do Cells Divide?
◦ Reproduction: new organisms are produced from parents
◦ Growth: multicellular organisms grow by producing more
cells
◦ Repair: damaged cells are replaced by producing new cells

The cell cycle is a regular pattern of growth, DNA
replication, and cell division.
The cell cycle has four main stages.
– Interphase: Longest phase of the cell cycle
– Gap 1 (G1): cell growth and normal
functions
– DNA synthesis (S): copies DNA
– Gap 2 (G2): additional growth and
prepares for division
– Mitosis (M): includes division of the cell
nucleus (mitosis) and division of the cell
cytoplasm (cytokinesis)
– Prophase
– Metaphase
– Anaphase
– Telophase
CELL CYCLE OVERVIEW
Put it all together!
1.
What are the stages of cell cycle?
◦ G1, S, G2, and Mitosis
2. What happens during G1?
◦ Cell grows
3. What happens during S?
◦ Replication of DNA
4. What happens during G2?
◦ Cell Prepares to divide
5. What happens during M?
◦ Cell divides
5.2 Mitosis and Cytokinesis
KEY CONCEPT : Cells divide during mitosis and cytokinesis.
Chromosomes condense at the start of mitosis.
DNA double
helix
Each continuous
,double-stranded
DNA molecule
makes one
chromosome.
DNA and
histones
DNA wraps
around proteins
called histones,
forming
chromatin.
Chromatin
Supercoiled
DNA
Interactions
between parts
of the histones
further compact
the DNA
The chromatin
coils more and
more tightly
around organizing
proteins.
Chromosome Structure
chromatid
• DNA plus proteins is called
chromatin.
• One half of a duplicated
chromosome is a chromatid.
• Sister chromatids are held together
at the centromere.
• Telomeres (far ends of each
chromatid) protect DNA and do not
include genes.
telomere
centromere
telomere
Condensed, duplicated chromosome
Telomeres and Aging
The Science of Aging
http://www.youtube.com/watch?v=x1zw6uRxKYU
http://www.youtube.com/watch?v=BkcXbx5rSzw
Cancer Risk With Telomere Length
http://www.youtube.com/watch?v=PylY3hVzrb4
Interphase
Longest phase of cell cycle
 Interphase has 3 stages:
◦ G1, S, & G2
 The cell contains a pair of
centrioles.
 The cell's chromosomes
have duplicated but are in
the form of chromatin.

Parent cell
centrioles
spindle fibers
centrosome
nucleus with
DNA
Mitosis
Mitosis produces 2 genetically identical daughter cells.
 Mitosis divides the cell’s nucleus in four phases.

◦
◦
◦
◦

Prophase
Metaphase
Anaphase
Telophase
I remember it as PMAT
1) Prophase:
o The nuclear membrane begins to disappear
o chromatin condense into chromosomes
o spindle fibers form
2) Metaphase:
o Spindle fibers attach to centromeres
o Spindle fibers line up chromosomes in the middle of
the cell.
3) Anaphase:
o spindle fibers condense and separate sister chromatids
to opposite sides of the cell.
4) Telophase:
o chromosomes begin to uncoil
o the nuclear membrane reforms
o the spindle fibers disappear
o Cytokinesis, which divides the cell in two, begins.
Cytokinesis
– Divides cytoplasm between 2 daughter
cells each with genetically identical
cells.
– Cytokinesis differs in animal and plant
cells
– In animal cells, cleavage furrow
separates two new nuclei
– In plant cells, a cell plate forms.
Cytokinesis: Animal Cells & Plant Cells
Mitosis
What stage is this?
What stage is this?
What stage is this?
What stage is this?
What stage is this?
Mitosis
http://www.youtube.com/watch?v=1cVZBV9tD-A
Elodea cells
Cheek cells
5.4 Asexual Reproduction
KEY CONCEPT: Many organisms reproduce by cell division.
Asexual Reproduction


Binary fission is similar in function to mitosis.
Asexual reproduction is the creation of offspring from a
single parent.
◦ Binary fission produces two daughter cells genetically identical to
the parent cell.
parent cell
◦ Binary fission occurs in
prokaryotes.
DNA
duplicates
cell begins
to divide
daughter
cells
PART TWO
Sections 3 & 5
5.3 Regulation of the Cell Cycle
KEY CONCEPT: Cell cycle regulation is necessary for healthy growth.
Apoptosis
◦
◦
◦
◦
Apoptosis is programmed cell death.
It’s a normal feature of healthy organisms
It’s caused by a cell’s production of self-destructive enzymes
It’s a mechanism by which organisms limit the growth and
replication of cells.
◦ Loss of apoptosis is one of the key mechanisms behind cancer.
PICTURE: http://www.brecorder.com/world/north-america/104165-half-of-worldcountries-unprepared-to-deal-with-cancer-who.html
Cell division is uncontrolled in cancer.

Cancer cells form disorganized clumps called tumors.
– Benign tumors
– Remain clustered and can be removed.
– Remain at the original site
– Malignant tumors
– metastasize, or break away, and can form more tumors.
– Spread in the body
normal cell
cancer cell
bloodstream

Cancer cells do not carry out necessary functions.
• Cancer cells come from normal cells with damage to
genes involved in cell-cycle regulation.

Carcinogens are substances known to promote cancer.
Carcinogens - College Biology
http://www.youtube.com/watch?v=9-I3kKYY7zE
Cancer Treatment
• Surgery: Remove tumor(s)
• Radiation & Chemotherapy: used to disrupt cell division
– May have undesirable side effects
• Standard cancer treatments typically kill both
cancerous and healthy cells
FYI: Number of deaths for leading causes of death
1.
2.
3.
4.
Heart disease: 597,689 Risk factors: obesity, smoking, high blood pressure & cholesterol, and diabetes
Cancer: 574,743 Lung cancer causes the most deaths among men & women, followed in women by breast cancer
Chronic lower respiratory diseases: 138,080 smoking & second hand smoking
Stroke: 129,476 Risk factors: alcohol, smoking, obesity, high blood pressure & cholesterol, and diabetes
•
Occurs when the blood supply to an area of the brain is obstructed, causing brain
cells to die
5. Accidents (unintentional injuries): 120,859
6. Alzheimer's disease: 83,494 It’s genetics; memory problems
7. Diabetes: 69,071 Risk factors: obesity, old age, a family history of diabetes and not exercising
• abnormally high blood sugar levels, and can lead to kidney failure,
blindness, heart disease
8. Nephritis and nephrotic syndrome: 50,476
•
•
Nephritis is the inflammation of the kidneys
Nephrotic syndrome is caused by different disorders that damage the kidneys
9. Influenza and Pneumonia: 50,097 caused by a virus; A seasonal flu shot can help prevent it
10. Intentional self-harm (suicide): 38,364
THE TEN LEADING CAUSES OF DEATH
What is cancer?
http://www.youtube.com/user/1cancercenter?v=SGaQ0WwZ_0I
Cancer Treatments: Radiation & Chemotherapy
http://www.youtube.com/watch?v=yrR_s0UzS1M
5.5 Multicellular Life
KEY CONCEPT: Cells work together to carry out complex functions.
Multicellular organisms depend on interactions
among different cell types.


Tissues are groups of cells that perform
a similar function.
Organs are groups of tissues that
perform a specific or related function.
Organ systems are groups of organs
that carry out similar functions.
CELL
TISSUE
leaf
stem
vascular
tissue
ORGAN
lateral
roots
primary
root
root system

shoot system
SYSTEMS
cells  tissues  organs  organ system
cells
tissue
Lung cell  Lung tissue 
organ
organ system
organism
Lung  Respiratory System  Person

http://www.bbc.co.uk/bitesize/ks3/science/organis
ms_behaviour_health/cells_systems/activity/
Specialized cells perform specific functions.
Cells develop into their mature forms through the process of cell
differentiation.
 Cells differ because different combinations of genes are
expressed.
 A cell’s location in an embryo helps determine how it will
differentiate.

Outer: skin cells
Middle: bone cells
Inner: intestines
Stem cells are unique body cells.

Stem cells have the ability to
◦ divide and renew themselves
◦ remain undifferentiated in form
◦ develop into a variety of specialized cell types
Stem cells come from adults and embryos.
–
–
–
–
Adult stem cells can be hard to isolate and grow.
The use of adult stem cells may prevent transplant rejection.
The use of embryonic stem cells raises ethical issues
Embryonic stem cells can be grown indefinitely in culture.
First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner
cell mass. These cells are then removed and grown with nutrients. Scientists try to
control how the cells specialize by adding or removing certain molecules.

The use of stem cells offers many currently realized and
potential benefits.
– Stem cells are used to treat leukemia and lymphoma.
– Stem cells may cure disease or replace damaged organs.
– Stem cells may revolutionize the drug development process.
Stem cells in bone marrow are being used to treat EB
http://www.youtube.com/watch?v=F8DLVTR1iiQ
http://www.youtube.com/watc
h?v=49YputwJ6YM
http://www.youtube.com/watch?v=8JT
w2RpDo9o
Bone Marrow Transplant-Mayo Clinic
http://www.youtube.com/watch?v=GIy2nMn
uGGI
Trachea Grown With Stem Cells
http://www.youtube.com/watc
h?v=XL72Dn3rJ_E