Download Stages of Cell Cycle

GOOD MORNING!
Today we will:
Turn in Chromosome Disorder Activity
• WARM UP
• Short Video
• Mitosis
– Somatic Cell Division (diploid)
– What causes Cancer?
• Onion Root Tip Lab
• HW: DUE Mon 5/2 Onion Root Tip Lab, Quiz on Meiosis &
Mitosis
KEEP Lizard Article Summary for Mon 5/2
WARM UP: Use karyotype to determine
1. Gender
2. Chromosome Disorder
What has to happen in
Meiosis II that causes
nondisjunction?
Stages of Cell Cycle
G1: Cell growth and
protein production,
cell is diploid
Interphase:
about 80% 90% of cell
cycle
Mitosis: begins
when maximum
cell size is reached
Or, apotosis:
programmed cell
death,
unnecessary cells
are eliminated
G2: Growth and
manufacturing of new
cell parts, preparing for
cell division
S: DNA is synthesized
and all chromosomes
are replicated,
double the number of
chromosomes
Interphase
Interphase is the longest phase of the cell cycle
when the cell grows and replicates
chromosomes
Homologous pair
Tetrad
Plant Cells in Various Stages of Cell Cycle
Stages of Mitosis: Cell division of body cells
Cells in Prophase have a nucleus that
looks like it is disappearing (it is
fragmenting around the edges) and
stringy, blob –like appearing structures
within them (these are the visible
chromosomes)
Humans have 23 DIFFERENT
chromosomes (n), but because they
get one complete set of copies from
mom (n), and one complete set of
copies from dad (n) they have a
TOTAL of 46 chromosomes in EACH
body cell (2n)
• 3. Metaphase (meta = middle)
– Each chromosome and its copy (made during DNA
replication) line up next to each other down the
middle of the cell
• 4. Anaphase
– Chromosome pairs are pulled apart, separating
sister chromatids from each other: One copy of
each chromosome is pulled toward OPPOSITE
ends of the cell (as the cell prepares to begin
dividing down the middle)
• 5. Telophase
– Chromosomes gather at the poles (ends) of the
cell as the cell begins to “pinch in”/ divide down
the middle (where it will split)
• Cytokinesis
– The cytoplasm of the cell completely divides and
2, new IDENTICAL daughter cells are formed (from
one original parent cell)
The Cell Cycle and Mitosis
• Make a Double Bubble map to show the
similarities and differences between meiosis
and mitosis.
The cells below are in varying stages of the cell cycle.
Put them in the correct order showing how mitosis
occurs.
Describe what is happening to the chromosomes and
the cell in each picture.
A
B
C
D
E
Somatic Cells: Cell Differentiation
Non gamete!
Body cells!
• Cells have different jobs
• How do they determine if
their job is a muscle cell vs.
a skin cell?
• GENE EXPRESSION: Genes
on the chromosome are
either turned “on” or “off”
How does a Cell Know When to Divide?
• The cell cycle is controlled by proteins (called
cyclins) and enzymes
• The interactions of these proteins depends on
factors in the cell and outside the cell
• Sometimes cells lose control of the cell cycle
when certain enzymes are not produced in the
proper amounts
• Cancer is the product of uncontrolled cell
division
What is cancer?
Changes in genes that produce the proteins and
enzymes controlling the cell cycle can result in
different forms of cancer.
• Cancer can be a tumor or mass of tissue that is
harmless (benign)
• Or, cancer cells can deprive normal cells of
nutrients
• Cancer can disrupt the function of organs
• It can enter the circulatory system and spread to
other areas
What causes cancer?
Both genetic and environmental factors can increase
cancer risk.
However, Inherited genetic defects
rarely cause cancer.
Environmental factors include:
•Chemicals (tobacco, alcohol, etc)
•Radiation
•Infection
•Diet and Exercise
•Hormones
Incidence of Skin Cancer in US
Color on Map
Interval (per
100,000)
Light green
8.6 to 16.7
Medium green
16.8 to 19.2
Medium blue
19.3 to 22.1
Dark blue
22.2 to 28.1
http://www.teachersdomain.org/resource/tdc02
.sci.life.stru.oncogene/
Review Meiosis and Mitosis
1. Which process produces gametes?
2. Which process produces new body (somatic) cells?
3. Compare the chromosomes in the daughter cells
after meiosis… After mitosis…
4. Compare the chromosomes in gametes when
crossing over does occur AND when
crossing over does NOT occur.
5.Why does a cell begin mitosis and what
percent of the cell cycle does mitosis
represent?