Module 9 Lesson 1 Part 2
Cellular Reproduction
Module 9 Lesson 1.2
Objectives
the stages of the cell cycle
the stages of interphase
the events of each stage of mitosis
the difference between a normal cell cycle and an abnormal cell cycle
the role of apoptosis
Standards covered ; HS-LS1-1 HS-LS3-2
HS-LS1-4
HS-LS3-1
New Vocabulary
Cyclin
cyclin-dependent kinase
apoptosis
cancer
carcinogen
Video links
Cell Cycle + Cell cycle regulation and cancer
Meiosis
Chromosome numbers
Sex chromosomes and autosomes
Hello!
Production activity
Mitosis
Week 2
Hi!
H
e
l
l
o
!
•
•
.
Choose ONLY ONE of the following ways on Google Classroom:
Create a ppt.
and submit on Google
Classroom
Create a hardcopy
poster, use markers
and colours.
Design a short video and
submit as a link
Avoid using READY MADE Posters from the internet (make your own copy :)
Please check the rubrics on slide 4
In a ppt. include the following information;
•
•
•
•
Draw the 4 phases
Label each phase
Label the content of each phase using arrows
Write a brief description of each phase
In a poster.
Using color pencils or crayons color each
of the following a different color and label
it:
phases of mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Poster / ppt.
Rubrics
category
4
3
2
1
Required
elements
The poster /
ppt. includes
all required
elements
All but 1 of the
required
elements are
included on
the poster/
ppt.
All but 2 of the
required
elements are
included on
the poster/
ppt.
Several
required
elements were
missing
Labels and
arrows
All items of
importance on
the poster/
ppt. are
clearly
labelled
All items of
Some items
importance on are labelled
the poster/
wrong
ppt. are
labelled but
not clearly
shown
Many labels
are missing or
wrong
The poster /
ppt. is
attractive in
term of
design, layout
and neatness
The poster/
ppt. is
distractingly
messy or very
poorly
designed . It is
not attractive
Attractiveness The poster/
ppt. is
exceptionally
attractive in
term of
design, layout
and neatness
The poster /
ppt.
acceptably
attractive
though it may
be a bit messy
Video Rubrics
EXAMPLES
Concept check 9.1.Part 2
=Answer; Week 2 Gr 11 bio. CCQ.
Module 9 lesson 1 Part 2 Cellular
reproduction on Google classroom
=Due….Before class
SESSION 1
Cell Cycle Regulation
=The timing and rate of cell division are important to
the health of an organism.
=The rate of cell division varies depending on
the type of cell.
=A mechanism involving proteins and enzymes
controls the cell cycle.
The Role of Cyclins
• The cell cycle in eukaryotic cells is driven by a
combination of two substances.
• Proteins called cyclins bind to enzymes called
cyclin-dependent kinases (CDKs).
• Different cyclin/CDK combinations control different
activities during different stages of the cell cycle.
How do cells use cyclin/CDK combinations?
Cells use different combinations of cyclin/CDK to
control activities at different stages in the cell cycle.
For instance;
=In the G1 stage, one cyclin/CDK combination signals
the start of the cell cycle.
=Other cyclin/CDK combinations signal DNA
replication, protein synthesis, nuclear division and
even the end of the cell cycle.
Checkpoint
What is the role of cyclins in a cell?
A
B
to control the
movement of
microtubules
C
to stimulate the
breakdown of the
nuclear membrane
to signal for the cell to
divide
D
to cause the
nucleolus to
disappear
Checkpoint
What substances form the cyclin-cyclin dependent
kinase combinations that control the stages in the
cell cycle?
A
fats and proteins
B
carbohydrates and proteins
C
proteins and enzymes
D
fats and enzymes
Cell Cycle Regulation
Quality control checkpoints
• Built-in checkpoints monitor the cycle and
can stop it if something goes wrong.
How do quality control checkpoints work?
=The cell cycle has built-in quality control checkpoints
that monitor the cell cycle
and can stop it if something goes wrong.
=For instance,
1.Near the end of the G1 stage the cell monitors its
DNA for damage and can stop the cell cycle before
entering the S stage.
2.There are other quality control checkpoints during
the S stage and the G2 stage.
3.During mitosis, the cell checks the spindle fibers
before it undergoes cytokinesis. If the cell detects
a failure, the cell cycle stops.
Cell Cycle Regulation
Apoptosis
Some cells go through apoptosis, or programmed cell
death because they are no longer needed, they shrink or
shrivel in a controlled process.
For example;
1. In the embryo, to remove tissue between developing
fingers and toes.
2.In cells that are damaged beyond repair or that could
turn into cancer cells.
3.In plants, localized death of cells results in leaves falling
from trees during autumn.
Checkpoint
Which describes apoptosis?
A
occurs in all cells
B
disrupts the normal development of an organism
is a response to hormones
D
is a programmed cell death
Cell Cycle Regulation
Abnormal Cell Cycle: Cancer
• Cancer is the uncontrolled growth and division of cells.
• Cancer results when cells stop responding to the
controls of the cell cycle.
Cancer cells can kill an organism by crowding normal
cells, causing tissues and organs to stop working.
Cell Cycle Regulation
Causes of Cancer
1. Mutations, or changes, in segments of DNA that
code for production of proteins, including those that
regulate the cell cycle.
2. Environmental factors (Tobacco, alcohol, some
viruses and radiation from the Sun or X-rays)
Carcinogens are substances or agents known to
cause cancer (tobacco, benzene, soot, wood dust,..)
=Avoiding known carcinogens can help reduce the
risk. (avoiding tobacco, using sunscreen to protect
skin from UV radiation)
Cell Cycle Regulation
Cancer Genetics
=More than one change in DNA is required to change
an abnormal cell into a cancer cell.
This might explain why risk increases with age where
older cells have had more time to accumulate the
mutations that lead to cancer.
=Cancer runs in some families. People might inherit
one or more DNA mutations from their parents,
increasing their risk of developing cancer.
Checkpoint
Which is a characteristic of cancer cells?
A
They have controlled cell division.
B
The cytokinesis stage is skipped.
C
They contain multiple genetic changes.
D
The cell cyclins function normally.
SESSION 2
Module 9 Lesson 2 Part 1
Meiosis and Sexual
Reproduction
Objectives
• • the stages of meiosis
• • how meiosis provides genetic variation
• • how nondisjunction leads to abnormal chromosome
numbers
• • why cellular differentiation is important
• • what stem cells are and how they can be used
Standards covered ; HS-LS1-1 HS-LS3-2
HS-LS1-4
HS-LS3-1
New Vocabulary
gene - homologous chromosome - gamete – haploid – fertilization
– diploid – sex chromosomes – autosome – meiosis – crossing
over .
Concept check 9.2.Part 1
=Answer; Gr 11 bio. CCQ. Module 9
lesson 1 Part 1 Cellular reproduction
on Google classroom
=Due date …..
Chromosome Numbers
• All cells contain genetic information in the
form of DNA molecules.
• The instructions for traits (for example, hair
color) are located on DNA.
• The DNA has segments called genes that
code for the formation of proteins, which
carry out most of the work of cells.
• Each DNA molecule consists of hundreds of
genes, each playing a role in determining
characteristics and functions of the cell.
Chromosome Numbers
Homologous Chromosomes
•
•
•
Human body cells have 46 chromosomes. Each
parent contributes 23, resulting in 23 pairs of
chromosomes.
Chromosomes that make up a pair, one from
each parent, are called homologous
chromosomes.
Homologous chromosomes (chromosomes
that make up a pair, one from each parent)have
the same length and centromere position. They
carry genes that control the same traits at the
same place (similar genes but not identical,
since each comes from a parent)
Chromosome Numbers
Haploid and Diploid Cells
• Gametes are sex cells that have half the number
of chromosomes. The symbol n is used to
represent the number of chromosome. In
humans, n is 23.
• A cell with n number of chromosomes is called
haploid cell.
• Fertilization is the process by which one haploid
gamete combines with another haploid gamete.
• A cell with 2n number of chromosomes is called
diploid cell.
Chromosome Numbers
Sex Determination
• Each cell in your body, except for gametes, contain
23 pairs of chromosomes.
• One pair, the sex chromosomes, determines an
individual’s gender.
• The other 22 pairs of chromosomes are called
autosomes.
• There are two types of sex chromosomes—X and Y.
Individuals with two X chromosomes are female.
Individuals with X and Y are male.
Meiosis
• Gametes form during meiosis, a type of cell
division that reduces the number of chromosomes.
• Meiosis occurs in the reproductive organs of
organisms that reproduce sexually, forming haploid
gametes.
• It reduces the chromosome number by half
through the separation of homologous
chromosomes.
• As shown on the next slide, a cell with 2n
chromosomes will have gametes with n
chromosomes after meiosis.
Meiosis I
Interphase
The same as in mitosis (G1 , S, G2) ..
Prophase I
• Chromosomes condense and become visible under the
microscope
• Homologous chromosomes pair in a process called synapsis
forming structures called tetrads (4 chromatids). (each
chromosome consists of two chromatids).
• During synapsis crossing over occurs,
where sections of a chromosome
change place with its homologue
(one reason for variation)
• The nuclear membrane and the nucleolus
break down.
• Spindles form.
Meiosis I
Crossing over is a process during which chromosomal
segments are exchanged between a pair of
homologous chromosomes. (one reason for variation)
Meiosis I
Metaphase I
• Chromosome centromeres attach to spindles.
• Homologous chromosomes line up randomly at the equator. (one
reason for variation because of the new combinations of traits)
Anaphase I
• Homologous chromosomes separate and move to opposite poles
of the cell.
Telophase I
• Spindle fibers break down, nucleolus appear,
• Chromosomes uncoil to form two nuclei.
• Nuclear membrane appears surrounding the new sets of
chromosomes
Cytokinesis The cytoplasm divides, the cell divides into two haploid
cells.(number of chromosomes is been reduced to half but the
genetic material is still doubled)
Meiosis II
Prophase II
• Chromosomes condense.
• Spindles form in each new cell.
• Spindle fibers attach to chromosomes.
Metaphase II
• Chromosomes line up randomly at the
equator of each cell.
Anaphase II
• Centromeres split.
• Sister chromatids separate and move to
opposite poles.
Meiosis II
Telophase II
• Four nuclei form around chromosomes.
• Spindles break down.
Cytokinesis The cytoplasm divides, each of the
two cells divides into two haploid cells.
Products
• Four haploid cells have formed.
The Importance of Meiosis
Meiosis Provides Variation
• Depending on how
chromosomes line up at the
equator, four gametes with
four different combinations
of chromosomes can result.
• This independent
assortment(random
separation) of alleles during
gamete formation is a
source of genetic variation.
Checkpoint
How many chromosomes would a cell have during
metaphase I of meiosis if it has 12 chromosomes during
interphase?
A
6
B
24
C
12
D
36
Checkpoint
Which is not a characteristic of homologous
chromosomes?
A
Homologous chromosomes have the
same length.
B
Homologous chromosomes have the same
centromere position.
C
Homologous chromosomes have the exact
same type of allele at the same
D
Homologous chromosomes pair up during
meiosis I.
Checkpoint
Which does not occur during telophase II?
A
Chromosomes
condense.
C
Spindles break down.
B
Four nuclei form
around
chromosomes.
D
Cells divide.
STP 9.2.1
=Answer; Week 2 Gr 11 bio. STP
Module 9 lesson 2 Part 1 Meiosis and
sexual reproduction on Google
classroom
=Due date …..
SESSION 3
Activity/Lab.
Lab. On mitosis
SESSION 4
In class Practice
Quizizz In-class practice
Cell cycle mitosis and meiosis
… Link =
https://quizizz.com/admin/quiz/625023af1f237a001de70f11?source=quiz_share
Kahoot activity
… Link =
https://create.kahoot.it/details/cell-cycle-and-regulation/d387a7b0-519a-4239-9c1dd321b26af9c3
Kahoot activity
… Link = Meiosis
https://create.kahoot.it/v2/details/f45d738a-a8c3-4da0-bafe-3b40f2a8ee44