Download Chapter 9 Notes (Cell Reproduction)

Chapter 9
The Cellular Basis of Inheritance
Cells have distinct phases of growth,
reproduction, and normal functions.
Objectives
• Describe the purpose of cell reproduction
• Contrast two ways that organisms
reproduce
All Cells Come From Cells
• Where have you heard that before?
– It is part of the Cell Theory!!
• Why do organisms need cellular
reproduction to occur?
– Allows living things to repair damage
– Allows organisms to grow
– Allows organisms to produce offspring
Repair and Growth
• Did you know that the outer layer of your skin is
all dead cells?
• New cells are continually reproducing
underneath and the new cells gradually move
upwards to replace dead ones.
Close-Up of your skin!!
2 Types of Reproduction
• Sexual Reproduction:
–
–
–
–
2 parents
Involve gametes (egg & sperm)
Genetic material combines
Offspring are genetically different from
parents
• Asexual Reproduction:
– 1 parent
– The process by which a single cell
duplicates its genetic material
– Offspring identical to parents
– Examples- Budding & regeneration
Types of Asexual Reproduction
1.
2.
3.
4.
5.
Budding
Binary Fission
Regeneration
Spores
Vegetative propagation
Asexual Reproduction YouTube
Warm Up
Match the type of asexual reproduction with
its description.
TYPE
DESCRIPTION
1. _____ budding
A. Small reproductive cells
2. _____ binary fission
B. Splitting of cells to make more (bacteria)
3. _____ vegetative
propagation
C. Re-growing lost parts to form a new organism
such as in lizards, starfish, and worms.
4. _____ regeneration
D. “runners”/stems of plants that form identical
plants.
5. Spores
E. A identical organism growing off the side of
another until it is able to live on its own.
Cell Cycle Objectives
• Describe the structure of a chromosome (9.2)
• Name and Describe the stages of the cell cycle
(9.2)
The Cell Cycle
• The cell cycle is a regular pattern of
growth, DNA replication, and cell division.
Interphase (preparation)
1. Gap 1 (G1) – cell
growth and normal
functions
2. Synthesis (S) – DNA
Replication = a 2nd copy
of the genetic material is
made
3. Gap 2 (G2) –
additional last minute
growth & doubling of
organelles
Note: Mitosis can ONLY occur if
the cell is large enough and the
DNA is not damaged by the end
of interphase!
Mitotic Phase (Mitosis or Meiosis)
Mitosis is the actual nuclear division of the
cell. It is composed of 4 major stages:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
**Cytokinesis = the final splitting of the
cytoplasm and “pinching” of the cell
membranes.
Cells divide at different rates.
• The rate of cell division varies with the
need for those types of cells.
Cell size is limited…Eventually they
MUST divide!
• S.A / Volume Ratio needs to be high…or
diffusion (essential for cell life) suffers!
Agar Cube Challenge
Trim your agar cube into a shape that you
think will allow for the highest surface
area/volume ratio!
Purpose: Design the largest cell possible into a shape that has the
highest surface area, test the diffusion rate of that cell, and compare
it with other designed cells.
Background: The agar cube is porous (meaning liquid can diffuse
through it). It is blue because it was made with a blue ink indicator
(Bromothymol Blue). This indicator turns yellowish green in the
presence of an acid. Therefore, when the agar cube is placed in acid,
the cube will turn yellowish wherever the acid diffused.
Rules:




Try to keep the cell as large as possible!
Not allowed to put holes in it
Must be 1 single piece
All plastic utensils must be returned to teacher
Procedure
1. Place the agar cube onto the paper
towel and use the plastic utensil to shape
it/design it following the directions above.
2. When told to do so, CAREFULLY
PLACE the “cell” into the acid solution and
wait 10 minutes.
3. Carefully spoon out the “cell” and
observe the color change / diffusion.
4. Answer Analysis Questions on your half
sheet.
5. Turn in half sheet (with your name on
it!)
WARM-UP
1. What part of the cell
cycle is the
“preparation” part?
2. What part of the cell
cycle is the actual
splitting of the
nucleus?
Surface area must allow for adequate
exchange of materials.!
Therefore…..Cells that must be large have unique
shapes.
With a crazy shape, their surface area/volume ratio
remains HIGH  and diffusion of materials into/out of
them is fast enough to survive!
Surface Area vs. Volume of Cells (Relay) GAME

How the game works:
• There will be 4 teams. Each team will get a chance to
work with each shaped cell.
• Your team must get the provided molecules (beads) into
the nucleus in the shortest amount of time!
• Only 1 team member can go into the cell at a time and
all team members must participate…..so its a relay!!!
• Be strategic!!!!
Cell B
• Remember your times for the data table!
Cell A
DATA TABLE
(write time & a team member’s name)
Cell A (long cell in hallway)
Cell B (round one in room)
AVERAGE TIME
AVERAGE TIME
WRAP UP
1. What process was represented by the transferring
of beads (molecules) into the center (nucleus) of
the cells?
2. Which cell went faster? (round or long?)
3. WHY did the above cell go faster?
4. This activity represented that a cells Surface
Area/Volume Ratio must be ___________ (high or
low) in order for it to be efficient and survive.
Cells divide during mitosis
and cytokinesis.
9
The Cell Cycle in body cells:
Mitosis and cytokinesis produce
two genetically identical daughter
cells.
Events that occur During Interphase
(G1) - The cell
grows and performs
normal functions
(S) The DNA is
duplicated (via DNA
Replication)
(G2) The cell
nucleus with
undergoes last
chromatin
minute growth &
organelle duplication
Parent cell
Interphase
centrioles
Nuclear Envelope
spindle fibers
centrosome
Chromatin condenses at the start of mitosis
into chromosomes!.
…By having the DNA
wrap around proteins.
…The end product is
chromosomes!!
Remember: DNA + proteins is called chromatin.
chromatid
• One half of a duplicated
chromosome is a
chromatid.
telomere
centromere
• Sister chromatids are
held together at the
centromere.
telomere
Condensed, duplicated chromosome
Events that occur during Prophase
– Chromatin (DNA)
condenses
and chromosomes
are visible
– spindle fibers form
– Nuclear envelope
disappears
Spindles Forming
Nuclear envelope
Sister Chromatids
Breaking apart
Events that occur during Metaphase
– chromosomes line up in the middle of the cell
– Spindle fibers attach to centromeres (between
sister chromatids)
Sister Chromatids
Centromere
Events that occur during Anaphase
– Sister chromatids separate (at the
centromere)
– Spindle fibers pull identical
chromosomes to opposite
sides of the cell.
Chromosome
Spindle Fiber
Centromere
Events that occur during Telophase & Cytokinesis
– The new nuclei form
– Chromosomes begin to
uncoil
Identical
Nuclear Envelope Chromosomes
– Nuclear envelope reappears
Cytokinesis:
– Cell splits into two
– Two identical daughter
cells form
Two Identical
Daughter Cells
Form (Cytokinesis)
Two Identical Daughter Cells form After
Cytokinesis
– In animal cells, the
membrane pinches
closed (cleavage
furrow)
– In plant cells, a cell
plate forms.
nucleus with
chromatin
• Animal Cells = Cleavage
Furrow (pinches the 2 daughter cells
apart)
• Plant Cells = cell plate
forms (to divide the 2 daughter cells)
Crash Course – Mitosis 
• Mitosis: Splitting Up is Complicated Crash Course Biology #12 - YouTube
Mitosis wrap-up
• Mitosis Rap
• Standard deviants videos
cell cycle | Search | Discovery
Education
Find a cell in the following stages:
Interphase, Prophase, Metaphase,
Anaphase, and Telophase of mitosis.
Cancer
• Do you know anyone (or of anyone) who
has been diagnosed with cancer?
• If so, what cancer did they have? And
what types of things did they go through?
• What type of cancers do you think are
most prevalent?
Cancer … Mitosis Out of
Control!!!!
• Cancer results from
out-of-control cell
production.
• Abnormal masses of
cells are called tumors.
Two Types of Tumors
Tumors can either be:
Benign – abnormal mass
of normal cells
Malignant – mass of cells
resulting from the
reproduction of cancer
cells.
Brain Tumor (MRI)
Metastasis
• When cancer cells break off tumors and
travel/spread to other places in the
body, the cancer is said to have
metastasized.
Video: How cancer spreads MayoClinic.com
Cancer Treatment
• Surgery
• Radiation Therapy
• Chemotherapy
Unwanted Side Effects – nausea, damage to
organs, sterility, hair loss, etc.
Common Cancers
• Melanoma (type of skin
cancer)
• Leukemia (cancer of the
circulatory system – blood)
•
•
•
•
Lung Cancer
Colon Cancer
Breast Cancer
Bladder Cancer
Warm - up
• Name the 3 reasons cell reproduction is
necessary for organisms?
Meiosis Objectives
 Contrast haploid and diploid cells
 Summarize the process of meiosis
 Compare mitosis & meiosis
 Explain how genetic variation occurs in offspring of
populations
9
KEY CONCEPT
Gametes (sex cells) have half the number
of chromosomes that body cells have and
they reproduce via meiosis (not mitosis)
Mitosis vs. Meiosis
Mitosis and meiosis are types of nuclear division
that make different types of cells.
Mitosis occurs in body cells
Occurs in testes & ovaries
Mitosis makes
2 diploid (2n) cells
Meiosis makes
4 haploid (n) gametes/sex cells
Sexual Reproduction relies on Meiosis
• Meiosis – a type of cell division that produces
gametes/sex cells (egg & sperm)
• Meiosis occurs in sex organs (testes & ovaries)
• Still part of cell cycle
(simply replace mitosis with meiosis)
You have somatic cells and germ cells.
(body cells)
(sex cells)
• Germ cells develop into gametes (sperm & eggs)
• Germ cells are located in the reproductive organs.
– Gametes have DNA that can be passed to offspring.
body cells (muscle cells)
sex cells (sperm)
sex cells (egg)
Each of your cells have:
1. autosomes (regular ones)
2. sex chromosomes
Your body cells have a total of 23
pairs of chromosomes.
That is ___ total chromosomes.
– Chromosome pairs # 1-22 are
autosomes. (=44 chromosomes)
– Pair # 23 are the Sex
chromosomes, X and Y,
(determine gender)
Girl = X X
Boy = X Y
Quick Check / Review
1. Meiosis is a type of cell division that makes
______ cells in the ______ & _______ (organs)
of our bodies.
2. Somatic (body) Cells reproduce through
____________ (mitosis or meiosis).
3. Sex Cells reproduce through __________.
(mitosis or meiosis)
4. How many total chromosomes are in your
body cells???? _______ (hint: 23 pairs)
Body cells are diploid
Gametes (sperm & eggs) are haploid
• Fertilization joining of egg and sperm; occurs in
sexual reproduction, results in a diploid zygote
• Diploid (2n) cells have two copies of every
chromosome. = 46 chromosomes
– Body cells are diploid*
– Total = 46 Chromosomes
(A set of chromosomes (23) come from each parent)
Haploid (n) cells have only one copy of
every chromosome (or ½ the normal amount)
– Gametes (sperm & eggs) are haploid.
– Total = 23 chromosomes (that’s ½ of 46!!)
Diploid (2n) vs. Haploid (n) Cells
•Body Cells
•Sex Cells
•Contain 2 copies of each
chromosome
•Contain 1 copy of each
chromosome
•Total = 46 chromosomes
•Total = 23 chromosomes
(44 autosomes & 2 sex)
• Reproduce through mitosis
(22 autosomes & 1 sex)
• Reproduce through meiosis
Meiosis results in 4 haploid gamete cells
– Meiosis occurs in reproductive organs (testes &
ovaries)
– Involves 2 cell Divisions = (meiosis 1 & meiosis 2)
– Meiosis produces 4 haploid (n) gametes*
Parent Germ Cell
2n
Meiosis 1
During interphase
2n
n
Meiosis 2
n
n
n
n
n
4 haploid gametes
Mitosis vs. Meiosis
Mitosis and meiosis are types of nuclear division
that make different types of cells.
Mitosis occurs in body cells
Occurs in testes & ovaries
Final product: 2 diploid
(2n) cells
Final product: 4 gametes
(haploid (n) cells)
How do we get genetic variation?
During Prophase 1 (of Meiosis 1)…
homologous chromosomes, while
paired in “tetrads” undergo
“Crossing Over” and swap genes
for traits.
This creates genetic variation in
populations!!!
Crash Course - Meiosis
• Meiosis: Where the Sex Starts - Crash
Course Biology #13 - YouTube
Meiosis video clip
Meiosis review clip
Let’s play a review GAME!
http://hrsbstaff.ednet.ns.ca/bfougere/Scienc
e%20Jeopardy_files/frame.htm