Download Chapter 9 Cellular Basis of Inheritance

Chapter 9
Cellular Basis of Inheritance
Brief Overview of Chapter
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9.1 All Cells from Cells
9.2 The Cell Cycle
9.3 Mitosis (asexual)
9.4 Cancer Cells
9.5 Meiosis (sexual reproduction)
9.6 Genetic Variation
Our Learning Goal Today
1.
2.
Unicellular Vs Multicellular Reproduction
Stages of the Cell Cycle
9.1 All Cells come from….Cells
• Organisms reproduce their own kind
– No humans with zebra babies or tigerman…
• Cells are important for:
– Repair, growth and reproduction
• Reproduction
• Asexual or Sexual
– Asexual
• Simple cell division with no genetic variation
– Sexual
• 2 parents involved, genetic material from each
combine to produce genetically different
offspring
• Union of egg and sperm
Reproduction
• Unicellular Organism
– Asexual usually; can sexually
• Multicellular Organism
– Sexually usually; some can asexually
Which they “choose” depends on
various reasons… anyone?
9.2 Cell Cycle
• Body makes 25 million new cells per
second!
– Most of time spent doing cellular
activities (not dividing)
• 2 Phases of Cell Division
– 1- Interphase
• G1, S, G2
– 2- Mitotic Phase
• Mitosis, Cytokinesis
But First…. Chromo WHATS?!
• Chromatin- fibers
made up of DNA
Forms
Squiggly
Where
One half
athey
“X”
of
like
join
lines
the
shape
in the
chromosome
inside
center
• Chromatid- one “side”
of chromosome
• Chromosomecondensed chromatin
• Centromere- where 2
chromatids join
The Cell Cycle
• How often a cell divides
depends on the type of cell
• Eukaryotic cells that divide
undergo cell cycle
• Prokaryotic cells go through
binary fission
The Cell Cycle
• Phase 1: Interphase
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90% cell life
Routine function
Metabolic functions
1. G1- First Growth
–
Is it healthy?
2. S- DNA copied
–
Copied correctly?
3. G2- Second Growth
The Cell Cycle
• Phase 2: Mitotic Phase
– Cell divides
4. Mitosis:
• Nucleus & duplicated chromosomes divide
into 2 daughter nuclei
5. Cytokinesis
• Cytoplasm divides
Process produces 2 genetically identical
daughter cells each with a single nucleus
Mitosis unique to eukaryotes
So… Did you LEARN Today?!
1. What are cells important for?
2. Describe how unicellular and multicellular cells
reproduce. (how are they different)
3.
Draw the Cell Cycle
– Label each phase/step
– Describe what’s happening
in each
– QUIZ
9.1/9.2/9.3 Thurs- CP BIOLOGY
General Bio
Cell Division (today’s notes)
Mitosis
• What’s happening?
– Cells make identical copies
– 4 steps
• Why?
1. Prep for meiosis
2. Means of asexual
reproduction
R E M E M B E R…
• Mitosis is PART of the Cell Cycle
– Interphase
• G1, S, G2
– Mitotic Phase
•Mitosis, Cytokinesis
These are the 4 steps to mitosis...
Step 1: Prophase
• Chromatin condenses into chromosomes
• Nuclear envelope disappears
• Spindles form (with microtubules)
Step 2: Metaphase
• Chromosomes gather across cell “equator”
• Chromatids attaches to spindle
microtubules
Step 3: Anaphase
• Sister chromatids pulled apart by
microtubules toward poles
• As they are pulled cell gets pushed out
farther
Step 4:Telophase
• Spindles disappear
• Nuclear envelopes appear around each
nuclei
• Chromosomes uncoil into chromatin
Cytokinesis
• Division of cytoplasm
• Completes Cell Cycle
– 2 genetically identical cells
– Animals cytoplasm pinches
– Plants cell plate forms
Do you Remember?
1. What are the 2 phases of cell division?
2. What are the 5 steps to cell division and what
phases are they found in?
3. What are the 4 steps of mitosis?
4. What is the purpose of mitosis?
5. How do prokaryotes reproduce?
6. What happens in each step of mitosis?
7. What is a pneumonic device to remember the
steps of mitosis in order?
Reinforcement Activity
• Pages 186-187
MITOSIS FLIP BOOK!!!
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
– Label each on opposite sides!!
9.4 Cancer
• Normal cells have “control system”
– Malfunctions
• Tumors & Cancer
9.4 Cancer
• Out of control cell reproduction
– Tumor (mass)
• Benign tumors mass of
normal cells
• Malignant tumor mass of
cancer cells
– Cancer (disease)
• Caused by severe disruption of
mechanism that normally
controls cell cycle
9.4 Cancer
• Cancerous cells spread
– Diseased cells replace normal ones (malignant)
– If not killed, removed it spreads to other parts of
the body and can form new tumors
• Metastasis spread of cancer cells beyond
their original site
Cures?
9.4 Cancer Treatments
• Malignant Vs Benign
• Surgery?
• Radiation Therapy (chemo)
– Try to stop cell division
– Anti-mitotic drugs… do what?
• Side effects?
9.4 Cancer
• Video Clips
– Awake Tumor Removal
– Angiogenisis
9.5 Meiosis
• Each offspring in a sexually
reproducing species inherits a
unique combination of genes from
its two parents
– Creates a unique combination of
traits
9.5 Meiosis
• Meiosis cell division that produces 4
cells
– Each with half the number of
chromosomes as parent cell
– Occurs in sex organs
9.5 Role of Chromosomes in Meiosis
• Almost all cells have same number and type
of chromosome within an organism
– Males and Females from same species also have
number and type
• Humans have 46 chromosomes
– Each has a twin (23 pairs)
• Homologous chromosomes
– Same sequences same inherited characteristics
9.5 Chromosome Role in Meiosis
• Homologous chromosomes
– Eye color gene
• Same locations
• Slightly different versions
– (blue, brown, green)
– DIFFERENT from sister chromatids!
» Those are identical in every way
9.5 Chromosome Role in Meiosis
• 23 homologous pairs of chromosomes (46
total)
• PAGE 193 karyotype
– Chromosome “map”
– Females all 23 homologous pairs look alike
– Males only 22; 1 pair look different
• SEX CHROMOSOMES
– Female XX
– Male XY
9.5 Chromosome Role in Meiosis
• Sex chromosomes
– Determine if male or female
– Most genes carried on “X”
– X genes not on Y and vice versa
9.5 Chromosome Role in Meiosis
• Have 2 sets of chromosomes (one from
each parent)…key to life cycle
– Diploid (2n) contain 2 homologous sets of
chromosomes
• Most cells are diploid
• 2n=46
– Haploid (n) single set of homologous
chromosomes
• Sex cells (sperm, eggs)
• n=23
• Formed through meiosis
The birds and the bees…
• Human Life Cycle
– Nucleus of sperm (n) cell fuses with
nucleus of egg (n) during fertilization
– Egg & sperm = gametes
– Forms human zygote (2n)
• 2 sets of homologous chromosomes
• Meiosis is the formation of these (n)
Do You Remember?
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Draw a benign and malignant tumor.
Draw homologous chromosomes.
What are the male and female sex chromosomes?
How many pairs of chromosomes do humans
have?
What are the male and female gametes?
What is a zygote?
What symbol represents haploid?
Diploid?
What is a karyotype?
The Process of Meiosis
• Alternating diploid/haploid stages
• w/o meiosis chromosome number would
increase exponentially!
• 2 Meiotic divisions
– Meiosis I
• Prophase I, Metaphase I, Anaphase I,
Telophase I
– Meiosis II
• Prophase II, Metaphase II, Anaphase II,
Telophase II
The Process of Meiosis
• Meiosis I
– Prophase I
• Homologous chromosomes stick lengthwise
• Chromosomes form tetrads
• Crossing over between tetrads
One Big, One Little
From each parent
9.5 Meiosis
• Metaphase I
– Tetrads move to middle of cell & line up
across spindle
9.5 Meiosis
• Anaphase I
– Homologous chromosomes separate as they
migrate to opposite poles of spindle
– Sister chromatids move together
– Only 2 chromosomes (w/2 copies) moving to
each pole
9.5 Meiosis
• Telophase I & Cytokinesis
– Poles have haploid daughter nucleus
– Nuclear envelope forms, cell divides
9.5 Meiosis
• Prophase II
– In each haploid daughter cell
• Spindle attaches to centromeres &
moves chromosomes to middle
9.5 Meiosis
• Metaphase II
– Chromosomes lined up in the middle
with microtubules attached to each
sister chromatid
9.5 Meiosis
• Anaphase II
– Sister chromatids separate & move to
poles
9.5 Meiosis
• Telophase II & Cytokinesis
– Individual chromosomes at poles
– Cytoplasm splits
Final Product = 4 haploid daughter cells
Review Game
• Meiosis Memory!!
• 6pm Appointments!!
• Play against each other
Meiosis
• Illustrate Meiosis
Prophase I:
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1. Draw cell- use colored pencils
2. Label Pictures
3. Write out step to the right
4. Put in correct order
Reflection Activity
• Complete Venn Diagram for Mitosis &
Meiosis
– How are they similar?
– Different:
• What happens in mitosis but NOT in
meiosis?
• What happens in meiosis but NOT in
mitosis?
• What are the products