Download Cell_Reproduction

Warm-up
• What is the difference between a diploid
and a haploid cell?
• Homework: 8.2 1-6. 8. Text 154-155.
Fluorescent In-Situ Hybridization (FISH) identification of human chromosomes
Chromosome
- replicated
DNA that is
wrapped around
histone proteins
and coiled up
- replicates and
condenses
before
mitosis/meiosis
Histones
- Proteins that help
maintain the
chromosome’s
shape
- aid in tight packing
of DNA
Chromosome Structure
Chromatid - each half of
the chromosome
Centromere – point
where chromatids attach
Chromatin
– Thin, uncoiled strands of
DNA and protein
– This form of DNA is
found during interphase
of the cell cycle
Chromosome Numbers
Autosomes
- Contain most of the genetic information; all
chromosomes that are not sex chromosomes
- Humans have 22 pairs of autosomes,
Sex Chromosomes
- Genetic information that determines gender of
an organism
- Humans have 1 pair of sex chromosomes.
- females - XX pair sex chromosome
- males - XY pair of sex chromosomes
2n Chromosomes
Honeybee (female) – 32 Adder’s Tongue Fern - 1262
Human - 46
Cat - 38
Common Frog - 26
Maize - 20
Organisms
more chromosomes
Does more with
chromosomes
mean a biggerare not
necessarily
more complex
or more complicated
organism?
Chromosome Numbers cont.
• HOMOLOGOUS CHROMOSOMES
– Two chromosomes that are the same size,
shape and DNA makeup
• Ex: gene for eye color protein on both
chromosomes.
Karyotype
A photomicrograph
of the chromosomes
in a normal dividing
cell found in a
human.
Does this karyotype
appear to be male
or female?
karyotyping
Questions
- What causes a dark band on the
chromosome?
- What is a centromere?
- How many total chromosomes are in your
karyotype?
- Is your set male or female?
Warm-up
Q: What is the difference between
chromatids, centromeres and chromatin?
Homework: Draw Binary Fission, outline pp.
156-159
3 Types of Cell Division
Prokaryotic cells (bacteria)
1. Binary fission: bacterial reproduction
- No nucleur division
Eukaryotic cells (animal, plant, protists)
- nuclear division
2. Mitosis: growth, healing, cell replacement
3. Meiosis: reproduction
Prokaryotes:
(bacteria cells
-Binary fission
-Cell mem. Divides
-No nucleus
-Circ. DNA (plasmid)
-Single celled
-Doubles in size
before dividing
Both:
-DNA is copied
-New cells have
identical
chromosome(s)
-Must prepare for
division
Eukaryote:
(plant, animal,
and protist cells)
Mitosis (cells
with identical
genetic material)
-Meiosis (cells
have half the
chromosomes)
-Cytoplasm and
nucleus divide
-Has a nucleus
-Many
chromosomes
(gametes and
somatic cells)
-Grows to
normal size after
dividing
Prokaryotic Cell Division
• binary fission.
• single ringshaped
chromosome is
duplicated
• cell membrane
divides
• prokaryotes do
no have a
nucleus
Binary Fission
Cell Division in Eukaryotes
GRRR – Growth, Repair, Replacement,
Reproduction
Mitosis – results in new cells with genetic
material identical to the original cell
- Asexual reproduction – the production of
offspring from one parent
Meiosis – occurs during the formation of
gametes
- Gametes – haploid reproductive cells
Eukaryotic Cell Division: Cell Cycle
Interphase
- the time between
divisions
- the cell spends most of
its time in interphase
Cell Division
- mitosis and cytokinesis
or meiosis and
cytokinesis
Interphase:
• G1
– Cell grows to normal size
– Cell carries out regular functions (protein synthesis,
etc…)
• S
– DNA is synthesized
• G2
– Organelles are replicated, preparing for cell division
• G0
– Cells stop dividing, sometimes permanently (ex:
nerve cells)
G1 → S → G2
OR
G1 → G 0
Eukaryotic cell division
Mitosis
- One division, produces 2 identical daughter cells
- Diploid (full set of chromosomes)
- Occurs in body cells, or somatic cells
Meiosis
- Two divisions, produces 4 cells
- Haploid (one of each chromosome pair)
- Occurs in gametes (reproductive cells)
- Gametes from male and female combine to form a
diploid zygote
http://www.johnkyrk.com/mitosis.html
Interphase & Mitosis – somatic cells
•
http://www.biologycorner.com/flash/mitosis.html
Prophase
1. Chromatin forms
chromosomes
2. Nucleolus and nuclear
membrane disappear
3. Centrioles and spindle
fibers appear
4. No centrioles in plant
cells
Metaphase
Spindle fibers:
• attach to
chromosomes at
the centromere
• move the
chromosomes to
the center of the
cell
• hold them there
Anaphase
1. Chromosomes are
pulled apart at the
centromere by spindle
fibers
2. The halves
(chromatids) are pulled
toward opposite poles
of the cell
3. Chromatids are
renamed chromosomes
Telophase
1. Two identical chromatids
are at opposite sides of
the cell
2. Centrioles and spindle
fibers disappear
3. Chromatids unwind and
elongate into chromatin
4. nuclear membrane
forms around each set
of chromatin
5. nucleolus appears
Don’t forget, chromosomes and chromatin are both DNA
Cytokinesis
• Division of cytoplasm, forming two new cells.
• Separates the organelles into two new cells
MEIOSIS – in reproductive cells, or gametes
MEIOSIS
• 2 sets of divisions
– Meiosis I
• Reduces chromosomes from diploid to haploid;
creates 2 daughter cells
– Meiosis II
• Splits the 2 cells into 4 haploid daughter cells
• Produces gametes (haploid cells)
http://www.johnkyrk.com/meiosis.html
Prophase I
• As in Mitosis:
– DNA is coiled into
chromosomes
– Spindle fibers appear
– Nucleolus and nuclear
membrane disassemble
• Unique to Meiosis:
– Synapsis - chromosomes
are sorted into
homologous pairs called
tetrads
– “Crossing over” –
chromosomes exchange
genetic information;
genetic recombination
Meiosis I cont.
Metaphase I: tetrads line up at
the nucleus
Anaphase I: homologous
chromosomes move to opposite
sides of the cell (independent
assortment)
Telophase I and Cytokinesis:
chromosomes reach opposite
sides of the cell and the cell
divides
Meiosis II
• Begins with the two cells formed in Meiosis I.
Prophase II, Metaphase II, and Anaphase II – similar to
Meiosis I, but each half receives only half of the genetic
information
Telophase II and Cytokinesis II – Like Meiosis I
Meiosis ends with four cells instead of two
• http://www.pbs.org/wgbh/nova/miracle/divi
_flash.html
Gametes
• gametes - the only
cells that use
meiosis.
• spermatogenesis –
makes 4 sperm cells
• oogenesis – makes
1 egg cell, or ovum,
and 3 polar bodies,
which are not used
• Sexual reproduction –
the production of
offspring through meiosis
and the union of a sperm
and an egg
• Zygote – a male gamete
and a female gamete
combine to form a new
organism; each
contributes half the
genetic information
Asexual and Sexual Reproduction
• Asexual
– Mitosis
– creation of one organism from one cell
– Ex: earthworm
• Sexual
– Meiosis
– Creation of one organism from two haploid cells
– Ex: most animals and plants
Control of Cell Division
3 checkpoints:
– Cell growth (G1) checkpoint
• decides whether cell
should divide
– Yes - cell begins G2
phase
– No - cell goes into G0
phase
– DNA synthesis (G2)
checkpoint
• signal the cell to enter
mitosis
– Mitosis checkpoint
• signal the cell to exit
mitosis
Cancer
the uncontrolled
growth of cells
• Mistake at cell
checkpoint
– Metastasis – the
spread of cancer
• Cells break off and
travel
Cancerous moles (melanoma)
http://oralcancerfoundation.org/facts/metastasis.htm
3 Types of Cell Division
Prokaryotic cells (bacteria)
1. Binary fission: bacterial reproduction
- No nuclear division
Eukaryotic cells (animal, plant, protists)
- nuclear division
2. Mitosis: growth, healing, cell replacement,
asexual reproduction
3. Meiosis: sexual reproduction
What is crossing over?
Crossing over occurs when pieces of
chromatids break off and attach to the
homologous chromosome by it.
What phase is this?
Metaphase, Mitosis (if organism had 4 chromosomes)
Metaphase II, Meiosis (if organism started with 8 chromosomes)
• Metaphase, Meiosis I (because there are tetrads)
Anaphase, Meiosis I (whole chromosomes are
moving)
What subphase is this?
• Anaphase, Meiosis II
Telophase II and cytokinesis in Meiosis II
Which stage?
Prophase, Mitosis
Flip Book: Animation
Pages 162 and 163
Flip Book
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Number boxes
Draw meiosis stages in labeled boxes.
Draw “intermediates” - animation
Color
Cut boxes out
Attach together with clip, rubber band