Download Cell Division and Reproduction

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NEW: VOCABULARY DO NOW
Chromosome
DNA is coiled to conserve space in
a structure called a chromosome.
When the DNA copies to prepare
for mitosis, the two copies are
each called chromatids and are
connected for a while in a
doubled chromosome.
REASONS FOR CELL DIVISION

1. Maintain a workable
volume to surface area ratio;
volume increases faster than
surface area in cells

a larger surface area: volume
ratio is preferable.
2. Growth: multi-cellular
organisms must increase in
the number of cells to grow
 3. Repair and replacement of
cells lost due to injury or cell
death requires cell division.

Larger
surface area:
volume ratio
Smaller
surface area:
volume ratio
EUKARYOTIC CELL CYCLE

Interphase: Longest part of
the cell cycle; DNA replication
takes place, carries out life
functions

Chromatin


Chromatid


Condensed DNA and proteins,
(will form a chromosome)
Identical copies of DNA making up
a duplicated chromosome,
attached at centromere
Doubled chromosome

Nicely packaged and duplicated
DNA
INTERPHASE INCLUDES G1, S (SYNTHESIS), G2

Here is what’s happening in each phase
MITOSIS





Prophase: Chromosomes visible,
spindles form
Metaphase: chromosomes move
to middle (equator) of the cell
Anaphase: doubled chromosomes
separate, chromatids move to
opposite ends of cell
Telophase: spindles breakdown,
nuclear envelope appears
Cytokinesis: Division of
cytoplasm



Plant Cells: cell plate is produced
and will become cell wall
Results: Two identical cells that
are diploid (2n) (have two of each
chromosome- one from mother
and one from father)
–The diploid number for our cells
is 46 chromosomes
PROBLEMS WITH MITOSIS

Cancer: Uncontrolled cell
division
A cancerous lung tumor
 Benign when it is localized
to one area, malignant when
cancer cells are in blood
stream and move to another
part of the body





Most Wanted Chromosome: Mr. Chrom.O.Some
DUE FRIDAY!
Draw a picture of Mr. Chrom.O.Some
Write a story/description on the where abouts and happenings of
Mr. Chrom.O.Some (during cell division) Include the following
words in your story, and underline the words as you use them.
Although this is a creative project/story, it should make logical
sense. I should be able to understand your story and clearly see
that you understand the where abouts of a chromosome during cell
division.
You will be graded using the following criteria:


8 points: creativity and neatness
32 points: accuracy of story- 2 pts for each word above
 Do you have an understanding of the terms used?
EXIT TICKET

Identify the stages
of the cell cycle in
the picture.





1.Interphase
2. prophase
3. metaphase
4. anaphase
5. Telophase
6. What is one problem that can arise from mitosis?
MITOSIS – GO FURTHER PACKET
Complete as much of the packet as you can
 This will be worth a quiz grade
 Exemplary packets will also get extra credit on
overall grade
 DON’T FORGET: You’re in a competition!

WELCOME BACK!
Turn in homework
Take out Vocabulary Do Now sheet
Reminders:
• Mr. Chrome-O-Some activity due
Friday!
• Quiz Friday!
VOCABULARY DO NOW
Mitosis
This type of ASEXUAL cell division
makes exact copies of a cell. It is
part of a cell’s life cycle, after
normal growth. The phases of
mitosis are Prophase, Metaphase,
Anaphase, and Telophase.
(PMAT) One parent cell divides to
become two daughter cells.
Meiosis
A form of SEXUAL
reproduction. This type of cell
division creates gametes or
sex cells. These are haploid
or have ½ the number of
chromosomes so that the
zygote has the correct
number after fertilization.
TYPES OF REPRODUCTION
Asexual Reproduction
TYPES OF REPRODUCTION

Asexual: one source of genetic material

Offspring = identical clones
Advantages: reproduction is fast, less
energy needed, no mate needed,
 Disadvantages: lack of genetic variation
(one thing could wipe out entire population)

TYPES OF ASEXUAL
REPRODUCTION
Binary Fission: unicellular organism
(ex. bacteria) divides into 2 equally
sized cells
 Budding: simple organisms (ex. hydra
and yeast) produce much smaller cells
than those of the parent
 Sporulation: organism (ex. mushroom)
produces spores (tiny pockets of DNA)

TYPES OF ASEXUAL REPRODUCTION


Vegetative propagation: a
portion of one plant produces a
new identical plant
Regeneration: part of animal is
repaired through cell division
ASEXUAL REPRODUCTION

Mitosis is usually the mechanism that allows
asexual reproduction to occur.

Ex. When an earthworm is cut in half, cells must use
mitosis to divide in order to produce cells which will
reconstruct the missing portion
TYPES OF REPRODUCTION
Sexual Reproduction
SEXUAL REPRODUCTION

Sexual: two sources of genetic material; makes
four haploid sex cells (gametes)

Offspring = genetic combinations of two parents
Advantages: genetic variation,
 Disadvantages: requires more time for mating,
risk of unfavorable genetic combinations

Fertilization
SEXUAL REPRODUCTION

Gametes: sex cells
Sperm and eggs
 Purpose = to fuse with another gamete to combine
genetic material (fertilization)


Zygote: cell produced by fertilization

Will become an embryo
SEXUAL REPRODUCTION


Although sexual reproduction begins differently
than asexual reproduction (two parents as
opposed to one), sexual reproduction also relies
on cell division.
Meiosis: a type of cell division that produces
gametes

Divides genetic material in half, allowing for
fertilization
MEIOSIS
Human body cells contain 46
chromosomes
 In order for a zygote
(fertilized egg) to contain
46 chromosomes, the
gametes (sperm and egg)
must each contain only 23
chromosomes
CHECK YOURSELF
EXIT TICKET
1. Give two examples of asexual reproduction and briefly
explain.
2. How is sexual reproduction different from asexual
reproduction.
3. What are the disadvantages of asexual reproduction?
4. What are the advantages of sexual reproduction?
4. Place the phases of the cell cycle and mitosis in the
correct order and give the name of the phase.
ASEXUAL V. SEXUAL WEBQUEST
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Take out vocabulary do now
Reminders:
- Mini project due TOMORROW
- Quiz TOMORROW
VOCABULARY DO NOW
Homologous
Chromosomes
Each species has a specific
number of chromosomes.
Humans have 46
chromosomes in 23
homologous pairs. Each
homologous pair has one
chromosome from the
mother and one from the
father.
Homologous chromosomes
code for same traits.
Diploid and
haploid
Somatic (body) cells are
diploid, meaning that they
have pairs of chromosomes.
When a cell undergoes
meiosis to prepare for
sexual reproduction, the
chromosome number must
be reduced by half, creating
a haploid cell.
HOW DOES MEIOSIS PRODUCE GAMETES?

A gamete is very different from a somatic (body) cell

A somatic (body) cell is diploid = two of each type of
chromosome

Chromosome pairs = homologous chromosomes
A human has 23 types of chromosomes.
A human somatic cell has 46 total
chromosomes consisting of 23 homologous
pairs.
HOW DOES MEIOSIS PRODUCE GAMETES?

A gamete is very different from a somatic (body)
cell

A gamete is haploid = only one of each type of
chromosome

One from each homologous pair
A human egg contains 23 total
chromosomes
THE CELL CYCLE AND MEIOSIS
At the end of interphase (the longest part of the
cell cycle in which the cell completes normal life
functions), the cell duplicates DNA
 This creates doubled chromosomes
 The cell is now ready to divide

Meiosis Animation
MEIOSIS SUMMARY

Meiosis requires two cell divisions

Meiosis I = reduction division
Homologous pairs of doubled chromosomes
are separated
 End result = 2 daughter cells, each of
which is haploid but contains doubled
genetic material


Meiosis II
Same basic steps as mitosis
 Doubled chromosome is separated
 End result = 4 daughter cells, each of
which is haploid and contains no
duplicated DNA

CHECK YOURSELF
THE ENTIRE PROCESS OF MEIOSIS
EXIT TICKET
Word Bank
Traits
Two
Mitosis
1.
2.
3.
4.
5.
Haploid
Four
Crossing over
Sexual
Diploid
Interphase
The number of cells produced as a result of meiosis
is ________.
Homologous chromosomes code for same ________.
Meiosis is used for _________ reproduction.
The process that allows for genetic variation is
called _________ during meiosis.
During meiosis the chromosome number must be
reduced by half, creating a ________ cell
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Get ready for your quiz!
VOCABULARY DO NOW
Crossing-Over

When homologous
chromosomes pair up
during prophase I of
meiosis a part of one
chromosome switches
places with the other.
Since they are coding for
the same traits this
process produces more
variation in the
offspring.
Nondisjunction

When homologous
chromosomes do not
separate during meiosis
resulting in cells with too
many or too few
chromosomes.
QUIZ TIME!
Bring to Ms. Fields when finished.
FINISH WEBQUEST! S
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Turn in any missing work
VOCABULARY DO NOW
Asexual
Reproduction
Sexual
Reproduction
 One
 Two
parent
 One set of genetic
material
 Fast cell division
 Identical offspring
(babies)
sets of genetic
material
 Slower reproduction
 Variation (differences)
in offspring (babies)
MEIOSIS & GENETIC VARIATION

Variation as a result of:

Crossing Over
Homologous pairs come together
during Meiosis I
 A part of one chromosome can switch
places with the same part of the
homologous chromosome.
 Then, when the homologous pairs are
separated, each chromosome will be
different than the original.

MEIOSIS ALLOWS FOR LOTS OF VARIATION
(DIFFERENCES)

Variation as a result of:

Random Assortment of
chromosomes


Allows a mix of chromosomes
from both parents
Random Fertilization of
any egg by any sperm

Allows for lots of variation
PROBLEMS WITH MEIOSIS:

Gene Mutations


Changes in the DNA
before meiosis or mitosis
begins
Nondisjunction:
Homologous chromosomes
do not separate resulting
in one too many or one too
few chromosomes
 Ex. Down syndrome :
trisomy 21


Nondisjunction Animation
PROBLEMS WITH MEIOSIS: GENE MUTATION
Progeria: accelerated aging
Blue Eyes: Caused by
a mutation on the
OCA2 gene
Hypertrichosis: werewolf syndrome
PROBLEMS WITH MEIOSIS: NONDISJUNCTION
Karyotype: a picture
of the chromosomes
NONDISJUNCTION
CHECK YOURSELF
EXIT TICKET
1. List two examples of asexual reproduction and
briefly EXPLAIN.
 2. What is one ADVANTAGE of asexual
reproduction?
 3. What is one DISADVANTAGE of asexual
reproduction?
 4. EXPLAIN the process of crossing-over.

VOCABULARY DO NOW
Haploid: having a single set of unpaired chromosomes.
 Diploid: containing two complete sets of chromosomes,
one from each parent.
 Draw and label the following pictures

MEIOSIS SQUARE DANCE

http://www.youtube.com/watch?v=iCL6d0OwKt8
&feature=related
TO DO:

Grade updates

Turn in any missing work
Finish WebQuest
 Begin review work

EXIT TICKET
1. How many cells are produced as a result of
Meiosis?
 2. If a parent cell has 4 chromosomes and goes
through MEIOSIS, how many chromosomes
would the daughter cells contain?
 3. Meiosis is used for (sexual or asexual)
reproduction?
 4. EXPLAIN the process of crossing-over.

VOCABULARY DO NOW

Deoxyribonucleic Acid: (DNA) the blueprint of
life.



Every living thing uses DNA as a code for making
proteins, which determines traits
Traits: a distinguishing quality or characteristic,
typically one belonging to a person
Heredity: the passing of traits from parent to
offspring
REVIEW: MITOSIS AND MEIOSIS
MEIOSIS IN THE REAL WORLD
TO DO:
Turn in any missing work
 Cell Division Review

Notes packet
 Accompaniments

VOCABULARY DO NOW



Double Helix: Strands of DNA; looks like a
twisted ladder
Nucleotide: building blocks of DNA; composed of
deoxyribose sugar, a phosphate group, and 4
nitrogen bases
Nitrogen Bases: Four possible bases




Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
BENCHMARK QUIZ
10 questions
15 minutes
REVIEW PACKETS
Finish up!
All 3 packets are worth a test grade.