Transcript Reproduction POWER POINT

Reproduction,
Mitosis and Meiosis
Spring 2012
All Living Things REPRODUCE…
 Without
reproduction all living
things would go EXTINCT…
HOW DOES A LIVING ORGANISM
REPRODUCE?
Living things can reproduce in 2 different ways:
SEXUALLY OR ASEXUALLY
Similarities: Both types produce an offspring.
Asexual reproduction - only one parent is needed for
reproduction. Offspring clone of parent.
Sexual Reproduction – Two parents are needed for
reproduction. Offspring is different than parents.
Asexual Reproduction:

Definition: Only one parent is needed for
reproduction.
 Offspring clone of parent.
Sexual Reproduction
Definition: Two parents are needed for
reproduction to combine sex cells.
 Offspring is different than parents.

5 Types of Asexual Reproduction
Binary Fission – simple cell division. Most
unicellular organisms like bacteria and
protists reproduce this way.
 KINGDOMS: Protists and bacteria

5 Types of Asexual Reproduction
Budding – occurs in simple multi–celled
animals and unicellular fungi, a small
individual grows off the body of the adult.
 KINGDOM : ANIMALS Hydra, jellyfish,
corals, sea anemone. FUNGI- yeast

5 Types of Asexual Reproduction
Spores- Are reproductive cells that grow
into new individuals when conditions are
right. Some ferns and fungi reproduce
this way.
 KINGDOM : Plants and Fungi

5 Types of Asexual Reproduction
Fragmentation – Occurs in multi-cellular
animals. Entire organisms grow from a
piece of the adult.
 KINGDOM: ANIMALS
 EX: Worms and Starfish.

5 Types of Asexual Reproduction
Vegetative Propagation – Cuttings from
plants grow into new individuals, or new
runners (root structures) are produced.
 KINGDOM: PLANT
 EX: Strawberry plants, monkey grass,
potatoes.

SEXUAL REPRODUCTION
Most multi-cellular organisms reproduce
this way, including KINGDOMS ANIMAL,
PLANT and FUNGI .
Sexual reproduction involves two sex cells.
One sex cell is needed from each parent.
The sex cells, also called gametes, are egg cells in
the female and sperm cells in the male.
How do Parent Compare to Offspring?

Asexual Reproduction – Only involves one
parent so offspring is a CLONE!!

Sexual Reproduction – Two parents genes
are combine to make a new organism.
Different from parents
SEXUAL REPRODUCTION: allows for variation.
Sexual reproduction always involves the combining
of 2 nuclei from 2 different sex cells.
FERTILIZATION is
the joining of egg and sperm.
The cell (fertilized egg) that comes from fertilization is
called the ZYGOTE.
HOW DOES SEXUAL REPRODUCTION OCCUR?
 Sexual reproduction is simple the joining of the egg cell
with the sperm cell.
 This can occur inside the body or even outside the body
of animals. Female fish and amphibians lay their eggs
and then the males spread their sperm over them.
 Plants join their egg and sperm by the help of the
wind or other animals.
The yellow pollen grains inside a flower
are SPERM cells.
 The egg is found in the base of the flower. Insects or
wind bring the pollen to the flower and then the sperm
travels down to the egg. When egg and sperm join, it
forms a SEED!!!!!
Chromosomes
Definition: The structure that DNA is
organized in.
 They come in pairs, half from each parent.

NUMBERS OF CHROMOSOMES VS COMPLEXITY
The number of chromosomes in the cells of eukaryotes
differs from one kind of organism to another and has
NOTHING to do with the complexity of the organism.
FOR EXAMPLE:
Goldfish - 98
Wheat - 42
Human - 46
Potato - 48
Fruit fly - 8
A fern called Ophioglossum reticulatum has 1,260
chromosomes per cell, more than any other known
organism.
CHROMOSOME ARRANGEMENT
All regular body cells have all the same parts in multi-cellular
organisms and the same # of chromosomes.
There are 46 chromosomes in human body cells.
Chromosomes always come in pairs.
There are 46 chromosomes for a total of 23 pairs.
22 of the pairs are similar.
The 23rd pair is different.
These are the sex chromosomes.
CHROMOSOME ARRANGEMENT
HUMAN BODY CELLS HAVE 46 CHROMOSOMES OR
23 PAIRS.
Nerve cell
Bone cell
BULLFROG BODY CELLS HAVE 26
CHROMOSOMES OR 13 PAIR.
FRUIT FLY BODY CELLS HAVE 8 CHROMOSOMES
OR 4 PAIR.
WHY ONLY ½ IN SEX CELLS???????
The sex cells (egg and sperm) are also called GAMETES.
Sex cells only have ½ the number of
chromosomes as body cells. So, when they unite
it equals a full 46...
They DO NOT have a full # of chromosomes
Human sex cells would have Bullfrog gametes would have -
23 chromosomes
13 chromosomes
Fruit fly egg and sperm would have - 4 chromosomes
FERTILIZATION
23
CHROMOSOMES
How many
chromosomes
will the human
fetus have?
FERTILIZATION
23
CHROMOSOMES
46 is correct!!
Just as it is
supposed to be.
WHAT IF A MISTAKE HAPPENS DURING
FERTILIZATION?
The resulting zygote is called a mutation.
Not all mutations are bad. There are
several useful living things that are
mutations.
BUT
All mutations have something
WRONG with them.
Good mutations are changes in a
living organisms natural
characteristics that benefit the
organism and allows it to survive
better in its changing environment.
CAN MUTATIONS HAPPEN IN HUMANS?
The boy on the right has
DOWN’S SYNDROME.
Remember that
chromosomes are
supposed to come in
pairs. Down’s
Syndrome is caused by
having three
chromosomes attached
together where the
21st pair should be.
Got 23 from one parent
and 24 from the other.
HAVE YOU EVER EATEN A TANGELO?
A tangelo is a
cross between an
ORANGE. It has 20
chromomoses in its body
cells so how many in the
sex cells?
10
Tangelos are a
HYBRID because it
will end up with an odd
number or chromosomes
(23). It has NO SEEDS
and cannot reproduce
And a TANGERINE.
It has 26
chromosomes in the body cells so how
many in the sex cells?
13
WHAT IS A MULE?
How many chromosomes will the body cell of a
mule have?
63 is an odd number. Knowing that all
chromosomes come in pairs makes this animal have
one single chromosome by itself. This causes ALL
mules to be sterile and not able to reproduce.
Body cells – 60 chromosomes
Sex cells – 30 chromosomes
Body cells – 66 chromosmes
Sex cells – 33 chromosomes
A mule is a cross between a horse and a donkey.
ADVANTAGES AND DISADVANTAGES OF ASEXUAL
REPRODUCTION
Advantages:
1. Quicker, no need to look for a mate.
2. Simpler to produce another just like yourself if you have
desirable traits.
Disadvantages:
1. No variation of traits, no individuality.
2. Offspring is a clone of the parent (can be bad if parent has
undesirable traits.
ADVANTAGES AND DISADVANTAGES OF SEXUAL
REPRODUCTION
Advantage:
1. Allows for individualism or variation. There will never
be two just alike unless they are identical twins.
 TWO different genetic codes from 2 different parents
results in variation in a species. For example, no two
quarter horses, pine trees, blue whales, dogwoods or
humans are exactly alike. (Good for “weeding” out bad
genes.
Disadvantages:
1. Takes more time (gestation).
2. More energy required to find a mate, etc.
What is a Liger?

Lions - 38
chromosomes
Tigers - 38
chromosomes
Sex Cells - ?
Sex Cells - ?
How many chromosomes do ligers have?
Can they reproduce?
Sometimes an egg will
split into two separate
parts soon after it is
fertilized. This creates
two embryos with the
same DNA: IDENTICAL
TWINS.
Sometimes two eggs are
fertilized at the same
time. The two embryos are
just like regular siblings
except that they develop
and are born at the same
time. These are called
FRATERNAL TWINS.
Conjoined Twins: Two theories
1.“Fission theory“ - conjoined twins occur when a
fertilized ovum (egg) begins to split into identical
twins, but is somehow interrupted during the
process and develops into two partially formed
individuals who are stuck together.
2.“Fusion theory“ - twins become conjoined after
the fertilized ovum intially splits into identical
twins.
HOW DOES A CELL REPRODUCE ITSELF?
The process is called CELL REPRODUCTION
Cell Reproduction S- imple cell division in which one cell divides into two
Multi-cellular organism use cellular reproduction to produce more
body cells for growth and repair.
Unicellular organisms use cell reproduction to reproduce period.
Mitosis:

Definition: A type of cell division that results in
two daughter cells that are exactly the same
as the parent cell.

Results in cells such as internal organs, skin, bones,
blood, etc. OR a new organism (clone).
Purpose of Mitosis:
Multicellular: To
produce new cells
to repair and
replace existing
body cells.
 Unicellular: To
produce a new
individual through
asexual
reproduction.

The Process of Mitosis

a cell wants to make a duplicate of itself, it
first must copy its DNA (part of a
chromosome).

The copies then must be separated &
sorted into two sides of the cell.

The cell then splits in two. Part of each
parent is carried to the two new cells.
Exact DNA is passed on to offspring.
End Product of Mitosis

Multicellular: Results in new body cells
such as internal organs, skin, bones, blood,
etc.
Heart (Cardiac) Cells
Liver Cells
Bone Cells
End Product of Mitosis

Unicellular: a new individual that is a
clone of the parent.
Number of Chromosomes
Total number of chromosomes is the
same as the parent.
 Example:
Yeast cells = 32 chromosomes… Since it
reproduces asexually, each offspring will
have 32 chromosomes from a single parent.

Meiosis:
Definition: A type of cell division that
results in two daughter cells each with
half the chromosome number of the
parent cell.
 Results in SEX CELLS!

Purpose of Meiosis

Multicellular: to produce new SEX
CELLS that can combine to form an
offspring.
End Product of Meiosis

New sex cells with half the number of
chromosomes as body cells.
Number of Chromosomes
Each sex cell will have HALF the number
of chromosomes than body cells.
 For humans, each sex cell will have 23
chromosomes.
 So, in mitosis in humans (reproducing
body cells), each new body cell will have
the TOTAL 46 chromosomes!!!
