Reproduction, Reproduction, Mitosis and MeiosisMitosis and Meiosis

Spring 2012

All Living Things All Living Things REPRODUCE…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:Asexual Reproduction:Definition: Only one parent is needed for reproduction.

Offspring clone of parent.

Sexual ReproductionSexual ReproductionDefinition: Two parents are

needed for reproduction to combine sex cells.

Offspring is different than parents.

5 Types of Asexual 5 Types of Asexual ReproductionReproductionBinary Fission – simple cell

division. Most unicellular organisms like bacteria and protists reproduce this way.

KINGDOMS: Protists and bacteria

5 Types of Asexual 5 Types of Asexual ReproductionReproductionBudding – 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 5 Types of Asexual ReproductionReproductionSpores- 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 5 Types of Asexual ReproductionReproductionFragmentation – Occurs in multi-cellular animals. Entire organisms grow from a piece of the adult.

KINGDOM: ANIMALS EX: Worms and Starfish.

5 Types of Asexual 5 Types of Asexual ReproductionReproductionVegetative Propagation – Cuttings

from plants grow into new individuals, or new runners (root structures) are produced.

KINGDOM: PLANTEX: Strawberry plants, monkey

grass, potatoes.

SEXUAL REPRODUCTION

Sexual reproduction involves two sex cells.

One sex cell is needed from each parent.

Most multi-cellular organisms reproduce this way, including

KINGDOMS ANIMAL, PLANT and FUNGI .

The sex cells, also called gametes, are egg cells in

the female and sperm cells in the male.

How do Parent Compare to How do Parent Compare to Offspring?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!!!!!

ChromosomesChromosomesDefinition: The structure that

DNA is organized in.They come in pairs, half from

each parent.

NUMBERS OF CHROMOSOMES VS COMPLEXITYThe 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:

A fern called Ophioglossum reticulatum has 1,260 chromosomes per cell, more than any other known organism.

Human - 46

Goldfish - 98

Potato - 48

Wheat - 42

Fruit fly - 8

CHROMOSOME ARRANGEMENT

All regular body cells have all the same parts in multi-cellular organisms and the

same # of chromosomes.

Chromosomes always come in pairs.

There are 46 chromosomes in human body cells.

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 ARRANGEMENTHUMAN BODY CELLS HAVE 46 CHROMOSOMES OR 23 PAIRS.

BULLFROG BODY CELLS HAVE 26

CHROMOSOMES OR 13 PAIR.

FRUIT FLY BODY CELLS HAVE 8 CHROMOSOMES OR 4 PAIR.

Nerve cell Bone cell

WHY ONLY ½ IN SEX CELLS???????The sex cells (egg and sperm)

are also called GAMETES.

They DO NOT have a full # of chromosomes

Sex cells only have ½ the number of chromosomes as body cells. So, when they unite

it equals a full 46...

Human sex cells would have -23 chromosomesBullfrog gametes would have -13 chromosomes

Fruit fly egg and sperm would have -

4 chromosomes

FERTILIZATION

23 CHROMOSOME

S

23 CHROMOSOM

ESFERTILIZATION

How many chromosomes will the human fetus have?

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?

And a TANGERINE. It has 26 chromosomes in the body cells so how many in the sex cells?

Tangelos are a HYBRID because it will end up with an odd number or chromosomes (23). It has NO SEEDS and cannot reproduce

10

13

WHAT IS A MULE?

A mule is a cross between a horse and a donkey.

Body cells – 60 chromosomes

Sex cells – 30 chromosomes

Body cells – 66 chromosmes

Sex cells – 33 chromosomes

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.

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?What is a Liger?Lions - 38 Tigers - 38

chromosomes 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 - Simple 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: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: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 MitosisThe Process of Mitosisa 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 MitosisEnd Product of MitosisMulticellular: Results in new

body cells such as internal organs, skin, bones, blood, etc.

Liver Cells

Bone Cells

Heart (Cardiac) Cells

End Product of MitosisEnd Product of MitosisUnicellular: a new individual

that is a clone of the parent.

Number of ChromosomesNumber of ChromosomesTotal 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: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 MeiosisPurpose of MeiosisMulticellular: to produce new

SEX CELLS that can combine to form an offspring.

End Product of MeiosisEnd Product of MeiosisNew sex cells with half the

number of chromosomes as body cells.

Number of ChromosomesNumber of ChromosomesEach 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!!!