Asexual and Sexual Reproduction

Types of Asexual Reproduction(hand out pages 159 – 161)

Meiosis 7.2 (206)Atypical Meiosis 7.9 (222)

Binary FissionOrganism splits directly into

2 equal-sized offspring.Each with a copy of the

parents genetics information.

This is common in single celled organisms.

Ex. Intestinal Bacteria

BuddingOffspring begins as a small outgrowth

from the parent.Bud eventually breaks off and

becomes an organism of its own.Happens in single-celled and multi-

celled organisms.

Ex. Yeast or hydra(freshwater polyp)

Budding

Asexual Offspring grows

out of parent Yeast, hydras + Fast,

somewhat easy - Same DNA

Fragmentation

A new organism is formed from a part that breaks off the parent

Ex. Starfish

Fragmentation/ regeneration

Moss

Spore Formation

Organism undergoes frequent cell division to produce many smaller identical cells called SPORES.

Ex. Penicillin (mold)

Vegetative Reproduction

Produce “runners” that can develop into another plant with identical genetic information.

Ex. Strawberries or spider plant

Questions

1. How is asexual reproduction different from sexual reproduction?

2. How is the zygote, produced by sexual reproduction, different from daughter cells, produced by asexual reproduction?

Zygote is a fertilized egg.

MeiosisThe function of meiosis is to produce eggs

and sperm for sexual reproduction. (sex cells)

1. Egg and sperm cells must have half the number of chromosomes as the parent cell so that when put together they will have the same number of chromosomes as the parent cells. (23 vs. 46 in our body cells.)

2. Egg and sperm cells are NOT genetically identical to the parent cell like you see in mitosis.

3. Although you may look more like one parent than the other, you receive the same amount of genetic information from each.

4. Chromosomes similar in shape, length and gene arrangement are called homologous chromosomes.

Summary of MeiosisFirst, the genetic material must be

replicated so that each daughter cell can be given the appropriate amount of genetic information. This occurs in Interphase.

Second, the genetic material must be divided twice so that each of the four daughter cells gets a set of information.

Interphase PMAT PMAT Interphase

Atypical Meiosis (7.9) FYI

Errors occurring during cell divisions may not harm an organism… but if something goes wrong during meiosis of reproductive cells, the resulting embryo is in serious trouble since all of its cells will be affected.

Nondisjunctive Disorders(failure to separate)

Is an error that occurs when two homologous chromosomes move to the same pole during meiosis.

… the resulting sex cell may have 22 or 24 chromosomes.

… Therefore, the resulting zygote may have 45 or 47 chromosomes rather than 46.

In general, people with Down Syndrome have an extra chromosome in pair 21 (trisonomy 21). Children may have mental disabilities and some muscular weakness.

Most common with elderly mothers.

Klinefelter Syndrome:

The child is a male, but at puberty he begins producing high levels of female sex hormone and can not father children. (1 in every 1000 births.)

Turner Syndrome: Females with T.S. do not mature sexually and are shorter in height. (1 in every 10000 births)

Both caused by nondisjunction.

Turner Syndrome also can occur

when nondisjunction happens during meiosis forming the human females gametes.