Cloning, Meiosis & Reproduction in Flowering Plants

Cloning

Cloning is the process of forming identical genetic offspring from a single cell.

It is a natural process that happens daily in nature when organisms produce exact duplicates of themselves by asexual reproduction (binary fission, budding…).

Cloning is referred to as asexual reproduction because the DNA originates from a single parent.

The First Clone

Cloning started in 1958 when Frederic Stewart grew a carrot from root cells.

Clones are not actually identical in appearance; rather they are identical in genetics.

Dolly the Sheep

In 1996, Dolly the sheep, a species much more complex than simple plants or bacteria, was cloned. She was the first fertile clone!

This is the most famous cloning case to date.

However, Dolly showed signs of premature aging, possibly due to using specialized somatic cell nucleus.

How Dolly was Cloned:

Other Clones

Dolly the Sheep (1996)Tetra the Rhesus monkey (2000)

Xena the Pig (2000)Alpha and Beta Male Cattle (2001)

CC the Cat (2001)Idaho Gem & Utah Pioneer the Mules (03)

Dewey the Deer (2003)Prometea the Horse (2003)

Meiosis: creating cells for sexual reproduction

Meiosis Meiosis is a form of cell division & is similar

to mitosis. However, meiosis produces eggs and sperm for sexual reproduction. (sex cells)

In sexual reproduction half the genetic information comes from each parent. Therefore, egg and sperm cells must have half the number of chromosomes as the parent cell.

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

How meiosis works:First, 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

Reproduction in Flowering Plants

Reproduction in Flowering PlantsPlants use sexual reproduction

two plants combine to make one zygote through the process of fertilization of a female sex cell by a male sex cell.

Some plants have separate sexes with one type of sex organ on each (poplar trees), while some plants have both sexes on one plant – hermaphrodites (tomatoes).

Most plants develop or mature in one growing season.

Plant Sex OrgansPlant sex organs are very different than humans. Male Sex Organs: Stamen- the male reproductive structure of the flower

(anther, pollen & filament) Anthers – create pollen, located on the tips of stamen Pollen – male sex cells Filament – long stalk that supports the anther

Female Sex Organs: Pistil – The female reproductive structure of the fSticky

surface for the pollen to land on. Eggs – female sex cells Style – traveling chamber from stigma and ovary. Ovary – holds the egg.Plant sex organs vary in length, size, colour, and shape

from plant to plant.

Anatomy of a Flowering Plant 7.3a

Stigma

Stem

Sepal

Petal

Filament

AntherPollen

Style

OvaryEggs

Pollination

The process by which pollen moves from an anther to the stigma so pollen can fertilize the egg.

Can occur between plants or in the same plant.

Wind, gravity, insects, animals, and water can carry pollen.

It is beneficial for pollen to be spread over large areas for greater genetic disbursement.

Fertilization

The combining of pollen and eggs to produce a zygote.In plants , the zygote is better known as seeds.In some plants the ovary enlarges into fruit, therefore we are actually eating ovaries.Fruit is used for protection and disbursement ex. A bear eats berries and leaves seeds through its droppings.

Practice and ReviewFill in the chart provided (flower parts

and life cycle of a tomato plant) using pages 208-210 in your text

Text questions: p197 #8, p207#3-4, p209 #1-4