Hi.

My name is Suzanne Madrick,

and I am a research scientist and senior lecturer at the

University of Newcastle studying in the Biosciences

Institute.

And in this series of mini lectures,

we will talk about reproduction.

We'll talk about asexual and sexual reproduction

and the different,

types of organisms that use these different versions of reproduction.

We'll talk about DNA.

We'll talk about the genome,

and we'll talk about protein synthesis as well.

So in this first topic,

we're going to learn about the main differences between

asexual and sexual reproduction.

Reproduction is essential to all living things.

It's during reproduction that genetic information

carried on chromosomes is passed on from parents to their offspring.

And reproduction can happen in two very different ways,

by asexual reproduction and bisexual reproduction.

Asexual reproduction involves only one parent and cells

divide to produce their offspring by mitosis.

There is no joining of cells, no fusion of gametes and so

no mixing of genetic information.

Asexual reproduction involves cell division by mitosis,

which if you remember passes on identical copies of parent cell genes.

This means that genetic material of all offspring is

identical to the parent and to each other.

In other words, all offspring of

asexual reproduction are clones and there is no variation.

Asexual reproduction is very common in the smallest

animals and plants and in fungi and bacteria as they reproduce

new versions of themselves.

However, many larger plants such as daffodils,

strawberries, and brambles, they can also reproduce asexually.

Remember too that the cells of your body, they're reproducing

asexually all the time.

They divide into two identical cells for growth and to

replace worn out tissue, but not to produce a new being.

This would involve sexual reproduction.

Sexual reproduction involves a male cell and a female cell

from two parents.

These two specialized cells or gametes form together to form a

zygote, that's the single cell embryo,

which then goes on to develop into a new individual,

which is genetically different from either parent.

This is possible because gametes are formed in a

different type of cell division known as meiosis that

rearranges DNA on chromosomes.

In addition, through meiosis,

the chromosome number of the original parent cell is halved

so that when gametes join together to form that zygote,

the zygote forms with the right number of chromosomes for that organism,

and importantly has inherited genetic information from both parents.

Offspring then have the characteristics from both

parents but are not identical to either of them.

In plants, the gametes produced by meiosis are called egg

cells and pollen.

And in animals, the gametes are egg cells and sperm.

Sexual reproduction introduces a level

of variation in offspring that is absent in the offspring

produced by asexual reproduction,

but it's risky.

Sexual reproduction relies on two sex cells, often from two

individuals, being able to meet and fuse.

However, the genetic variation that it introduces is key to the long

term survival of that species.

This is why sexual reproduction takes place in a vast number of

living things ranging from single celled organisms to humans.

We will talk a little bit more in the next lesson about

asexual and sexual reproduction and some of the advantages and

disadvantages of both of these different strategies.