The Making of New Life: Multiplication or Division?

14A define heredity as the passage of genetic instructions from one generation to the next generation14B compare the results of uniform or diverse offspring from sexual reproduction or asexual reproduction

It is a running joke in the Biology field:

Recall the modern cell theory?

• All known living things are made up of one or more cells

• All living cells arise from pre-existing cells by division.

• The cell is the fundamental unit of structure and function in all living organisms.

• Energy flow (metabolism and biochemistry) occurs within cells.

• Cells contain DNA , genetic material to pass on traits to the next generation

• All cells are basically the same in chemical composition. (what they are made of)

In order to replicate,

or to make more, you must start at the very beginning

The beginning is copying the

genetic material and

other components

of the cell

So how exactly does life begin?

Replication comes in many forms

• But one thing remains the same, the genetic material and parts of the cell need to replicate before anything else can happen.

• Heredity is the passage of genetic instructions from one generation to the next generation

• Video – DNA Replication

Cell Division• Eventually cells need to duplicate. There are two

main methods of replication, mitosis and meiosis.

• Mitosis - is the simple duplication of a cell and all of its parts. It duplicates its DNA and the two new cells (daughter cells) have the same pieces and genetic code.

Meiosis

• Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information.

• These cells are our sex cells – sperm in males, eggs in females.

Meiosis

What is Reproduction?

• Reproduction is the process by which new organisms are generated.

• It is the mechanism of species continuation.

• There are two means of reproducing: asexual and sexual reproduction.

Purpose of Reproduction

• To make sure a species can continue

• To make new cells

Asexual Reproduction

• New organism is produced from ONE parent

• Offspring are IDENTICAL to the parent and each other.

• Genetic material is donated from that one parent. (so is there variety in the genes?)

• Very common in plants; less so in animals

Examples of Asexual Reproduction

• Budding – living organisms make offspring that form from outgrowths (buds) on the bodies of the parent.

• some organisms like hydra and corral can form a mass of cells called a “bud”.

• That bud specializes to form a new organism on the side of the parent.

• It will drop off and become its own organism.

Examples of Asexual Reproduction

• Vegetative propagation – some plants can grow whole new plants from divided parts

• It will drop off and become its own organism.

Ex. spider plant

Examples of Asexual Reproduction

• Spores – seed like capsules of DNA and tissue that can grow under the right conditions.

• They are produced by nonflowering plants, bacteria, fungi, and algae, and are often able to travel over long distances.

• Ex. mushrooms, molds

Examples of Asexual Reproduction

• Regeneration –some organisms (starfish and the salamander) can replace an injured or lost part, and many plants are capable of total regeneration (the formation of a whole individual from a single fragment such as a stem, root, or leaf)

Examples of Asexual Reproduction

• Binary Fission - The process in which a parent cell splits into two daughter cells of approximately equal size.

Advantages and Disadvantages Asexual Reproduction

Advantages (Pros):

o Faster and easier – no partner needed

o Less chance of mutation – less steps to follow, so less chance things can go wrong

• Disadvantages (cons):

o Less genetic diversity (parents = to offspring) means less chance of survival if the environment changes

Sexual Reproduction

Sexual Reproduction - the production of new living organisms by combining genetic information from two individuals of different types (sexes).

• Genetic material is donated from two parents

• The process is called fertilization

• Half of the genes for each trait come from the male parent and half from the female parent.

• Offspring differ (vary) from each parent and from each other.

• Parents typically care for their offspring.

• There are less offspring (in general); more chance for survival

Examples of Sexual Reproduction

• Pollination - Plants that rely on flowers for reproduction are also very dependent on outside help such as insects and animals.

• A bee might go to one flower and get a little pollen on its back. If it goes to another flower of the same species, that pollen can land on the stigma. If successful, an embryo and seed/fruit develop respectively.

• https://www.youtube.com/watch?v=1OFF2qYvLag

Sexual Reproduction examples:

Sexual reproduction in animals (external or internal fertilization)

• Animal male gamete is called sperm. Sperm is a mobile cell that moves using its 'tail', called flagellum. Female gamete is called an ovum. It does not move and it is much larger than sperm

• The egg and sperm combine for fertilization.

Frogs mate through the process of external fertilization (occurs outside of the body)

Advantages and Disadvantages of SexualReproduction

• Advantages (Pros):– Greater genetic diversity due to large

number of gene combinations that can occur (think increased biodiversity).

– Half of the genes come from each parent.– Disadvantages (Cons):

• It is a slow process, and a greater chance of mutations in the DNA replication process

• Energy is expended finding a mate• Only works in complex organisms

Key Points!

• Asexual reproduction results in offspring that are genetically identical to the parent organism

• Sexual reproduction results in offspring that are genetically different from the parent organisms

Asexual Reproduction Stations:

• Complete each station, we will rotate through them

• Here is the page you need:

Cloning does not allow for variation.

Why might this be a

problem? What is your opinion about

cloning?What do you know about

it?

But if nature “clones”, why is it so controversial if humans make clones?