ASEXUAL REPRODUCT

ION

OVERVIEWClone: an identical genetic copy of its

parents Bread mold comes from a single mold sporeA duplicate tree growing from the bottom of

another tree

Asexual Reproduction: only 1 parent is required to produce offspring

Clones can also be created artificially (agricultural or horticultural industries, or biomedical labs) Trying to create heartier breeds and increase

plant production Clone healthy genes to replace mutated ones Potentially cloning the genes of extinct

animals like Tasmanian Tigers!

We might be able to use cloning to reproduce extinct species like Tasmanian

tigers!

Types of Asexual Reproduction

There are 5 main methods of asexual reproduction:

1. Binary Fission2. Budding 3. Fragmentation 4. Vegetative Reproduction5. Spore Formation

1. Binary Fission A single parent cell replicates its genetic

material, dividing into 2 equal parts Method used by small, one-celled eukaryotic

organisms like amoeba

Ex.: Amoebas Have between 30-40 chromosomes Chromosomes duplicated during

mitosis

Binary fission is the only method of reproduction for some bacteria!

No nucleus = no mitosis!

Instead, one ring of DNA is replicated...

Under ideal conditions, it can replicate every 20 min. Ex. Streptococcus bacteria

Mutations can occur during binary fission! Mutations in the DNA

of bacteria can make it very resistance to antibiotics

2. Budding Areas of an individual undergo mitosis

and cell division, developing into an identical organism

Used by some multicellular organisms (hydras and sponges) that only have a few different cell types

The “buds” might detach from the parent and become a new individual OR remain attached

1. Hydra develops a “bud”

2. The bud develops a mouth and tentacles

3. When it’s fully formed the daughter hydra detaches from parent

4. The daughter is fully independent

Budding is great for organisms like sponges because they attach to rocks and move very little. Colonies can grow in the same area or break off and colonize new locations.

3. Fragmentation Occurs when a piece of an organism

breaks apart (ex. injury) and each fragment develops into a clone of the parent

Ex.: Starfish If a broken arm contains enough DNA it

can develop into an identical copy

Plants can also reproduce by fragmentation IF the environment doesn’t change and IF there are enough nutrients available.

Example: Eurasian milfoil Introduced to North America Chopped up by propellers and spread

through lakes

4. Vegetative Reproduction Occurs when special cells (usually in plant

stems and roots) divide repeatedly to form structures that will eventually develop into an identical plantDevelop off of the bulb

or as sprouts (“eyes”)

Ex.: Tulips, daffodils, hyacinth bulbs, and potatoes

Disadvantage Daughter plants grow very close to

parent plants Will complete for soil, nutrients, and light

Benefits of Vegetative Reproduction

Potatoes #1 tuber crop in world Used globally

Common Camas An important part of the First Nations

diet Also used for trading

Human Assisted Methods of Vegetative Reproduction

1. CUTTINGS The plant grower removes a part of the

stem (or leaf/root) and plants the cutting in a special growing medium

Plant hormones, which are chemical messengers, are often applied to the cut stem

Hormones signal nuclei to stimulate cell division, causing some cells to develop into root tissue

House plants can reproduce in this method

2. GRAFTING Stems called “scions” are attached to

the rotted stock (“rootstock”) of a similar plant

Often used for apple trees and rose plants

Another form called “budding” is used to grow apple trees

Advantages: Can help scion benefit from a more

rigorous root system

Produce fruit within 2-3 years instead of 5-10 years

Helps control eventual size of plant

5. SPORE FORMATION Method used by some bacteria, micro-

organisms, fungi (ex. bread mold), mosses, and ferns

Reproduction through the formation of single-celled spores

Spores: a reproductive cell that grows into a new individual by mitosisVery light in weight Rely on wind or water for

transportation

If conditions are right (enough moisture and food, and proper temperature) a new individual will grow wherever it lands

Many spores have tough outer coatings that allow them to survive in harsh conditions (drought or extreme temp.) until the conditions are right

Summary of Asexual Reproduction