Asexual Reproduction

Unit Four, Lesson 4.1

By Margielene D. Judan

Lesson Outline

Reproduction

Types of Reproduction

Methods of Asexual Reproduction

Reproduction

Reproduction is the creation of “new

individuals” from existing individuals.

Two Types of Reproduction

Sexual – involves sex cells (egg, sperm)

Asexual – does not involve sex cells

Refer to p.125

In asexual

reproduction, the

parent cell is SINGLE

AND DIVIDING.

(ex. amoeba, hydra,

fungi, bacteria, etc.)

Refer to p.125

In sexual reproduction, the offspring are genetically identical (exact clones) to their parents.

(ex. humans, elephants, dogs, fishes, plants, etc.)

Asexual Reproduction

Formation of new individuals from the cell(s) of a single parent

Very common among plants, fungi, microbes, and invertebrates

Advantage: organism can reproduce even without a mate or partner

Common Types of Asexual

Reproduction

Budding

Fission

Fragmentation

Spore formation or sporulation

Vegetative propagation

Grafting

Layering

1. Budding

New individual is formed

by formation of a bud

It new organism is

attached as it grows,

separating only when it

is mature, which leaves

a scar on the parent.

2. Fission

Body divides into two

(binary) or more

(multiple) pieces

3. Fragmentation

Keyword: fragment

The breaking of any

parts of the body into

several pieces

The broken parts

develop into complete

individuals via

regeneration.

3. Fragmentation

In starfishes, they can cast a part of their body to lure and escape predators. It is called autotomy. (You can cut a starfish in half and in a year-time, you will have 2 starfish. But not all starfish can bounce easily to injury.)

Stem cells are responsible for that.

4. Spore formation or sporulation

A spore contains haploid cells (n) enclosed in a thick case and held together by the sporangium.

Upon maturation, the sporangium bursts and releases the spores to become new organisms.

Common among fungi and simple plants (mosses and ferns)

4. Spore formation or sporulation

Spores finally become living organisms via sexual reproduction. It combines with the male sex cell forming a diploid cell (2n)

n + n = 2n

n= half the # of chromosomes

5. Vegetative propagation

Roots, stems and leaves are “special

vegetative structures”, meaning they can

reproduce clone offspring.

Used mostly by gardeners and

agriculturists to produce plants with

desirable traits.

5. Vegetative propagation (Cutting)

Example 1: Cuttings (ex. Banana)

5. Vegetative propagation (Grafting)

Example 2: Grafting(ex. apples)

2 plants are used to develop a new plant

scion – a piece of young stem or bud inserted to the root stock

stock – a rooted stem which a scion is grafted

5. Vegetative propagation (Grafting)

The scion is

selected for good

quality of fruits,

flowers, resistance

to diseases, etc.

The stock is

selected for good

quality of roots.

5. Vegetative propagation (Layering)

Example 3: Layering (ex. raspberries)

Laboratory Task 2.1: Refer to pp.146-

147. (by group)

Choose only one: either product 1 or 3.

For product 1, you need to produce copies for each group in both section, plus one for the teacher. The content will be included in the exam.

For product 3, you need to make a presentation (ex. skit, performance, song, play, etc.) with your group.

The judges are your classmates, and your score will depend on the average times 10. If your average is 9.2, then 9.2 x 10 = 92/100 = 92%

This task will comprise almost half of your laboratory grade.

Laboratory Task 2.1: Refer to pp.146-

147. (by group)

The performance of each group will be scheduled on

different dates, to be performed at the start of the class

period. (minimum of 5 minutes; maximum of 15). In the

mechanics section in the rubric, instead of checking the

spelling and punctuation, we will check the diction and

creativity.

The output is due on different dates also. In the mechanics

section, the layout of the brochure is to be considered also.

Only one group per day will perform.

Laboratory Task 2.1: Refer to pp.146-

147. (by group)

Available dates for Agate

o Sept. 8-10 (Tue to Thurs)

o Sept. 14 (Mon)

o Sept. 16 (Wed)

Available dates for Amber

o Sept. 9-11 (Wed to Fri)

o Sept. 15 (Tue)

o Sept. 17 (Thurs)

Sources:

Science Links 7

http://leavingbio.net/vegetativepropagatio

n.htm