Methods of Asexual Reproduction

This is what it would look like

if

humans reproduced by fragmentation!

bud

Budding

• • A

new organism grows on another one

and

then separates from

the

parent

organism only

when

it is

mature

.

Examples

of organisms that reproduce by budding include:

yeasts, sponges and hydra bud bud

Binary Fission

• Division into

two parts

(daughter cells) which

each daughter cell has

the

potential to grow

to the

size of

the

original cell (parent cell)

• An

example

of an organism that reproduces by binary fission is a

paramecium

.

Daughter cells

Regeneration

• When an animal that is capable of regeneration loses a body part, it can grow a replacement part.

• • If the

lost body part contains enough genetic information

from the parent, it

can regenerate

into an entirely

new organism

.

Echinoderms

and the in molds are

examples hydra

of organisms that reproduce by regeneration.

Fragmentation

• • • A new organism

grows from

a

fragment of

the

parent

.

Each fragment

develops into a mature,

fully grown individual

.

Examples

of organisms that reproduce by fragmentation include:

molds and planaria

.

Vegetative Reproduction

• New individuals are

formed without

the production of

seeds or spores

• • May

produce bulbs, tubers or rhizomes (runners) Examples

of organisms that reproduce by vegetative reproduction include:

tulips, dahlia, strawberries rhizome bulb

Vegetative Propagation

• • The production of a

new plant from

a

portion of

another

plant

, such as a

stem or branch

.

Examples

of organisms that reproduce by vegetative propagation include:

spider plants, potatoes, aloe

and various other plants.

cutting New spider plant

Spores

• • In

some organisms

,

meiosis

leads to the

formation of haploid spores

rather than gametes. These

spores grow into multicellular individuals without being fertilized.

Examples

of organisms that reproduce by forming spores include:

mushrooms, molds and ferns spores

Asexual Reproduction

Method

Asexual

Number of Parents Genetics

1 parent • •

Pros

Identical 100% of genes come from 1 parent • • No mate Identical to parent

Cons

• • Mutations are definite No variety

Sexual Reproduction

Sexual Reproduction

• Two parents • Genetically speaking, the offspring get info from both parents: ½ from mother (egg) ½ from father (sperm) There are 46 chromosomes in human cells, so 23 from mom + 23 from dad = 46 total

Sexual Reproduction

• Requires sex cells (gametes) – Male sex cell (gamete) – sperm – Female sex cell (gamete) – egg • Fertilization is the process in which sperm and egg unite – Chromosomes double Ex) 2 + 2 = 4

Cell division by mitosis

Step 3 Chromosomes line up along the middle of the cell and each centromere attaches to a spindle fiber. Step 4 •

Mitosis

is cell division of

body cells

• Mitosis produces

exact copies

of the parent cell • The new

daughter cells

have the

diploid

number of chromosomes Spindle fibers go to work like tugboats, pulling each pair towards opposite ends of the cell. Step 5 Nuclear membrane returns around

Meiosis

• Cell division that results in the formation of gametes (sex cells) – Sperm and egg – Cells are haploid • Cells are NOT identical – Each cell contains half the number of chromosomes but not necessarily the same chromosomes as the others

How many chromosomes?

• Humans have

23 pairs

of chromosomes like these • The

diploid

number of chromosomes is 23x2 =

46

• Sex cells (gametes) have

23 single

chromosomes - the

haploid

(half) number

So……what’s the point?

• An

egg

cell is

haploid

• A

sperm

cell is

haploid

• When they join at

fertilization

the resulting cell is

diploid

• This makes a

full set

of instructions to make a new organism!

Mitosis vs Meiosis