Sexual/Asexual Reproduction

SEXUAL/ASEXUAL

REPRODUCTION

SEXUAL REPRODUCTION Sexual Reproduction – type of reproduction

in which the genetic materials from two different cells combine, producing an offspring

Sperm – male sex cell

Egg – female sex cell

Fertilization – joining of the sperm and egg cell

The new cell that forms is called a zygote.

DIPLOID CELLS Organisms that reproduce sexually make 2

kinds of cells- body cells and sex cells (gametes -sperm & egg)

Diploid cells – cells that have a pair of chromosomes; divide by mitosis (full # of chromosomes) ex. body cells

Different Organisms have different numbers of chromosomes. Ex: Humans have 46 chromosomes.(23 pairs)

Homologous chromosomes – pairs of chromosomes that have genes for the same trait arranged in the same order

HAPLOID CELLS Sex cells are Haploid – only have one

chromosome from each pair; divide by meiosis (half the # of chromosomes)ex. sex cells (sperm and egg)

MEIOSIS Meiosis – process by which one diploid

cell divides into four haploid cells; occurs in the formation of sex cells

Meiosis is important because: It ensures the correct number of

chromosomes in offspring ex. sperm (23) + egg (23) = human (46)

creates more genetic diversity by producing haploid cells.

MITOSIS VS. MEIOSIS Starts as diploid

cell Body cells 1 division of

nucleus Produces 2

daughter cells Diploid daughter

cells Used for growth

and repair of cells

Starts as diploid cell

Reproductive cells 2 divisions of

nucleus Produces 4

daughter cells Haploid daughter

cells Used to produce

sex cells

SEXUAL REPRODUCTION +/- Advantages

Genetic Variation offspring inherit half

their DNA from each parent

helps with adaptations to changing environments

Selective Breeding breeding species with

desirable traits ex. dog breeding,

farming

DisadvantagesTime and Energy

development of sex cells

finding a mate Exposure to predators,

disease, or harsh environmental conditions

ASEXUAL REPRODUCTION Asexual reproduction – one parent

organism produces offspring without meiosis and fertilizationoffspring are genetically identical to parent

(clones)

TYPES OF ASEXUAL REPRODUCTION Fission

simple cell division in prokaryotic (bacteria) cells

Mitosis simple cell division in

eukaryotic cells

Budding a new organism grows

by mitosis on the body of its parent ex: hydra

TYPES OF ASEXUAL REPRODUCTION

Animal Regeneration offspring grows from a piece of its parent Many animals can regenerate damaged or

lost body parts. This is not reproduction; new individuals are not produced.

Vegetative Reproduction offspring grow from a part of a parent plant

Cloning A type of asexual reproduction developed

by scientists and performed in laboratories.

production of an identical individual from a cell, or cluster of cells, taken from a multicellular organism

The clone is a genetic copy of the parent

ASEXUAL REPRODUCTION +/-

Advantages no mate

required Enables some

organisms to produce a large # of offspring

Disadvantages little genetic variation which

can decrease an organism’s chance of surviving if the environment changes.

more likely to suffer mutations