Reproduction
Cell Reproduction
• Cells of all organisms go through similar
processes to reproduce.
• There are two types of reproduction: sexual
reproduction and asexual reproduction.
Sexual Reproduction
• A type of reproduction in which the genetic
materials from two different cells combine,
producing an offspring.
• The female sex cell, an egg, forms in an ovary.
The male sex cell, a sperm, forms in a testis.
During a process called fertilization, an egg
cell and a sperm cell join together. The new
cell that forms from fertilization is called a
zygote.
Meiosis
• Organisms produce sex cells using a special
type of cell division called meiosis.
• In meiosis, one diploid cell divides and makes
four haploid sex cells.
• (Diploid cells have pairs of chromosomes
while haploid cells have only one chromosome
from each pair)
Sexual Reproduction
Advantages
• Offspring inherit half their
DNA from each parent,
which means each offspring
has a different set of traits.
• Results in genetic variation
among the offspring.
Disadvantages
• Takes time and energy
• Before they can reproduce,
most organisms have to find
mates.
Asexual Reproduction
• One parent organism produces offspring
without meiosis and fertilization.
• Because the offspring inherit all their DNA
from one parent, they are genetically identical
to each other and to their parent.
Types of Asexual Reproduction
• Fission-cell division in prokaryotes that forms two
genetically identical cells
• Mitotic Cell division-an organism forms two offspring
through mitosis and cell division
• Budding- a new, genetically identical, organism grows
by mitosis and cell division on the body of its parent
• Animal Regeneration- occurs when an offspring grows
from a piece of its parent
• Vegetative Reproduction-offspring grow from a part of
a parent plant
• Cloning-a type of asexual reproduction performed in a
lab that produces identical individuals
Mitosis
• A process during which the nucleus and its
contents divide
• Begins with one cell and results in two
identical cells.
Asexual Reproduction
Advantages
• Organisms can reproduce
without a mate
• Some organisms can rapidly
produce a large number of
offspring
• Less time and energy
Disadvantages
• Little genetic variation,
which can lead to less
chance of surviving
environmental changes
• Involves genetic changes
(mutations). If the
organisms has a harmful
mutation, it will be passed
to its offspring.