SEXUAL REPRODUCTION
Quiz 6B
sexual reproduction
• the joining of haploid
gametes to form a diploid
zygote, which develops
into a new individual
• each offspring receives
genes from both its
parents
• get genetic variety
Information about genes
most
organisms
have 2
genes for
every trait
Information about genes
genes are
parts of
chromosomes
Information about genes
most genes come in pairs
Information about genes
most chromosomes come in pairs
Diploid
•having 1 pair of each
type of chromosome in an
organism
•have 2 of every kind of
chromosome
•symbol is 2n
Haploid
•a cell that has only 1
chromosome of every pair
•symbol is 1n
Diploid vs Haploid
Normal human cells have
23 pairs of chromosomes
which is a total of 46
chromosomes.
Human diploid number is 46
Human haploid number is 23
Diploid & Haploid Examples
Haploid
Diploid
Honey bee
16
32
Crayfish
100
200
Rabbit
22
44
Watermelon
11
22
Corn
10
20
Meiosis
•the process whereby 1
diploid cell forms
haploid cells (gametes)
•a dividing process during
which the # of
chromosomes is cut by 1/2
in each resulting cell
•also called reduction
division
Meiosis
Gamete
•a cell that contains only 1
of each type of chromosome
found in an organism
•a reproductive cell
•in order to form a haploid
cell (gamete)- meiosis
occurs
•in most organisms meiosis
produces 1 of 2 types of
gametes
2 types of gametes
•Ova (singular-ovum) female gametes; usually
larger than the male
gamete and does not have
that power to move itself
•Sperm - male gametes;
usually smaller than ova,
but they have some means
of moving themselves
2 types of gametes
ovum
sperm
Spermatogenesis
Oogenesis
Where are gametes formed?
In reproductive organs
• Testes – male reproductive organs
• Ovaries – female reproductive organs
Fertilization
the formation
of a zygote
from the
union of 2
gametes
Zygote
a diploid
cell formed
by the union
of 2 gametes