Transcript Reproduction and Heredity

Reproduction and Heredity
Sexual Reproduction
• The process in which new offspring are
produced by two parents
Asexual
Reproduction
-Some organisms
produce offspring with
only one parent
-Offspring is an exact
copy of parent with
exact same genetic
information
-Some plants
reproduce this way:
spores (ferns) or buds
(potatoes), and
runners
Asexual Reproduction
• Cells divide in stages called MITOSIS
-
Prophase
Metaphase
Anaphase
Telephase
Mitosis – phases of asexual
reproduction
Sexual
Reproduction
-When two parents
join together to form a
new individual
-offspring will NOT be
identical to one
parent.
-It will have traits from
both parents
-flowers, animals, and
humans reproduce
this way
Sperm cell
Contains male
genetic
information that
will combine with
female egg cell to
produce a new
“individual”
Egg cell
female cell that
contains genetic
information that
will combine with
the male sperm
cell to produce
offspring
Chromosomes
-Carries genetic
information inside
the nucleus of the
sperm and egg cell.
-Humans have 46
chromosomes; 23
from the mother
and 23 from the
father
Fertilization
When the egg and
sperm cell come
together to form a
new individual
Meiosis
The process cell
use to divide for
SEXUAL
reproduction
First stage begins
with 23
chromosomes from
each parent, for a
total of 46
Variation
The differences
between
organisms of a
species
Gene
Specific parts of a
chromosome that
are responsible for
one trait in that
offspring.
For example: hair
color, eye color in
humans; the genes
of a tree control
the size, shape,
and color of its
leaves.
Inherited
Traits
Features that
an organism
is born with
Dominant
Trait
When gene from
one parent
overpowers the
gene from the
other parent
Brown eyes, cleft chin,
tongue-rolling are all
dominant traits
Other dominant traits
•
•
•
•
•
•
Straight thumb and pinky
Dimples
Freckles
Straight hair line
Curly hair
Detached earlobes
Recessive Trait
When gene from
one parent is
overpowered by
the gene of the
other parent
Blue eyes, attached ear
lobes, bent pinky/thumb
are all recessive traits
Dominant vs Recessive
Dominant traits are more common than recessive traits
Learned
Behavior
Skills that animals are
taught during their
lifetime by parents or
other animals, and
through experience.
Inherited
Behaviors/
Instincts
Behavior that
animals are born
knowing; they are
instinctual. Animals
do not have to be
taught an inherited
behavior.
nest and web building, migration,
hibernation.
Scientists’ Work
• Gregor Mendel
• Thomas Hunt Morgan
Gregor Mendel
• Studied tall and dwarf pea
plants and what happens when
you cross-breed them
• Formulated 3 laws that became
the basis of the science of
heredity
• Wrote a paper to describe his
findings, but no one seemed to
care about his work
• Later, after his death, other
scientists, who were working
on the same ideas, discovered
his important work.
Thomas Hunt
Morgan
• American biologist
• Discovered the role the
chromosome plays in
heredity
• Demonstrated that genes
are carried on
chromosomes by
researching and using fruit
flies in an experiment