Download ®Genetics- the study of how traits are inherited ®Heredity

Genetics-
By: Miss Murphy
Some
the
study of how traits
are inherited
Heredity- the
passing of traits
from parent to
offspring
examples of traits include:
Genes
eye color
hair color
are made
up of DNA and
are located on the
chromosomes.
Genes control the
traits that show
up in an organism
nose shape
•
Chromatin –long
strands of hereditary
material within the
cell nucleus that are
made up of proteins
and DNA.
•
Chromosomes- rodshaped structures in
the cell nucleus that
carry hereditary
information.
•
Genes- section of DNA on a chromosome
•
DNA- (deoxyribonucleic acid) an
organism’s information code made up of 2
twisted strands of molecules
Gregor
MendelAustrian monk
responsible for the
first recorded
scientific study of
how traits pass
from one
generation to the
next
1. Mendel started with purebred tall
pea plants and purebred short pea
plants
In
1856 Mendel started an experiment
with common garden peas
Mendel felt that one could predict the
type of flowers and fruit a plant would
produce by looking at the parent plant
After 8 yrs. he published his work
“Experiments With Plant Hybrids”
Mendel’s work was ignored until the
1900’s
2.He cross-pollinated the two
types of plants.
Took pollen from the
male reproductive
structures of the tall
plants and placed it on
the female reproductive
structures of the short
plants
3. Mendel allowed the new tall
plants to self-pollinate
Tall plants crossed with short plants
produced ALL tall plants.
Pollen is
transferred
from the male
to the female
reproductive
structure in the
same plant
Mendel
planted these seeds and found
that both tall and short plants grew.
Tool
used to predict results in Mendelian
genetics
Alleles- the different forms a gene may
have for a trait.
Dominant and recessive alleles are
represented by letters
Capital letters = dominant allele
Lowercase letters = recessive allele
• An organism with 2 alleles
that are exactly the same
or
For
every 3 tall plants, there
was one short plant or a 3:1
ratio.
Mendel called the tall-height
form that appeared the
dominant factor and the
short-height form the
recessive factor.
Letters
show the genotype of an
organism
Genotype = genetic makeup
Most
cells in the body have 2
alleles for every trait
• An organism that has 2
different alleles for a trait
One allele
for tall
One allele
for short
• the physical expression of a
particular genotype
Tall appearance
Short appearance
Tall appearance
x
http://thinkquest.org/terms
ofuse.shtml (pea plant
crosses slides 10 and 12)
http://www.botany.uwc.ac.za
/ecotree/flowers/pollination
1.htm
(self and cross-pollination
slides 9 and 11)