Warm ups:
1. What do I mean if I say I “INHERITED” my
green eyes from my mother?
2. Give examples of some “TRAITS” that you
inherited from your parents….
Word
1. Alleles
Definition
Two forms of a
gene (one from
mother, one
from father)
Examples:
Height – short and
tall
Hair – straight or
curly
Tail – long or short
Picture
Word
2.
Dominant
Gene
Definition
The strong form
of the gene
(you ALWAYS
see it)
Written as:
Capital Letter
Picture
Word
3.
Recessive
Gene
Definition
The weak form
of the gene
(NOT always
seen)
Written as a
lowercase
Picture
DOMINANT AND RECESSIVE TRAITS
Traits in the left-hand column dominate over those listed in the
right-hand column.
Dominant
Recessive Traits
Traits
Eye
coloring
Brown eyes
Gray, green,
hazel
Blue
Grey, green, hazel,blue eyes
Blue
Albino (pink)
Vision
Farsightedne Normal vision Nearsightedness
ss
Night vision
Normal
Color blindness
vision
Normal sight
Normal color
vision
Hair
Dark hair
Non-red hair
(blonde,
brunette)
Curly hair
Full head of
hair Widow's
peak hairline
Blonde hair, light hair
Red hair
Straight hair
Baldness
Normal hairline
Practice
B = brown eyes
C = curly hair
b = blue eyes
c = straight hair
1. What is the symbol (letter) for someone who
has brown eyes? B
2. What is the symbol for someone who has
straight hair? c
3. What is the symbol for someone who has blue
eyes? b
4. A capital letter represents ? Dominant
gene or
trait
Practice
G = green plant
T = tall plant
1.
2.
3.
4.
g = yellow plant
t = short plant
What is the symbol a plant that is green? G
What is the symbol for a plant that is short? t
What is the symbol for a plant that is yellow? g
A lowercase letter represents ?
Recessive
gene or
trait
Using symbols in genetics
1. Use letters to represent genes
2. Always have two letters – 2 genes for
each trait
Word
4. Purebred
or
Homozygous
Definition
Having the
same two
Always two
Dominants or
two recessives
Picture
Word
5. Hybrid –
“mutt” or
Heterozygous
Definition
Having two
different alleles
Always a
Dominant and a
recessive
Picture
Purebreds vs. Hybrids Practice
Homozygous
Heterozygous
Examples:
a. Two dominant tall genes --- TT
b. Two recessive short genes --- tt
c. One dominant and one recessive --- Tt
Hybrid and Purebred Practice
problems
T = tall
G = green
t = short
g = yellow
1. A plant is purebred tall. What genes
does it have? TT
2. A plant is hybrid green. What genes
does it have? Gg
3. A plant is purebred yellow. What genes
does it have? gg
Hybrid and Purebred Practice
problems
B = brown
C = curly
b = blue
c = straight
1. A dog is purebred with brown eyes.
What genes does it have? BB
2. A person is hybrid with curly hair. What
genes does he have? Cc
3. A dog has blue eyes. What genes does
it have?
bb
Physical vs. Actual
Word
6.
Genotype
Definition
Genes written
in letter
symbols that
show possible
traits.
Picture
Word
Definition
An organism’s
7.
inherited
Phenotype
appearance.
(What
physically
shows.)
Picture
Phenotype and Genotype
Practice Problems
T = tall
t = short
1. What is the phenotype for a person who is tall?
2. What is the genotype for a person who is short?
3. What is the phenotype for a person who is
short?
4. What is the genotype for a person who is tall?
The relationship between the
genotype and phenotype is a
simple one ...
The genotype
codes for the
phenotype!
Sum it all up!
• Traits from an organism pass from the
parents to the offspring.
• Gene pairs determine traits.
• Organisms inherit genes in PAIRS. One
from each parent.
• Genes are dominant and recessive.
(When the two go a walking, the capital
does the talking! Hybrid)
Exit slip: Five finger summary!
Take out a piece of paper. Trace your hand
on the paper and write genetics in your
palm. List five things that you learned from
today’s lesson and write them in each of
your five digits.