1
1
Genetics
Study of Heredity
2
2
Gregor Mendel suggested and predicted
what?
Genes carry inherited traits
3
3
Fertilization
Male and Female reproductive cells join to
produce a new cell.
4
4
Trait
A specific characteristic
Ex, Seed color and shape
Predicted how traits were inherited by
studying pea plants
5
5
True breeding plants produce offspring
_________ to the parents
Identical
6
6
Characteristics are determined by
Genes that are passed from parent to
offspring
7
7
P Gen –
F1 –
F2 -
Parents
Offspring of Pgen
Offspring of F1
8
8
In each heterozygous cross, one parents
traits seem to __________________
Disappear
9
9
Principle of Dominance
Some alleles are dominant, others are
recessive
10
10
A dominant trait is expressed if at least
_____ dominant allele is present
One
11
11
A recessive trait is expressed if ____
Dominant allele is present.
No
A recessive trait is expressed only if
there are ________ recessive alleles.
Two
12
12
Alleles are _________ forms of a gene.
Different
Organisms have ____ alleles for each trait.
Two
One from _______
Egg
One from _________
sperm
13
13
Alleles segregated during formation of the
______________
Gametes
14
14
Describe Dominant Alleles
Stronger of the genes, represented by a
capital letter, written first
Ex T
15
15
Describe Recessive Alleles
Weaker gene, Hidden if dominant gene is
present. Represented with a lower case
letter.
Ex t
16
16
Homozygous
Two of the same gene (alleles) for a trait
Give the two examples and what they are
called.
TT – homo dom
Tt – homo rec
17
17
Allele
Another name for a gene
18
18
Heterozygous
Two different alleles for a trait
Example of alleles.
Ex - Tt
19
19
Phenotype
Physical characteristics
Ex – tall, short
Examples
20
20
Probability
Likelihood that an event will occur
21
21
Genotype
Combination of alleles for a certain trait
Examples
Ex TT tt Tt
22
22
The Principal of Independent Assortment
Says that genes _____________ independently
and one gene ______ ______ effect another
Genes segregate independently
23
23
In a dihybrid cross how many traits are
involved?
2
24
24
Different genes _____ _____ influence each
others inheritance
Do not
Does not
25
25
Incomplete Dominance Definition
Alleles Blend (mix) and neither is dominant
Ex.
Ex. Heterozygous phenotype is a blend
Red+white=pink
26
26
Codominance Definition
Both alleles are dominant
Ex
Heterozygous expresses both, “NO
BLENDING”
Ex. Spots on a cow
Black and white = Black and white
27
27
Multiple Alleles
Single gene with more than two alleles
Ex.
Ex. Human Blood Type 4 kinds
28
28
Polygenic Traits
Traits controlled by many genes
Ex.
Wide range of phenotypes
Ex. Human skin type: AaBbCcDd
29
29
Karyotype
Chart of chromosome pairs
Shows genome-full set of genetic info
30
30
Sex Chromosomes
X and Y
Females:
Males:
Females are XX
Males are XY
Determine what?
The sex of the offspring
31
31
We have 2 sex chromosomes, all other
chromosomes are _________________ and we
have how many of them ? ________
Autosomes
32
32
Sex Linked traits are traits inherited on ____
and ___ chromosomes. Most are inherited
on the _____ chromosome
X and Y
Males show recessive sex linked traits
______ than females
More
44
X
33
33
Sex linked traits cont.
Carriers
Heterozygous females are _________
34
34
When do Barr bodies form?
In female cells one X chromosome is
randomly switched off
35
35
Pedigree Studies are Method of
determining the genotype of individuals by
looking at __________ _____________
Inheritance patterns
36
36
In a pedigree:
What shape represents males?
What shape represents females?
Square
Circle
37
Punnet Squares
37
Cross two birds that are heterozygous for
large beaks (B = large beak, b = small beak)
What is the probability of having a large
beak?
A small beak?
Heterozygous?
3:4
38
38
Multiple alleles that are in
pairing of 2 means __________ ______________
Multiple Alleles
1:4
2:4
Ex. AB AA BB Ai Bi
39
39
Combinations of many alleles like
AaBbCcDd are ___________ ___________
Polygenic traits
Ex Tree size
40
40