Download basic Genetics PPT

Genetics
The Study of Inherited
Characteristics
Chromosome
DNA
Code
for
traits
Gene
Segments
of
DNA
Code for a
trait
Hair
Color
Eye
Color
Gene
Segment
For
Hair color
Trait
Characteristic
Feature
Variations
in
a population
Dominant Trait
 “Dominates”
 Shows
in the
outward
appearance
 Even when
recessive trait is
present
Bb
BB
or
Bb
Recessive Trait
Albinism
bb
“hidden”
May
be
masked by a
dominant
trait
Bb
Alleles
 Letters
of the
alphabet
 Code for a
trait
 One from
father
 One from
mother
Dominant
Allele:
Recessive
Allele:
 Upper
 Lower
case
letter of the
alphabet
 Codes for
dominant
traits
case
letter of the
alphabet
 Codes for
recessive
traits
Chromosomes in Nucleus
Gene
Segments
For a
Trait=
“A” or “a”
Monohybrid Cross
Cross
for
one trait
Example:
Hair color
Bb
B BB Bb
B BB Bb
Punnet Square
F1 Generation
 Genetic
Cross=
Mating
 F1=
Children
 1st “filial”
generation
Parents
B
B
B b
BB Bb
BB Bb
nd
2
Filial Generation- F2
 Children
of
the cross
between the
children of an
F1
 “Incest”
among F1
 Only after
pure x pure


F1=
B
B
b
Bb
Bb
b
Bb
Bb
F2=
B
b
B b
BB Bb
Bb bb
Phenotype
 Outward
appearance
 Trait that is
shown
 Bb looks brown
(has “b” =white
allele)
Genotype
Allele set
True genetic
makeup of
the
chromosome
Homozygous: Heterozygous:
Pure
 Hybrid
condition
condition
2 same case
 2 different case
alleles
alleles
BB=
 Bb appears
dominant
dominant
bb= recessive
Dihybrid Cross
Cross with
two traits parents
 Example:
1. Hair Color
2. Eye Color
2 types of
alleles

Children Children Children Children
Children Children Children Children
Children Children Children Children
Children Children Children Children
Codominance
 “Incomplete”
dominance
 Hybrid is a blend of
traits
 Example:
RR=red
Rr=pink
rr=white
Pink Carnation
Multiple Alleles
More
than
one type of
allele for a
trait
Example:
Blood Type
 TYPES:
A
B
AB
O
IAIA, IAi
IBIB , IBi
IAIB
ii
X-Linked Traits
 Sex-linked
 Trait
in on the sex
chromosome
XX=
 Female
XY
 Male
 Ex:Red & white
eyes
Female=
XX
Add eye trait=
XRXR or XRXr
XrXr
Male=
XY
Add eye trait=
XRY or XrY
“Y” is empty
Karyotype
Chromosome Number
Different # for different
Homologous
species
Chromosomes
 Full set = 2N=Diploid
are
the
sets
of
 N=
pair
each
# pairs





1 pair from mother
1 pair from father
Humans= 23 pairs or
46 total
Autosomes & Sex Chromosomes
Autosomes = # 122 for all traits
except sex
Sex chromosomes=
Pair # 23 XX(female) or
XY(male)
Down Syndrome= 3 of #21
Klinefelter’s = XXY
Pedigree Charts
 Male
=
 Female=
 Sexual
Union=
 Offspring=
Pedigree Chart -Cystic Fibrosis