Genetics. Genotype

1. GENETICS

2.

• GEN: the part of the DNA where the code
for a certain proteins are found, and this
is called a gene. Genes are found on
chromosomes in the nucleus of
eucaryotic cells. Genes that carry
hereditary information pass to the
offspring via reproductive cell.
ALLELE : One pair of genes one coming
from mother the other from the father, in
the chromosomes of a living thing, is
called an allele.

3.

• Alleles can be similar or different. These gene
pairs control trait.(two genes responsible for the
same trait.)
• HOMOZYGOTE: when the two alleles for some
trait are the same.
• HETEROZYGOTE: when the two alleles for
some trait are different.

4.

• Dominant gen:
The presence of this gene
is always expressed in the phenotype.
Recessive gen:
The presence of this gene is
expressed only in the homozygote.

5.

• Genotype: The complete set of genes
is called its genotype.
Phenotype: The external appearance of a
living things (green seed,,brown eye ,etc.)
The phenotype of a living things is
determined by its genotype and
environment.

6.

• Monohybrid: A genetic investication in
to the effect of heterozygote genes on a
single trait.
• Dihybrid: A genetic investication in to the
effect of heterozygote genes on two traits.

7.

• Independent genes: Alleles for
separate traits located on different
chromosomes.
• Linked gene : More than one gene on a
single chromosome.Linked genes can be
separated from each other by crosing-over
in meiosis.

8.

• The probability that two genes will be
separated by crosing-over is proportional
to the distance between them in the
chromosome.

9.

• Principle of segregation: During
meiosis the alleles that control one
character separate: one goes to one
gamete, the other goes to the other
gamete.
• P (Parental) Cross: Mating of the father
and mother.
• F (Filia :) generation: The individuals
produced by crossing the father and
mother.

10.

• Finding the gamet type:
Determining and recording the gamete type
are very important in genetics
studies.Genetic crosses can not be made
without knowing the gamete type.
Therefore, before crossing the subjects,
the genes
(Homozygous,heterozygous,independent),
that from the traits and determine the types
of gametes, should be known.

11.

• A) Homozygous case:
Homozygous for just one character.
2n =formula
AABBCC homozygote dominant
20 = 1 gamet
B) Heterozygous case:
AaBbCc heterozygote
2n =formula
23 = 8 gamet

12. GEORGE GREGORY MENDEL (1822-1884)

• He was the Austrian monk that study
genetic first time.
• He use in experiments pea plant.

13. Principles of Mendel

1.Principle of Dominance
2.Principle of Segregation
3.Principle of Independent Assortment

14.

• The rules of mendel and Their
Application:
Pea Plants have a lot of features available
for crossing. These plants:
1-Produce five generations in a short time .
2-Have many different types.

15.

• 3- Have genes that are independent. That
is, pairs of genes found on different
chromosomes control different traits.
• 4- Have reproductive stractures
completely enclosed by the petals. Selffertilization is easily prevented, and the
plants are easily protected from other
sources of polen.

16.

17.

18.

19. Monohybrid Cross

• Mating two individuals with different
expressions of one trait is called a
monohybrid cross.
• For example let’s make a cross between
homozygous dominant, yellow-seeded pea
plants and homozygous recesive,greenseeded pea plants, and let’s try to find the
F1 offsipring.

20.

• Pay attention to the next example,
phenotype ratio 3:1
genotype ratio 1:2:1
Ss x Ss

21. Dihybrid cross

• Mating two true breeding individuals which
are different from each other in two traits is
called as dihybrid cross.
In a dihybrid cross, the phenotype ratio at F2
is 9:3:3:1 (this ratio was 3:1 in
monohybrid cross). Example: SsDd X
SsDd

22. Trihybrid Cross

• A trihybrid cross is mating two individuals
are heterozygous for three traits.In a
trihybrid cross,the most important thing is
writing the gamete type,we can determine
the traits of the offspring by making a
table. The phenotype ratio in a trihybrid
cross is 27:9:9:9:3:3:3:1

23.

• Example:
• K ; Red flower
D : Round seed
S : Yellow seed
Homozygote dominant
Red flower
Round-Yellow
k: White flower
d : Wrinkled seed
s : Green seed
Homozygote resesive
White flower
Wrinkled-Green

24.

KKDDSS X kkddss

25.

• Polyhybrid Crossing:
• It is a crossing for more than two traits. If
we want to calculate the probability of
formed genotypes we use this method. The
traits are crossed one by one. And the
results are crossed.
• E.g
AaBbCC and aaBbCc genotypes
are crossed. What is the formation of
AaBbCC genotype from this crossing?

26.

Multiple Alleles
• More than two alleles control a trait
• Ex: K1 K2 K3 Alleles for K trait
K1K1 K2K2 K3K3 6 different genotype
K1K2 K1K3 K2K3
• Ex: Fur color in rabbits
C > cch
> ch
> c
Silver grey spot
white spot
albinism

27.

HUMAN BLOOD TYPES
In 1904 Landsteiner discovered there are
four blood types. There are A,B,AB,O
Erythrocytes from one person are mixed with
the serum from another person,either the
erythrocytes scatter in the serum
homogeneously or gather together in clumps
(agglutinotion),after which they repture
(hemolysis).

28.

• If a persons erythrocytes contain protein A
(antigen) ,that person has type A blood.
• If protein B (antigen) person has type B
blood.
• If both proteins A and B , then the blood is
type AB.
• If there is no antigen present, that person
has type O blood.

29.

Ex: In human Blood type
A: Dominant B: dominant O: recessive
-IAIA, IAIO : A blood type
-IBIB, IBIO : B blood type
-IAIB: AB blood type (A and B Co-Dominant
to each other)
-IOIO:
O blood type

30.

• Blood type is determined by antigens
found on the membrane of erythrocytes .
(antigens,usualy proteins in from,cause
antibody formation when they are given to
a living things.antibady proteins formed to
defent against antigens.).

31.

Ex: Human Blood Types
• ( A,B,O System)
A and B are dominant
O recessive
Phenotype Genotype Antigen Antibody
A
AA, AO
A
B
B
BB, BO
B
A
AB
AB
AB
-O
OO
--A, B

32.

Incomplete Dominance
Results in new trait that mixing two contrast trait
Ex: Red(R) is incomplete dominant to White(r)
P:
RR
x
rr
Red
white
F1:
Rr
100% Pink
P:
Rr
x
Rr
F2: RR
Rr Rr
rr
Red
Pink
White
Phenotype Rate: 1:2:1
Genotype Rate: 1:2:1

33. Mendel’s findings can be summarized as follows:

• 1- Traits are inherited through genes.
• 2- The traits of a pea plant are related to
its alleles,which can be the same or
different.
• 3- If the pair of alleles forming a gene are
different, effect of the dominant allele
appears in the phenotype (the ressesive
allele remains hidden)

34.

• 4-Variety in organisms arises from the fact
that, during fertilization, the gametes
combine randomly, allowing the genes for
various traits to from new combinations.
• 5-Traits are visible in offspring in
predictable ratios, acording to the
principals of probabilty.

35.

Co-Dominance
Two dominant allele expressed in phenotype at the
same time
Ex: CR: red hair in cattle (dominant)
CW: white hair in cattle (dominant)
P:
CRCR
x
CWCW
F1:
CRCW
100% Roan
CRCW
x
CRCW
F2: CRCR
CRCW
CRCW
CWCW
Red
Roan
Roan
White
Phenotype Rate: 1:2:1
Genotype Rate: 1:2:1

36.

The Test Cross ( Back Hybridization )
- Determining the unknown genotype
- Unknown genotype is crossed with its
contrasting recessive trait
EX: Find the genotype of yellow plant
Yellow is dominant to green
Unknown Yellow x Recessive Green
Y?
x
yy
F1:
Yy
or
yy
If F1 are all yellow; the unknown will be YY
If there is green trait in F1; it will be
Yy

37. Chromosome Theory (Walter s. Sutton) According to this hypothesis

• Genes are located on chromosomes
• An allele gene is found on each member of one
homologous chromosome pair
• Allele genes separated in meiosis, through the
gametes equally
• Gene pass with chromosomes to the next
generation

38. Linkage (Thomas H. Morgan)

• - Morgan used Drosophila (fruit fly) in his
experiments (8 chromosomes)
• Number of chromosomes is smaller than
number of its genes
• If all genes are independent, Chromosome
number = gene number
• The genes found on same chromosome,
pass together to next generation (linkage)

39.

40. Sex-Linked genes

A) Phenotypic Sex Determination:
Environmental factors determine sex of an
organism
• Growing area
• Nutrition
• Temperature
• Day length

41.

B) Genotypic Sex Determination : Sex
chromosomes determine the sex of an organism
a) XX-XY Mechanism: human, drosophilia
XX: female♀ XY: male♂
b) ZZ-ZW Mechanism: butterfly, reptiles, some fish,
Birds
ZZ: male♂
ZW: female♀
c) XX-XO Mechanism: insects
XX: female♀ XO: male♂
d) Haploid-Diploid Mechanism: honey bee, wasp
Haploid (n): male ♂
Diploid (2n): female♀

42.

-- Primary Sex Characteristics: Male and
female reproductive organs; testes and ovary
-- Secondary Sex Characteristics: Controlled
by sex hormones that produced
-From sex organs
-Milk glands and breast development
-Deepening of voice
-Beard and mustache
-Muscles

43.

Sex linked Inheritance
A) X’linked inheritance
a) Color Blindness (Green-Red) Daltonism
X linked and recessive
Ex: Xr color blind XR Normal vision
XRXr
x XRY
G: XR, Xr
XR, Y
F: XRXR, XRY, XRXr, XrY
normal, normal, carrier, color blind

44.

b) Hemophilia: is a disease in which blood clot
very slowly or not
X linked, recessive
• Ex: XH normal Xh hamophilia
XHXh x XhY
G: XH , Xh
Xh, Y
F: XHXh XhXh XHY XhY
Carrier,
hem,
normal , hem

45.

B) Y linked inheritance
-Genes are located on non-homologous
segment of Y chromosome
-Found in only in males
• Ex: Attached fingers, hair in the ear canal and
scaled skin
C) X, Y linked inheritance
• -Genes are located on homologous part of X
and Y chromosomes
• Ex: complete color blindness, over sensitivity
of eyes and skin to light

46. NONDISJUNCTION

• -Is the failure of chromosome to separate properly during
anaphase of meiosis
a) In Autosomes:
Mongolism (Down’s syndrome)
-Have extra chromosome on 21. Chromosome
23+X ♀ x ♂22+ Y
23+X♀ x ♂22+ X
45+ XY (mongoloid)
45+ XX
Down syndrome, trisomy, 47, 21+,
- Physical and mental development retarded,
- Life expectancy is short
- Higher incidence in women over 35

47. Down’s syndrome

48. In Sex Chromosomes P: 44+XX x 44+XY

P:
In Sex Chromosomes
44+XX x 44+XY

49.

F: 44+XXX (47): Super Female (Trisomy)
44+XXY (47): Klinefelter Syndrome (Trisomy)
44+X0 (45): Turner Syndrome (Monosomy)
44+0Y (45): Not viable

50. 47, XXX syndrome Super female

- Female differentiation, highly variable.
- Often normal, but can result in
underdeveloped secondary sex
characteristics,
- Sterility
- Mental retardation.

51. Turner Syndrome (45, XO)

• - Sterile
• - Immature sex organs Ovaries are
rudimentary
• - Short stature,
• - Short webbed neck.
• - Mental abilities are in the low-normal
range

52. Turner’s syndrome

53. Klinefelter syndrome (47, XXY)

- Sterile male
- has many female body characteristics
- Enlarged breasts
- Testes underdeveloped and do not
produce sperm
• - Some mental retardation.

54. Klinefelter’s syndrome 47 XXY

55. Change in Genetic Material

• Mutation: Change in structure of genetic
material
Chromosome Mutations
Structural changes in Chromosomes

56.

a) Deletion: removal a piece of chromosome

57.

• b) Duplication: Adding same genes from
other chromosomes

58.

c) Inversion: a piece of chromosome flips
180o and reattaches back to the chromosome

59.

• d) Translocation: exchange of chromosome
parts between non-homologous chromosomes

60. 2) Change into number of chromosome

• a) Euploidy:
n =7
monoploid (haploid)
2n = 14 diploid
3n = 21 triploid
4n = 28 tetratploid
Polyploid
5n = 35 pentaploid
• Colchicin: is a chemical substances is used to
produce polyploid cells by deactivating
cytokonesis

61.

• b) Aneuploidy:
2n =6
normal
2n–1= 5 monosomy
2n-2= 4 nullusomy
2n-3= 3 polysomy
2n+1= 7 trisomy
2n+2= 8 tetrasomy or double trisomy

62.

• mutagens: are the factors that cause the
mutation
- Temperature
- Radiation with high energy
- Chemical compounds
- pH level