Methods in behavioral genetics

1.

Methods in behavioral
genetics
What are gene’s
properties and
interactions?

2.

In karyotype one half of chromosomes comes from one parent and the second
one from the other.
Parental chromosomes compose a pairs in which both components have the
same size, a centromere localization and a gene sequence.
The majority of the pairs consists mainly of body genes and have a name of
autosomes.
The pair of sex chromosomes is partially an exception of this rule because of
their differences in their size and amount of genes.
In addition, the gene set of the heterochromosomes is not the same due to
their forming history, which includes an extensive mutation in the Y progenitor.

3.

As far as genetic information in sister chromosomes is
identical and linear so genes, which are responsible for
the same trait lay in them on the same places.
These points are called loci (singular – locus).
There are mainly two forms of the gene or alleles:
one is prevaled or dominant (A) and
the other hided or recessive (a).
If sister chromosomes include identical variants
AA or aa
the genotype is called homozygous
(the choice of a letter does not matter because it is only
a code name of a gene so it may be even Z).
If the homologous loci carry on opposite gene forms
Aa
such genotype is heterozygous.

4.

Alleles and Genes
https://www.youtube.com/watch?v=pv3Kj0UjiLE

5.

The set of parental gene alleles is important to understanding of offspring
genotype and phenotype.
Monohybrids and the Punnett Square Guinea Pigs
https://www.youtube.com/watch?v=i-0rSv6oxSY
Dihybrid and Two-Trait Crosses
https://www.youtube.com/watch?v=qIGXTJLrLf8
If the described gene is localized in autosome the type of inheritance is
autosomal and the majority of human genes belong it.
Accordingly to an allele form there are autosomal dominant and recessive
types.
Some genes responsible for body properties could be found in sex
chromosomes therefore they correlate with sexual belonging. The amount of
such ones depends on the size of the heterochromosome. As far as X
chromosome is much more larger than Y it includes a majority of such genes.
Punnett Squares and Sex-Linked Traits
https://www.youtube.com/watch?v=h2xufrHWG3E

6.

The Mendel rules had been discovered in experiments with strict dominance –
recessivity gene relationships.
After Mendel there were found out another gene interactions.
Multiple Alleles (ABO Blood Types) and Punnett Squares
https://www.youtube.com/watch?v=9O5JQqlngFY
Incomplete Dominance, Codominance, Polygenic Traits, and Epistasis!
https://www.youtube.com/watch?v=YJHGfbW55l0

7.

Autosomal dominant traits in human
- white curl over the forehead,
- coarse and straight hair (as in hedgehog),
- woolly hair - short, easily split, curly, fluffy,
- tongue roller,
- hitch-hicker’s thumb
- Habsburg’s lip - lower lip, protruding forward, lower lip, sagging and halfopen mouth,
- polydactyly - multi-pitched, when there are from six or more fingers,
- brachydactyly (short bones) - underdevelopment of the distal phalanges of
the fingers,
- arachnodactyly - highly elongated spider fingers,
- familial hypercholesterolemia - a cholesterol metabolic disorder, an
increase in its blood pressure in the blood. Accompanied by the development
of atherosclerosis and risk of heart attack.
- Recklinghausen’s disease or neurofibromatosis – caused by defective form
of neurofibrin, which is needed for normal function in many human cell
types. Results in skin lesions of various manifestations.
- Otospongiosis - manifested in adults with progressive deafness.
- Achondroplasia - dwarfism.
- Marfan’s disease - hereditary disease characterized by a systemic lesion
of the connective tissue.
- Huntington’s chorea disease - occurs in an adult, manifests as impaired
movement and progressed dementia

8.

Autosomal recessive traits in human
- soft and straight hair,
- negative rhesus factor,
- intaste of phenylcarbamide,
- inability to put the tongue in a roll,
- phenylketonuria or Felling’s disease - is caused by a biochemical defect in
the conversion of the amino-phenyl phenylalanine.
- Galactosemia - accumulation in the blood of galactose, which inhibits the
absorption of glucose and has a toxic effect on the function of the liver,
the brain, the lens of the eye. This disease is manifested by a lag in physical
and mental development, severe damage to the liver, nervous system, eyes
and other organs.
- Albinism – the absence of melanin pigment in body tissues.
- Tay-Sachs’ disease - is associated with a sharp increase in the cells of the
brain, as well as the liver and spleen of the gangliosides, due to the
deficiency of hexosaminidase A in the body. Mental changes are
progressing. Gradually muscle hypotension develops, limb paralysis occurs

9.

Sex-linked traits in human
- Pigment xeroderma - a disease in which, under the influence of
ultraviolet rays, pigmented spots appear on exposed areas of the body
with tumors appearance in the end. For the majority of patients the
deseas means the death.
- Oguchi's disease - in a layer of rods and cones, in the pigment epithelium
of which degenerative changes are observed (the disease is more common
in Japan).
- Spastic paraplegia - spasticity and weakness of the lower extremities,
resulting from the degradation of the pyramidal tracts in the thoracic and
lumbar spinal cord, occasionally in the brain stem.
- Epidermolysis bullosa - blistering after mechanical injuries of the skin.
- General color blindness - the complete absence of color vision. Of great
importance for medical practice is the study of blood groups that depend
on antigens located on the surface of red blood cells.
- Duchenne muscle dystrophy - progressive muscle weakness is founded
exeptionally in boys.
- Hemophilia A and B – blood coagulation disorder, which is manifested
mainly in men.

10.

Monohybrid and one-trait crosses
1. A blue-eyed woman being a spouse of a brown-eyed man has a brown-eyed
child. What are the genotypes of the parents?
2. Cousins had got married. The wife was able to roll the tongue into a tube.
The feature was absent from the husband. From this marriage was born a
child who is unable to roll the tongue. Try to found the genotypes o fall
family members.
3. In humans classical haemophilia is a recessive trait linked to the X
chromosome.
In a family one of spouses has a blood with normal coagulation but they have
a son, who was born with haemophilia.
What is the probability of the illness in the second son?

11.

Dihybrid and two-trait crosses
1. A father with curly hair (dominant trait) and without freckles, and a
mother with straight hair and freckles (dominant trait) has three children.
All children have freckles and curly hair.
Try to reveal the genotypes of the parents and their children.
2. In humans myopia (M) or short sight dominates over normal vision, and
brown eyes (B) do over blue.
The only child of myopic brown-eyed parents has blue eyes and normal sight.
Set the genotypes of all the family members.
3. The brown-eyed woman, whose father has saw colours well, has blue eyes
and sufferes from color blindness, gets married a blue-eyed man with
common eyesight.
What offspring could be expected from this pair, if it is known that the
brown eye gene is inherited as an autosomal dominant trait, and the color
blindness gene is a recessive and linked to the X chromosome?

12.

13.

Alleles and Genes
https://www.youtube.com/watch?v=pv3Kj0UjiLE
Monohybrids and the Punnett Square Guinea Pigs
https://www.youtube.com/watch?v=i-0rSv6oxSY
Dihybrid and Two-Trait Crosses
https://www.youtube.com/watch?v=qIGXTJLrLf8
Incomplete Dominance, Codominance, Polygenic Traits, and
Epistasis!
https://www.youtube.com/watch?v=YJHGfbW55l0
Multiple Alleles (ABO Blood Types) and Punnett Squares
https://www.youtube.com/watch?v=9O5JQqlngFY
Mutations: The Potential Power of a Small Change
https://www.youtube.com/watch?v=GieZ3pk9YVo
Pedigrees
https://www.youtube.com/watch?v=Gd09V2AkZv4
Punnett Squares and Sex-Linked Traits
https://www.youtube.com/watch?v=h2xufrHWG3E
Genetic Drift
https://www.youtube.com/watch?v=W0TM4LQmoZY