Download INBREEDING Definition

INBREEDING
Definition: Inbreeding is simply defined as the mating of relatives.
History of inbreeding
 1858, Bemiss studied of inbreeding and its effects on human health
 1871, Darwin effects of cousin marriages
Explanation:
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Inbreeding occur naturally in plants via self pollination
Inbreeding results in increased homozygosity
It effects by recessive or deleterious traits.
Deleterious trait decrease fitness of a population inbreeding depression
The level of inbreeding is determined by inbreeding coefficient
Inbreeding coefficient
Closer the relatives are the higher the inbreeding coefficient is and thus riskier.
Zero % means if the parents do
not share a common ancestor
100% means genes are shared
from same ancestor
100% IC can’t be achieved in Humans
INBREEDING IN HUMAN
A. Harmful effects
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Fertility
Mortality
Morbidity
Reproductive performance
Characteristics
B. Beneficial Effects
 Decrease in allergies
 Decrease in nephritis (Rare genetic disorder that causes inflammation of the
kidneys)
Example
1. Queen Victoria carrier recessive X-linked hemophilia gene
2. In lions, prides (Lions living in a groups)
HETEROSIS
Definition: It is the tendency of a crossbred organism to have qualities superior to
those of either parent.
History
 Heterosis was first described by Charles Darwin (1876)
 Shull called Heterosis as “Stimulation of heterozygosity”.
Explanation:
 Role of Pure breeding line
 Heterozygotes are more fit than the homozygotes
 Advantages:
Better health
More Yields and Fertility
Out-Breeding Depression
 It is possible for a hybrid to be less fit for survival.
 Example: Crosses between wild and hatchery fish
Hatchery fish
Wild fish
Hypothesis
1. The dominance hypothesis
 Dominant Gene suppress recessive gene
 Effect of Heterozygotes = Homozygotes
2. The Over-dominance hypothesis
 Dominant Gene + Recessive Gene = heterosis
 Recessive Gene in homozygous = Deleterious effect
Heterosis in Humans
 Human population has limited gene pool.
 Heterosis in human occurs in different blood line.
Heterosis and Out-breeding depression
 Heterosis is strong in F1 generation and weak in F2-F3
 Out-breeding is weak in F1 and Strong in F2 and F3
Reason
 Genes fail to show full expression in F1 and re-arrange to show
maximum capability in F2-F3.
PLASMID
“An extra-chromosomal DNA that can replicate independently of the chromosomal DNA
is called Plasmid”.
History: J. Lederberg in 1952.
Properties of Plasmid
Show Resistance against the antibiotics, produce toxins.
Examples
1. pSC 101 Tetracycline
2. pBR 322 Penicillin and Tetracycline
Categories of Plasmid
Stringent plasmids
Relaxed plasmids
Replicate only when the chromosome replicates
Capability to replicate on their own
Classification
Fertility Plasmid
helps in the process of conjugation
Resistance Plasmid
show resistance against antibiotics or poisons
Col Plasmid
produces protein “bacteriocins”; that can kill other bacteria
Degradative plasmid
digestion of unusual substances e.g. salicylic acid
Virulence plasmids
plasmid can turn the bacterium into a pathogen
Plasmid as Vector
Structure of Plasmid
1. ORI: Origin of replication
2. Selectable Marker or Resistance Site: antibiotic resistance
3. Multiple Cloning Site (MCS): Insertion site of new gen
Applications
1.
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Recombinant DNA research
Gene therapy.
Host metabolism to digest different nutrition like lactose and galactose.
Root Nodule of Legume plants to fix Nitrogen.
APPLICATIONS OF RECOMBINANT DNA TECHNOLOGY
1. Recombinant human insulin
 Used for treatment of Insulin-dependent diabetes
2. Recombinant human growth hormone
 Role of Somatotropin
 Cadavers Pituitary gland
 Illegal used by athletes
3. Recombinant blood clotting factor VIII
 Used for the treatment of the bleeding disorder
“hemophilia”
 In past, obtained from multiple donor
4. Recombinant hepatitis B vaccine
 Hepatitis B virus surface antigen that is produced in yeast
cells.
5. Herbicide Resistant crops
 Crops like corn, soya and cotton Insect-resistant crops
6. Insect-resistant crops
 Bacillius thuringeiensis produces a protein called as Bt toxin
with insecticidal properties
7. TI-Plasmid
 Agrobacterium tumefaciens contain Ti plasmids which usually
cause crown gall disease in plants.
 Ti stands for tumor inducing.
GENE THERAPY
“Gene therapy is the insertion of genetic material into human cells for the
treatment of a genetic disorder”.
A. EX-Vivo
In ex-vivo condition a number of genes are carried by vector viruses like
retrovirus and adenovirus.
Examples EX-Vivo
1. Severe Combined Immunodeficiency Syndrome (SCID)
 Lack of Adenosine deminase for maturation of T and B cells
2. Familial Hyper Cholesterolemia
 Liver cells fail to remove cholesterol from blood
3. Cancer diseases
B. In-Vivo
 In Parkinson disease (shaking problem of body), Dopamine-producing cells
could be grafted directly to the brain.
Examples Vivo
1. Cystic Fibrosis
 Liposome tubes consists of lipoprotein
 Lipoprotein used for chloride ion regulation
2. Coronary artery angioplasty
 Balloon is coated with the gene for vascular
endothelial growth factor.
 This factor, relax the blood vessels to minimize the
chance of the blockage.
TRANSFORMATION IN BACTERIA
Definition: The process of transferring exogenous DNA into cells is call “transformation”
History
1. F. Griffith work on Streptococcus pneumoniae
2. Avery, MacLeod and McCarty
3. Conjugation and transduction by J. Lederberg
4. In 1972, Stanley Cohen using CaCl2
5. In 1980, E. Neumann electroporation
Competent cells
1 % of bacterial species are capable of naturally taking up DNA.
Transfection
1. Calcium phosphate + electroporation
2. Liposomes
Transformation in Plants
a. Particle bombardment
b. Using Agrobacterium tumefactions
c. Electroporation
Screening of Plasmid transformation
1. Selectable markers (is a gene introduce in the cell for
the identification)
2. Radioactive substances
LacZ gene------Beta gluctosidease------Lactose hydrolysis
1. Blue colonies-------Remain same
2. White colonies-----Transformed
Gilbert Method
Dimethyl sulphate……. Purines……… (Glycoside bond)
Hydrazine………….. Pyrimidines
Pepperdine…….Phosphodiester linkage
Polyacrylamide gel
Autoradiography……….. (Phosphodiester bond)
CLONING VECTOR