This document provides information about genetics and heredity. It discusses key topics like Mendel's experiments with pea plants which laid the foundations of modern genetics. Some of Mendel's important findings included developing the laws of inheritance and proposing the concept of genes. The document also explains other genetic concepts like incomplete dominance, codominance, linkage and recombination which were later established through the work of scientists like Morgan using the fruit fly Drosophila. Sex determination mechanisms in different organisms are also summarized. Overall, the document gives an overview of the history and basic principles of genetics.
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Law of Dominance - Recessive alleles will always be masked by dominant alleles .
Law of Segregation - At the time of gametes formation the two copies of each hereditary factor segregates so that offspring get one factor from each parent .
Law of Independent Assortment - Genes for one trait are not inherited together with another trait .
An introduction to genetics...Mendelian inheritance is the set of laws, originally recognised by Gregor Mendel, according to which traits are inherited from generation to generation.A special thanks to my professor..
Genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity in organisms. Though heredity had been observed for millennia, Gregor Mendel, Moravian scientist and Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene.
Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded beyond inheritance to studying the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the context of a population. In science and especially in mathematical studies, a variational principle is one that enables a problem to be solved using calculus of variations, which concerns finding functions that optimize the values of quantities that depend on those functions.
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Principles of Inheritance
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Law of Dominance - Recessive alleles will always be masked by dominant alleles .
Law of Segregation - At the time of gametes formation the two copies of each hereditary factor segregates so that offspring get one factor from each parent .
Law of Independent Assortment - Genes for one trait are not inherited together with another trait .
An introduction to genetics...Mendelian inheritance is the set of laws, originally recognised by Gregor Mendel, according to which traits are inherited from generation to generation.A special thanks to my professor..
Genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity in organisms. Though heredity had been observed for millennia, Gregor Mendel, Moravian scientist and Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene.
Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded beyond inheritance to studying the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the context of a population. In science and especially in mathematical studies, a variational principle is one that enables a problem to be solved using calculus of variations, which concerns finding functions that optimize the values of quantities that depend on those functions.
Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits. He recognized the mathematical patterns of inheritance from one generation to the next.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
3. Genetics
• Organisms reproduce- formation of
offspring of the same kind.
• The resulting offspring most often do not
totally resemble the parent.
• Branch of biology that deals with the
inheritance and variation- Genetics.
• Inheritance- the process by which
characters are passed on from parent to
progeny.
• Variation-it is the degree by which
progeny differ from their parents.
4. History • Human knew before
8000- 1000 B. C
variation is due to
sexual reproduction
• Exploited variations
present in wild plants
& animals to
selectively breed &
select organism with
desirable characters
• Artificial selection &
domestication of wild
cow- Sahiwal cows in
Punjab
5. Terminology
• Genetics is the branch of life science that deals with the
study of heredity and variation.
• Heredityis the transmission of characters from parents to
their offsprings.
• Variation is the difference among the offsprings and with
their parents.
• Hereditary variations: These are genetical and
inheritable.
• Environmental variation: These are acquired and
non inheritable.
6. Gregor Johann Mendel: Father ofGenetics
• Known as the father of
modern genetics
• Gregor Mendel developed
the principles of heredity
while studying seven
pairs of inherited
characteristics in pea plants.
• Although thesignificance of
his work was not recognized
during his lifetime, it has
become the basis for the
present-day field of genetics.
7. Mendel’s ApproAch
• Conducted hybridization (artificial pollination/ cross
pollination) experiment for 7 years 1856-1863 & proposed
law of inheritance
• Applied statistical analysis & mathematical logic for
biology problems
• Large sampling size- greater credibility to data
• Experiments- true breeding pea lines
(continuous self pollination)
• Confirmation of inference from experiments on
successive generations of test plants, proved general
rules of inheritance
• Mendel investigated two opposing traits- tall & dwarf,
yellow & green seed
8. Seven pair of contrasting characters selected
by Mendel for his experiment.
9. Terminologies
• Phenotype: The external appearance of an organism due to
the influence of genes and environmental factors.
• Genotype: The genetic constitution of an individual
responsible for the phenotype .
• Phenotypic ratio: The correct proportion of phenotype
in population.
• Genotypic ratio: The correct proportion of genotype
in population.
• Homozygous: The individual heaving identical genes in
an allelic pair for a character. Ex: TT, tt.
• Heterozygous: The individual heaving un-identical genes
in an allelic pair for a character. Ex: Tt.
10. Terminologies
• Dominant gene: The gene that expresses its character in
heterozygous condition.
• Recessive: The gene that fails to express its character
in heterozygous condition.
• Hybrid: The progeny obtained by crossing two parents
that differ in characters.
• Back cross: The cross between F1 hybrid and one of
its parents.
• Test cross: The cross between hybrid and its
homozygous recessive parent. It is used to identify the
genotype of the hybrid.
11. Why Mendel selected pea plant?
• Pure variety are available.
• Pea plants are easy to cultivate.
• Life cycle of plants are only few months. So that
result can be got early.
• Contrasting trait are observed.
• Flowers are bisexual and normally self pollinated.
• Flowers can be cross pollinated only manually.
• Hybrids are fertile.
12. Inheritance of one gene
• Inheritance of one gene can be explained by monohybrid
cross.
• The cross between two parents differing in one pair of
contrasting character is called monohybrid cross.
• Crossed tall & dwarf pea plants- Collected seeds & grew to
generate first hybrid generation/ Filial generation/F1
• F1 plants- Tall & none were dwarf
• For other traits also- F1 generation resembled only one
parent & trait of other parent were not shown
• Self pollinated F1 –Filial 2 generation/ F2
• F2 generation- 1/4th were dwarf & 3/4th tall- identical to
parents
• F1 generation one parent trait shown & F2 both parent trait
shown in the ratio- 3:1 & no blending were seen
13.
14. • Mendel proposed- Something is stably being passed to the
next generation through gametes‘factors’–genes
• Genes/factors- unit of inheritance, contain the information
required to express particular trait
• Genes which code for pair of contrasting trait- alleles
• Alphabetical symbols were used; T-Tall, t- dwarf
• Plants pair of alleles for height- TT, Tt & tt
• Mendel proposed- true breeding tall or dwarf plant- identical
or homozygous allele pair of TT or tt (genotype)
• Descriptive term tall or dwarf- phenotype
• Mendel found phenotype of heterozygote Tt of F1 was same
as parent with TT & proposed, in a pair of dissimilar factors
one dominates the other & hence called dominant (T) &
recessive (t)
15. P x
F
1 All
Tall
Monohybrid Cross
F
2
Tall is dominant
to Dwarf
Tal
l
T
T
Dwar
f
tt
Phenotyp
e
Genotyp
e
Homozygous
Dominant
Tt
Homozygous
Recessive
Heterozygo
us
Self
pollinated Gamets T t
T TT
tall
Tt
tall
t Tt
Tal
l
tt
dwar
fPhenotypic ratio Genotypic ratio:
16. • Production of gametes & formation of zygotes-
Punnett Square
• Developed by- British scientist Reginald C. Punnett
• Graphical representation- calculate probability of
possible genotypes in genetic cross
• Gametes- on two sides, top row & left columns
• Self- pollination- 50%
• F2- 3/4th tall & 1/4th
Dwarf- phenotypically
• 1/4 : ½ : ¼ ratio of TT:
Tt: tt- genotype
17. Test cross: The cross between hybrid
and its homozygous recessive parent I
called test cross. It is used to identify the
genotype of the hybrid.
18. Mendelian laws of heredity.
• Rules were proposed- Principles or Laws of
Inheritance: First Law or Law of Dominance &
Second law or Law of Segregation
• Law o f dominance
1. Characters are controlled by discrete units called
Factors
2. Factors occurs in pair
3. In a dissimilar pair of factors one member of the
pair dominates (dominant) the other (recessive)
Used to explain the expression of only one of the parental
characters in monohybrid cross (F1) & expression of both
in F2. Also explains proportion 3:1 in F2
19. Law of segregation
• It states that, ‘when a pair of factors for a character
brought together in a hybrid, they segregate
(separate) during the formation of gametes.
• Alleles do not blend & both characters recovered in F2
& one in F1
• Factors which is present in parent segregate &
gametes receives only one of two factors
• Homozygous parent- one kind gamete
• Heterozygous parent- two kind gamete each one have
one allele with equal proportion
20. Incomplete dominance:
• Correns discovered Incomplete dominance in
Merabilis jalapa.
• It is also called partial dominance, semi dominance.
• The inheritance in which allele for a specific character
is not completely dominant over other allele is called
Incomplete dominance.
• Snapdragon or Antirrhinum sp.- Cross between true
breed red flower (RR) & white flower (rr), F1
generation- Pink (Rr) & after self pollination in F2
generation- 1 (RR) Red: 2 (Rr) Pink: 1 (rr) white
• Genotype ratio same as Mendelian cross & Phenotype
ratio different than Mendelian cross
23. Parent: Red X White
Genotype
.
RR WW
Gametes R W
F1 generation Pink (Hybrid)
RW
Self pollination
F2 generation
Gametes R W
R RR
Red
RW
Pink
W RW
Pink
WW
white
The phenotypic ratio is
1:2:1.
The genotypic ratio is
1:2:1
24. CO-DOMINANCE
• Both the alleles for a character are dominant and express
its full character is called co-dominance.
• Ex AB blood group of human being.
• Blood group in humans are controlled by 3 alleles of a gene
I.
• They are IA IB and i.
• The ABO locus is located on chromosome 9.
• IA is responsible for production of antigen –A.
• IB is responsible for production of antigen –B.
• i does not produces any antigen.
25. • IA and IB are co-dominant and dominant
over i.
Blood Group Genotype
A- Group IAIA or IA i
B-Group IBIB or IBi
AB-Group IAIB
O-Group ii
27. • ABO blood grouping- multiple allele
• Three alleles govern same character
• Multiple allele is found when population studies are
made
• Single gene product may produce more than one effect
• Eg.- Starch Synthesis in Pea seeds- controlled by a gene
havingtwo allele B & b
• Starch synthesis effective if homozygote BB & produce
large starch grains
• Homozygote bb –lesser efficiency in starch synthesis &
seeds are wrinkled
• Heterozygote Bb –round seeds, intermediate size
28. Inheritance of two gene:
Mendel’s 2nd law or Law of independent
assortment:
• It states that, ‘factors for different pairs of contrasting
characters in a hybrid assorted (distributed)
independently during gamete formation.
Mendel’s 2nd law can be explained by dihybrid cross.
• Dihybrid cross: The cross between two parents, which
differs in two pairs of contrasting characters.
31. Dihybrid test cross.
• F1 hybrid is crossed with recessive green wrinkled pea
plant.
• Recessive green wrinkled – rryy, Gamete ry
• F1 hybrid : round yellow- RrYy, Gametes:
RY, Ry, rY, ry.
Gametes RY Ry rY ry
ry RrYy Rryy rryY rryy
Phenotypic ratio – 1 : 1 : 1 :1
32. • Mendel work published 0n 1865 but remain unrecognized
till 1900
• Reasons for that:
1. Lack of communication
2. Concept of genes / factors- clear
3. Mathematical approach for biology was not acceted
4. No proof for existence of factors
33. Chromosomal theory of inheritance:
• It was proposed by Walter Sutton and Theodore Boveri .
• They work out the chromosome movement during meiosis.
• The movement behavior of chromosomes was parallel to the
behavior of genes. The chromosome movement is used to
explain Mendel’s laws.
• The knowledge of chromosomal segregation with
Mendelian principles is called chromosomal theory of
inheritance.
• According to this, Chromosome and genes are present in
pairs in diploid cells.
• Homologous chromosomes separate during gamete
formation (meiosis)
• Fertilization restores the chromosome number to diploid
condition.
35. • Thomas Hunt Morgan and his colleagues conducted
experimental verification of chromosomal theory of
inheritance
• Morgan worked with tiny fruit flies, Drosophila
melanogaster.
36. • He selected Drosophila because,
• It is suitable for genetic studies.
• Grown on simple synthetic medium in the laboratory.
• They complete their life cycle in about two weeks.
• A single mating could produce a large number of progeny
flies.
• Clear differentiation of male and female flies
• Many types of hereditary variations can be seen with low
power microscopes.
37. SEX DETERMINATION
• Henking (1891) traced specific nuclear structure
during spermatogenesis of some insects.
• 50 % of the sperm received these specific
structures, whereas 50% sperm did not
receive it.
• He gave a name to this structure as the X-body.
• This was later on named as X-chromosome.
38. XX-XO type
• Sex-determination of grass hopper:
• The grasshopper contains 12 pairs or 24
chromosomes. The male has only 23 chromosome.
• All egg bears one ‘X’ chromosome along with
autosomes.
• Some sperms (50%) bear’s one ‘X’ chromosome and
50% do not.
• Egg fertilized with sperm having ‘X’ chromosome
became female (22+XX).
• Egg fertilized with sperm without ‘X’ chromosome
became male (22 + X0)
39. XX-XY type
Sex determination in insects and
mammals
• In this type both male and female has same
number of chromosomes.
• Female has autosomes and a pair of X chromosomes.
(AA+ XX)
• Male has autosomes and one large ‘X’ chromosome and
one very small ‘Y-chromosomes. (AA+XY)
• In this type male is heterogamety and female
homogamety.
40. ZZ – ZW type
Sex determination in
birds:
• In this type female birds has two different sex chromosomes
named as Z and W.
• Male birds have two similar sex chromosomes and called ZZ.
• In this type of sex determination female is heterogamety and
male is homogamety.
41. Linkage recombination
• Morgan carried dihybrid cross in Drosophila to study
genes that are sex linked
• Crossed- yellow bodied, white eyed females with
brown bodied, red eyed males & intercourse F1
progeny
• Two genes did not segregate independently of each other
& F2 ratio deviated from 9:3:3:1
• The genes present on X –chromosome & two genes in a
dihybrid cross- situated on same chromosome- parental
gene combination is much higher than non
parental- this is due to physical association/ linkage of
two genes on chromosome- Linkage
• Generation of non parental combination-
Recombination
42. • He found genes are grouped in same chromosome, some
genes
are tightly linked- less recombination
• When genes are present in different chromosome-
higher recombination
• Eg.- Genes for white & yellow- tightly linked- 1.3%
recombination while genes for white & miniature
wings- 37.2% recombination
• Student Alferd Sturtevant used frequency of
recombination between gene pairs on chromosome as
a measure of the distance between genes & mapped
genes position on chromosome
43.
44. • Linkage: physical association of genes on a chromosome is
called linage.
• Recombination: The generation of non-parental
gene combinations is called recombination.
• It occurs in crossing over of chromosomes during meiosis.
45. MUTATION
• Phenotypic variation occurs due to change in gene or
DNA sequence is called mutation. The organism that
undergoes mutation is mutant.
• Phenomenon which result in alternation of DNA
sequence & result in change in genotype & phenotype
1. Loss (deletion) or gain (insertion/duplication) of a
segment of DNA results in alteration in chromosomes-
abnormalities/ aberrations- Chromosomal
aberrations
2. Gene Mutations:The mutation takes place due to change
in a single base pair of DNA is called gene mutation or
point mutation. E.g. sickle cell anemia.
3. Frame shift mutations: Deletion or insertions of base
pairs of DNA is called frame shift mutations.
46. Pedigree
Analysis:
• The study of inheritance of
genetic traits in several
generations of a family is
called the pedigree analysis.
• Pedigree study- strong tool
of human genetics to trace
inheritance of specific
trait/ abnormality/
diseases
• Pedigree analysis of
inheritance of a traits is
represented in family tree
• It helps in genetic counseling
to avoid genetic disorders.
47. Genetic disorders
• Genetic disorders grouped into two categories –
1. Mendelian disorder
2. Chromosomal disorder
Mendelian Disorders
• Mendelian disorders are mainly determined by alteration or
mutation in the single gene.
• It obey the principle of Mendelian inheritance (principles of
inheritance) during transmission from one generation to other.
• Mendelian disorder- traced in family by pedigree analysis
• E.g. Haemophilia, Colorblindness, Cystic fibrosis, Sickle
cell anemia, Phenylketonuria, Thalesemia etc.
• Dominant or recessive- pedigree analysis
• Trait may linked to sex chromosome, Eg. Haemophilia
• X- linked recessive trait- transmitted from carrier female to
male progeny
48. Haemophilia:
• It is a sex linked recessive disease.
• The defective individual continuously bleed to a simple cut.
• The gene for hemophilia is located on X chromosome.
• In this disease a single protein that is a part of cascade of
proteins
that involved in the clotting of blood is affected.
• The diseases transmitted from unaffected carrier female to
some of the male progeny.
• Heterozygous female (carrier)- transmit to sons
• Female being hemophilic is rare- Mother should be
carrier & father Haemophilic
53. • Autosome linked recessive trait
• Transmitted from parents- both partners are
carrier/ heterozygous
• Controlled by single pair of allele HbA & Hbs
• Homozygous individuals of Hbs (HbSHbS)- diseased
• Heterozygous individuals HbAHbS- unaffected but carrier
• Defect is due to substitution of Glutamic acid(Glu) by
Valine (Val)- at the 6th position beta globin chain of Hb
• Due to substitution of single base at 6th codon of beta
globin gene from GAG to GUG
• Mutant haemoglobin- polymerization under low oxygen
tension causing change in shape of RBC from biconcave
to sickle like structure
54.
55. Phenylketonuria
• Inborn error of metabolism- inherited as
autosomal recessive trait
• Affected individual lack enzyme that convert amino
acid phenylalanine to tyrosine
• Phenylalanine accumulates & convert to
phenylpyruvic acid & other derivatives
• Accumulation in brain result- mental retardation
• Excreted in urine- poor absorption by kidney
56. Chromosomal Disorder
• Caused due to absence or excess or abnormal
arrangement of one or more chromosome.
Causes:
1. Failure of segregation of chromatids- cell division cycle-
gain or loss chromosome- Aneuploidy, Eg.- Down’s
syndrome (Extra copy of 21 chromosome)- Trisomy,
Turner’s syndrome (loss of an X chromosome in female)-
Monosomy
2. Failure of cytokinesis after telophase- increase in
whole set chromosomes- Polyploidy, seen in plants
57. Down's Syndromes
• Presence of an additional copy of chromosome no. 21-
Trisomy of 21
• Described- Langdon Down (1866)
• Short statured, small round head, furrowed tongue,
partially open mouth, broad palm with palm crease;
physical, psychomotor & mental- retardation
58. Klinefelter’s Syndrome
• Presence ofan additional copy of X- chromosome
• Karyotype- 47, XXY
• Overall masculine development along with feminine
development- development of breast (Gyanaecomastia),
Sterile
59. Turner’s Syndrome
• Absence of one of X- chromosome, Monosomy
• Karyotype- 45, X0
• Females-sterile, ovaries are rudimentary, lack of
secondary sexual character