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PRESENTED BY – VIPIN KUMAR SUBMITED TO DR.SAJAD AHMED
RAJESH KUMAR DEPARTMENT OF BIOCHEMISTRY
INTERNATIONAL MEDICAL
SCHOOL(UIB) ALMATY
GREGOR MENDAL
Gregor Mendel, in full Gregor Johann Mendel, original
name (until 1843) Johann Mendel, (born July 20, 1822,
Heinzendorf, Silesia, Austrian Empire and died January 6,
1884, Brünn, Austria-Hungary botanist, teacher, and
Augustinian prelate, the first person to lay the
mathematical foundation of the science of genetics, in
what came to be called Mendelism.
Through his careful breeding of garden peas, Gregor
Mendel discovered the basic principles of heredity and
laid the mathematical foundation of the science of
genetics. He formulated several basic genetic laws,
including the law of segregation, the law of dominance,
and the law of independent assortment, in what became
known as Mendelian inheritance.
Mendel Law Of Inheritance
 Between 1856-1863, Mendel
conducted the hybridization
experiments on the garden peas.
During that period, he chose some
distinct characteristics of the peas
and conducted some cross-
pollination/ artificial pollination on
the pea lines that showed stable
trait inheritance and underwent
continuous self-pollination. Such
pea lines are called true-breeding
pea lines.
He selected a pea plant for his experiments for the following reasons:
 The pea plant can be easily grown and maintained.
 They are naturally self-pollinating but can also be cross-pollinated.
 It is an annual plant, therefore, many generations can be studied within a short period of time.
 It has several contrasting characters.
 Mendel conducted 2 main experiments to determine the laws of inheritance. These
experiments were:
 Monohybrid Cross
 Dihybrid Cross
 While experimenting, Mendel found that certain factors were always being transferred down to the offspring
in a stable way. Those factors are now called genes i.e. genes can be called the units of inheritance.
Monohybrid Cross
In this experiment, Mendel took two pea plants of
opposite traits (one short and one tall) and crossed
them. He found the first generation offspring were
tall and called it F1 progeny. Then he crossed F1
progeny and obtained both tall and short plants in
the ratio 3:1. To know more about this experiment,
visit Monohybrid Cross – Inheritance Of One Gene.
Mendel even conducted this experiment with other
contrasting traits like green peas vs yellow peas,
round vs wrinkled, etc. In all the cases, he found
that the results were similar. From this, he
formulated the laws of Segregation And
Dominance.
Dihybrid Cross
In a dihybrid cross experiment, Mendel
considered two traits, each having two alleles.
He crossed wrinkled-green seed and round-
yellow seeds and observed that all the first
generation progeny (F1 progeny) were round-
yellow. This meant that dominant traits were the
round shape and yellow colour.
He then self-pollinated the F1 progeny and
obtained 4 different traits: round-yellow, round-
green, wrinkled-yellow, and wrinkled-green
seeds in the ratio 9:3:3:1.
Law of Dominance
 Characters are controlled by discrete units called factors.
 Factors occur in pairs.
 In a dissimilar pair of factors one member of the pair dominates (dominant) the
other (recessive).
 The law of dominance is used to explain the expression of only one ofthe
parental characters in a monohybrid cross in the F1 and the expression of
both in the F2.
 It also explains the proportion of 3:1 obtained at the F2
LAW OF INDEPENDENT ASSORTMENT
 This law is based on dihybrid cross
Also known as Mendel’s second law of inheritance, the law of
independent assortment states that a pair of traits segregates
independently of another pair during gamete formation. As the
individual heredity factors assort independently, different traits
get equal opportunity to occur together.
LAW OF SEGREGATION
This law is based on the fact that the alleles do not show any blending
and that both the characters are recovered as such in the F2
generation though one of these is not seen at the F1 stage. Though
the parents contain two alleles during gamete formation, the factors
or alleles of a pair segregate from each other such that a gamete
receives only one of the two factors. Of course, a homozygous parent
produces all gametes that are similar while a heterozygous one
produces two kinds of gametes each having one allele with equal
proportion.
Conclusions from Mendel’s Experiments
 The genetic makeup of the plant is known as the genotype. On the contrary, the
physical appearance of the plant is known as phenotype.
 The genes are transferred from parents to the offspring in pairs known as alleles.
 During gametogenesis when the chromosomes are halved, there is a 50% chance of
one of the two alleles to fuse with the allele of the gamete of the other parent.
 When the alleles are the same, they are known as homozygous alleles and when the
alleles are different they are known as heterozygous alleles.
Pedigree Chart
 A pedigree chart is a diagram that shows the occurrence and appearance of
phenotypes of a particular gene or organism and its ancestors from one generation to
the next
 A pedigree results in the presentation of family information in the form of an easily
readable chart. It can be simply called as a "family tree". Pedigrees use a standardized
set of symbols, squares represent males and circles represent females.
 Relationships in a pedigree are shown as a series of lines. Parents are connected by a
horizontal line and a vertical line leads to their offspring. The offspring are connected
by a horizontal sibship line and listed in birth order from left to right. If the offspring
are twins then they will be connected by a triangle. If an offspring dies then its symbol
will be crossed by a line.
 Analysis of the pedigree using the principles of Mendelian inheritance can determine
whether a trait has a dominant or recessive pattern of inheritance. Pedigrees are often
constructed after a family member afflicted with a genetic disorder has been
identified.
biochemistry 02.pptx
In a Y-linked disorder, only males can be affected. If
the father is affected all sons will be affected. It also
does not skip a generation.
FOR EXAMPLE – HYPERTRICHOSIS OF THE EAR
WEBBED TOES
In mitochondrial disorders it is only passed on
if the mother is affected. If the mother is
affected, all offspring will be affected. If the
father is affected, he does not pass it on to his
offspring.
FOR EXAMPLE – ALZHEIMER DISEASE
MUSCULAR DISTROPHY
In an autosomal recessive disorder, both parents can not
express the trait, however, if both are carriers, their
offspring can express the trait. Autosomal recessive
disorders typically skip a generation, so affected offspring
typically have unaffected parents. With an autosomal
recessive disorder, both males and females are equally
likely to be affected.
FOR EXAMPLE -SICKEL CELL ANEMIA
Autosomal dominant disorders do not skip a
generation, so affected offspring have affected
parents. One parent must have the disorder for its
offspring to be affected. Both males and females
are equally likely to be affected, so it is an
autosomal disorder
FOR EXAMPLE –HUNTINGTONS DISEASE
In a X-linked recessive disorder, males are more likely to
be affected than females. Affected sons typically have
unaffected mothers. The father also must be affected for
daughter to be affected and the mother must be
affected or a carrier for the daughter to be affected. The
disorder is also never passed from father to son. Only
females can be carriers for the disorders. X-linked
recessive disorders also typically skip a generation.
FOR EXAMPLE – COLOR BLINDNESS
HEAMOPHILIA
In a X-Linked dominant disorder, if the father is affected all
daughters will be affected and no sons will be affected. It
does not skip a generation and if the mother is affected
she has a 50% chance of passing it onto her offspring.
FOR EXAMPLE –RETTE SYNDROME
MULTIFACTORIAL DISEASES
 Multifactorial diseases are not confined to any specific pattern of single gene
inheritance and are likely to be associated with multiple genes effects
together with the effects of environmental factors.
 In fact, the terms ‘multifactorial’ and ‘polygenic’ are used as synonyms and
these terms are commonly used to describe the architecture of disease
causing genetic component.
 Although multifactorial diseases are often found gathered in families yet, they
do not show any distinct pattern of inheritance. It is difficult to study and treat
multifactorial diseases because specific factors associated with these diseases
have not yet been identified.
Some common multifactorial disorders
 diabetes
 asthma
 depression
 high blood pressure
 Alzheimer’s
 obesity
 epilepsy
 heart diseases,
 Hypothyroidism
 club foot
 even dandruff.
biochemistry 02.pptx

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biochemistry 02.pptx

  • 1. PRESENTED BY – VIPIN KUMAR SUBMITED TO DR.SAJAD AHMED RAJESH KUMAR DEPARTMENT OF BIOCHEMISTRY INTERNATIONAL MEDICAL SCHOOL(UIB) ALMATY
  • 2. GREGOR MENDAL Gregor Mendel, in full Gregor Johann Mendel, original name (until 1843) Johann Mendel, (born July 20, 1822, Heinzendorf, Silesia, Austrian Empire and died January 6, 1884, Brünn, Austria-Hungary botanist, teacher, and Augustinian prelate, the first person to lay the mathematical foundation of the science of genetics, in what came to be called Mendelism. Through his careful breeding of garden peas, Gregor Mendel discovered the basic principles of heredity and laid the mathematical foundation of the science of genetics. He formulated several basic genetic laws, including the law of segregation, the law of dominance, and the law of independent assortment, in what became known as Mendelian inheritance.
  • 3. Mendel Law Of Inheritance  Between 1856-1863, Mendel conducted the hybridization experiments on the garden peas. During that period, he chose some distinct characteristics of the peas and conducted some cross- pollination/ artificial pollination on the pea lines that showed stable trait inheritance and underwent continuous self-pollination. Such pea lines are called true-breeding pea lines.
  • 4. He selected a pea plant for his experiments for the following reasons:  The pea plant can be easily grown and maintained.  They are naturally self-pollinating but can also be cross-pollinated.  It is an annual plant, therefore, many generations can be studied within a short period of time.  It has several contrasting characters.  Mendel conducted 2 main experiments to determine the laws of inheritance. These experiments were:  Monohybrid Cross  Dihybrid Cross  While experimenting, Mendel found that certain factors were always being transferred down to the offspring in a stable way. Those factors are now called genes i.e. genes can be called the units of inheritance.
  • 5. Monohybrid Cross In this experiment, Mendel took two pea plants of opposite traits (one short and one tall) and crossed them. He found the first generation offspring were tall and called it F1 progeny. Then he crossed F1 progeny and obtained both tall and short plants in the ratio 3:1. To know more about this experiment, visit Monohybrid Cross – Inheritance Of One Gene. Mendel even conducted this experiment with other contrasting traits like green peas vs yellow peas, round vs wrinkled, etc. In all the cases, he found that the results were similar. From this, he formulated the laws of Segregation And Dominance.
  • 6. Dihybrid Cross In a dihybrid cross experiment, Mendel considered two traits, each having two alleles. He crossed wrinkled-green seed and round- yellow seeds and observed that all the first generation progeny (F1 progeny) were round- yellow. This meant that dominant traits were the round shape and yellow colour. He then self-pollinated the F1 progeny and obtained 4 different traits: round-yellow, round- green, wrinkled-yellow, and wrinkled-green seeds in the ratio 9:3:3:1.
  • 7. Law of Dominance  Characters are controlled by discrete units called factors.  Factors occur in pairs.  In a dissimilar pair of factors one member of the pair dominates (dominant) the other (recessive).  The law of dominance is used to explain the expression of only one ofthe parental characters in a monohybrid cross in the F1 and the expression of both in the F2.  It also explains the proportion of 3:1 obtained at the F2
  • 8. LAW OF INDEPENDENT ASSORTMENT  This law is based on dihybrid cross Also known as Mendel’s second law of inheritance, the law of independent assortment states that a pair of traits segregates independently of another pair during gamete formation. As the individual heredity factors assort independently, different traits get equal opportunity to occur together.
  • 9. LAW OF SEGREGATION This law is based on the fact that the alleles do not show any blending and that both the characters are recovered as such in the F2 generation though one of these is not seen at the F1 stage. Though the parents contain two alleles during gamete formation, the factors or alleles of a pair segregate from each other such that a gamete receives only one of the two factors. Of course, a homozygous parent produces all gametes that are similar while a heterozygous one produces two kinds of gametes each having one allele with equal proportion.
  • 10. Conclusions from Mendel’s Experiments  The genetic makeup of the plant is known as the genotype. On the contrary, the physical appearance of the plant is known as phenotype.  The genes are transferred from parents to the offspring in pairs known as alleles.  During gametogenesis when the chromosomes are halved, there is a 50% chance of one of the two alleles to fuse with the allele of the gamete of the other parent.  When the alleles are the same, they are known as homozygous alleles and when the alleles are different they are known as heterozygous alleles.
  • 11. Pedigree Chart  A pedigree chart is a diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors from one generation to the next  A pedigree results in the presentation of family information in the form of an easily readable chart. It can be simply called as a "family tree". Pedigrees use a standardized set of symbols, squares represent males and circles represent females.  Relationships in a pedigree are shown as a series of lines. Parents are connected by a horizontal line and a vertical line leads to their offspring. The offspring are connected by a horizontal sibship line and listed in birth order from left to right. If the offspring are twins then they will be connected by a triangle. If an offspring dies then its symbol will be crossed by a line.  Analysis of the pedigree using the principles of Mendelian inheritance can determine whether a trait has a dominant or recessive pattern of inheritance. Pedigrees are often constructed after a family member afflicted with a genetic disorder has been identified.
  • 13. In a Y-linked disorder, only males can be affected. If the father is affected all sons will be affected. It also does not skip a generation. FOR EXAMPLE – HYPERTRICHOSIS OF THE EAR WEBBED TOES In mitochondrial disorders it is only passed on if the mother is affected. If the mother is affected, all offspring will be affected. If the father is affected, he does not pass it on to his offspring. FOR EXAMPLE – ALZHEIMER DISEASE MUSCULAR DISTROPHY
  • 14. In an autosomal recessive disorder, both parents can not express the trait, however, if both are carriers, their offspring can express the trait. Autosomal recessive disorders typically skip a generation, so affected offspring typically have unaffected parents. With an autosomal recessive disorder, both males and females are equally likely to be affected. FOR EXAMPLE -SICKEL CELL ANEMIA Autosomal dominant disorders do not skip a generation, so affected offspring have affected parents. One parent must have the disorder for its offspring to be affected. Both males and females are equally likely to be affected, so it is an autosomal disorder FOR EXAMPLE –HUNTINGTONS DISEASE
  • 15. In a X-linked recessive disorder, males are more likely to be affected than females. Affected sons typically have unaffected mothers. The father also must be affected for daughter to be affected and the mother must be affected or a carrier for the daughter to be affected. The disorder is also never passed from father to son. Only females can be carriers for the disorders. X-linked recessive disorders also typically skip a generation. FOR EXAMPLE – COLOR BLINDNESS HEAMOPHILIA In a X-Linked dominant disorder, if the father is affected all daughters will be affected and no sons will be affected. It does not skip a generation and if the mother is affected she has a 50% chance of passing it onto her offspring. FOR EXAMPLE –RETTE SYNDROME
  • 16. MULTIFACTORIAL DISEASES  Multifactorial diseases are not confined to any specific pattern of single gene inheritance and are likely to be associated with multiple genes effects together with the effects of environmental factors.  In fact, the terms ‘multifactorial’ and ‘polygenic’ are used as synonyms and these terms are commonly used to describe the architecture of disease causing genetic component.  Although multifactorial diseases are often found gathered in families yet, they do not show any distinct pattern of inheritance. It is difficult to study and treat multifactorial diseases because specific factors associated with these diseases have not yet been identified.
  • 17. Some common multifactorial disorders  diabetes  asthma  depression  high blood pressure  Alzheimer’s  obesity  epilepsy  heart diseases,  Hypothyroidism  club foot  even dandruff.