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Human Genetics
And Population
GeneticsSubmitted to –
Dr Sapna sharma
Dept of Genetics
MDU Rohtak
Presented by –
Deepak Sai...
Genetics
• Human genetics- scientific study of human
variation and Heredity
2/19/2017 2Deepak Saini
.Genetics is the study...
Terms you should know
• CHROMOSOME: thread of DNA, made up of a string of
genes.
• GENE: a length of DNA that is the unit ...
Terms you should know:
• GENOTYPE: genetic makeup of an organism in term of the
alleles present ( e.g. Tt or GG).
• PHENOT...
•Genes control the characteristics of living
organisms
•Genes are carried on the chromosomes
•Chromosomes are in pairs, on...
2/19/2017 Deepak Saini 6
Heredity is the genetic information passing
for traits from parents to their offspring, either
th...
In most populations of animals there are approximately equal
numbers of males and females.
This is the result of a pair of...
X
Y
X
X
X
Y
X
X
X
X
X
X
X
Y
X
Y
sperm mother cell
ovum mother cell
meiosis
fertilization
female
female
male
male
Sex ratio...
• People have been fascinated at how children will
resemble their parents and vice versa.
• As years went by, scientists b...
• In human,
chromosom
es number 1
is the
biggest
containing
8,000 genes
and
chromosom
es 21 is the
smallest
with 300
genes...
Mutation
• - is a change of the nucleotide sequence of the
genome of an organism, virus, or extra
chromosomal genetic elem...
Types of Mutation
•Substitution
•Insertion
•Deletion
•Frameshift
2/19/2017 12Deepak Saini
Substitution
A substitution is a mutation
that exchanges one base for
another (i.e., a change in a
single "chemical letter...
2/19/2017 14Deepak Saini
Insertion
Insertions are
mutations in which extra
base pairs are inserted
into a new place in the
DNA.
2/19/2017 15Deepak ...
2/19/2017 16Deepak Saini
Inversion
a DNA sequence of
nucleotides is reversed.
Inversions can occur among a
few bases within a gene or
among longer ...
2/19/2017 18Deepak Saini
Deletion
Deletions are
mutations in which a
section of DNA is lost, or
deleted.
2/19/2017 19Deepak Saini
2/19/2017 20Deepak Saini
Frameshift
Since protein-coding DNA is
divided into codons three bases
long, insertions and deletions
can alter a gene so ...
2/19/2017 22Deepak Saini
Gene Mutation
is a permanent change in the
DNA sequence that makes up a
gene. Mutations range in size from
a single DNA bu...
Inherited
• hereditary mutations or germline
mutations
• This type of mutation is present
throughout a person’s life in
vi...
Acquired
• or somatic mutations
• occur in the DNA of individual cells
at some time during a person’s life.
• caused by en...
Natural cause
• DNA fails to copy accurately
–when a cell divides, it makes a
copy of its DNA and sometimes
the copy is no...
External Influences/Mutagens
• In genetics, a mutagen is a
physical or chemical agent that
changes the genetic material,
u...
2/19/2017 28Deepak Saini
Population genetics
• Investigates genetic variation among individuals
within groups (populations, gene pools).
• Examines...
• Different types of population genetics:
– Empirical population genetics: measures and
quantifies aspects of genetic vari...
Types of questions studied by population geneticists:
• How much variation occurs in natural populations, and
what process...
Population Genetics:
• One of the oldest and richest examples of success of
mathematical theory in biology.
• Provided syn...
Laid the first early groundwork the modern synthesis:
Charles Darwin 1809-1882
The Origin of Species
Alfred Russell Wallac...
Theoretical/mathematical population geneticists:
Ronald A. Fisher 1890-1962
The Genetical Theory of Natural Selection
J. B...
Architects the modern synthesis, extended theoretical work of Fisher, Haldane, and
Wright to real organisms:
Theodosius Do...
Ways to describe genetic structure of populations:
Genotypic frequency
• Count individuals with one genotype and divide by...
Ways to describe genetic structure of populations:
Allelic frequency
• Allelic frequencies offer more information than gen...
Allelic frequencies with multiple alleles:
Example: A1, A2, and A3
p = f(A1) = (2 x A1A1) + (A1A2) + (A1A3)/2 x total indi...
Allelic frequencies at X-linked loci:
Females have 2 X-linked alleles, and males have 1 X-linked allele.
p = f(XA) = (2 x ...
Hardy-Weinberg law:
• Independently discovered by Godfrey H. Hardy
(1877-1947) and Wilhelm Weinberg (1862-
1937).
• Explai...
Hardy-Weinberg Equilibrium
Allele Frequencies don’t change over generations
Assumptions:
1. Population is infinitely large, to avoid effects of genetic
drift (= change in genetic frequency due to ch...
Referecnes
• Wikkipedia.net
• Slide share.in
• Dr ravi prakash ppt
• Genomics text book
2/19/2017 Deepak Saini 43
2/19/2017 44Deepak Saini
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human genetics and population genetics

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human genetics and population genetics

  1. 1. Human Genetics And Population GeneticsSubmitted to – Dr Sapna sharma Dept of Genetics MDU Rohtak Presented by – Deepak Saini M sc Forensic science 4th sem Roll no -1602 2/19/2017 1Deepak Saini
  2. 2. Genetics • Human genetics- scientific study of human variation and Heredity 2/19/2017 2Deepak Saini .Genetics is the study of genes, genetic variation, and heredity in living organisms. It is generally considered a field of biology, but intersects frequently with many other life sciences and is strongly linked with the study of information systems.
  3. 3. Terms you should know • CHROMOSOME: thread of DNA, made up of a string of genes. • GENE: a length of DNA that is the unit of heredity and codes for a specific protein. A gene may be copied and passed on to the next generation. • ALLELE: any of two or more alternative forms of a gene. • HAPLOID NUCLEUS: a nucleus containing a single set of unpaired chromosomes (e.g. sperm and egg) • DIPLOID NUCLEUS: a nucleus containing two sets of chromosomes (e.g. in body cells) 2/19/2017 3Deepak Saini
  4. 4. Terms you should know: • GENOTYPE: genetic makeup of an organism in term of the alleles present ( e.g. Tt or GG). • PHENOTYPE: physical or other features of an organism due to both its genotype and its environment (e.g. tall plant or green seed) • HOMOZYGOUS: having two identical alleles of a particulat gene (e.g. TT or gg).Two identical homozygous individuals that breed together will be pure-breeding. • HETEROZYGOUS: having two different alleles of a particular gene (e.g. Tt or Gg), not pure- breeding. • DOMINANT: an allele that is expresed if it is present (e.g. T or G) • RECESSIVE: an allele that is only expresses when there is no dominant allele of the gene present. ( e.g t or g ) 2/19/2017 4Deepak Saini
  5. 5. •Genes control the characteristics of living organisms •Genes are carried on the chromosomes •Chromosomes are in pairs, one from each parent •Genes are in pairs •Genes controlling the same characteristics occupy identical positions on corresponding chromosomes 2/19/2017 5Deepak Saini
  6. 6. 2/19/2017 Deepak Saini 6 Heredity is the genetic information passing for traits from parents to their offspring, either through asexual reproduction or sexual reproduction. .This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve through the natural selection of specific phenotype traits. -The study of heredity in biology is called genetics,
  7. 7. In most populations of animals there are approximately equal numbers of males and females. This is the result of a pair of chromosomes; the sex chromosomes called the X and Y chromosomes. The X and Y chromosomes are a homologous pair but in many animals the Y chromosome is smaller than the X. Females have two X chromosomes in their cells. Males have one X and one Y in their cells. At meiosis, the sex chromosomes are separated so the the gametes receive only one: either an X or a Y. Sex chromosomes 2/19/2017 7Deepak Saini
  8. 8. X Y X X X Y X X X X X X X Y X Y sperm mother cell ovum mother cell meiosis fertilization female female male male Sex ratio 2/19/2017 8Deepak Saini
  9. 9. • People have been fascinated at how children will resemble their parents and vice versa. • As years went by, scientists began to search for more information on how these traits are passed on. • The passing of traits from parents to offspring is HEREDITY and the science that deals with the study of heredity is GENETICS. 2/19/2017 9Deepak Saini
  10. 10. • In human, chromosom es number 1 is the biggest containing 8,000 genes and chromosom es 21 is the smallest with 300 genes. In short, the 44 chromosomes are autosomes andes. 2/19/2017 10Deepak Saini
  11. 11. Mutation • - is a change of the nucleotide sequence of the genome of an organism, virus, or extra chromosomal genetic element. • Mutations result from errors during DNA replication or other types of damage to DNA. 2/19/2017 11Deepak Saini
  12. 12. Types of Mutation •Substitution •Insertion •Deletion •Frameshift 2/19/2017 12Deepak Saini
  13. 13. Substitution A substitution is a mutation that exchanges one base for another (i.e., a change in a single "chemical letter" such as switching an A to a G). 2/19/2017 13Deepak Saini
  14. 14. 2/19/2017 14Deepak Saini
  15. 15. Insertion Insertions are mutations in which extra base pairs are inserted into a new place in the DNA. 2/19/2017 15Deepak Saini
  16. 16. 2/19/2017 16Deepak Saini
  17. 17. Inversion a DNA sequence of nucleotides is reversed. Inversions can occur among a few bases within a gene or among longer DNA sequences that contain several genes. 2/19/2017 17Deepak Saini
  18. 18. 2/19/2017 18Deepak Saini
  19. 19. Deletion Deletions are mutations in which a section of DNA is lost, or deleted. 2/19/2017 19Deepak Saini
  20. 20. 2/19/2017 20Deepak Saini
  21. 21. Frameshift Since protein-coding DNA is divided into codons three bases long, insertions and deletions can alter a gene so that its message is no longer correctly parsed. 2/19/2017 21Deepak Saini
  22. 22. 2/19/2017 22Deepak Saini
  23. 23. Gene Mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome. 2/19/2017 23Deepak Saini
  24. 24. Inherited • hereditary mutations or germline mutations • This type of mutation is present throughout a person’s life in virtually every cell in the body. 2/19/2017 24Deepak Saini
  25. 25. Acquired • or somatic mutations • occur in the DNA of individual cells at some time during a person’s life. • caused by environmental factors • cannot be passed on to the next generation. 2/19/2017 25Deepak Saini
  26. 26. Natural cause • DNA fails to copy accurately –when a cell divides, it makes a copy of its DNA and sometimes the copy is not quite perfect. 2/19/2017 26Deepak Saini
  27. 27. External Influences/Mutagens • In genetics, a mutagen is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level. 2/19/2017 27Deepak Saini
  28. 28. 2/19/2017 28Deepak Saini
  29. 29. Population genetics • Investigates genetic variation among individuals within groups (populations, gene pools). • Examines the genetic basis for evolutionary change and seeks to understand how patterns vary geographically and through time. 2/19/2017 29Deepak Saini
  30. 30. • Different types of population genetics: – Empirical population genetics: measures and quantifies aspects of genetic variation in populations. – Theoretical population genetics: explains variation in terms of mathematical models of the forces that change allele frequencies (genetics drift, selection, gene flow, etc.). 2/19/2017 30Deepak Saini
  31. 31. Types of questions studied by population geneticists: • How much variation occurs in natural populations, and what processes control the variation observed? • How does geography and dispersal behavior shape population structure? • What forces are responsible for population differentiation and how do they affect genetic diversity? • Mutation  genetic diversity • Selection  genetic diversity • Genetic drift  genetic diversity • Migration  genetic diversity • Non-random mating  genetic diversity • Recombination  genetic diversity2/19/2017 31Deepak Saini
  32. 32. Population Genetics: • One of the oldest and richest examples of success of mathematical theory in biology. • Provided synthesis of Mendelian genetics and Darwinian natural selection in the first part of the 20th century  “modern synthesis”. • Modern synthesis is the foundation for modern evolutionary biology and population genetics. 2/19/2017 32Deepak Saini
  33. 33. Laid the first early groundwork the modern synthesis: Charles Darwin 1809-1882 The Origin of Species Alfred Russell Wallace 1823-1913 “Wallace’s Line” Thomas H. Huxley 1825-1895 “Darwin’s Bulldog” 2/19/2017 33Deepak Saini
  34. 34. Theoretical/mathematical population geneticists: Ronald A. Fisher 1890-1962 The Genetical Theory of Natural Selection J. B. S. Haldane 1892-1964 The Causes of Evolution Sewall Wright 1889-1988 Evolution and the Genetics of Populations - 4 vol. 2/19/2017 34Deepak Saini
  35. 35. Architects the modern synthesis, extended theoretical work of Fisher, Haldane, and Wright to real organisms: Theodosius Dobzhansky 1900-1975 Genetics and the Origin of Species Julian Huxley 1887-1975 Evolution: The Modern Synthesis Ernst Mayr 1904-2005 Systematics and the Origin of Species “Biological Species Concept” George G. Simpson 1902-1984 Tempo and Mode in Evolution George L. Stebbins 1906-2000 Variation and Evolution in Plants 2/19/2017 35Deepak Saini
  36. 36. Ways to describe genetic structure of populations: Genotypic frequency • Count individuals with one genotype and divide by total number of individuals. Repeat for each genotype in the population: f(BB) = 452/497 = 0.909 f(Bb) = 43/497 = 0.087 f(bb) = 2/497 = 0.004 Total = 1.000 2/19/2017 36Deepak Saini
  37. 37. Ways to describe genetic structure of populations: Allelic frequency • Allelic frequencies offer more information than genotypic frequencies and can be calculated in two different ways: 1. Allele (gene) counting method: p = f(A) = (2 x count of AA) + (1 count of Aa)/ 2 x total number of individuals 2. Genotypic frequency method: p = f(A) = (frequency of the AA homozygote) + (1/2 x frequency of the Aa heterozygote) p = f(a) = (frequency of the aa homozygote) + (1/2 x frequency of the Aa heterozygote) 2/19/2017 37Deepak Saini
  38. 38. Allelic frequencies with multiple alleles: Example: A1, A2, and A3 p = f(A1) = (2 x A1A1) + (A1A2) + (A1A3)/2 x total individuals q = f(A2) = (2 x A2A2) + (A1A2) + (A2A3)/2 x total individuals r = f(A3) = (2 x A3A3) + (A1A3) + (A2A3)/2 x total individuals Or p = f(A1) = f(A1A1) +f(A1A2)/2 + f(A1A3)/2 q = f(A2) = f(A2A2) + f(A1A2)/2 + f(A2A3)/2 r = f(A3) = f(A3A3) + f(A1A3)/2 + f(A2A3)/2 2/19/2017 38Deepak Saini
  39. 39. Allelic frequencies at X-linked loci: Females have 2 X-linked alleles, and males have 1 X-linked allele. p = f(XA) = (2 x XA XA females) + (XA Xa females) + (XA Y males)/ (2 x # females) + (# males) q = f(Xa) = (2 x Xa Xa females) + (XA Xa females) + (Xa Y males)/ (2 x # females) + (# males) If number of females and males are equal: p = f(XA) = 2/3[f(XAXA) +1/2f(XAXa)] + 1/3f(XAY) q = f(Xa) = 2/3[f(XaXa) +1/2f(XAXa)] + 1/3f(XaY) 2/19/2017 39Deepak Saini
  40. 40. Hardy-Weinberg law: • Independently discovered by Godfrey H. Hardy (1877-1947) and Wilhelm Weinberg (1862- 1937). • Explains how Mendelian segregation influences allelic and genotypic frequencies in a population. 2/19/2017 40Deepak Saini
  41. 41. Hardy-Weinberg Equilibrium Allele Frequencies don’t change over generations
  42. 42. Assumptions: 1. Population is infinitely large, to avoid effects of genetic drift (= change in genetic frequency due to chance). 2. Mating is random (with regard to traits under study). 3. No natural selection (for traits under study). 4. No mutation. 5. No migration. 2/19/2017 42Deepak Saini
  43. 43. Referecnes • Wikkipedia.net • Slide share.in • Dr ravi prakash ppt • Genomics text book 2/19/2017 Deepak Saini 43
  44. 44. 2/19/2017 44Deepak Saini

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