1. Biological
Science
By
Daisie S. Nubla
Assistant professor I
de la salle araneta university

2. Animal and Plant
Cell

5. GENETICS

6. GENETICS
 Ancient Greek γενετικός genetikos
means genesis or origin
 discipline of biology
 science of genes, heredity and variation
in living organisms
 deals with the molecular structure and
function of genes
 with pattern of inheritance from parent
to offspring
 gene distribution and variation in
change in population

7. GENETICS
 can be applied to the study of any living
system from viruses and bacteria
through plants (crops) and humans
(Medical Genetics)
 living things inherit traits from their
parents has been used since prehistoric
times to improve crop plants and
animals through selective breeding
 modern science of Genetics, which
seeks to understand the process of
inheritance only began with the work of
Gregor Mendel.

8. GREGOR MENDEL

9. GREGOR JOHANN MENDEL
 July 22, 1822 – January 6, 1884
 Austrian Monk
 During his child hood, worked as a
gardener and studied beekeeping
 studied at University of Olomouc
 Upon recommendation of his physics
teacher Friedrich Franz he entered the
Augustinian Abbey of St. Thomas in
Brno in 1843
 He took the name Gregor upon
entering monastic life

10. GREGOR JOHANN MENDEL
 He was ordained into priesthood in
August 1847
 In 1849, he was assigned as a teacher
to a secondary school in the city of
Znaim
 He took the licensure exam for teachers
but he was failed
 During middle part of his life, he did
groundbreaking into the theory of
heredity
 Using pea pod plants, he studied the seven
characteristics of it.

11. GREGOR JOHANN MENDEL
 By tracing these characteristics,
Mendel discovered 3 basic laws which
governed the passage of a trait from
one member of a species to another
member of the same species
 1st Law states that the sex cells of a
plant may contain two different traits
but not both of those traits

12. GREGOR JOHANN MENDEL
 2nd Law stated that the characteristics
are inherited independently from
another (the basis of recessive and
dominant gene composition)
 3rd Law stated that each inherited
characteristic is inherited by two
hereditary factors (known more
recently as genes. One from each
parents, which decides whether a gene
is recessive or a dominant.

13. GREGOR JOHANN MENDEL
 If a seed gene is recessive, it will not
show up within a plant, however the
dominant trait will.
 His work later became the basis for the
study of modern genetics, and are still
recognized and used today‟
 His work led to the discovery of
particulate inheritance, dominant and
recessive traits, genotype and
phenotype, concept of heterozygous
and homozygous

16. MENDEL‟S EXPERIMENTAL
QUANTITATIVE APPROACH
 Hybridization is matting and crossing of
two true-breeding varieties
 P generation(parental) is the true –
breeding parents
 F1 generation (first filial generation) is a
hybrid offspring
 F2 generation ( second filial
genentation) produced if allowing
F1 hybrid to self-pollinate

17. LAW OF SEGREGATION
 allele pairs separate during gamete
formation and randomly unite at
fertilization.
 two purpose of this are
 developed pure lines
 counted the results
and kept
the statistical notes

18. PURE LINE
 a population that breeds true for a
particular trait [ this was an important
innovation because any non-pure
(segregating) generation would and did
confuse the results of genetic
experiments]

20. Results from Mendel's Experiments
Results from Mendel's Experiments
F1
Parental Cross F Phenotypic Ratio F2 Ratio
Phenotype 2
Round x 5474 Round:1850
Round 2.96:1
Wrinkled Seed Wrinkled
Yellow x Green 6022 Yellow:2001
Yellow 3.01:1
Seeds Green
Red x White
Red 705 Red:224 White 3.15:1
Flowers
Tall x Dwarf
Tall l787 Tall:227 Dwarf 2.84:1
Plants

21. PHENOTYPE
 literally means, “the form that it
shown”
 the outward, physical appearance of a
particular trait
 Mendel‟s pea plants exhibited the
following phenotypes
 round or wrinkled seed
 yellow or green seed
 red or white flower
 tall or dwarf plant

22. Pea
color
Pea
shape

23. DOMINANT
 The allele that expresses itself
at the expense of an alternate
allele, the phenotype that is
expressed in the from the cross
of two pure lines

24. RECESSIVE
An allele whose expression is
suppressed in the presence of a
dominant allele, the phenotype
that disappears in the F1
generation from the cross of two
pure lines and reappears in the F2
generation

25. MENDEL‟S CONCLUSION
1. The hereditary determinants are of
a particulate nature. These
determinants are called genes
2. Each parent has a gene pair in each
cell for each trait studied. The F1
from a cross of two pure lines
contains one allele for the dominant
phenotype and one from the
recessive phenotype. These two
allele comprise the gene pair

26. MENDEL‟S CONCLUSION
3. One member of the gene pair
segregates into a gamete, thus each
gamete only carries one member of
the gene pair.
4. Gametes unite at random and
irrespective of the other gene pairs
involved.

27. MENDELIAN GENETICS
DEFINITION
Allele one alternative form of a given
allelic pair, tall and dark are the
allele for the height of pea plant;
more than two alleles can exist for
any specific gene, but only two of
them will be found in any individual
Allelic pair the combination of two
alleles which comprise the gene
pair.

28. MENDELIAN GENETICS
DEFINITION
Homozygous an individual which
contains only one allele at the
allelic pair, for example DD is a
homozygous dominant; while dd
is homozygous recessive, pure
lines are homozygous for the
gene of interest.

29. MENDELIAN GENETICS
DEFINITION
Heterozygous an individual which
contains one of each member
of the gene pair, example the
Dd.
Genotype the specific allelic
combination for a certain gene
or set of genes.

30. DIFFERENT TYPE OF CROSS
IN GENETICS
Backcross the cross of an F1 hybrid to
one of the homozygous parents;
for pea plant height the cross
would be Dd x DD or Dd x dd;
most often though a backcross is
a cross to a full recessive parent.

31. DIFFERENT TYPE OF CROSS IN
GENETICS
Testcross the cross of any individual to
a homozygous recessive parent,
used to determine if individual is
homozygous dominant or
heterozygous.
Monohybrid cross a cross between
parents that differ at a single
gene pair (usually AA x Aa)

32. DIFFERENT TYPE OF CROSS IN
GENETICS
Monohybrid the offspring of two parents
that are homozygous for
alternate alleles of a gene pair.
 is good for describing the
relationship between alleles.
 when an allele is homozygous it
will show its phenotype
 it is the phenotype of the
heterozygous which permit us to
determine the relationship of
the allele

33. DIFFERENT TYPE OF CROSS
IN GENETICS
Dominance the ability of one allele to
express its phenotype at the expense of an
alternate allele.
 the major form of interaction
between alleles
 generally the dominant allele
will make a gene product that
the recessive can not.
 therefore the dominant allele
express itself whenever it is
present

34. PUNNETT SQUARE
A handy diagrammatic device for
predicting the allele composition of
offspring from a cross between
individuals of known genetic make up

38. LAW OF INDEPENDENT
ASSORTMENT
Mendel derived this law by performing
breeding experiments in which he
followed only a single character.
 He identified this law by
following two characteristics at
the same time.
 example 2 of the 7 characters
Mendel‟s studied is were seed
color and seed shape
 Each pair of alleles segregates
independently of other pairs of alleles
during gamete formation

39. LAW OF INDEPENDENT
ASSORTMENT
 seed color may be yellow (Y) or green
(y) seed shape round (R) or wrinkled (r)
 example YYRR will have a parental
cross with yyrr
 F1 plants will be dihybrids
heterozygous YyRr
 phenotypic categories with a
ratio of 9:3:3:1
 9 yellow-round to 3 green-round
to 3 yellow-wrinkled to one-
green
wrinkled

42. COMPLETE DOMINANCE
Occurs when the phenotype o the
heterozygote is completely
indistinguishable from that of the
dominant homozygote

43. INCOMPLETE DOMINANCE
Occurs when phenotype of the
heterozygous genotype is an
intermediate of the phenotypes of the
homozygous genotypes.
 example the snap dragon
flower color is either
homozygous for red or white
 when the red homozygous
flower is paired with the white
one, the result is pink
 pink now is being called as
this

45. CO - DOMINANCE
Occurs when the contributions of both
alleles are visible in the phenotype
 example is A and B alleles are
codominant in producing AB
blood group phenotype
 in which A- and B- type
antigens are being made

46. TAY SACHS DISEASE
 fatal, recessive genetic disorder in
children that causes progressive
destruction of the Central Nervous
System
 Infants having this kind of disease
are normal for the first few months
 relentless deterioration of mental
and physical abilities
 becomes blind, deaf and unable to
swallow

48. EPISTASIS
 Greek word that means „stopping‟
 A gene at one locus alters the
phenotypic expression of a gene at a
second locus

50. PLEIOTROPY
 from a Greek word pleion
 have multiple phenotypic effects
 responsible for the multiple symptoms
associated with certain hereditary
diseases
 cystic fibrosis
 sickle cell disease

52. Many Human
Traits Follow
Mendelian
Patterns of
Inheritance

53. PEDIGREE ANALYSIS
 To analyze the results of matting
that have already occurred
 collection of information about a
family‟s history for a particular
trait and assembling this
information into a family tree
 describing the interrelationship of
parents and children across the
generation

54. PEDIGREE ANALYSIS
 one importance of this is to help us
predict the future
 a serious matter when the alles in
question cause disabling or deadly
hereditary diseases instead of
innocuous human variation such as
hairline or earlobe configuration

56. Recessively
Inherited Disorder

57. CYSTIC FIBROSIS
 Most common lethal genetic disease in
U.S.
 chloride transport of channels are
defective or absent in the plasma
membrane of a children
 result is abnormally high concentration
of extracellular chloride which causes
mucus that coats certain cells to
become thicker and stickier
 Most children die before their 5th
birthday

58. SICKLE CELL DISEASE
 most common inherited disorder
 caused by substitution of single amino
acid by the hemoglobin protein of red
blood cells.
 multiple effect of a double dose of this
is an example of pleiotropy
 no cure

59. MATING OF CLOSE RELATIVES
 forbidden love
consanguineous a disease causing
recessive allele
 more likely produce offspring
homozygous for recessive traits

60. DOMINANTLY INHERITED
DISORDERS
 Achondroplasia a form of dwarfism
 heterozygous individuals have the
dwarf phenotype
 therefore all people who are not
achondroplastic dwarf are homozygous
for recessive allele

62. NEW BORN SCREENING
 some genetic disorders can be
detected at birth
 one common screening program is
Phenylketonuria (PKU)
 phenylalanine and its by-product
phenylpyruvate can accumulate to
toxic levels in the blood causing
mental retardation.

64. NEW BORN SCREENING
 some genetic disorders can be
detected at birth
 one common screening program is
Phenylketonuria (PKU)
 phenylalanine and its by-product
phenylpyruvate can accumulate to
toxic levels in the blood causing
mental retardation.