Transcript
Bio. Sci. Dept.
What is Genetics?
From Greek word:
Genetikos=
generative
Gen=to produce,
= to become,
= to grow into
something
What is Genetics?
• Explains one’s origin or ancestry
• “HOW ONE BECOMES
WHAT HE IS LIKE”
• Individuals of the same species may have
characteristics common to all of them
(Species characteristics=denote common
origin), and yet they may differ from one
another (Individual characteristics)
Variations
The basic quality of living organisms
It denotes species characteristics
Provides individual characteristics
Provides the raw materials for
adaptation
Some terms that can be associated to
VARIATIONS
PHENOTYPE – various observable
features by which we recognize the
organism
GENOTYPE – unobservable features-
hidden traits of an organism
PHENOCOPIES – environmental
alterations of phenotype
Ex. Straightening of curly hair
TYPES OF VARIATIONS
1. MORPHOLOGICAL or STRUCTURAL
A. Physical traits or gross anatomical
feature
•shape of the face, ears, eyes
•color of the eyes, hair,
TYPES OF VARIATIONS
B. Cellular, Subcellular and
Molecular Characteristics
• Kind of hemoglobin in the RBC
• Kind of glycoproteins on the cell
membrane
• Kind of DNA
TYPES OF VARIATIONS
2. PHYSIOLOGICAL or FUNCTIONAL
1. biochemical and biophysical processes
- inability to absorb glucose
- inability to distinguish colors
- failure to perform photosynthesis
- inability to synthesize certain amino
acid
TYPES OF VARIATIONS
3. BEHAVIORAL
- Combined structural and physiological
characteristics
- Pattern of reactions to its
environment
Ex. IQ, Mental retardation
Tolerance level
TYPES OF VARIATIONS
4. SEXUAL
- The most important phenotypic
characteristics of an organism
- Capacity for reproduction together with
the features associated with it
TYPES OF VARIATIONS
Sexual Variations are classified as
A. Primary Sexual Traits – differences in
external genitalia and gonads
B. Secondary Sexual Traits – non-
sexual but related to mating and rearing
of youngs
-developed breast in human female
-smaller body of male frogs
VARIATIONS can be described as:
A. CONTINUOUS VARIATION:
- when the characteristic varies in small
amounts between individuals
- height
- weight
VARIATIONS
B. DISCONTINUOUS VARIATION
- one of several discrete alternatives
Ex. Tongue-rolling
Sex
http://biologyataglance.wikispaces.com
Variations in Man
Variations in Man
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Variations in Animal
Variations in Animals
Variations in Plants
Variations in Plants
CAUSES OF VARIATION
Genes (Inherited)
- sex determination
- mental retardation
- infant deformities
Environment
(Acquired)
- physical deformities
- obesity
Fields of Genetics
1. TRANSMISSION GENETICS /
CLASSICAL GENETICS – deals with
heredity and variation
Methods:
• Planned Experimental/Cross Breeding
• Pedigree Analysis
Mendel’s Experiments
Mendel chose true-breeding/pure breeding
(between homozygous) garden peas for
his experiments
Mendel first worked with single-character
crosses (Monohybrid cross).
Fig. 14-2a
Stamens Carpel
Parental generation (P)
TECHNIQUE
1
2
3
4
Fig. 14-2b
First
filial gener-
ation offspring (F1)
RESULTS
5
Pea Characters
A Pedigree
Fields of Genetics
2. CYTOGENETICS
- study the genes in the cell particularly
in the chromosome
- provide the chromosomal basis of
sex determination
- explain the distribution of boys and
girls in the family
Cytogenetics
Fields of Genetics
3. MOLECULAR GENETICS
- investigate in detail the nature of
genetic material, it’s structure, mode
of replication and how it acts to
produce the phenotype
DNA – genetic material
Molecular Genetics
Fields of Genetics
4. POPULATION GENETICS
- genetic structure of a population
- patterns of genetic variation in
populations
- changes in genetic structure through
time
200 white
500 pink
300 red
• genotype frequencies
• allele frequencies
200/1000 = 0.2 rr
500/1000 = 0.5 Rr
300/1000 = 0.3 RR
total = 1000 flowers
genotype
frequencies:
Describing genetic structure
Population Genetics
Fields of Genetics
5. APPLIED GENETICS
– practical applications of Genetics
A. Animal husbandry & plant breeding
- to produce high yielding varieties of
food crops like disease-resistant
plants and varieties of cows and
pigs
Applied Genetics
B. Epidemiological Genetics – for better
therapy, management and prevention
of recurrence of inherited disease
C. Eugenics – choice of partners for
marriage and have an estimate of the
likelihood of appearance of desirable
trait
Applied Genetics
D. Medicolegal Genetics – to solve legal
problems like dispute in paternity and
exchange of babies in the hospital
nursery
E. Genetic Counseling – for deciding
abortion and planning responsible
parenthood through amniocentesis
Human Genome Project
So what if there would
be a database for the
Human Genome?!?
Amelogenesis imperfecta This condition causes teeth to be
unusually small, discolored, pitted or
grooved, and prone to rapid wear
and breakage
CAUSE: Mutation in the AMELX,
ENAM, and MMP20 genes
TREATMENT: Crowning for the soft
enamel
In case of worse scenario, teeth may
have to be extracted and implants or
dentures are required
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