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