Introduction to genetics, variation

1. Lecture 1
Genetics: The Science
of Heredity and Variation

2. Intended Learning Outcomes
After the completion of the chapter, the
students will be able to:
1. define Genetics;
2. identify people who had significant
contributions in Genetics; and
3. cite specific applications of Genetics.

3. Genetics
 study of heredity and variation
transmission of traits
from parent to
offspring.
similarities
and
differences

4. BRANCHES OF GENETICS
1. Molecular genetics- is the field
of biology and genetics that studies the structure and
function of genes at a molecular level.
2. Developmental Genetics - the study of how genes
control the growth and development of an organism
throughout its life-cycle
3. Cytogenetics - is a branch of genetics that is concerned
with the study of the structure and function of the cell,
especially the chromosomes

5. 4. Biochemical Genetics - the study of the
fundamental relationships between genes, protein,
and metabolism. This involves the study of the
cause of many specific heritable diseases
5. Behavioral Genetics - is the field of study that
examines the role of genetics in animal (including
human) behavior.

6. 6. Population Genetics - is the study
of allele frequency distribution
7. Quantitative Genetics - is the
study of continuously measured traits
(such as height or weight) and their
mechanisms.

7. The Beginnings of Genetics

8. Discovery of Cells
 In 1665, Robert Hooke used a
microscope to examine thin slices of
cork.
 He observed that cork is made of tiny,
hollow compartments. The
compartments reminded him of small
rooms so he gave the 'rooms' the
name 'cells'.
 He actually observed the cell walls
and empty space.

9. 1. The cell is the basic unit of
life.
2. All organisms are composed
of cells.
3. All cells come from
preexisting cells.
# 1 and 2
Matthais Schleiden ( German
botanist, 1838) & Theodor
Schwann (German zoologist, 1839)
#3
Rudolph Virchow (German
physician, 1850’s)

10. Before Mendel's time
⚫Heredity was thought to be a blending
process
⚫Offsprings were mixtures of
characteristics from both parents.

11. Mendel’s Work on Transmission of
Traits
Gregor Mendel, an
Augustinian monk, conducted
a decade long series of
experiments using pea plants
(Pisum sativum).
He applied quantitative data
analysis to his results and
showed that traits are passed
from parents to offspring in
predictable ways.

12. 1
5
4
3
2
Removed stamens
from purple flower
Transferred sperm-
bearing pollen from
stamens of white
flower to egg-
bearing carpel of
purple flower
Parental
generation
(P)
Pollinated carpel
matured into pod
Carpel
(female)
Stamens
(male)
Planted seeds
from pod
Examined
offspring:
all purple
flowers
First
generation
offspring
(F1)
Crossing Pea Plants

14. He further concluded that each trait in
pea plants is controlled by a pair of
factors (which we now call genes) and
that members of a gene pair separate
from each other during gamete formation
(the formation of egg cells and sperm).
Mendel’s findings explained the
transmission of traits in pea plants and
all other higher organisms. His work
forms the foundation for GENETICS

15. Gregor Johann Mendel published a paper
in 1866 showing how traits were passed
from generation to generation in pea plants
and offered a general model of how traits
are inherited (not blending of traits).
His research was little known until it was
partially duplicated and brought to light by
Carl Correns, Hugo de Vries, and Erich
Tschermak around 1900.

16.  By the early part of the twentieth century, it
became clear that heredity and development
were dependent on genetic information residing
in genes contained in chromosomes, which
were then contributed to each individual by
gametes—the so-called chromosome theory
of inheritance.

17.  Sutton and Boveri each proposed
that genes are carried on
chromosomes. They independently
formulated the chromosomal
theory of inheritance, which states
that inherited traits are controlled by
genes residing on chromosomes
faithfully transmitted through
gametes, maintaining genetic
continuity from generation to
generation.

18. Applications of
Genetics

19. 1)Eugenics and Euphenics
 improvement of human
existence
positive eugenics
• encouraged parents displaying favorable
characteristics to have large families
(superior intelligence, artistic talent)
negative eugenics
•restrict reproduction of parents displaying
unfavorable characteristics
(low intelligence, mental retardation, criminal
behavior)

20. In the United States:
(1907) sterilization of those considered
‘genetically inferior”
(idiots, convicted rapists, and habitual criminals,
sexual perverts, drunkards and epileptics)
immigration to the US from certain areas of Europe
and from Asia was restricted to prevent the influx of
what were regarded as genetically inferior people

21. In Nazi Germany (1930):
Adolf Hitler and the Nazi regime aimed at the
extinction of these ”impure” human population
(Jews and Gypsies)
⚫ forced sterilization and mercy killings led to
mass murder

22. Eugenics
 There were mistaken notions that
superior and inferior traits are totally
under genetic control.
⚫ The potential impact of the
environment and the genetic theory
underlying population genetics were
ignored.
Many geneticists chose not to study
human genetics for fear of being
grouped with those who supported
eugenics.

23. Today:
A new term, euphenics, has replaced
eugenics
Euphenics
⚫ refers to medical/genetic intervention
designed to reduce the impact of
defective genotypes on individuals
⚫ use of insulin by diabetics; dietary control
of newborn phenylketonurics

24. 2.Advances in agriculture
2.1. selective breeding
techniques (plants)
a. enhanced potential for
more vigorous growth
and increased yields
b. increased resistance to
natural predators and pests,
including insects and
disease-causing
microorganisms

25. 2.1. selective breeding techniques (plants)
c. selection of genetic variants with
desirable qualities
(increased protein value)
e. smaller plant size reducing vulnerability
to adverse weather conditions

26. 2.2. selective breeding (in animals)
a. chickens that grow
faster
b. produce more quality
meat per chicken
c. lay greater numbers of
larger eggs

27. 2.3. artificial insemination has been
applied to larger animals (pigs, cows)
a. Sperms from a single male
with superior genetic traits may
now be used to fertilize
thousands of females

28. 3. Advances in
medicine
3.1. numerous disorders in humans have been discovered
(hemophilia, Tay-Sachs disease, diabetes)
3.2. more effective early detection of cancer and more
efficient approached to treatment
3.3. Advances in immunogenetics have made possible
compatible organ transplants

29. 4. Legal Applications
DNA fingerprinting

30. 4. Legal Applications
⚫solve problems of disputed parentage in settling
child support/baby mix-up in hospitals

31. References
Klug, W. S., & Cummings, M. R., Spencer, C.A., Killian D.,
Palladino M.A. (2019). Essentials of genetics. USA:
Pearsom Prentice Hall.
Mendioro et al. (2018). Genetics laboratory manual. 13th
revision. UPLB: Lakes Printing Press.
Images from the internet.
Prepared by: ACPanaligan