Title: Introduction to Genetics Lecture
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S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
History, Scope, and Applications of Genetics
The traits we inherit from our parents
shape our features and biological
identities.
Each of us carries a unique set of
genes responsible for our physical
characteristics.
traits are determined by the
combination of genes (hereditary
unit) we receive from our parents
with some traits being dominant and
others recessive .
Studying genetics will help us gain
insight into not only our appearance
but also the broader connections we
share with our family and the
genetic legacy that influences who
we are.
Genetics
coined in 1905 by William Bateson (a
British geneticist).
comes from the ancient Greek word
( genetikos ), which means
"generative" or "related to origin". This
word is then derived from
(genesis ), meaning "origin".
Studies how traits are passed down
from one generation to the next;
how genes and DNA vary and how
they interact with the environment.
The Hereditary Material
Before the 1950s, this concept was not well
understood. But it was believed to have the
following features:
Capable of replication
Store information
Variability - capable of change,
undergo variations
Historical Timeline of Genetics
Introduction to Genetics Lecture Module
02
This timeline revisits significant people,
landmark scientific discoveries, and
inventions from the 19th century to the
present that have contributed to the
development of genetics as a science.
These events have shaped our
understanding of heredity, genetic
variation, and the molecular mechanisms
underlying these processes.
1801 Jean Baptiste Lamarck
Profession: French biologist
Theory: Theory of Inheritance of
Acquired Characteristics
(Lamarckism or Lamarckian
inheritance)
Key Idea: Organisms can pass on
traits acquired during their lifetime to
their offspring
Example: Giraffe's long neck early
giraffe ancestors had shorter necks
and stretched to reach higher
leaves. Lamarck believed this
acquired trait could be passed on to
offspring, resulting in longer necks in
the next generation
1865 Gregor Mendel
Profession: Austrian monk, biologist,
and mathematician
Title: "Father of Modern Genetics"
Contribution: Published results of pea
plant experiments
Key Discoveries: S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
Laid the fundamental
knowledge for the field of
genetics
Uncovered essential rules of
inheritance and their
mathematical foundations
Influenced understanding of
transmission of traits across
generations
1866 Ernst Haeckel
Profession: German biologist and
physician
Contribution: Proposed hereditary
material resides in the nucleus
Key Idea: The cell nucleus plays a
role in inheritance (theoretical
proposal)
1868 Charles Robert Darwin
Profession: English naturalist
Contribution: Introduced Pangenesis
Theory in his book The Variation of
Animals and Plants Under
Domestication
Key Idea: Each part of an organism
releases tiny units called gemmules
which travel to the reproductive
organs and influence genetic traits
of the next generation
Impact:
Pangenesis was ultimately
disproved
Modern genetics revealed
that inheritance is
determined by genes (actual
hereditary units), not
gemmules
Darwin is best known for his
widely accepted theory of
natural selection , presented
in his 1859 book On the Origin
of Species by Means of
Natural Selection, or the
Preservation of Favored
Races in the Struggle for Life
Later discoveries in genetics,
especially the role of genes
and variations, have further
validated the principles of
evolution
Here's the continued and fully detailed
Historical Timeline of Genetics , preserving all
original information and organizing it clearly:
1869 Friedrich Miescher
Full Name: Johannes Friedrich
Miescher
Profession: Swiss biologist and
physician
Contribution: First scientist to isolate
nucleic acid , which he named
nuclein
Context:
Conducted research in Felix
Hoppe-Seylers laboratory at
the University of Tbingen
Extracted phosphate-rich
compounds from the nuclei
of white blood cells
In 1874, further experiments
revealed that nuclein
consisted of both nucleic
acid and protein
Impact: Mieschers discovery laid the
foundation for identifying DNA as the
hereditary material S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
18791892 Milestones in Cell Division
This period marked significant progress in
understanding cellular processes, especially
mitosis and the structural components
involved in cell division.
Key Terminologies Introduced and Defined:
Chromatin: Complex of DNA and
proteins found in the nucleus;
condenses to form chromosomes
during cell division
Mitosis: Process of cell division
resulting in two genetically identical
daughter cells
Cytoplasm: Gel-like substance within
the cell membrane, excluding the
nucleus; contains organelles
Nucleoplasm: Viscous fluid within the
nucleus; contains chromatin and
nucleolus
Prophase: First stage of mitosis;
chromatin condenses into visible
chromosomes, nuclear envelope
breaks down
Metaphase: Stage of mitosis where
chromosomes align at the cells
equatorial plane before separation
Key Contributors:
Eduard Adolf Strasburger
Polish-German botanist
Studied cell division in plants
Contributed to
understanding of cytoplasm
and nucleoplasm during cell
division
Walther Flemming
German biologist and
philanthropist
Known as the Father of
Cytogenetics
Observed and described
mitosis in detail (coined the
term in 1882)
Coined the term chromatin
to describe the material
forming chromosomes
Edouard van Beneden
Belgian embryologist and
cytologist
First to describe meiosis at the
chromosomal level in 1883
Observed meiotic division in
Ascaris eggs
1888 Heinrich Wilhelm Gottfried von
Waldeyer-Hartz
Profession: German neuroanatomist
Contribution: Coined the term
chromosome
Definition: Chromosomes are the
compact form of genetic material
present in the nucleus
Impact: Provided a standardized
term for the physical carriers of
genetic information
1893 August Weismann
Profession: German evolutionary
biologist
Contribution: Developed the Germ
Plasm Theory
Key Idea: Inheritance in multicellular
organisms occurs solely through
germ cells (gametes such as egg
and sperm)
Impact: Distinguished between germ
line and somatic cells , influencing
modern genetics and evolutionary
biology S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
1900 Rediscovery of Mendels Work
Three scientists independently rediscovered
Gregor Mendels foundational research on
inheritance:
Hugo de Vries Dutch botanist and
geneticist
Carl Erich Correns German
botanist and geneticist
Erich Tschermak von Seysenegg
Austrian agronomist
Significance:
Their rediscovery validated Mendels
principles of inheritance
Sparked renewed interest in genetics
as a scientific discipline
Marked the beginning of classical
genetics as a formal field of study
1902
Clarence Erwin McClung
American zoologist
Proposed that specific chromosomes
play a role in determining the sex of
animals
Walter Sutton
American geneticist
Theodor Boveri
German zoologist
Developed the Chromosomal Theory
of Inheritance (also known as the
BoveriSutton chromosome theory or
SuttonBoveri theory )
Key Concepts:
Chromosomes are the
carriers and transmitters of
genetic material
Chromosomes are linear
structures that house genes
at specific sites called loci
William Bateson
English biologist
First to use the term genetics to
describe the science of heredity
Also credited with introducing the
following terms:
Homozygote: An organism
with two identical alleles for a
particular gene
Heterozygote: An organism
with two different alleles for a
specific gene
Epistasis: A genetic
interaction where one genes
expression is affected by
another gene
F1: The first filial generation,
offspring of the parental
generation (P)
F2: The second filial
generation, produced by
crossing individuals from the
F1 generation
Allelomorph (or allele):
Different forms of a gene that
can exist at a specific locus
on a chromosome
1905
William Bateson
Continued contributions to
terminology and genetic theory
Reginald Punnett S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
British geneticist
Discovered genetic linkage through
experiments with sweet peas
Defined genetic linkage as the
tendency of DNA sequences close
together on a chromosome to be
inherited together
Also noted that multiple genes can
influence the function of other genes
Lucien Claude Cunot
French geneticist
Described the lethal gene at the
agouti locus (responsible for coat
color) in mice
Identified the concept of multiple
alleles
Nettie Marie Stevens
American geneticist
Edmund Wilson
American zoologist and geneticist
Discovered the XY sex-determination
system in insects
Later, in the 1920s, Theophilus Painter
confirmed that the XY system also
applies to humans and other
mammals
1908
Godfrey Harold Hardy
British mathematician
Wilhelm Weinberg
German obstetrician-gynecologist
Together, Hardy and Weinberg
demonstrated the Hardy-Weinberg
principle (or Hardy-Weinberg
theorem )
Principle states that allele and
genotype frequencies in a
population remain constant over
generations if no evolutionary forces
are acting on it
1909
Wilhelm Johannsen
Danish botanist and geneticist
Introduced the terms gene ,
phenotype , and genotype in his
book Elemente der exakten
Erblichkeitslehre ("Elements of the
Exact Theory of Heredity")
Definitions:
Gene: The fundamental unit
of heredity responsible for
transmitting traits from
parents to offspring
Phenotype: Observable
physical and physiological
traits of an organism resulting
from interaction between
genotype and environment
Genotype: The genetic
constitution of an organism,
specifically the alleles it
possesses for a particular
gene
1910 Thomas Hunt Morgan
Profession: American evolutionary
biologist and geneticist
Contributions:
Discovered sex linkage in
Drosophila (fruit flies),
showing that certain traits are
associated with sex
chromosomes
Along with Calvin Bridges ,
discovered chromosomal
nondisjunction in Drosophila, S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
a phenomenon where
chromosomes fail to
separate properly during cell
division
1913 Alfred Henry Sturtevant
Profession: American geneticist
Contribution:
Mapped the genes of
Drosophila within their
chromosomes
Created the first genetic
map of the fruit fly,
establishing the concept of
gene order and linkage on
chromosomes
1914 Calvin Blackman Bridges
Profession: American geneticist
Contributions:
Collaborated with Thomas
Hunt Morgan to observe
nondisjunction in Drosophila
Made key observations in
Drosophila genetics:
Chromosomal
deficiencies (1917):
segments of
chromosomes missing
Duplications (1919):
segments of
chromosomes
repeated
Translocations (1923):
rearrangement of
chromosome
segments between
non-homologous
chromosomes
1928 Frederick Griffith
Profession: British bacteriologist
Contribution:
Conducted the Griffith
experiment (also known as
the Transformation
experiment )
Demonstrated bacterial
transformation , showing that
bacteria can transfer
heritable genetic information
Key Findings:
Heat-killed III-S
(smooth strain) mixed
with live II-R (rough
strain) caused death
in mice
Live III-S and II-R strains
were recovered from
the mice
Concluded that a
"transforming
principle" from dead
III-S bacteria
converted II-R into
lethal III-S
Later research identified this
transforming principle as DNA
1931 Harriet Creighton and Barbara
McClintock S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
Professions:
Harriet Creighton: American
botanist and geneticist
Barbara McClintock:
American cytogeneticist
Contribution:
Published a groundbreaking
paper describing
chromosomal crossover
Demonstrated that linked
genes undergo physical
exchange of chromosome
segments
Confirmed that
chromosomes carry genetic
information , and genes are
located on these structures
1941 George Beadle and Edward Tatum
Professions: American geneticists
Contribution:
Proposed the one geneone
enzyme hypothesis
Hypothesis states that each
gene produces a specific
enzyme, which influences a
single step in a metabolic
pathway
This concept linked genes
directly to biochemical
functions
1944 Oswald Avery, Maclyn McCarty,
and Colin MacLeod
Professions:
Oswald Avery:
Canadian-American
molecular biologist
Maclyn McCarty: American
geneticist
Colin MacLeod:
Canadian-American
geneticist
Contribution:
Conducted the
AveryMacLeodMcCarty
experiment
Aimed to purify and
characterize the
"transforming principle" from
Griffiths 1928 experiment
Demonstrated that DNA , not
protein, is responsible for
bacterial transformation
Challenged the prevailing
belief that proteins were the
carriers of genetic
information
1948 Barbara McClintock
Profession: American cytogeneticist
Contribution:
Discovered transposable
genes , also known as
"jumping genes"
Observed that certain DNA
segments can move from
one location to another
within the genome
This discovery revealed a
dynamic aspect of the
genome and gene
regulation
1950 Erwin Chargaff
Profession: Austro-Hungarian-born
American biochemist
Contribution:
Formulated Chargaffs rules
Key Principles: S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
In DNA, the amount
of guanine (G) equals
cytosine (C)
The amount of
adenine (A) equals
thymine (T)
There is a 1:1
stoichiometric ratio of
purine (A + G) to
pyrimidine (T + C)
bases
These findings were critical to
understanding DNA structure
1951
Rosalind Franklin British chemist Maurice
Wilkins New Zealand-born British
biophysicist Raymond Gosling British
physicist
Conducted X-ray diffraction studies
revealing the helical structure of
DNA
Franklin produced high-quality
images, notably Photo 51 (taken by
Gosling), indicating DNAs helical
shape and dimensions
1953
James Watson American molecular
biologist Francis Crick English biophysicist
and molecular biologist
Elucidated the chemical structure of
DNA using Chargaffs data and
Franklins X-ray images
Along with Wilkins, Watson and Crick
were awarded the 1962 Nobel Prize
for Physiology or Medicine
1957
Francis Crick
Proposed the Central Dogma of
Molecular Biology
Described in his 1970 Nature paper:
1958
Matthew Meselson and Franklin Stahl
American geneticists and molecular
biologists
Conducted the MeselsonStahl
experiment
Provided strong evidence for the
semiconservative model of DNA
replication proposed by Watson and
Crick
1961
Jacques Monod French biochemist
Franois Jacob French molecular biologist
Published Genetic Regulatory
Mechanism
Described the lac operon in E. coli ,
explaining gene regulation in
prokaryotes
1966
Marshall Nirenberg , Har Khorana , Severo
Ochoa , Robert Holley
Deciphered the genetic code
Revealed how nucleic acids
determine the sequence of amino
acids in proteins
1960s
Werner Arber , Daniel Nathans , Hamilton
Othanel Smith S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
Discovered restriction enzymes ,
capable of cleaving DNA into
specific fragments
Awarded the 1978 Nobel Prize for
Physiology or Medicine
1970s
Allan M. Maxam , Walter Gilbert , Frederick
Sanger
Developed early methods of DNA
sequencing
Gilbert and Sanger received the
1980 Nobel Prize for Chemistry
1972
Paul Berg American biochemist
Created the first recombinant DNA
molecule by splicing bacterial and
viral DNA
Established a general method for
combining distinct DNA molecules
1982
Establishment of GenBank
DNA sequence database founded
by Walter Goad and Los Alamos
National Laboratory
Became part of the National Center
for Biotechnology Information (NCBI)
in 1988
1983
Kary Mullis American biochemist
Invented the polymerase chain
reaction (PCR)
Technique amplifies specific DNA
sequences from small samples
Awarded the 1993 Nobel Prize for
Chemistry
1990
Human Genome Project (HGP)
International effort to map and
understand the complete human
genome
Objectives:
Identify all genes on each
chromosome
Elucidate their biochemical
characteristics
Spanned 15 years
2001
Publication of the Human Genome
Sequence
Approx. 2,900 Mbp in length
Initial gene count estimate:
35,00040,000
Revised in 2002 to ~30,000 genes
2002
International HapMap Project
Mapped genetic variations linked to
human diseases
Cataloged ~3.1 million variants by
Phase II (2007)
Advanced understanding of disease
genetics and personalized medicine
2008
1000 Genomes Project (1KGP)
Ran from 2008 to 2015 S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
Sequenced genomes of over 2,500
individuals from diverse ethnic
backgrounds
Created the most complete catalog
of human genetic variation at the
time
2011
DNA Sequencing of Various Organisms
Organism Completed Ongoing
Viruses 2,688 0
Microbes 1,710 6,085
Fungi 208 205
Animals 182 256
Plants (+algae) 47 107
2020 to Present Recent Developments
Emmanuelle Charpentier French
microbiologist and geneticist Jennifer A.
Doudna American biochemist
Awarded the 2020 Nobel Prize in
Chemistry
Recognized for developing a
method for genome editing
(CRISPR-Cas9)
Svante Pbo Swedish geneticist
Awarded the 2022 Nobel Prize in
Physiology & Medicine
Honored for discoveries concerning
the genomes of extinct hominins and
human evolution
Katalin Karik Hungarian-American
biochemist Drew Weissman American
immunologist
Awarded the 2023 Nobel Prize in
Physiology & Medicine
Recognized for discoveries in
nucleoside base modifications
enabling mRNA vaccine
development against COVID-19
# Branches of Genetics
Genetics is a broad scientific field that
investigates heredity, variation, and
molecular mechanisms. Each branch
focuses on specific aspects of genetic
function and inheritance, with applications
across biology, medicine, and
biotechnology.
Classical Genetics
Focuses on how genetic traits are
inherited through reproduction
Based on patterns observed before
molecular techniques were
developed
Key areas:
Mendelian Genetics
Genetic Linkage
Genetic Mapping
Cytogenetics S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
Studies the relationship between
chromosomes and cell division
processes
Includes analysis of mitosis and
meiosis
Investigates chromosomal
abnormalities
Molecular Genetics
Examines how changes in DNA
structure or gene expression lead to
variation among organisms
Topics include:
Gene editing
Genetic engineering
Microbial Genetics
Investigates inheritance and genetic
function in microorganisms
Covers:
Conjugation
Bacterial transformation
Horizontal gene transfer
Incorporates molecular techniques
such as genetic engineering and
gene editing
Human Genetics
Focuses on inheritance and genetic
factors specific to humans
Encompasses a wide range of
applications studied within the
human context
Medical Genetics
Concentrates on the genetic basis
of diseases, disorders, and conditions
Explores implications for patient care
and treatment
Population Genetics
Studies genetic variation within and
between populations
Central to evolutionary biology
Examines processes such as:
Adaptation
Speciation
Determination of allelic and
other genetic characteristics
of populations
# Scope and Applications
# of Genetics
Genetics has broad applications across
multiple fields, from agriculture and
medicine to law and biotechnology. These
applications demonstrate how genetic
principles are used to solve real-world
problems and improve quality of life.
Plant and Animal Improvement
Selective breeding is used to choose
parents with favorable traits
Offspring are more likely to inherit
and express those traits
Widely applied in agriculture and
livestock production to enhance
yield, resistance, and quality
Medicine
Involves:
Studying inheritance patterns
Mapping disease-related
genes
Diagnosing and treating
genetic disorders S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
Providing genetic counseling
to patients and families
Applications include personalized
medicine and gene therapy
Legal Applications
Genetics is used in:
Criminal investigations (e.g.,
DNA fingerprinting)
Paternity disputes and family
law cases
DNA evidence helps establish
identity and biological relationships
Genetic Engineering
Enables mass production of medical
products through recombinant DNA
technology
Examples include:
Insulin
Human growth hormone
Follistim (infertility treatment)
Human albumin
Monoclonal antibodies
Antihemophilic factors
Vaccines
Other therapeutic drugs
# Practice: Applying
# Genetics in Forensics
Scenario #1 Murder
Investigation
Five DNA samples collected:
One from the victim
One unknown sample
Three from suspects
Task: Compare the banding patterns
in the gel electrophoresis image
Goal: Identify which suspects DNA
matches the unknown sample by
aligning the bands
(Note: Image analysis required to determine
match. If you upload the gel image, I can
help interpret it.)
Scenario #2 Paternity Test
Individuals tested:
Jane (Mother)
Joe (F1)
Thomas (F2)
Child
Task: Compare DNA bands of the
child with those of Jane, Joe, and
Thomas
Goal: Determine which man shares
the most matching bands with the
child, excluding maternal bands
Conclusion: The biological father will
share all remaining bands with the
child that do not come from the
mother
(Again, image analysis is needed. If you
provide the gel image, I can help identify
the father based on band patterns.)
# Lesson Summary
Introduction to Genetics Lecture Module
02
Historical Timeline of Genetics
Genetics began in the mid-1800s
with Gregor Mendels pea plant
experiments, establishing the basic
principles of inheritance. S-BIOL3 27a Introduction to Genetics Lecture
Module 1 - History, Scope, and Applications of Genetics | 1st Semester | BSY43
In the early 20th century, discoveries
about chromosomes and DNA
expanded this foundation.
A major breakthrough occurred in
the 1950s when James Watson and
Francis Crick identified the double
helix structure of DNA , using data
from Rosalind Franklin , Maurice
Wilkins , and Erwin Chargaff .
This discovery revolutionized our
understanding of heredity and
propelled genetic research forward
in the decades that followed.
Branches of Genetics
Genetics is divided into multiple specialized
branches, each focusing on different
aspects of heredity and variation:
Classical Genetics : Studies
inheritance through reproduction;
includes Mendelian genetics,
genetic linkage, and mapping.
Cytogenetics : Examines
chromosomes and cell division
(mitosis and meiosis), including
chromosomal abnormalities.
Molecular Genetics : Investigates
how changes in DNA structure or
expression lead to variation; includes
gene editing and genetic
engineering.
Microbial Genetics : Focuses on
genetic mechanisms in
microorganisms, including
conjugation, transformation, and
horizontal gene transfer.
Human Genetics : Explores genetic
traits and inheritance patterns
specific to humans.
Medical Genetics : Studies genetic
causes of diseases and disorders,
with implications for diagnosis,
treatment, and patient care.
Population Genetics : Analyzes
genetic variation within and
between populations, contributing
to evolutionary biology.
Scope and Applications of
Genetics
Genetics has wide-ranging applications
across science, medicine, and society:
Plant and Animal Improvement :
Selective breeding is used to
produce offspring with
desirable traits.
Medicine :
Involves studying inheritance
patterns, mapping
disease-related genes,
diagnosing genetic disorders,
and providing genetic
counseling.
Legal Applications :
Used in criminal investigations
and paternity cases through
DNA analysis.
Genetic Engineering :
Enables mass production of
medical products such as
insulin , vaccines , human
growth hormone ,
monoclonal antibodies , and
other essential drugs.
Addresses healthcare
demands and medication
shortages globally.