The document provides an extensive overview of genetics, detailing its history, key concepts, and terminologies such as DNA, genes, and alleles. It highlights major discoveries and contributions from figures like Gregor Mendel and Charles Darwin, as well as the implications of genetics in various fields including medicine, biotechnology, and wildlife conservation. The document also explains Mendel's laws of inheritance and the significance of genetic variation and heredity in organisms.

1. BIO 15
Introduction to
Genetics
VE RA MA R I E MI RA B U EN O

2. Overview of
this topic
LIST OF KEY CONCEPTS
• The beginning of Genetics
• Terminologies used in this topic
• The Scope of Genetics

3. What is
Genetics?
THE SCIENCE OF COMING INTO
BEING
The term Genetics was introduced by Bateson
in 1906. It was derived from the Greek word
“Gene” which means “to become” or “to grow
into”

4. What is
Genetics?
THE SCIENCE OF COMING INTO
BEING
The branch of biology deals with heredity,
especially the mechanisms of heredity
transmission and the variation of inherited
characteristics among similar or related
organisms.
GENETICS is the branch of biological sciences
that deals with the transmission of
characteristics from parent to offspring.

5. History of
GENETICS
19TH CENTURY
• In 1859, Charles Darwin gave the theory
of evolution.
• How organisms evolve with time.
• He visited the Galapagos Island to study
finches.

6. History of
GENETICS
GREGOR MENDEL
“Father of Genetics”
• He experimented on a pea plant and
discovered how traits are passed from one
generation to the next.
• Laws of Mendel
- “Law of Independent assortment”
- “Law of Segregation”

7. History of
GENETICS
FREIDRICH MIESCHER, 1869
• He had successfully isolated the “nuclein”
inside the nuclei of the human white
blood cells.
• Not long after, he was able to prove that
“nuclein” is present in other cells as well.

8. History of
GENETICS
ERNST HAECKEL, 1871
• A German Zoologist and a naturalist.
• His experiments proved that the genetic
material is indeed located in the nucleus.

9. History of GENETICS
During the 20th century to current,
• 1902: Walter Sutton and Theodore Boveri postulated the
Chromosomal theory which describes that chromosomes carry
the cell’s genetic material (gene).
• 1905: Nettie Stevens observed the sex chromosomes X and Y.
• In the same year, Thomas Morgan discovered the sex linked
inheritance of the white eye traits in fruit flies (Drosophila
melanogaster).
• 1905: William Bateson coined the term “genetics” from the Greek
word “genno” which means “to give birth” in order to describe
the study of inheritance and variation.
• 1909: Bateson published his book entitled “Mendel’s Principles of
Heredity.

10. History of GENETICS
During the 20th century to current,
• 1910: Reginald Punnett and William Bateson discovered the
science of genetic linkage. They also coined the term “epistasis:
to describe the interaction between two different traits.
• 1944: The experiments of Oswald Avery and his colleagues
proved that the DNA is the molecule responsible for inheritance.

11. History of GENETICS
During the 20th century to current,
• 1953: James Watson and Francis Crick
The three-dimensional and double helix model of the DNA was
proposed by James Watson and Francis Crick. Such discovery also
paved the way for the formation of basis of other fields like cell
biology and biotechnology. In the same year, the process of DNA
replication was discovered.

12. History of GENETICS
During the 20th century to current,
• Frederick Sanger, 1977
In 1977, a british biochemist named Frederick
Sanger introduced the process of sequencing the
genome (set of genes of an organism) of a
bacteriophage. Later, scientists have done it in other
organisms as well and he is The first to determine the
amino acid sequence of insulin.

13. History of GENETICS
During the 20th century to current,
• 1983: Kary Mullis invented the process called Polymerase Chain
Reaction. In this technique, a segment of the DNA is amplified
until millions of copies are produced in just a short period.
• 1990: In this year, the Human Genome Project was started.
• 1996: In this year, Ian Wilmut and Keith Campbell have
successfully cloned DOLLY the sheep. Dolly was the first
mammal to be cloned from an adult cell.

14. History of GENETICS
• 2003: The Human Genome project was completed in 2003. The
results of the project showed for the first time the complete
genetic make up for building a human being.
• And the work goes on.

15. • DNA is made up of four similar
chemicals (called bases and
abbreviated A, T, C, and G)
repeated over and over in pairs.
TERMINOLOGIES
What is DNA?
• DNA (deoxyribonucleic acid)
carries the genetic information
in the body’s cells.
• Adenosine, Thymine, Cytosine,
Guanine

16. • Genes are coded instructions
for making everything the body
needs, especially proteins.
TERMINOLOGIES
What is a Gene?
• A gene is a distinct portion of a
cell’s DNA.
• Human beings have about
25,000 genes. Researchers have
discovered what some of our
genes do, and have found that
are associated with disorders
(such as cystic fibrosis or
Huntington’s disease). There
are, though, many genes whose
functions are still unknown.
• Gene holds the information to
maintain their cells and pass
genetic traits to offspring.

17. TERMINOLOGIES
What is an Allele?
• Alleles are pairs or series of genes on
a chromosome that determines the
hereditary characteristics. An example
of an allele is the gene that
determines hair color.
• An allele is located at a fixed position on a
chromosome. Chromosomes exist in pairs, so
organisms have two alleles for each gene—
one on each chromosome in the pair. Because
each chromosome in the pair comes from a
different parent, organisms inherit one allele
for each gene from each parent. The two
alleles inherited from parents can be the same
(homozygous) or different (heterozygous). This
article explains the key difference between
gene and allele.

18. TERMINOLOGIES
What is an Allele?
• A dominant allele produces a
dominant phenotype in individuals
with one copy of the allele, which can
come from just one parent.
• For a recessive allele to produce a
recessive phenotype, the individual
must have two copies, one from each
parent.
• An individual with one dominant and
one recessive allele for a gene will
have the dominant phenotype. They
are generally considered “carriers” of
the recessive allele: the recessive allele
is there, but the recessive phenotype
is not.

19. TERMINOLOGIES
What is a Phenotype?
• A phenotype (from Greek phainein,
meaning "to show", and typos,
meaning "type") is the composite of an
organism's observable characteristics
or traits, such as its morphology,
development, biochemical or
physiological properties, phenology,
behavior, and products of behavior
(such as a bird's nest).

20. INSIDE THE CELL

21. SCOPE/APPLICATIONS
OF
GENETICS

22. 1.GENETICS AS BASIS OF BIOLOGICAL
SCIENCES;
Genetics has scope/role in the
following fields:
Provide foundation for biological studies. Laws of
inheritance help us to understand the principles of
embryology, population, taxonomy, evolution and ecology.
2. ROLE OF GENETICS IN FOOD PRODUCTION
Rules of genetics help to introduce new verities of plants
and livestock.

23. 3. DISEASE CONTROL
Genetics has scope/role in the
following fields:
Gene therapy help to cure many genetics based diseases.
4. CONSERVATION OF WILDLIFE
Conservation of wildlife can be achieved in one way by
conserving the germplasm of endangered species.
5. GENETIC ENGINEERING/BIOTECHNOLOGY:
Genetic Engineering has many applications including
a. Development of transgenic crops.
b. Gene therapy
c. Improvement in Food production
d. Control of Genetic Diseases
e. Gene Mapping

24. 6. BEHAVIORAL GENETICS
Genetics has scope/role in the
following fields:
It studies the influence of varying genetics on animal
behavior.
7. CLINICAL GENETICS
There are several genetic disorder exist physicians are
trained to diagnose and treat.
8. MOLECULAR GENETICS
It focus on structure and function of gene.

25. 9. POPULATION AND ECOLOGICAL GENETICS
Genetics has scope/role in the
following fields:
Population and ecological genetics are closely related
subfields of genetics. Population genetics is the study of
distribution and change in allele.
10. GENOMICS
It allows the study of large scale genetic pattern
i.e GENOMIC SEQUENCE

27. MENDELIAN PATTERNS OF
INHERITANCE

28. GREGOR JOHANN MENDEL (1822-1884)
Born in 1822 near Brunn in Austria, in a poor family
Studied the inheritance of traits in the garden pea.
FATHER OF GENETICS
Austrian monk
Published his theory in 1866 “Experiments on Plant Hybrids”
In 1900, the work of Mendel was independently rediscovered by
• Hugo de Vries (Holland)
• Carl Correns (Germany)
• Erich Tshermak (Austria)

29. PEA PLANTS are a
GOOD MODEL
• Peas are easy to grow
• They reproduce quickly
• Emasculation and pollination quite
easy
• They are capable of self fertilization

30. Mendelian’s Pattern of
Inheritance
TRUE BREEDING
Organisms that are homozygous for genes. This
means that both alleles are the same, so PP or TT as
opposed to Pp or Tt. When true breeding organisms
are crossed, all progeny will have the same phenotype
as the parents.
HYBRIDS
The process of cross-fertilization also called as genetic
cross.
HYBRIDIZATION
Offspring of two different varieties
P generation
True breeding parents (P for parental) and their hybrid
offspring are called the F1 generation (F for filial, from
latin word for “son”). When F1 plants self-fertilize or
fertilize each other, their offspring are the F2
generation.

31. Quick Question.
IF TRUE-BREEDING WHITE AND TRUE-BREEDING
PURPLE PEAS WERE CROSSED, WHAT TERMS WOULD
BE USED TO DESCRIBE THEIR OFFSPRING?

32. Quick Question.
IF TRUE-BREEDING WHITE AND TRUE-BREEDING
PURPLE PEAS WERE CROSSED, WHAT TERMS WOULD
BE USED TO DESCRIBE THEIR OFFSPRING?
Answer: Their offspring would be F1 generation,
and they would be called hybrids.

33. GENE
Important terms to remember!
Unit of inheritance usually occurring at specific locations, or loci,
on a chromosome. Physically, a gene is a sequence of DNA bases
that specify the order of amino acids in a protein. Genes are
responsible for hereditary traits in plants and animals.
ALLELE
An alternative form of a gene
that occurs at the same locus
on homologous
chromosomes

34. DOMINANT ALLELE
Important terms to remember!
An allele that masks the presence of a recessive allele in the phenotype. Dominant
alleles for a trait are usually expressed if an individual is homozygous dominant or
heterozygous.
RECESSIVE ALLELE
An allele that is masked in the phenotype by the presence of a dominant allele.
Recessive alleles are expressed in the phenotype when the genotype is homozygous
recessive.
The uppercase letters are used
to denote dominant alleles,
whereas the lowercase letters
are used to denote recessive
alleles.

35. HOMOZYGOUS
Important terms to remember!
Having the same allele at the same locus on pair of homologous chromosomes.
Homozygous also refers to a genotype consisting of two identical alleles of a gene
for a particular trait. Individuals who are homozygous for a trait are reffered to as
homozygotes.

36. HETEROZYGOUS
Important terms to remember!
a genotype consisting of two different alleles of a gene for a particular trait (Bb).
Individuals who are heterozygous for a trait are referred to as heterozygotes.

37. Mendel’s Laws of
Inheritance
1.LAW OF DOMINANCE
2.LAW OF SEGREGATION
3.LAW OF INDEPENDENT ASSORTMENT

38. GENOTYPE
Important terms to remember!
refers to an individual’s the “genetic potential” - what kind of genes he or she carries.
PHENOTYPE
(from the Greek word “pheno” meaning “to show”) refers to teh traits an individual
actually shows.

39. Law of Dominance
In a cross of parents that are pure for contrasting traits, only one form of the trait
will appear in the next generation. All offspring will be hybrid for a trait and will have
only the dominant trait express the phenotype. The phenotype trait that is NOT
expressed in the hybrid is called recessive.

40. Law of Dominance
Genotypic Ratio: 1:2:1
Phenotypic Ratio: 3:1

41. Law of Segregation
Mendel’s LAW of SEGREGATION states that TWO ALLELES of a GENE that are
found on a chromosome pair separate, with the offspring receiving one from
the mother and one from the father. According to Mendel’s Law, the two alleles
act in a segregated fashion and do not mix or change each other.
These two alleles will be separated from each other during meiosis. Specifically,
in the second of the two cell divisions of meiosis. Specifically, in the second of
the two cell divisions of meiosis the two copies of each chromosome will be
separated from each other, causing the two distinct alleles located on those
chromosomes to segregate from one another.
This law is also referred to as LAW OF PURITY OF GAMETES.

42. Law of Segregation

43. The Law of Independent Assortment
It states that inheritance of one character is always independent of the
inheritance of other characters within the same individual.
Law of independent assortment is based DIHYBRID CROSS.
The alleles of two more genes get sorted into gametes independent of each
other. The allele received for one gene does not influence the allele received for
another gene.
Genes linked on a chromosome can rearrange themselves through the process
of crossing-over. Therefore, each gene inherited independently.

44. The Law of Independent Assortment

45. Activity
Suppose you crose a pure-breeding, black-coated dog with curly fur to a pure-breeding,
yellow-coated dog with straight fur. In the F1 generation, all the puppies have straight, black
coats. Next, you interbreed the F1 dogs with one another to get an F2 generation.
If coat color and coat texture are controlled by two genes that assort independently, what
fraction of the F2 puppies are expected to have yellow, straight fur?
a. 3/16 b. 1/4 c. 1/16 d. 3/4
Choose 1 answer, list down the phenotypes and genotypes, use a punnet square and show
the ratio, refer in slide 44 as reference on how to answer;