CYTO311: CYTOGENETICS
WEEK 2: INTRODUCTION TO CYTOGENETICS
BRANCHES OF GENETICS environment are better able to survive and
reproduce than those with less adaptive traits.
1. Classical genetics - refers to the study of the
laws of hereditary transmission in living GREGOR MENDEL
organisms. It began with Mendel’s study of - Published a paper describing how traits are
inheritance in garden peas. passed from one generation to the other,
utilizing pea plants as models
2. Population genetics - The study of genes in - Proposed that traits are passed from parents to
populations of animals, plants, and microbes offspring in a predictable manner
provides information on past migrations, - He further concluded that each trait in pea plants is
evolutionary relationships and extents of mixing controlled by a pair of factors (which we now call
among different varieties and species, and genes) and that members of a gene pair separate
methods of adaptation to the environment. from each other during gamete formation (the
formation of egg cells and sperm)
3. Cytogenetics – branch of genetics that studies
the structure of the DNA within the cell nucleus. CHROMOSOME THEORY OF INHERITANCE
It studies the number and morphology of the
chromosomes. • Heredity is dependent on the genes
contained in the structures called
4. Molecular genetics - the study of the molecular chromosomes. The chromosomes were
structure of DNA, its cellular activities (including contributed to the individual by the gametes.
its replication), and its influence in determining the • Diploid number (2n) – the characteristic
overall makeup of an organism. number of chromosomes a eukaryote has in
most of its cells.
EARLY HISTORY OF GENETICS AND THEORIES • Chromosomes in diploid cells exist in pairs
OF INHERITANCE called homologous chromosomes.
• Aristotle – proposed that “humors” served as
bearers of traits
• William Harvey – proposed the theory of
epigenesis
Preformationism
- states that the fertilized egg contains a
complete miniature adult called a homunculus
Cell theory vs Spontaneous Generation
• Chromosomes behave differently during the
two forms of cell division, mitosis and
meiosis.
Mitosis - the chromosomes are copied and
distributed to each daughter cell. Both cells
obtain a diploid set of chromosomes.
Meiosis, the cells receive only one chromosome
from each chromosome pair, and the resulting
CHARLES DARWIN number of chromosome is called the haploid
- proposed that existing cells species arose by number (n).
descent with modification from ancestral
species. Finally, the chromosomal theory of inheritance states
- Formulated the theory of Natural Selection that “inherited traits are controlled by genes residing
- Natural selection states that individuals with on chromosomes faithfully transmitted through
heritable traits that allow them to adapt to their gametes, maintaining genetic continuity from
generation to generation.”
1
M.M.
WEEK 2: INTRODUCTION TO CYTOGENETICS
BRANCHES OF GENETICS environment are better able to survive and
reproduce than those with less adaptive traits.
1. Classical genetics - refers to the study of the
laws of hereditary transmission in living GREGOR MENDEL
organisms. It began with Mendel’s study of - Published a paper describing how traits are
inheritance in garden peas. passed from one generation to the other,
utilizing pea plants as models
2. Population genetics - The study of genes in - Proposed that traits are passed from parents to
populations of animals, plants, and microbes offspring in a predictable manner
provides information on past migrations, - He further concluded that each trait in pea plants is
evolutionary relationships and extents of mixing controlled by a pair of factors (which we now call
among different varieties and species, and genes) and that members of a gene pair separate
methods of adaptation to the environment. from each other during gamete formation (the
formation of egg cells and sperm)
3. Cytogenetics – branch of genetics that studies
the structure of the DNA within the cell nucleus. CHROMOSOME THEORY OF INHERITANCE
It studies the number and morphology of the
chromosomes. • Heredity is dependent on the genes
contained in the structures called
4. Molecular genetics - the study of the molecular chromosomes. The chromosomes were
structure of DNA, its cellular activities (including contributed to the individual by the gametes.
its replication), and its influence in determining the • Diploid number (2n) – the characteristic
overall makeup of an organism. number of chromosomes a eukaryote has in
most of its cells.
EARLY HISTORY OF GENETICS AND THEORIES • Chromosomes in diploid cells exist in pairs
OF INHERITANCE called homologous chromosomes.
• Aristotle – proposed that “humors” served as
bearers of traits
• William Harvey – proposed the theory of
epigenesis
Preformationism
- states that the fertilized egg contains a
complete miniature adult called a homunculus
Cell theory vs Spontaneous Generation
• Chromosomes behave differently during the
two forms of cell division, mitosis and
meiosis.
Mitosis - the chromosomes are copied and
distributed to each daughter cell. Both cells
obtain a diploid set of chromosomes.
Meiosis, the cells receive only one chromosome
from each chromosome pair, and the resulting
CHARLES DARWIN number of chromosome is called the haploid
- proposed that existing cells species arose by number (n).
descent with modification from ancestral
species. Finally, the chromosomal theory of inheritance states
- Formulated the theory of Natural Selection that “inherited traits are controlled by genes residing
- Natural selection states that individuals with on chromosomes faithfully transmitted through
heritable traits that allow them to adapt to their gametes, maintaining genetic continuity from
generation to generation.”
1
M.M.
