Genetics Introduction

Genetics

the study of heredity and the variation of inherited characteristics.

Heredity

biological process where a parent passes certain genes onto their children or offspring.

Genes

are the units of heredity and are composed of DNA.

Claudius Galenus

argued that active "humors" in various parts of the body served as the bearers of hereditary traits.

Galen

proposed that both males and females produce "seed" (seminal material), which combines during reproduction to create offspring.

Epigenesis

proposed that the male semen contained a “vital heat” with the capacity to produce offspring of the same “form” as the parent.

Preformation

States that that organisms develop from miniature versions of themselves

Pangenesis

"Gemmules" or "Pangenes" from different body parts are transported to the reproductive organs and passed to the offspring.

Germplasm Theory

Argued that heredity is carried by germ cells (eggs and sperm) rather than somatic (body) cells.

Blending Inheritance

suggests that offspring are a blend of parental traits.

Particulate Inheritance

traits are inherited as discrete units (genes), which segregate and assort independently during reproduction

Gregor Mendel

Father of genetics

Law of Segregation

traits are determined by "factors" that segregate independently during formation of gametes.

Law of Independent Assortment

Genes for different traits are inherited independently of each other.

Dominant Trait

Visible trait

Recessive Trait

hidden trait

Francis Galton

coined the term eugenics

Eugenics

practice of improving human life by having a selective breeding

semi-conservative model

two strands of a DNA molecule separate during replication and then strand acts as a template for synthesis of a new, complementary strand.

conservative model

proposes that the entire DNA duplex acts as a single template for the synthesis of an entirely new duplex.

dispersive model

two strands of the double helix breaking into units that which are then replicated and reassembled duplex acts as a single template for the synthesis of an entirely new duplex.

DNA

double stranded polymer consisting of a chain of nucleotides

RNA

single stranded polymer of ribonucleotides.

Genome

complete set of genetic information for an organism

Beadle and Tatum:

States that each of the enzymes that act in a biochemical pathway is encoded by a different gene.

Alleles

variants of a gene

Chromosomes

Composed of DNA and protein

Karyotype

chromosomes organized by the size of the chromosome pairs

Chromosomal Theory of Inheritance

traits are controlled by genes residing on chromosomes faithfully transmitted through gametes