ENT 137 - MODULE 1

Genetic Specimen

Insects have several characteristics that make experiments easier.

Genetic and Physiological Similarities to Mammals

Many insects and human genes and biological processes are similar.

Easy to Mass Produce

Generally easy to breed in large numbers.

Short life cycle

Scientists can observe multiple generations relatively quickly.

High reproductive rate

Can produce many offspring.

Equivalent organs and similar biological systems

Different body, similar biological machinery.

Drosophila melanogaster

Fruit fly.

Galleria mellonella

Greater wax moth.

Tribolium castaneum

Red flour beetle.

Drosophila melanogaster genome size

1.32 x 10^9 bp genome.

Number of genes in Drosophila

Approximately 14,000 genes.

Chromosome pairs in Drosophila

4 chromosome pairs.

Homolog

Homologous when evolved from a common ancestral gene.

Ortholog

Homologous genes found in different species that came from a common ancestral gene through speciation.

Mutant

Organism whose DNA has undergone mutation.

Chemical mutagenesis

Scientists use chemicals that cause changes in DNA.

Irradiation

Can damage DNA and produce mutations.

Transposon Insertion

A piece of DNA that can move around the genome.

Chromosomal Theory of Inheritance

Genes are located on chromosomes, and the behaviour of chromosomes during cell division helps explain how traits are inherited.

Mitosis

Cell division that produces daughter cells while maintaining chromosome number.

Meiosis

Produce reproductive cells and involves the separation of chromosome pairs.

Henking, 1891

Observed an extra chromosome in the sperm-producing cells of the bug Pyrrochoris.

McClung, 1902

Observed the extra chromosome in grasshoppers.

Sutton's Big Idea

Proposed the Chromosome Theory of Inheritance.

Reciprocal Crosses

Reverse which parent has which phenotype/sex.

Sex-linked inheritance

Mother - Son - Granddaughter

Nondisjunction

Chromosomes fail to separate properly

Bridge

During oogenesis - egg formation - the maternal X chromosomes can fail to separate

Exceptional Females

XXY

Exceptional Males

X0