Basic Principles of Genetics

Define heredity

Offspring are similar to their parents.

Define variation

Offspring are different from their parents.

Define phenotype

Discerbale properties of an individual.

Define genotype

Genetic info that influences phenotypes.

Define molecular/developmental genetics

Transmitted from DNA to affect cell function + phenotypes.

Define transmission genetics

Transmitted from parent to offspring in families.

Define population/evolutionary genetics

Transmitted over many generations within large populations.

State features of eukaryotes

Animals, plants, fungi + protists. Multicellular or unicellular. Membrane-bound nucleus + organelles. Nuclear genes on multiple, linear chromosomes composed of chromatin (DNA + protein).

State features of prokaryotes

Bacteria. Unicellular. No nucleus. Genes typically on single circular ‘chromosomes’.

Define histones

Highly conserved protein that DNA is wrapped around to form a compact structure.

What is chromatin made of?

DNA + histones.

Define telomeres

Structures at each end of linear chromosomes that protect them from degradation.

Define centromere

Specialised region that acts as a site for the binding of kinetochore proteins. Important for mitosis + meiosis. Can be found at any point in the chromosome.

Define p arm

Stands for petite. Is the shorter chromosome arm.

Define q arm

Longer chromosome arm.

Define loci

Genes are found along the length of the 2 chromosome arms at diff positions.

Define epigenetics

Modifications to chromatin structure can alter gene activity without changing the DNA sequence. Controlled by addition of methyl + acetyl groups to the histone proteins. Heritable.

Define euchromatin

Loosely packed chromatin that can be readily transcribed.

Define heterochromatin

Condensed structure that does not allow expression of genes in that region.

What are methyl groups associated with?

Silent DNA (heterochromatin).

What are acetyl group associated with

Euchromatin.

Define diploid

2n. 2 homologous chromosomes with the same genes but diff alleles.

Define haploid

n. 1 copy of each chromosome, ie gametes.

Define gene

Unit of hereditary info that occupies a fixed position (locus) on a chromosome.

Define cytogenetics

Study of chromosomes.

What is G-banding?

Technique where a chemical called Giemsa is used to stain chromosomes which gives unique banding pattern.

Define karyotype

The chromosome complement of an individual.

Where is most eukaryotic genetic material found?

Nuclear chromosomes.

Apart from in nuclear chromosomes, where else can some DNA be found?

Mitochondria, chloroplasts.

What are mitochondria + chloroplast DNA inherited with?

Cytoplasm that contains these organelles.

What does cytoplasmic inheritance indicate?

That mitochondria + chloroplasts are inherited maternally because egg has large volume of cytoplasm whereas sperm does not.