Lecture 1 Genetics BIOL3401

Introduction to Genetics

Genetics

The study of genes, genetic variation and heredity

Traits

Are observable characteristics of an organism

DNA

Deoxyribonucleic acid, double helix of two polynucleotide chains that carry genetic information

Gene

unit of heredity/ a sequence of DNA that encode a functional product

Chromosome

structure found inside the nucleus made of DNA packaged around proteins

Genome

all the DNA found within all our chromosomes

The central dogma

Genetic information flows only in one direction, from DNA, to RNA, to protein, or RNA directly to protein.

DNA replication

the two strands separate and each serve as template to make two identical copy

DNA is what into RNA and then what into protein?

DNA is transcribed into RNA, which is translated into protein based on genetic code.

What directs the order of each amino acid base code?

genetic code

A protein coding gene always starts with what?

start codon (ATG - Met)

A protein coding gene always ends with what?

stop codon (TAA, TGA, TAG)

Gene expression

the process by which information stored in DNA is accessed through transcription and translation

Gene expression dictates what

Cell differentiation

Proteome

All of the proteins that a cell makes at a given time

Biological function of proteins

• Structural proteins

• Transport proteins

• Membrane proteins

• Enzymes

Four main types of large molecules

• Nucleic acids

• Proteins

• Carbohydrates

• Lipids

What type of trait: The color of a flower

Morphological Trait

What type of trait: Ability to metabolize a sugar

Physiological trait

What type of trait: Mating calls of birds species

Behavioral trait

Molecular level

Different alleles of a gene produce different proteins

Allele – one variant (version) of a gene

Cellular Level

Changes of cellular function

Organismal Level

Changes in appearance, behavior and other trait

Population Level

Survival, fitness and evolution

Traits are the result of what?

The interaction between genes and the environment

Sexually reproducing species are commonly what?

Diploid

Homologs contain….

The same genes, not necessarily the same alleles

Biological Evolution

The genetic makeup of a population can change over many generations

Natural Selection

the process in which individuals with greater reproductive success are more likely to pass their genes to future generations

Model organisms

Non-human species that are extensively studied to reveal the mechanisms of biological phenomena

Knockout (KO)

complete loss of function

Necessity

Loss of function analysis

Sufficiency

Rescue or gain of function anaysis

Transmission Genetics

Question: Inheritance patterns of traits as they are passed from parents to offspring

Approach: Genetic cross

Molecular Genetics

Question: Biochemical understanding of the hereditary material

Approach: Detailed analysis of DNA, RNA and proteins

Population Genetics

Question: Genetic variation and its role in evolution

Approach: Mathematical theories to explain the prevalence of certain alleles within populations

“Kingsley 3” rules – If you want to prove that factor A causes phenomena B, you need to show:

1. A is there at the right place and right time when B happens

2. Necessity: Loss of function analysis – Loss of A causes change of B

3. Sufficiency: Rescue or gain of function analysis – restoring A fixes B, more of A causes more of B