BIOL 243 Lecture Notes - Lecture 1: Color Depth, Molecular Genetics, Gene Expression
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Lecture 1 - Introduction to the course
January 11th 2019
What is molecular genetics?
Genetics: study of heredity and variation in cells, individuals and populations
Gene: functional unit (causes) of heredity and variation
Therefore, molecular genetics is the study of the structures and function of genes at a molecular
Genotype → Phenotype
Gene: DNA sequence involved in making RNA and protein
Alleles: variant forms of a gene caused by differences in DNA sequence (ex. Variation in eye
Genotype: gene(s) inherited by an organism
Phenotype: visible traits (ex. Body plan, behaviour, illnesses/diseases)
Genome: entire DNA sequence (ACGT) of an organism
What is gene expression?
Genes: found on chromosomes and are parts of the genome that encode RNA and protein
Gene expression: basically “turning on” a gene to produce RNA and protein (coding gene)
Genes transcribed into RNA which are then translated to protein
Protein expression specifies phenotype
Protein expression: the type and abundance of proteins in the cell
Although DNA is the information molecule that directs protein expression, proteins ultimately
determine the phenotype of the cell because they control every reaction in the cell
Enzymes: catalyzing the synthesis and transformation of all biomolecules
Structural proteins, signaling proteins
Phenotypic variation: what makes individuals different from one another?
1. Different alleles: slight variation in gene sequence results in changes in amino acid
sequence of proteins
2. Differential regulation of gene and protein expression
- Gene for eye colour
- Alleles for eye pigment gene: blue, green, brown, etc.
- Amount of gene and protein expression: pale versus deep colour
- Unique alleles and differential regulation of thousands of genes among
individuals leads to countless phenotypic possibilities in a population
- Individuals that possess common alleles and gene regulation leads to more
similar protein expression and phenotypes (immediate family, relatives)
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