Gene Expression

Week 1

Gene Regulation

Control of the activation or deactivation of a gene. Mostly in response to environmental factors

DNA Genome comparison

A vast recipe book with the instructions needed for all proteins and organisms.

Transcription

First step of gene expression. Information in a gene is used to synthesize RNA.

Two things the transcriptional control does

Enhance/stimulate gene expression - positive control

Repress/inhibit gene expression - negative control

Transcriptional control: Lactose Operon

If the lactose operon is not present in the repressor protein, the RNA polymerase can not attach.

Lac Operon DNA organization with and without lactose.

No lactose: repressor protein binds to the operator =blocking transcription. The operon is off. 

Lactose allows the RNA polymerase to transcribe lactose. Operon is on

Mutation

alteration in the sequence of bases in DNA

(essential for adaptatioian and evolution) 

3 types of mutations

Neutral- No positive or negative effect

Detrimental- harms the organism's survival

Beneficial- enhances the organism’s fitness.

How do faulty genes code for faulty enzymes?

A nonfunction enzyme can’t catalyze the reaction. —> molecules accumulate in the cell—> causing sickness or deathA

Example of mutation to illness

Tay-Sachs

Mutation in body (non-sex) cell

Somatic mutation (bad health consequences). Not passed to offspring.

Mutations in sex cells (sperm and egg)

germ line mutations (no health effects)

Can be passed to offspring

Two types of changes to DNA based of mutations

Point mutations - small scale

Chromosomal abberrations - large scale

Point mutations

One DNA nucleotide base pair is replaced, inserted, or deleted.

Insertion and Deletion effects on Protein coding

Disrupt the order in which codons are read. Result in detrimental effects to the phenotype.

Chromosomal Aberrations

Structure of chromosomes or their number

, deletions, duplications, inversions, or relocations. 

entire chromosomes can be added or lost (down syndrome)

Two causes of mutation

Spontaneous - accident during DNA replication

Environment- radiation, chemical, virus.