Genetic expression

Define genetic expression

Mechanism by which genetic info in a gene is expressed as a functional protein

How is transcription regulated

• Promotor regions

• Enhancers

• Transcription factors

What is the promoter region

Located near the beginning of the gene, non coding. Serve as binding site for RNA polymerase

What are enhancers

Regulatory sequence of DNA which are located away from the gene

What are transcription factors

Bind to the enhancer region which interacts and activates the promoter region and enhancer regioins

Different transcription factors can activate or repress transcription by interacting with each other, other porteins, and RNA polymerase

What controls translation

Quantity of mRNA that is produced → Regulate transcription

Can be further regulated by degradation of mRNA by nuclease enzymes

What is epigenesis

Process by which a multicellular organism develops from a zygote through a sequence of steps where cells differenciates and organs form. 

What is epigenetics

Study of changes in organisms due to modifications of gene expressions using epigenetic tags. Phenotype changes, genotype doesn’t

What is epigenetic tags

Chemical markers that attaches to DNA or histone proteins and influence the transcription of genes

What is transcriptome

All of the RNA molecules transcribed at a specific time within a cell or organism

Represents the active genes and their expression within a cell or organism

What is a proteome

Complete set of proteins present in a cell or organism at a given time.

Proteome is larger than genome due to

• Alternative splicing or mRNA exons producing multiple proteins

• Modifications of proteins after translation, increases proteome

How can methyl groups act as epigenetic tags

Attaches to DNA and histone proteins

Attaches to cytosine nucleotides in the promotor region, represses activity of the promotor, prevents the gene from being transcribed

Can also attache to amino acids of histone proteins, found is some nucleosomes

What is methylation

Attachment of a methyl group to promotor regions or histones

Methylation of histone proteins can cause transcription to be repressed by the DNA binding tighter to the nucleosome, or activate transcription by unwinding DNA from nucleosome.

Air pollution affect on gene expression

Diesel fumes ect

Can add or remove methyl epigenetic tags from a persons epigenome

Why are epigenetic tags generally removed during fertilisation

Most of the epigenetic tags are removed at fertilisation of egg and sperm in the process of reprogramming

Epigenome of sperm and eggs allows them to be specialised cells

Reprogramming of the epigenome of a zygote produces stem cells. 

What are monozygotic twins

Identical twins resulting from fertilisation of one egg. Are clones and have the same genome

E coli and lactose

E.coli bacteria regulate the production of enzymes involved in lactose metabolism

Lac operons regulate transcription of enzymes required for lactose metabolism

Lac operons consists of promoter region, operator, and a sequence of 3 genes

Repressor proteins can bind to the operator, regulating the transcription of the gene

When Lactose is not present, repressor protein binds to operator

When lactose is present, repressor protein changes shape, released from operator

Testosterone regulating gene expression

Steroid hormone testosterone diffuses through the plasma membrane of the cell, where it binds to a testosterone receptor → hormone-receptor complex

Hormone-receptor complex moves to the nucleus, interacting with a speciefic DNA sequence (androgen response elements), which are present in the regulatory section of the target gene

Enhance or repress transcription of the target gene.