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GENE STRUCTURE AND REGULATION (GENE STRUCTURE: (Regulatory genes: A gene…
GENE STRUCTURE AND REGULATION
GENE STRUCTURE:
Regulatory genes:
A gene that codes for transcription factors (which in turn controls gene expression at the transcription stage).
Promotor regions:
Upstream region of a gene (a specific DNA sequence) to which RNA polymerase attaches, initiating transcription.
Operator regions:
The operator region effectively switches the gene on or off by allowing transcription to begin or cease.
Transcription is halted by the stop region downstream of the structural gene.
Structural genes:
A gene that codes for proteins and RNA molecules that are not involved in gene regulation (eg. enzymes).
Introns:
Section of DNA that does not code for proteins and is spliced during mRNA processing in eukaryotes.
Exons:
The region of a gene that codes for a protein.
Operon:
a unit of DNA under the regulation of a single promoter that codes for several proteins.
PROTEINS:
STRUCTURE:
1:
Primary Protein Structure:
Polypeptide formation (occurs during translation)
2:
Secondary structure:
Polypeptide becomes coiled or pleated.
3:
Tertiary structure:
Coiled polypeptide folds into 3-dimensional form.
4:
Quaternary structure:
Two or more 3-dimensional polypeptide molecules bonded together.
FUNCTIONS:
Catalyst:
Eg. enzymes
Structural:
Eg. muscle tissue
cell membranes
cytoskeleton
cilia
Communication:
Eg. hormones
Neurotransmitter
Carrier molecules:
Eg. Haemoglobin
Transport:
Eg. channels in cell membrane.
PROTEOME:
the total complement of all the proteins in an individual organism.
an organisms proteome is determined by the DNA sequence of its genome.
