Genetics !! Flashcards
What is a mutation?
A change in the sequence of bases in DNA
Name different types of mutation?
Insertion, substitution and deletion
Describe a substitution mutation?
A single nucleotide changes in a codon, DNA is degenerate so the codon could remain the same. Can be catastrophic or just the same
What is a point mutation?
If only one nucleotide is affected
Depurination?
The loss of a purine base
What does an insertion and deletion lead to?
Frameshift mutation, it will change every codon
Different effects of mutations?
No effect, damaging non-functional proteins, or beneficial
What increases the rate of mutation?
Mutagen - a chemical, physical or biological agent
Depyrimidine?
The loss of a pyrimidine
What examples can affect the structures of nucleotides?
Free radicals, oxidizing agents and antioxidants
Inversion mutation?
A section of chromosome breaks off, is reversed, and then joins back onto the chromosome
Translocation mutation?
A section of one chromosome breaks off and joins another non-homologous chromosome
Difference between heterochromatin and euchromatin?
Heterochromatin = tightly wound DNA causing it to be less accessible and inactive genes.
Euchromatin = loosely wound DNA with accessible and active genes
Why is gene regulation required?
It is required for cells to specialize and work in a coordinated way
What is transcriptional gene regulation?
Transcriptional = Genes turned on and off
Post - transcriptional = mRNA can be modified which regulates translation and types of proteins produced
What is translational gene regulation?
Translational = Translation stopped or started
Post - Translation = proteins modified
Which cell does the Lac Operon work in?
Prokaryotes
The purpose of the lac operon?
Efficient way of saving resources, specifically lactose
How are lactose and glucose correlated?
If glucose in short supply, lactose is used as the respiratory substrate
The role of cAMP in the lac operon?
If glucose high = cAMP levels decrease and reduce the transcription
What does beta-galactosidase do (lacZ) ?
Breaks down lactose
Describe the process of the lac operon?
If lactose not present the repressor protein is activated and binds to operator, preventing transcription of RNA
If lactose present the repressor is inactive and binds to the lactose, RNA transcribes and produces beta-galactosidase
What is the promoter in the lac operon?
A section of DNA where the RNA polymerase binds to
What does lactose permease do (lacY) ?
Helps transport lactose across membranes
