B1 Genetics Flashcards
What is a gene?
A distinct sequence of nucleotides forming part of chromosome.The order determines the order of monomers in a polypeptide/ nucleic acid molecule that the cell may synthesise
What is the purpose of non-coding RNAs?
Controlling levels of genes that do code for proteins
What is the process that converts DNA to pre-mRNA?
Transcription
What is the process that converts pre-mRNA into mRNA?
Splicing
What is the process that makes protein from mRNA?
Translation
How is the location and time of gene transcription controlled?
Promoter and regulatory sequences
What enzyme is responsible for the transcription of the gene?
RNA polymerase(DNA helicase helps!)
What is the role of transcription factors?
They bind to the promoter and regulatory sequences and influence gene transcription
Which strand is the template strand? Sense or antisense?
Antisense
Which DNA strand corresponds with the amino acid selected?
Sense
In addition to splicing, what modifications occurbefore translation?
CappingPolyadenylation
What is capping?
Cap structure is added to the 5’ end of the mRNAs shortly after the beginning of transcription
What is polyadenylation?
Poly-A polymerase adds 100 to 300 Adenine residues to form a poly-A tail on the 3’ end.
How are the levels of mature mRNA regulated after transcription?
microRNAs destabilise them and inhibit initiation of their translation
What is the process that microRNAs are responsible for?
RNA-induced silencing
The genetic code is degenerate, but unambiguous. What does this mean?
An amino acid can have more than one codon, but no codon codes for two different amino acids.
What is the start codon/ initiator and what does it code for?
AUG - Methionine
What is the stop codon known as?
Open reading frame (ORF)
What is the small ribosomal sub-unit responsible for?
Binding mRNA and tRNA
What is the large ribosomal sub-unit responsible for?
Catalyzes addition of amino acids to extending peptide chain.
What end of the mRNA does the small sub-unit scan from?
5’ end
What end is the initiator at on the mRNA?
5’ end
In termination, what recognises the stop codon?
A releasing factor
What are releasing factors responsible for?
Causing the ribosome complex to fall apart; ending translation
True or false? Many antibiotics are inhibitors of protein synthesis in bacteria?
True
What is the key to good antibiotics?
Making use of the structural and functional differences between prokaryotic cells (them) and eukaryotic cells (us)
Following translation,what modifications can occur for proteins?
GlycosylationPhosphorylationUbiquitination for misfolded proteins
How is the function and localisation of a protein determined?
Structure and post-translational modification
What is ubiquitin?
A small chemical moiety
What happens in ubiquitination and why?
Proteins are degraded because they were misfolded.
Many proteins in the nucleus contain what kind of signal?
Nuclear localisation signal
In cases where there are not specific signals in the peptide sequence, how are proteins transported to the nucleus?
They are phosphorylated
What signal do proteins secreted from the cell/ inserted into the plasma membrane have at their amino terminus?
ER/ endoplasmic reticulum signal sequence / peptide
What is the location of protein modification?
Golgi Apparatus
What is the contents of a nucleus?
Chromatin
Nuclear Envelope
Nuclear Pore
Nucleolus
What is the majority of a nucleolus made from?
RNA
What is a nucleoplasm?
A nuclear substance containing chromatin and RNA.
What is genetic polymorphism?
2 or more variants of an allele
True or false? Most genes are polymorphic?
True
List examples of point mutations in base sequences
Insertion
Deletion
