maintaining the cell - from genes to proteins Flashcards
differences between DNA and RNA
DNA double stranded, RNA single stranded
RNA less stable than DNA
DNA has deoxyribose, RNA has ribose
DNA has thymine, RNA has uracil
what occurs in transcription
promotor indicates start site
RNA polymerase unwinds the helix and creates an RNA copy of a DNA strand (mRNA) using ribonucleotide triphosphates
how do you get different tissue types?
genes are either on (expressed) or off in a given cell - not all genes are expressed in all tissues at all times
what are promotors
made up of sequence elements found immediately 5’ to the gene
what are enhancers
increase transcription from a nearby gene, can operate over large distances
what to promotors and enhancers contain
sequences that transcription factors can specifically bind to
what are transcription factors
proteins which bind to specific DNA sequences within the promoter or enhancers so as to increase or decrease gene expression
what causes one gene to encode for different products
alternative promotors
alternative splicing
alternative polyadenylation
waht are gene sequences split into
introns and exons
differences between introns and exons
exons contain coding sequences, introns don’t
whats the difference between a primary transcript and a functional mRNA molecule
primary transcript contains introns and exons, mRNA doesn’t
what is the purpose of introns
allows alternative splicing - different combinations of exons creating different types of proteins
RNA processing steps before it leaves the nucleus?
slicing
capping
polyadenylation
what is RNA capping
modification of 5’ end of RNA transcript protecting it from degradation, stabilising it and enhancing pre-RNA splicing
what is polyadenylation
polyA tail added to 3’ end of stand. allows cell to recognise it as mRNA once it leaves the nucleus
