L15: Information transfer in cells Flashcards
What is the ‘central dogma’ of molecular biology?
an explanation of the flow of genetic material within a biological system. It involves:
- Replication
- Transcription
- Translation
What is the ‘central dogma’ of molecular biology?
an explanation of the flow of genetic material within a biological system. It involves:
- Replication
- Transcription
- Translation
Structural differences between RNA and DNA x3
- strandedness
- functional groups
- nucleotides
- DNA is double stranded, RNA is single stranded
- RNA has an OH group at ribose C2, DNA just has an H
- DNA uses thymine, RNA uses uracil
What makes RNA unstable and easily degraded?
- OH group means RNA can be attacked by water and undergo hydrolysis reactions
What is the difference between purine and pyrimidine bases?
Purine: A and G
Pyrimidine: C, T and U
What percentage of our genome is genes?
less than 5%
Give examples of some gene regulatory elements. What are they?
promotor sequence: bind TF’s
enhancer sequences: bind TF’s
some make regulatory RNA that doesn’t lead a protein
Structural differences between RNA and DNA x3
- strandedness
- functional groups
- nucleotides
- DNA is double stranded, RNA is single stranded
- RNA has an OH group at ribose C2, DNA just has an H
- DNA uses thymine, RNA uses uracil
What makes RNA unstable and easily degraded?
- OH group means RNA can be attacked by water and undergo hydrolysis reactions
What is the difference between purine and pyrimidine bases?
Purine: A and G
Pyrimidine: C, T and U
Give examples of some gene regulatory elements. What are they?
promotor sequence: bind TF’s
enhancer sequences: bind TF’s
some make regulatory RNA that doesn’t lead a protein
Introns are removed from primary RNA by…
splicing machinery
What is on the 3’ and 5’ ends of DNA
5’ = hydroxyl
3’ trisphosphate
What are the basic building blocks for DNA synthesis?
deooxynucleoside trisphosphates (dNTPs)
Which direction does the enzyme DNA polymerase work?
5’ to 3’
What must there be for DNA polymerase to start? and why?
RNA primer provides a free 3’ end which receives incoming dNTP’s
What is the difference between the action of DNA polymerase on the leading and lagging strand?
On the leading strand, DNA polymerase travels from one end to the other in the 5’ to 3’ direction
The lagging strand is in the 3’ to 5’ direction so DNA polymerase replicates the DNA in fragments in the 5’ 3’ direction. These are called okazaki fragments which are later polymerised by ligase
Describe what is meant by the replication ‘bubble’
The whole genome cannot be unzipped in order to be replicated. It is there replicated in sections, which look like bubbles
How does DNA polymerase proof read?
Adds a base, moves back to check it, excises it if its wrong and then moves on
Which direction does RNA polymerase work in?
5’ to 3’
What is the predominant level of control in gene expression?
Control of transcription
What is it called when more than one ribosomes attaches to a single mRNA?
polyribosome
Which three codons are stop codons?
UAA, UGA, UAG
The genetic code is redundant. However, which amino acid is coded for by only one codon?
Methionine = AUG
