Transcription and translation Flashcards
The central dogma describes
a …
…flow of information in an
organism
How many nucleotides in DNA and RNA?
4
DNA is …
…double stranded
RNA is …
…single stranded.
flow of information in an organism?
DNA -> RNA -> Protein
How does DNA flow into RNA?
Transcription of genes into mRNA
How does RNA flow into proteins?
Translation of mRNA.
What is a gene?
- the DNA sequence that is translated into a protein
- the open reading frame (ORF) and the control region of the gene including its promoter
genes are not separate from the rest of the DNA that they inhabit – they are part of the …
…DNA sequence
Genes are information units…
…which allow the production of proteins
Eukaryotes tend to have more genes than …
…prokaryotes
Eukaryotes tend to have more genes than prokaryotes but there is little correlation between our own conception of …
…‘higher’ organisms and the number of genes
– all multi-cellular organisms have similar numbers of genes.
there can be little correlation between the size of the genome and the…
…number of genes.
DNA is folded in the nucleus into …
…higher structures by interaction with histone proteins.
This makes the DNA highly packaged
genes are encoded on …
…either strand of the double helix
genes are encoded on either strand of the double helix – in general these do not overlap in eukaryotes but often do in…
…viral genomes where there are space constraints
RNA molecules are transcribed so that the RNA molecule is complementary to the sequence of the …
…antisense or template strand
RNA molecules are polymerised by the addition of…
…ribonucleotides to a growing strand
RNA molecules are polymerised by the addition of ribonucleotides to a growing strand
– the addition of an individual nucleotide is determined by the …
…base present on the antisense strand of the gene – where the antisense strand has a C then a G is added to the growing strand, where there is an A then a U is added and so on
transfer RNAs are not …
…translated
Transfer RNAs act as…
…adaptor molecules between base pairing via their anticodon and the construction of proteins as they are attached to a specific amino acid
the 3D structure of rRNA provides …
…binding sites for 3 tRNA molecules (complete with their amino acids) and the mRNA in the ribosome
because individual nucleotides are able to form ‘base pairs’ then whole RNA molecules fold up into a …
…three dimensional structure (as with proteins.
because individual nucleotides are able to form ‘base pairs’ then whole RNA molecules fold up into a three dimensional structure (as with proteins) due to …
…intramolecular forces (in this case hydrogen bonds)
– the three dimensional shape is related to their function.
Transcription is controlled by …
…DNA-protein interaction
in order for a gene to be transcribed there is a requirement that the proteins involved in transcription are able to …
…interact with DNA
in order for a gene to be transcribed there is a requirement that the proteins involved in transcription are able to interact with DNA
- without this interaction they would not be able to…
…‘read’ the DNA sequence and transcribe the gene.
DNA binding proteins have conserved …
… ‘motifs’
DNA binding proteins have conserved ‘motifs’
one of the most common is the …
…helix-turn-helix motif
In helix-turn-helix motifs an alpha-helix is positioned into the…
…major groove of DNA by intramolecular forces between amino acids and nucleotides
Purpose of recognition motifs?
recognises particular sequence in the DNA molecule
Transcription requires …
…RNA polymerase
RNA polymerases are enzymes which …
…catalyse the formation of RNA polymers in a similar way to DNA polymerases acting in replication.
RNA polymerase requires a …
…dna template
RNA polymerase requires a DNA template – it consists of…
…multiple protein subunits which enable it to unwind DNA, denature the double strands, add ribonucleotides to a growing chain and proofread the transcripts it is producing.
CDK 8 is a component of the …
… mediator complex
In prokaryotes, RNA polymerase requires an associated protein (sigma factor) to recognise …
…where transcription begins
associated protein is also known as…
…sigma factor
as RNA polymerase begins to produce mRNA…
…sigma factor is released
as RNA polymerase begins to produce mRNA sigma factor is released – the polymerase then progresses along the gene until it reaches a …
…termination signal where it is released
In prokaryotes, promoter sequences are …
… heterogenous