U2L11 Flashcards
What are the links between genotype and phenotype?
Proteins
What is gene expression?
Process by which DNA directs protein synthesis
What 2 stages are included in gene expression
Transcription and translation
What is a primary transcript?
Initial RNA transcript from any gene prior to processing
What is the central dogma?
Concept that cells are governed by cellular chain of command
In eukaryotic cells, where does transcription and translation take place?
Transcription - nucleus
Translation - cytoplasm
In bacterial cells, where does transcription and translation take place?
Cytoplasm
What is a triplet code?
A series of non overlapping, three nucleotides where the flow of information from gene to protein is based on
What happens to the triplet codes in mRNA?
Translated into a chain of amino acids forming a polypeptide
Transcription creates…
An mRNA strand from the template strand
Translation creates….
An amino acid sequences from the codons on mRNA
Where does the RNA polymerase read the DNA template strand?
Reads it from 3’ to 5’ - next nucleotide will be added to the 3’ end
What is the template strand used for?
Provides a template for ordering the sequence of complementary nucleotides in an RNA transcript
During translation, codons are read in the
5’ -> 3’ direction
What are codons used for?
Each codon specifies an amino acid placed at the corresponding position along the polypeptide
How many codons in total
64
The template strand is read
3’ to 5’
What promoter is a polymerase II bounded to?
Transcription initiation complex
Why is the TATA box crucial?
Forms the initiation complex in eukaryotes
As RNA polymerase moves along the DNA, how many bases at a time does it untwist the double helix
10-20 bases
How does the termination of transcription differ in bacteria and eukaryotes
In bacteria, the polymerase stops transcription at the end of terminator, in eukaryotes RNA polymerase II transcribes a polyadenylation signal sequence
What is RNA processing
Enzymes in the nucleus of eukaryotes modify pre mRNA before it goes to the cytoplasm
How are the ends of mRNA altered?
5’ end receives a modified nucleotide called the 5’ cap
The 3’ end gets a Poly A tail
What are introns
Non coding regions
What are exons
Regions that are expressed and translated into amino acid sequences
What does RNA splicing do?
Removes introns and joins exons creating an mRNA molecule with continuous coding sequence
Alternative RNA splicing
Some introns contain sequences that may regulate gene expression - treated as exons during splicing
Number of different proteins an organism can produce is much greater than…..
It’s number of genes
Domains
Are discrete regions in proteins
Exon shuffling
Individual exons can code for different domains in a protein - exon shuffling may result in the evolution of new proteins
