Block A Flashcards
During intron splicing, what site does the splicing proteins recognise
The GU site at the 5’ splice site
During intron splicing, what happens after the splicing proteins recognise the specific site
The proteins recruit other proteins into a large complex called the spliceosome
Which bases are purines
Guanine, Adenine
Which bases are pyrimidines
Cytosine, Thymine
Whats a nucleoside
Base conjugated to a sugar
Whats a nucleotide
Nucleoside conjugated to 1 or more phosphates
How many H bonds in a G-C
3
How many H bonds in a A-T
2
Which is harder to break, G-C or A-T
G-C
Introns are ____ regions
Non-coding (intervening DNA)
Extrons are _____ regions
Coding (Expressed DNA)
In DNA replication, how is RNA primer produced and state its role
RNA primer provides a starting point for DNA replication. Produced by primase
In DNA replication, which enzyme catalyses specific DNA bases to the free 3’ hydroxyl on the primer
DNA polymerase
Whats the role of mRNA
Template for the synthesis of proteins
Whats the role of tRNA
Carries amino acids to ribosomes in translation
Whats the role of rRNA
A major component of ribosomes
Describe the initiation phase of transcription
The binding of transcription factors to certain gene sequences (like CAAT box and TATA box) at the promotor site opens the DNA and phosphorylates the carboxyl-terminal domain (CTD). This allows RNA polymerase II to leave the promotor site and begin transcription.
How many base pairs need to be open for the promotor site to be open
17
Describe the elongation phase of transcription
RNA poly II moves along DNA template to synthesize mRNA, growing in a 5’ to 3’ direction
Describe the termination phase of transcription
RNA polymerase ceases transcription at defined sites. mRNA strand is stabilised by modifications like 5’ cap and poly A tail at 3’
Whats the equation for Aminoacyl tRNA synthetases
Amino acid + ATP +tRNA +H²0 –> Aminoacyl-tRNA + AMP + 2Pi
Describe how Translation is initiated
Initiated through a complex. This complex scans the mRNA, looking for an AUG codon. Once found, an 80S is formed on the ribosome and protein synthesis begins.
What is intercellular signalling
Communication between different cells
Whats intracellular signalling
Signalling within the cell
Define epigenetics
Modifications to the genome that affect gene expression but do not alter the DNA sequence
When CpG is methylated, the ____ is methylated
Cytosine
Explain how methylation of CpG regions repress gene expression
Methyl binding proteins bind to methylated DNA and prevent the binding of transcription factors.
Describe how DNA is packaged in the nucleus
DNA wraps around a histone octomer. A histone octomer is four histone units assembled.
Whats the name for a DNA-histone complex
Chromatin
Describe the properties of euchromatin (3 marks)
-loosely packed
-under active transcription
-enriched in genes
Describe the properties of heterochromatin (3 marks)
-tightly packed form of chromatin
-inaccessible to transcription factors
-genetically inactive
What determines the state of the chromatin
Methylation and acetylation of histones
How can epigenetic changes cause disease
The methylation of a tumor suppressor gene could inhibit gene expression. This could lead to cancer.
Give an example of how RNA interference (RNAi) may be used experimentally
It can be used to knockdown protein production from a particular gene
Outline the experimental use of CRISPR-Cas?
To generate genetic mutations at a desired location in the genome
How does CRISPR-Cas complex target specific regions of the genome
with a guide RNA that is complementary to the target DNA sequence
Why does the movement of electrons from glucose to oxygen release energy
because oxygen has a higher redox potential than glucose
TRUE/FALSE: RNA polymerase II is located only in the cell cytosol
false
TRUE/FALSE: RNA polymerase II synthesizes RNA in a 3’ to 5’ direction
false
TRUE/FALSE: RNA polymerase II transcribed genes encoding aminoacyl tRNA synthetases
true
Put the following events (1-5) in the correct order:
1. Splicing
2. Elongation
3. Capping
4. Initiation of transcription
5. Assembly of the basal transcription complex
5,4,3,2,1
TRUE/FALSE: Cytosolic proteins are always membrane bound
false
TRUE/FALSE: Cytosolic proteins are polar on the surface
true
Is the conversion of ADP to ATP carried out by the electron transport chain
no
What is the correct order of events in the chain elongation part of the fatty acid synthesis pathway.
Condensation, reduction, dehydration, reduction
PCR is used to indentify microsatellite variation between individuals because….
PCR product size differences indicate microsatellite variation
A father will share ____ of his genetic variation with his child.
50%
