Unit 8 - The control of gene expression Flashcards
Types of mutations
Substitution
Deletion
Addition
Duplication
Inversion
Translocation
Why don’t all mutations affect the order of amino acids
Because Dna is degenerate
Why do additions, duplications and deletions have a higher chance of causing mutation?
They cause a frame shift which affects more codons
3 ways that mutagenic agents can cause mutation
Act as a base
Alter bases
Changing structure of DNA
Features of benign tumours
Non cancerous
Slow growing
Cannot form metastases
Features of malignant tumours
Grow rapidly
Form metastases
Travel using blood/ lymphatic system
Features of tumour cells
Irregular in shape
Larger nucleus
Don’t produce full proteome
Dont respond to growth- regulating processes
Divide more frequently than other cells
Features of tumour cells
Irregular in shape
Larger nucleus
Don’t produce full proteome
Dont respond to growth- regulating processes
Divide more frequently than other cells
Two types of factors that increase risk of cancer
Environmental factors
Genetic factors
Two types of factors that increase risk of cancer
Environmental factors
Genetic factors
What are stem cells
An unspecialised cell which can multiply indefinitely and can differentiate to become a specialised cell
4 types of stem cells
Totipotent
Pluripotent
Multipotent
Unipotent
What can stem cells be used to treat?
Spinal cord injuries
Heart disease and damage
Bladder conditions
Respiratory diseases
Organ transplants
3 sources of stem cells
Adult stem cells (Bone marrow)
Embryonic stem cells (Embryos 4-5 days old)
Induced pluripotent (Specialised cells which have been treated)
Ethical issues with embryonic stem cells
It is destruction of an embryo which could become a fetus
At the moment of fertilisation the induvidual has the right to life
Adult stem cells ar not as useful as embryonic stem cells
Some induced pluripotent stem cells may be rejected by the body
Steps for oestrogen promoting transcription of genes
- Oestrogen binds to a transcription factor forming an oestrogen- oestrogen receptor complex
- This activates the transcription factor
- This then binds to the promoter region of the gene
- This allows RNA polymarase to bind and transcription to occur
Types of interfering molecules
SiRNA
miRNA
Which is more complementary to the DNA- miRNA or siRNA
siRNA
How does siRNA work
Associates with proteins which cut the DNA when siRNA binds
How does miRNA work?
Associates with proteins which block transcription when miRNA binds
How does methlation affect transcription?
Decreases transcription of gene
How dooes acetylation offect transcription?
Increases transcription of gene.
Why is ot harder to translate the genome of complex organisms?
- They have large sections of non- coding DNA
- ## They have large complex regultory genes
Why use newer sequencing methods?
- Less labour intensive
- Cheaper
- Can be done on a much larger scale
methods of isolating genes
Using reverse transcriptase to produce CDNA
Using restriction endonuclease enzymes
Gene machine
Methods of gene amplification
In vivo- gene inserted into a vector- vector inserted into host cell
In vitro- using PCR
Methods of identification of transgenic host cells
Marker genes
Types of gene mutations
Addition
Deletion
Substitution
Inversion
Duplication
Translocation
Step 3- Identification of transformed organisms
- Marker genes inserted at same time as gene being replicated
- Host cells grown on agar plates
- Marker gene can code for antibiotic resistance
- Colonies which survive in antibiotic are grown (replica plating)
Two types of gene therapy
Somatic therapy- Body cells
Germ line therapy- Sex cells
Uses of screening using DNA probes and hybridisation
Identifies heritable conditions
Determines how a patient will respond to specific drugs
To identify health risks
Using electrophoresis to compare DNA of samples
- DNA cut
- Using restriction endonuclease
- Use electrophoresis
- Separate according to length
- Add absorbent paper to make them visible (southern blotting)
- Make single-stranded by heating/ using alkali
- Apply radioactive probe and use autoradiography
- Different tandem repeats= different length
Uses of genetic fingerprinting
- Determine genetic relationships
- Determine genetic variability within a population
- Determine culprit in forensic science
- Medical diagnosis
- Animal and plant breeding
Uses of human genome project
- Aids the understanding of gene function and interaction
- Scientists can identify genes which are linked to cancer
- Identified genes related to Alzheimers
Medical uses of Identifying genes
Identifying dangerous alleles which have been inherited
General uses of identifying genes
Checking parents of child
Selective breeding
Forensic science in crime
Application of genome projects
Genetic screening for inherited diseases
Developing medical treatments for genetic diseases
What are primers and what do they do?
Single-stranded DNA
Mark beginning and end of DNA being amplified
What is a vector
Carrier of DNA/ gene into another cell
Steps in PCR
Temperature is increased to 95 degrees to split DNA into single strands
Temperature then cooled to 55 degrees to allow primers to anneal
Heated again to 72 degrees which is optimum temperature for DNA polymerase to replicate DNA
In what direction do strands move in electrophoresis
From negative to positive electrode
What can DNA hybridisation be used for
Screen for heritable conditions
Check potential drug responses
Check for health risks
