3.8 Control of Gene Expression

Substitution
Addition
Deletion
Duplication
Inversion
Translocation

Extra base is added to sequence.
Frame-shift

Deletes a base
Frame shift

Changes a base to another
Varied effects due to degenerate code

Section of bases detach and retach but inverted
eg:
TAC TTC AGG TGG
TO
TAC GGA CTT TGG

Section of bases detach on one chromosome and retaches to a different chromosome.
Significant impact

section of DNA is duplicated once or multiple times
eg: TAC TTC AGG TGG
TO
TAC TTC AGG TTC AGG TGG

Undifferentiated cells that can continually divide and become specialised

Totipotent
Pluripotent
Multipotent
Unipotent

Can differentiate into any types of cells
Occur for little time in early mammal embryos

Can differentiate into almost any type of cells
Found in embryos and can be used to treat human disorders

Can differentiate into limited types of cells
Found in bone marrow,placenta,umbilical cord

Can differentiate into one type of cell(same)

Induced pluripotent cells - produced from adult cells by using appropiate protein transcription factors

Heritable change in gene function without changing DNA base sequence.
Caused by environment and can inhibit transcription

Addition of methyl groups to bases that have cytosine causes DNA to wrap MORE TIGHTLY preventing transcription factors from being able to bind
INHIBITS TRANSCRIPTION

Addition of actyl groups(acetylcoenzyme a ) to histones causing it to loosen its association with DNA making DNA wrap LESS TIGHTLY, exposing genes allowing transcription factors to bind

Controls and slows down cell division and can cause cell death if DNA corrupted.
Can be affected by chemical tags

Proteins which regulates transcription, binds to a specific base sequence on DNA(promoter region) and initiate transcription
Without it binding, genes are inactive and proteins wont be made

Can initiate transcription via binding onto receptor site of TRANSCRIPTIONAL FACTOR and changing its shape so it becomes active and abling it to bind to DNA.

Cellular process that silences specific genes and destroys mRNA b4 it gets translated.
This can be done by small interfering RNA (SiRNA)

1) An enzyme cuts double stranded molecule of RNA(dsRNA) into siRNA
2)One strand of siRNA combines with an enzyme forming siRNA-enzyme complex
3)This thens bind to another mRNA molecule in which then the enzyme cuts up the mRNA so it can't be translated

B:
Not cancerous and grow slowly
Doesnt invade other tissues
Cause damage like blockades/excess pressure
M:
Cancerous and grow rapidly
Can invade other tissues
Secretes chemicals forming blood vessels to it
Can regrow after removal

Proto oncogenes that got mutated to become oncogene leading it to drastically overstimulate the duplication of cells by being permanently active

1)Reverse transcriptase
2)Restriction endonucleases
3)Gene machine

1)mRNA needed to create proteins is isolated from cell that produces it (eg beta cells)
2)mRNA acts as template strand to create single strand copy of DNA with DNA nucelotides using reverse transcriptase called cDNA
3)DNA polymerase used to turn it into double stranded DNA

Found in bacteria and able to hydrolyse phosphodiester bonds of both dna strands at specific area
Can cut in two ways:
1) Blunt- straight down
2)Staggered/zigzag way - Forms ends that are palindromic known as sticky ends which can join to DNA with complementary base pairs

1)Desired sequence of nucleotide is determined from the proteins
2)This is entered to the PC which checks for biosafety
3)PC creates small overlapping single strands of nucleotides which make up a gene called oligonucleotides
4)Oligonucleotides then joined to create gene
- This can be replicated via PCR

1)Restriction enzymes used to cut out gene and leaves sticky ends.
2)Then promotor and terminator region is added which tells where RNA polymerase is to start and end transcription
3)Plasmid(vector) is cut open using same restriction enzyme creating same sticky ends so GENE ends are complementary to those in plasmid
4)DNA ligase sticks both of them together by forming phosphodiester bond via condensation reaction

To insert vector into host cell we increase membrane permeability via mixing the vector and host cell in a medium with Ca 2+ and do a big change in temperature
HOWEVER NOT ALL HOST CELL WILL TAKE VECTOR UP
So we need to identify which did take it up

We uses marker genes to identify being:
- Anti biotic resistance genes
- Florescent marker(GFP)
- Enzyme markers(lactase)

E and G has gene we placed

After host cell now has recombined plasmid/vector this is cloned/ grown in fermenter

1- DENATURATION = All stuff is added and Temperature increased to 95C breaking hydrogen bonds and splitting strands to two

2-ANNEALING = Temperature decreased to 55C so primers can attach which provide starting point for taq polymerase

3- AMPLIFICATION = Temperature increased to 72C so taq polymerase CATALYSES FORMATION OF phosphodiester bonds between nucleotides to form new double strands of DNA

Variable number tandem repeats= Section of DNA bases that are introns and repeat throughout genome.
Very unlikely for two people to have same VNTR

1)Sample of DNA is collected via blood,hair etc.
2)Restriction enzymes used to cut DNA into smaller fragments. They cut it just before and after VNTRS
3)Gel electrophoresis occurs.
4)Lots of different DNA probes are mixed with VNTRs to bind.
5)DNA probes and VNTR transferred to nylon sheet and UV light/ x ray is shined
6) Position of DNA bands are then compared to known ones.

Small single strands of DNA complementary to a specific VNTR and are radioactively/florescently labelled

-Used to separate DNA fragments by size
1)DNA fragments placed onto agar gel and voltage is applied across
2)Resistance of gel means the larger a fragment, the slower they move towards anode
3)So over a fixed period of time, smaller fragments move further than large ones.
-Separating them