Genetics

Front 1

Purine bases?

Back 1

Adenine and Guanine = double rings

Front 2

Chromosome shapes

Back 2

Meta- submeta- and acro- centric

Front 3

precursor of RNA

Back 3

rNTPs

Front 4

Nucleoside

Back 4

Nucleotide without phosphate

Front 5

addition of dNTP to strand

Back 5

free 3 OH group of nucleotide attacks the incoming 5' phosphate of dNTP to create phosphodiester linkage
Therefore both RNA and DNA strands created in 5' to 3' direction

Front 6

How is DNA polymerisation driven?

Back 6

Cleavage of PPi (released from dNTP) to 2Pi drives eqm far right!!

Front 7

Which way does DNA polymerase move along a strand (refering to the conserved strand)

Back 7

3 to 5

Front 8

Mitochondrial DNA linear?

Back 8

No circular
probably from symbiotic bacteria living inside humans before - replicates more like prokaryotes

Front 9

Does RNA occur as a folded molecule?

Back 9

Yep

Front 10

What stage of the cell cycle does dna rep take place

Back 10

Synthesis
Disorders in this synchrony lead to disease - cancer

Front 11

Mitochondrial DNA replication requires..

Back 11

many nuclear proteins
E = defects cause neuromuscular dysfunction or diabetes

Front 12

Meselson stahl?

Back 12

Experiments with N15 labelled strands in ecoli show semiconservative process

Front 13

Bacteria replication vs Eukaryotic

Back 13

replicates from single origin of replication in both directions their circular DNA - faster - proven by radiolabelled dNTPs. And also under EM, DNA looked like a theta (shows rep in both directions)
For Eu, would take too long, therefore many origins of replication (A-T rich motifs) - but still in forks!!

Front 14

Initiation of replication (Eu)

Back 14

recognition motifs (AT rich - weak so dissociate) bound by multi-protein origin recognition factors - recruit replication machinery and forms bubble by dissociating.
Helicase opens strands, then single strand BP binds exposed strands to prevent them rehybridising, replicase (contain 2 DNA polymerases) systems bind.
This process STRICTLY REGULATED so only occurs once per cell cycle

Front 15

DNA polyms can only add dNTPs to the

Back 15

3 Oh group of an existing strand (ie. needs primer (10-30bps long) - RNA, formation by primase which is part of primosome complex just ahead of replicase)

Front 16

Why need 2 DNA polyms in each replicase?

Back 16

One for replicating each strand - one is replicating simple 3-5 strand, one is doing 5-3 strand in Okizaki fragments

Front 17

Problem with lagging strand is that it has loads of nicks where RNA primers were

Back 17

RNA removed by RNAse H which targets hybrids
also DNA polymerase 1 has 5-3 exonuclease (for RNA, 3-5 exonuclease for mispaired bases!) activity to remove them too
DNA polym 1 fills gaps
DNA ligase seals

Front 18

Topoisomerases

Back 18

processes dna tangles and sorts out coiling

Front 19

Helicase

Back 19

Unwinds DNA, also moves the replicase forward using the energy from ATP hydrolysis.

Front 20

Key components of transcription machinery

Back 20

mRNA, tRNA, Ribosomes, Aux protein factors (Initiation factors, elongation Fs, Release Fs)

Front 21

tRNA

Back 21

made of RNA in cloverleaf shape!
Amino acyl (activated) group added to each by an ester linkage

Front 22

degenerate code?

Back 22

some aas coded by more tyhan one codon

Front 23

less tRNAs than there are codons? how bond?

Back 23

Have modified base (ie.inosinate) bonds weakly to A, U or C

Front 24

Aminoacyl tRNA synthetases very specific

Back 24

substrate recognition
also separate proofreading site to remove incorrectly acylated tRNAs and hydrolyses them

Front 25

Ribosome makeup

Back 25

35%protein 65%rRNA
amino group formed first

Front 26

which way does ribosome read strand?

Back 26

5 to 3
makes sense because thats also the way mRNA strands are synthesised

Front 27

Ribosome sites?

Back 27

3 - Aminoacyl, Peptidyl (where peptide bond formed) and Exit

Front 28

Only the sense strand of DNA is copied...

Back 28

false

Front 29

Splice sites for removing introns characteristically have....

Back 29

GU at 5 end and AG at 3 end

Front 30

RNA polymerase adds poly(A) tail to the transcript shortly after stop codon

Back 30

false

Front 31

A transition is...

Back 31

a point mutation that changes a purine to another purine or pyrimidine to another pyrimidine
(can be caused by tautomerisation or oxidative deamination)

Front 32

An indel is...

Back 32

an insertion and/or deletions net effect

Front 33

Huntingtons disease caused by...

Back 33

gain in function mutation of huntingtin protein

Front 34

direction of translation

Back 34

Amino to carboxy
(5 to 3)

Front 35

Steps of translation

Back 35

Initiation steps (3), 1.Small subunit binds P site over start codon. 2. 1st Aminoacyl tRNA loaded onto P site by IF. 3.large ribosome joins
Elongation steps: 1.Another aminoacyltRNA added to A site (helped via EF) 2.Peptide bond formation3.translocation - moves up one 4. 1st tRNA (now without AA) ejected from E site 5. continue cycling
Release:RF - mimics tRNA, but causes the last bond to be made to water - thus releasing the protein!
Ribosome release factor

Front 36

Difference between pro and eu transcription/translation

Back 36

Coupled in Pro - because no sub cellular compartmentalisation

Front 37

mature mRNA, what happens?

Back 37

Poly(A) tail added
Cap binding protein and PolyA binding protein added which target it to the nuclear pore complex for export.
The cap protein and tail protein bind - making human mRNA circular!! Ribosome recognises this complex and binds to it

Front 38

Why Poly(A) tail?

Back 38

By 6 crazy binding factors and enzymes
multiple A's added to 3 end
prevents degradation and targets it for export from the nucleus.
As it is gradually shortened - makes the mRNA more prone to breakdown and less prone to translation.

Front 39

Proteins for export made ...

Back 39

...on RER
Cytosolic ribosomes (sometimes in trains of ribosomes called polyribosomes - speeds it up) make cytosolic proteins

Front 40

Evidence that the Mitochondrial genome from an aerobic prokaryote

Back 40

Own genome - circular
no introns
has overlapping genes (not in nuclear genome except HLA complex - plenty of space!)
small!

Front 41

rRNA

Back 41

Many copies of genes for it
Transcription as multigenic transcript ie. 45S RNA to 28,18 and 5.8S ribosome components

Front 42

Satellite DNA

Back 42

accounts for most of heterochromatic (not transcribed) regions of DNA
repeated short sequences
used to assess whether DNA repair is working ok - if not - slippage may occur - cancerous tissue

Front 43

Finding a gene for a specific character/mutation with in it that causes pathology

Back 43

Make complimentary probe - (by knowing AA sequence) - probe cDNA library
Linkage analysis for bloody loads of markers
then sequence the region you've narrowed it down to

Front 44

SNP

Back 44

Single nucleotide polymorphism

Can be due to substitution or insertion/deletion

Front 45

Important considerations for single gene disorders after mapping the gene to a specific location

Back 45

allele and locus heterogeneity

(many alleles cause same disease at that locus/different loci mutations can cause same pheno/pathology)

Front 46

Linkage analysis for polymorphic

Back 46

Do analysis on affected sibling pairs

Front 47

Mutation

Back 47

heritable change in the genetic material

Front 48

How do mutations occur

Back 48

Mainly through errors in DNA replication and repair
or through mutagens (smoke, radiation, chemicals)

Front 49

Why inc risk of consainguinity?

Back 49

Each person carries approx 6 lethal mutations on recessive genes
Close relatives more likely to carry the same mutations - therefore :S

Front 50

Point mutations

Back 50

(substitutions)
Transitions = purine to purine etc
Transversions = purine to pyramidine

Front 51

Which bases are purines?

Back 51

A and G
(2 ring)

Front 52

Synonymous and non-synonymous mutations

Back 52

Doesnt change AA sequence due to redundancy of code / does

Front 53

Missense and Nonsense mutations

Back 53

Missense - change one base changes 1 AA
Nonsense - change one base - premature stop codon

Front 54

Deletion caused disease

Back 54

Duchenne MD (X linked rec condition)

Front 55

Anticipation

Back 55

Trinucleotide repeat sequences common in genome - may become unstable in replication (strand slippage) - leading to expansion of sequence - protein function disrupted
Expansion progresses through generations leading to progressively earlier onset /more severe - Huntingtons

Front 56

Huntington Disease

Back 56

Caused by expansion of CAG repeat in exon of Huntingtin gene
Degeneration of neurons in basal ganglia and cortical regions of brain
progressive dementia

Front 57

Myotonic dystrophy 1

Back 57

Caused by triplet repeat expansion in untranslated region of Dystrophia myotonica protein kinase (DMPK) gene
muscle pain, myotonia (hyperexcitability of muscles) cardiac arrhythmias

Front 58

Point mutation in intron

Back 58

consequences if in splice site - intron retention and therefore not translated or exon skipped (truncation) or if reg element of mRNA mutated not capped or not translated

Front 59

Loss of function mutation because of ...

Back 59

...either
Mutation affects normal level or mRNA;
-frameshift (prem stop)
-Nonsense mutation
-mutation in regulatory elements
or...mutation in critical domain of protein (ie. ligand binding)

tend to be recessive, unless haploinsufficiency or dominant negative mutation.

Front 60

Haploisufficiency disease?

Back 60

Waardenburg syndrome type 1
hearing loss, pigment abnomalities

Front 61

Gain of function diseases...

Back 61

...huntingtons, MD1, Achondroplasia - FGF3 receptor mutation - signals constantly instead of just when ligand bound - causes constant inhibition of endochondral bone growth by inhibiting chondrocyte proliferation and differentiation

Front 62

Synonymous and non-synonymous mutations

Back 62

Doesnt change AA sequence due to redundancy of code / does

Front 63

Missense and Nonsense mutations

Back 63

Missense - change one base changes 1 AA
Nonsense - change one base - premature stop codon

Front 64

Deletion caused disease

Back 64

Duchenne MD (X linked rec condition)

Front 65

Anticipation

Back 65

Trinucleotide repeat sequences common in genome - may become unstable in replication (strand slippage) - leading to expansion of sequence - protein function disrupted
Expansion progresses through generations leading to progressively earlier onset /more severe - Huntingtons

Front 66

Huntington Disease

Back 66

Caused by expansion of CAG repeat in exon of Huntingtin gene
Degeneration of neurons in basal ganglia and cortical regions of brain
progressive dementia

Front 67

Myotonic dystrophy 1

Back 67

Caused by triplet repeat expansion in untranslated region of Dystrophia myotonica protein kinase (DMPK) gene
muscle pain, myotonia (hyperexcitability of muscles) cardiac arrhythmias

Front 68

Point mutation in intron

Back 68

consequences if in splice site - intron retention and therefore not translated or exon skipped (truncation) or if reg element of mRNA mutated not capped or not translated

Front 69

Loss of function mutation because of ...

Back 69

...either
Mutation affects normal level or mRNA;
-frameshift (prem stop)
-Nonsense mutation
-mutation in regulatory elements
or...mutation in critical domain of protein (ie. ligand binding)

tend to be recessive, unless haploinsufficiency or dominant negative mutation.

Front 70

Haploisufficiency disease?

Back 70

Waardenburg syndrome type 1
hearing loss, pigment abnomalities

Front 71

Gain of function diseases...

Back 71

...huntingtons, MD1, Achondroplasia - FGF3 receptor mutation - signals constantly instead of just when ligand bound - causes constant inhibition of endochondral bone growth by inhibiting chondrocyte proliferation and differentiation