Cells Flashcards
Xeroderma pigmentosum
They have an excision endonuclease (excinuclease) deficiency
This enzime target a thymine dimers damage cause by a UV radiation
Is autosomal recessive disorder
Who fix the thymine dimers damage?
DNA polymerase
DNA ligase
Mutation on one of this two genes hMSH2 and hMLH1 what cause?
Lynch syndrome or hereditary nonpolyposis colorectal cancer ( HNPCC)
Cause by a DNA replication errors
Is caused by DNA mismatch
Who prevents a cell with damaged DNA from entering the S phases?
And how they prevents that?
P53
Inducing the apoptosis
Inactivation or deletion from P53 are associated whit ?
Li fraumeni syndrome and others solid tumor
What is ATM?
Encodes a kinase essential for P53 activity.
Is inactivated in ataxia telangiectasia, characterized by hypersensitivity to x ray and predisposition to lymphomas
What cause lych syndrome in the chromosomes?
Microsatellite instability
Can produce a Broke’s chromosome
Purines
PURe As Gold
Purines Adenine Guanine
Purines have 2 rings
NH2 - adenine
Pyrimidines
CUT the PY (pie)
C- cytosine
U- uracil. RNA
T- thymine. DNA
Have two rings
What is a nucleoside?
Base + sugar
What is a Nucleotide?
Base + sugar + phosphate
What inactivate the shiga’s toxin or verotoxim shiga-like toxin?
Inactivate the 28 s RNA in the 60s subunit
What is the consequence of 28s rna in 60s subunit inactivate?
Avoid the synthesis of protein and the patient die
Every gene has ?
He’s own promoter and the DNA polymerase recognizes every promoters
Alternative splicing
The production of two protein from one gene
Why we have more proteins in their sales that gene in the chromosome
Because the alternative Splicing
Why the iG’s have the same protein but different function
Because the alternative Splicing
Example for alternative splicing
Dopamine receptors D1 D2 D3
The membrane igG and secreted iGg
Example of nonsense mutation
Hemophilia—> deficiency in F VIII
What it’s the mean of nonsense mutation?
A nucleotide substitution resulting in early stop codon (UAG, UAA, UGA)
Usually results in nonfunctional protein
Frameshift mutation
It’s a deletion or insertion of a number of nucleotides NOT DIVISIBLE BY 3
Example of frameshift mutation
Duchenne muscular dystrophy
Deficiency —-> dystrophin
Insertion of 4 nucleotides
Tay Sachs diseases
deficiency enzyme —>Hexoseminidose A
What it’s a codon?
How many codons we have ?
It’s a triplete if nucleotides
64
How many encodes codon we have ?
Why if we have 64 codons ?
61
Because 3 of this codon are stops codons
UAA UAG UGA
Trinucleotides repeat expansions
mention the Pathologys
1) huntignton diseases
2) fragile X chromosome
3) fredeich’s ataxia
4) spinoblubar muscular dystrophy
5) mio tonic syndrome
The name of the trinucleotide repeat expansion in Huntington diseases
CAG —> glutamine
5 repeats
What it’s the anticipation’s phenomenon
The number of repeats often increases with the successive generations and correlates with increasing severity and decreasing age of onset
Missense mutation
Nucleotide substitution resulting in changed amino acid
Example of missense mutation
Sickle cells anemia
Substitution of glutamic acid for valine
