keywords:
Bookmark and Share



Front Back
homologous genes
genes similar due to evolution from a common ancestral gene
paralogous genes
homologous genes within a species

evolve new functions
orthologous genes
different, but related genes. retain functions.

homologous genes in different species
analogous genes
genes of similar functions but of different origins
convergent evolution
evolution in which organisms evolve analogous structure of functions in sprite of their evolutionary ancestors being unrelated
transposons
a transposable element that moves thinin a genome by means of DNA intermediate
molecular diagnostics
the use of molecular tools to diagnose a disease

blots, elisa, pcr, microarrays
gene therapy
introduction of functional copies of a gene into an individual with 2 defective alleles
transgenic
an individual plant or animal whose genome contains a gene introduced from another organism, either from teh same or different species
Bioinformatics
gathering, manipulating, storing, retrieving, classifying biological information in DNA & RNA
Multiple alignments
lining multiple NT or aa sequences to compare members of a gene or protein family ( isoforms)

used to identify conserved DNA sequences that are important regulatory elements and identify conserved functional domains.
BLAST
basic local alignment search tool

a program that enables you to search for NT and aa sequences to compare with a sequence you produced and to see related sequences in other species
BArbara McClintock
studied maize genetics

identified all 10 maize chromosomes and connected them with linkage groups

elucidated genetic properties fo transposable elements

ideas weren't well received at the time, but are now significant
L1 element and human genome
principal transposable element belongs to a class of sequences known as the long intersperese nuclear element

l1-->L1 RNa
translated and creates 2 polypeps via 2 ORF
ORF2 nicks DNA (1 strand)
rev transcriptase used to synthesize DNA
3 types of transposable elements
  1. excising element from one position on chromosome and then pasting it in another by the transposase enzyme "cut and paste" transposition
  2. replicative transposons- element is replicated and one copy remains at original site while another copy is inserted at new site
  3. retrotranspositions- reverse transcriptase synthesizes DNA from RNA templates. Then the DNA is isnerted at new chromosomal sites.
Types of mutations caused by transposons
inserations, deletions, translocations
interchromosomal recombination
unequal crossover

transposon can insert itself to genome anywhere and anytime creating change in the gene it interrupt. it can stop the gene from being expressed. When gene moves it can cause errors in repairs and can further affect gene expression. Also, the insertation can create translocation mutations in which the reading frames are affected
interchromosomal crossover
sequences in 2 different chromosomes (homologous or nonhomologous) pair and crossover to create novel produces
intrachromosomal crossover
exchanges between sequences at different sites within a single chromosome

deletions- 2 transposons oriented in same direction

inversion- 2 transposons oriented in opposite direction
unequal crossover
deltions and insertions
how to determine if someone is a carrier of a mutation
use positional cloning

find area of interest by looking for genetic markers that are linked to the gene
since they are linked they will usually be inherited together

genetic amrkers can indicate general region where gene fo interest is located

walk/jump along gene until gene of interest is located

introduce wild type into mutant cell, if it converts then gene is located

look CGs upstream bc all humans have them
important sequences conserved in related species
cDNA library prepared from symptoms
transgenic delivery types (somatic)
retroviral vecors- wild type gene is integrated with retroviral DNA into host cell. Transgene transmitted to all cell progeny. Possible mutations because no control on where it inserts

adenoviral vectors- transgene present in host cells. No mutation on integration. only transient, and last as long as viral infection persists. Can be destroyed by immune system if individual has prior exposure to closely related virus.
What makes a gene a good candidate for delivery?
  1. must be cloned and well characterized (available in pure form)
  2. have an effective method to deliver genes into desired tissues or cells
  3. risks must be known and minimal
  4. must be last option for treaetment
  5. data from preliminary experiments should suggest that the therapy is effective
Anti-sense RNA silencing
  • produce antisense RNA
  • close gene of interest
  • separate coding sequence from its promoter by cleaving with a restriction enzyme
  • ligate coding sequence inverse irentation
  • introduce into cell by transformation
  • transcribe antisense gne to produce antisense mRNA, will hybridize with it
inverted gene can be inserted using recominant DNA methods (plasmid or cosmid vectors)

normal and inverted sequences are present and when transcribed, complex together to stop translation
RNAi
RNAi is amplified with dsRNA, diser, RISC, and Slicer

they produce a sequence in which dsRNA is cut and used to degrade mRNA of a gene of interest

the dsRNA is introdued to the cell, dicer recodnized this molecule and cleaves it. Risc attaches tot he antisense strand and slicer removes the other strand

risc then moves to the mRNA and attaches to the complementary site

cleaves the mRNA down the middle of the complex

the risc detaches and mRNA is degraded or used as a template for dsRNA in which creates mroe dsRNA to restart the cycle and create more risc complexes
RNAi components
RNA induced silencing complex

dicer- endoribonuclease cleaves dsRNA into shrot dsRNA fragments

slicer- removes the strand opposite of the one risc is attached to
x of y cards