Study Unit 1 Flashcards
human genome project
low resolution physical amp obtained from chromosome banding patterns
focuses on euchromatin that is transcriptionally active
human genome project process
map poly morphic markers in individual chromosomes
build a genetic map from the segregation that occurs in the reference families
use the map to assign short DNA sequences to chromosomal regions
Giemsa staining
stains chromosomes to show alternating light and dark patterns
light bands = AT-rich regions
dark bands = GC-rich regions
constitutional abnormality
present in all nucleated cells
present in early development - due to abnormal gamete, fertilization or abnormal event early in the embryo
somatic/acquired abnormality
present in only a few cells and tissue of an individual creating a genetic mosaic
occurs post-zygotically
genetic mosaicism
possessing two populations of cells with altered chromosome or DNA content, each deriving from the same zygote
chimera
possessing two populations of the same cells deriving from different zygotes
structural abnormalities
when part of an individual chromosome is missing, extra, switched to another chromosome, or turned upside down
abnormal chromosome breaks
caused by double strand breaks in DNA
result of unrepaired DNA damage or faults in the recombination process – G1 phase = breaks in both sister chromatids, G2 phase = breaks in only one sister chromatid
errors in meiosis
recombination between mispaired homologs
intrachromosomal recombination
non-homologous recombination that occurs as a result of crossing over between two linked genes on two non-homologous pairs
natural somatic recombination
cellular DNA in B and T cells undergoes programmed rearrangements that produce antibodies and T cell receptors
abnormalities in this process can lead to structural abnormalities that are commonly associated with cancer
numerical abnormalities
when a whole chromosome is missing or extra to the normal pair
karyotyping
process used to determine a karyotype in order to detect chromosomal abnormalities
conventional karyotyping
stains chromosomes arrested in metaphase or pro-metaphase when they are the most condensed
shows chromosome banding
detects balanced rearrangements, balanced translocation, and inversions
spectral karyotyping (SKY)
evaluates complete karyotype in a single experiment by using 24 different chromosome painting probes
SKY technique
individual chromosomes obtained by flow cytometry
each chromosome labelled with a specific combination of fluorescent dyes to give unique signal
signals analyzed by computer
fluorescence in situ hybridization (FISH)
used to detect balanced and unbalanced chromosome abnormalities
used after aCGH if duplication or deletion is suspected
screens for amplified oncogenes
detects acquired translocation in cancer that cause breaks in genes leading to hybrid genes that are inappropriately expressed
PCR and southern blotting
used for small changes such as unstable oligonucleotide repeats
reciprocal translocation
two chromosomes each with a break that exchange broken segments
no loss of chromatin
Robertsonian translocation
long arms of two acrocentric chromosomes join with the loss of the two short arms
inversion
internal segment of chromosome broken in two places, flipped 180 and rejoined
