Study Unit 1

Question 1

human genome project

Answer 1

low resolution physical amp obtained from chromosome banding patterns

focuses on euchromatin that is transcriptionally active

Question 2

human genome project process

Answer 2

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

Question 3

Giemsa staining

Answer 3

stains chromosomes to show alternating light and dark patterns

light bands = AT-rich regions

dark bands = GC-rich regions

Question 4

constitutional abnormality

Answer 4

present in all nucleated cells

present in early development - due to abnormal gamete, fertilization or abnormal event early in the embryo

Question 5

somatic/acquired abnormality

Answer 5

present in only a few cells and tissue of an individual creating a genetic mosaic

occurs post-zygotically

Question 6

genetic mosaicism

Answer 6

possessing two populations of cells with altered chromosome or DNA content, each deriving from the same zygote

Question 7

chimera

Answer 7

possessing two populations of the same cells deriving from different zygotes

Question 8

structural abnormalities

Answer 8

when part of an individual chromosome is missing, extra, switched to another chromosome, or turned upside down

Question 9

abnormal chromosome breaks

Answer 9

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

Question 10

errors in meiosis

Answer 10

recombination between mispaired homologs

Question 11

intrachromosomal recombination

Answer 11

non-homologous recombination that occurs as a result of crossing over between two linked genes on two non-homologous pairs

Question 12

natural somatic recombination

Answer 12

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

Question 13

numerical abnormalities

Answer 13

when a whole chromosome is missing or extra to the normal pair

Question 14

karyotyping

Answer 14

process used to determine a karyotype in order to detect chromosomal abnormalities

Question 15

conventional karyotyping

Answer 15

stains chromosomes arrested in metaphase or pro-metaphase when they are the most condensed

shows chromosome banding

detects balanced rearrangements, balanced translocation, and inversions

Question 16

spectral karyotyping (SKY)

Answer 16

evaluates complete karyotype in a single experiment by using 24 different chromosome painting probes

Question 17

SKY technique

Answer 17

individual chromosomes obtained by flow cytometry

each chromosome labelled with a specific combination of fluorescent dyes to give unique signal

signals analyzed by computer

Question 18

fluorescence in situ hybridization (FISH)

Answer 18

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

Question 19

PCR and southern blotting

Answer 19

used for small changes such as unstable oligonucleotide repeats

Question 20

reciprocal translocation

Answer 20

two chromosomes each with a break that exchange broken segments

no loss of chromatin

Question 21

Robertsonian translocation

Answer 21

long arms of two acrocentric chromosomes join with the loss of the two short arms

Question 22

inversion

Answer 22

internal segment of chromosome broken in two places, flipped 180 and rejoined