Chapter 8: Human Karyotyping and Chromosomal Behavior Flashcards Preview

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Flashcards in Chapter 8: Human Karyotyping and Chromosomal Behavior Deck (59)
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What is a Giesma Stain?

a stain that produces bands along a chromosome for karyotyping purposes


G bands vs R bands, when do the corresponding genes replicate?

G bands do not containing as many genes, often appear darker. the genes in the G bands replicate in LATE S PHASE

R bands on the karyotype contain many genes and appear lighter. the genes in the R band replicate in EARLY S PHASE


p vs q arm of a chromosome

p arm is the short arm
q arm is the long bottom arms


What're the alphabetical groups of a human karyotype?

A; 1-3
B; 4-5
C; 6-12
D; 13-15
E; 16-18
F; 19-20
G; 21-22

and the sex chromosomes XY



terminal position in the p arm



terminal position in the y arm


What does a positive symbol on a karyotype indicate?

that there is an extra chromosome of a paritcular number


What does a negative symbol on a karyotype indicate?

that they are missing a chromosome of a particular number


What is a metacentric centromere

a centromere in the middle of the chromosome, the length of the p arms thus equal the length of the q bottom arms.


What classes of chromosomes on a karyotype would you expect to see a metacentric centromere?

on A; 1-3, and maybe C (6-12) and F (19-20)


What classes of chromosomes on a karyotype would you expect to see a submetacentric/subterminal centromere?

in chromosome groups B (4-5), some C(6-12), E (16-18) and X chromosomes.


What is an acrocentric centromere?

a centromere that is almost at the end. Found in D (13-15) G (21-22) and the Y chromosome.


What does dosage compensation do? What would happen if this did not occur?

Dosage compensation is the regulation of protein is corrected by increasing the activity of the X Chromosome in males or limiting the activity in females. If this did not happen, boys would have a serioud deficiency in protein because structural proteins would be less available.


What kind of dosage compensation occurs in mammals?

X-inactivation, where only one X chromosome in females are expressed.


What is X mosaicism?

The presence in different X activations differing between cells in the same individual. Can be seen phenotypically, like in a calico cat. Different cells have different X chromosomes that are activated, thus resulting in patches of either orange or black.


What're the genes that still remain active on both X chromosomes in females even though the rest of one chromosome is inactivated?



What parts of an inactive X chromosome can undergo recombination with the Y chromosome?

PARp and PARq have HOMOLOGUES on the Y chromosome, enabling it to exchange genetic information.


What is the region in the Y chromosome that does not have a homologue in the X chromosome?

the SRY region- produces proteins that are involved in male development and fertility.


What is TDF on the Y chromosome? What region is it foud in?

TDF is the testis determining factor. found in the SRY region.


What is holohandric inheritance?

Inheritance of genes on the Y chromosome. Because only males normally have Y chromosomes, Y-linked genes can only be transmitted from father to son.


What is a transcription factor?

Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA.


What is euploidy?

gain of one or more complete sets of chromosomes. Involves balanced translocations, inversions, triploidy, tetra ploidy etc.


What is aneuploidy?

more or less of ONE CHROMOSOME or part of a chromosome. ex/ trisomy, monosomy, duplications etc.


Balanced Translocations

A euploid condition in which nonhomologous chromosomes have a change of part, but all parts and genes are still present.


T/F you will lose genetic content if a balanced translocation occurs

false. genes will be on different chromosomes that are non homologous, but all the genes will be there regardless


Unbalanced Translocation

an aneuploid condition in which some part of the genome is missing



an aneoploid condition where the entire chromosome is missing. Results from a nondisjunction


What kind of aneuploidy events contributes to loss of genetic material?

Monosomy and Unbalanced Translocation


What is nondisjunction

failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division (improper segregation)


Usually, monosomy in humans results in death. What is the one chromosomal exception

You can have an X chromosome monosomy, results in turner syndrom (X,O)