CH 13-HG spr 26

How can a child inherit two recessive PKU alleles if only the father is a carrier?

Germline mutation in egg and uniparental disomy

What are the possible sperm chromosome numbers following Meiosis II nondisjunction in a diploid organism with 16 chromosomes?

7, 8, 9

What are the possible sperm chromosome numbers following Meiosis I nondisjunction?

7, 9

What is a chromosome made of?

Mostly DNA and proteins with a small amount of RNA

Where do spindle fibers attach on a chromosome?

Centromere

What term describes a chromosome with equal arm lengths?

Metacentric

What are the heterochromatic regions at the ends of chromosomes called?

Telomeres

What do the satellite regions on chromosomes 13, 14, 15, 21, and 22 contain?

Repeated rRNA genes

What field links traits to chromosome variations?

Cytogenetics

What is the region between protein-rich areas and telomeres called?

Subtelomeres

What is the telomere repeat sequence?

TTAGGG

How are chromosomes arranged in karyotypes?

By length

What term describes a chromosome with a very short arm, such as chromosome 15?

Acrocentric

What can amniocentesis not detect?

Intelligence

What is a key feature of CVS (Chorionic Villus Sampling)?

Karyotype made directly from collected cells

What is the primary advantage of CVS over amniocentesis?

Provides earlier results

What is the normal male karyotype?

46, XY

Why can't CVS detect metabolic errors?

It doesn't sample amniotic fluid

When are chromosomes distinguishable?

When tightly coiled

How were early karyotypes used to distinguish chromosomes?

General size classes

What does FISH (Fluorescence In Situ Hybridization) use?

Fluorescent DNA probes

What is a 46, XX individual?

Normal female

What are diagrams showing chromosome regions called?

Ideograms

What is the condition of having an extra set of chromosomes?

Polyploidy

What is the term for having three copies of every chromosome?

Triploid

What is a common cause of polyploidy?

Haploid sperm fertilizing a diploid egg

What is the term for an extra chromosome condition?

Trisomic

How can a father with trisomy 21 pass Down syndrome to offspring?

Produces sperm with two chromosome 21 copies

What error causes aneuploidy?

Nondisjunction

Why do few aneuploids survive?

Most are lethal early

What is the most common autosomal aneuploidy?

Trisomy 21

What is the karyotype for Turner syndrome?

XO

What is the karyotype for Klinefelter syndrome?

XXY

What is the diagnosis for a 47, XX, +21 karyotype?

Down syndrome

What is the diagnosis for a 45, X karyotype?

Turner syndrome

What is the diagnosis for a 47, XYY karyotype?

Jacobs syndrome

When does mosaic aneuploidy arise?

Nondisjunction in the early embryo

Which human karyotype is considered nonviable?

YO male

What are the physical characteristics of males with an extra Y chromosome?

Tall, otherwise normal

What syndrome results from nondisjunction in both parents?

XXYY

What is the cause of Cri-du-chat syndrome?

Deletion on chromosome 5

What is an inversion that excludes the centromere called?

Paracentric

What is a chromosome with identical arms called?

Isochromosome

What is a reciprocal translocation?

Two chromosomes with swapped colored segments

What is uniparental disomy?

Two alleles inherited from one parent

What can uniparental disomy explain?

Recessive disease with only one carrier parent

The loss of what leads to ring chromosomes?

Telomeres

What is an example of a balanced chromosomal abnormality?

Inversion

What is the structure of an isochromosome?

LMNO-centromere-ONML

What is a chromosomal effect of radiation exposure?

Ring chromosomes

Why is uniparental disomy often undetected?

The parent is usually not a disease carrier

What is the abnormality 47, XY, +18?

Trisomy 18

What is the cause of Wolf-Hirschhorn syndrome?

Deletion on the short arm of chromosome 4 (4p16.3)

Which cell type is unusable for karyotyping?

Red blood cell

What is a long chromosome formed from two acrocentrics called?

Robertsonian translocation