Chromosomal Abnormalities

Question 1

genetic information is transmitted to daughter cells under 2 circumstances:

Answer 1

-mitosis - diploid replicates itself

-germ cells undergo meiosis - reduction of diploid (2n) to haploid state (1n) - when fertilized diploid state is restored to form zygote

Question 2

what is mosaicisim? when does it occur?

Answer 2

the presence of 2 or more cell lines with different chromosome compositions in an individual

occurs bc of non-dysjunction after fertilization - when chromosomes don’t separate correctly

Question 3

2 chromosome abnormalities?

Answer 3

numerical

structural

Question 4

name 5 chromosome numerical abnormalities

Answer 4

euploidy
triploidy
tetraploidy
aneuploidy
monosomies

Question 5

what is euploidy

Answer 5

chromosomal numeral abnormality

the addition of loss of complete sets of chromosomes - so the category of chromosomes changes

Question 6

what is triploidy and what is it caused by?

Answer 6

possession of a complete extra set of chromosomes

caused by polyspermy (fertilization of an egg by more than 1 sperm)

sponatneously aborts

Question 7

tetraploidy is a result of….

Answer 7

failure of the first zygotic division
lethal to the embryo

chromosomal numeral abnormality

Question 8

what is aneuploidy
when does it occur?

Answer 8

the category of chromosome changes but does NOT involve whole sets

failure of a single chromosome to complete division

Question 9

all autosomal __ are lethal in very early embryogenesis

they abort too early to even be recognized as a conception

Answer 9

monosomies

Question 10

name 2 meiosis errors

Answer 10

homologs fail to separate (meiosis 1)

chromatids fail to separate (meisosis 2)

Question 11

give 2 examples of autosomal aneuoploidies

Answer 11

down syndrome (Trisomy 21)
edwards syndrome (trisomy 18)

Question 12

trisomy 18

Answer 12

edwards syndrome

aneuploidy

Question 13

trisomy 21

Answer 13

downs syndrome

aneuploidy

Question 14

karyotype for complete androgen insensitivity syndrome

Answer 14

46, XY

Question 15

karyotype for triple X female

Answer 15

47, XXX

Question 16

karyotype for klinefelter syndrome

Answer 16

47, XXY

Question 17

karyotype for jacobs syndrome

Answer 17

47, XYY

Question 18

true or false

the karyotype for klinefelter syndrome is 47, XYY

Answer 18

FALSE

47, XXY

Question 19

Karyotype for Turner Syndrome

Answer 19

45, X0

Question 20

random X-inactivation is established by the expression of what gene?

Answer 20

XIST gene

inactive X is coated by XIST RNA

Question 21

once the XIST gene is expressed and the X is coated by XIST RNA, how is X inactivation maintained?

Answer 21

by methylation of DNA cytosine residues

Question 22

explain what happens to females with turner syndrome

Answer 22

45, XO

they’re missing an X chromosome

they have delayed menarche and premature menopause

however, most of their offspring are chromosomally normal

Question 23

men born with an extra X chromosome

Answer 23

klinefelter syndrome

Question 24

men have FSH and LH

Answer 24

klinefelter syndrome (extra X chromosome)

Question 25

females are

Answer 25

XX

Question 26

what are the 2 major types of chromosomal translocations?

Answer 26

reciprocal - 2 chromosomes exchange genetic material robertsonian - fusion of 2 chromosomes with the loss of short arms

Question 27

what are isochromosomes

Answer 27

split the wrong way in mitosis both long arms remain attached and both short arms remain attached - moving to opposite poles and an ISOCHROMOSOME is formed

Question 28

what are ring chromosomes

Answer 28

both telomeres removed - mutation repaired by sealing the ends together, forming a RING CHROMOSOME

Question 29

not all genes have only 2 variations (alleles) give an example of this

Answer 29

ABO blood type has 3 different alleles IA IB i (O type)

Question 30

explain the recessive and dominant alleles in ABO blood type

Answer 30

Type O is recessive to A or B type A and B are co-dominant and both fully expressed

Question 31

give an example of something that follows polygenic inheritance

Answer 31

1 trait related to many genes skin, hair, eye(color), height

Question 32

what determines the pigment of eye/skin/hair?

Answer 32

it's a polygenic trait - so the # of dominant alleles determines how much pignment is produced and the DOMINANT GENE (A/B/C) produces the pigment itself

Question 33

what is epistasis

Answer 33

when a gene's phenotype is blocked by certain alleles of a second gene

Question 34

the mammalian mitochondrial genome has how many genes?

Answer 34

37 genes

Question 35

explain LHON and what causes it

Answer 35

leber hereditary optic neuropathy optic nerve death in late teens and 20s maternal inheritance - mainly homoplasmic (either mutant or normal mitochondria)

Question 36

differentiate between heteroplasmy and homoplasmy

Answer 36

heteroplasmy - mutant AND normal mitochondria homoplasmy - either mutant OR normal mitochondria

Question 37

what are congenital anomalies

Answer 37

aka birth defects alterations in the form or size of part(s) of the body

Question 38

what is the etiology of congenital abnormalities

Answer 38

either genetic (intrinsic) or environmental (extrinsic)

Question 39

within the first _____ weeks of postdevelopment conception: a fertilized egg is cleaved to become collection of blastomeres, then morula, then blastocyte

Answer 39

1st 2 weeks

Question 40

in which weeks of development is the basic body plan established and the initiation of nervous system occurs, then organogenesis

Answer 40

weeks 4-8

Question 41

name 3 prenatal tests to determine if there are congenital defects

Answer 41

amniocentesis (amniotic fluid) CVS (chorionic villus sampling) PGT (preimplantation genetic testing)

Question 42

what is the name for the tiny camera used in ultrasound

Answer 42

fetoscopy

Question 42

explain how deformations normally occur

Answer 42

late in pregnancy due to uterine constraint

Question 42

what are the 3 major groups of congenital abnormalities

Answer 42

malformations (intrinsic development issues) deformation (extrinsic issues) disruption (extrinsic disturbance in morphogenesis)

Question 42

explain what disruption is

Answer 42

an extrinsic disturbance in morphogenesis. a previously formed organ is damaged by something in the uterus (like the amnion)

Question 42

what is agenesis

Answer 42

complete absence of an organ/part of an organ/ certain cell type in an organ

Question 42

what is potter sequence

Answer 42

reduced amount of amniotic fluid

Question 42

jaundice is related to....

Answer 42

inability for the liver to conjugate bilirubin

Question 42

hypoplasia

Answer 42

reduced size due to incomplete development of whole or part of an organs

Question 42

division failures are caused by...

Answer 42

incomplete apoptosis in embryonic tissues results in syndactylyl (fingers are conjoined or not fully separated)

Question 43

microcephaly is an example of....

Answer 43

hypoplasia (small brain and head)

Question 43

what is the acronym for in utero infections

Answer 43

TORCH Toxoplasmosis Other (syphilis) Rubella Cytomegalovirus Herpes simplex virus

Question 43

what is fetal hydrops

Answer 43

mild edema or localized fluid collections in infants they may be stillborn or die shortly after caused by Rh incompatibility between fetus and mom

Question 43

what are dysraphic anomalies?

Answer 43

defects causes when structures fail to fuse

Question 43

what is atresia

Answer 43

incomplete formation of an orifice or tubular passage

Question 43

what are.... hamartomas choristomas hemangiomas lymphangiomas

Answer 43

benign tumors of childhood

Question 43

explain thalidomide crisis

Answer 43

impaired limb production by blocking angeiogensis 1960

Question 43

true or false nicotine and alcohol are teratogenic drugs

Answer 43

true