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36 Cards in this Set
- Front
- Back
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Comparing the size, the mass of a gene, and a chromosome, which of the following is correct?
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chromosome>gene>genetic code
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If the codon of a mRNA is AUC then the genetic code would be
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TAG
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Incorrect statement
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a carrier of a gene is homozygous
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Nucleotide includes
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phosphorous+deoxyribose+guanine
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Incorrect statement
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dominant trait expresses only in homozygous pairing
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Due to overexposure to UV rays a person develops cancer of the skin. What is true related to the son of the above person
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if the son of the above person overexposes himself to UV rays he may develop cancer of the skin
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Correct statement
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gene is stored in the DNA molecule, chromosome is made up with DNA, one gene carries one specific genetic information
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Genotype of turner syndrome
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45,X0
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A man with this hair is married to a woman with thin hair. Assume that T: gene for thick hair and t gene for thin hair and T is dominant to t. Possible genotype for this couple.
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male:T,t, female t,t
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The above couple asks you the chance of having a baby with thick hair. What would be your answer?
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50%
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How many percent chance of having a carrier baby carrying thin hair gene?
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50%
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If the above man is married to a homologous thick hair women, then what is the chance of having a baby with thin hair?
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0%
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Incorrect statement?
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a man affected by an x linked recessive disorder will transmit his defective gene to all his sons (considering his wife is completely normal)
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A man is having protruded eyes. It is known that it is x-linked recessive disorder. Assume that P is the defective gene for protruded eyes. His genotype would be
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XpY
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If the above man is married to a healthy women, the possibility of havign a baby boy without the above defect would be (knowing the fetus is a boy)
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100%
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Name the birth defect related to folic acid deficiency
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neural tube defect??
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A decrease in AFP may indicate...
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down syndrome
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Most vunerable period during the development of the baby
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organogenesis (15-60 days after conception)
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Autosomal recessive disorders
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both mutant gene pair needed to express
onset usually early in life more uniform |
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Sex linked disorders
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assoc with x chromosome
affected male transmits defective gene to all his daughters. Not transmit defective gene to sons |
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Multifactoral disorders
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multiple genes, environmental factors
desc. as threshold phenomenon |
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nondisjunction
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is the failure of chromosome pairs to separate properly during meiosis
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Monosomy X (turner's Syndrome)
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45,X,0
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Trisomies
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A trisomy is a genetic abnormality in which there are three copies, instead of the normal two, of a particular chromosome.[1] A trisomy is a type of aneuploidy (an abnormal number of chromosomes).
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Trisomy 21
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down syndrome
manifestations: upward slanting eyes, small, low-set and malformed ears, opened mouth with large protruding tongue, short hand with simian line, cardiovascular and GI defects, High risk of developing acute leukemia and Alzheimers |
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Polysomy
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caused mainly by maternal nondisjunction.
manifestations: may not be detected at birth testicular dysgenesis,impotence, infertility |
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teratogenic agents
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agents that produce abnormalities during embryonic or fetal development
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Irradiation
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radiation is teratogenic&mutagenic
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Drugs-can cross the placenta can cause damage to the embryo &fetus
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thalidomide-short flipper like appendages
antimetabolites (used in treatment of cancer) anticoagulant, anticonvulsant derivative of vitamin A:used in treatment of acne |
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Fetal Alcohol syndrome
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manifestations:short papebral fissure, thin upper lip, elongated&flattened midface and philtrum, low birth weight. behavioral dysfunction, intellectual impairment
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Cocaine babies
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uteroplacental blood flow decreases, fetal vasoconstriction, stimulation of uterine contraction.
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Folic acid deficiency
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manifestations:neural tube defect
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Infections
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mechanism:microorganism cross placenta
manifestations:microcephaly, hydrocephaly, eye and hearing defects |
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AFP- AlphaFetoprotein
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rises from 13 weeks. Peaks @32 eeks gestation
maternal blood, amniotic fluid -screening done by 16th to 18th week |
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AFP clinical value
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increase AFP neural tube defect, missed abortion, multiple pregnancy
decrease AFP Down syndrome |
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Diagnostic tools
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Maternal-serum markers, ultrasound, AMniocentesis,Chorionic villus sampling, percutaneous umbilical blood sampling, fetal biopsy
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