genetics conception fetal development

Question 1

euploidy

Answer 1

correct or normal number of chromosomes

Question 2

polyploidy

Answer 2

too many chromosomes (even number)

Question 3

aneuploidy

Answer 3

uneven number of chromosomes

Question 4

monosomy

Answer 4

aneuploidy with one missing chromosome

Question 5

trisomy

Answer 5

aneuploidy with extra chromosome

Question 6

translocation

Answer 6

chromosome breaks and exchange of material between two chromosomes occurs- all or part of the broken chromosome is transferred to different part of same chromosome OR to another chromosome

Question 7

deletion

Answer 7

loss of chromosomal material, partial monosomy for chromosome involved

Question 8

inversion

Answer 8

portion of chromosome has been rearranged in reverse order

Question 9

most common sex chromosome abnormality: females

Answer 9

Turners Syndrome

Question 10

Turners Syndrome

Answer 10

45 XO- 1/2500- short stature, broad chest, thick/webbed neck, infertile, amennorhea, heart disease

Question 11

most common sex chromosome abnormality: males

Answer 11

Klinefelter Syndrome

Question 12

Klinefelter Syndrome

Answer 12

47, XXY- 1/500 to 1/1000- typically asymptomatic, however: taller, gynecomastia, reduced facial/body hair, infertility, delayed puberty

Question 13

multifactorial inheritance: definition

Answer 13

combination of genetic and environmental factors shape this genetic transmission pattern

Question 14

multifactorial inheritance: examples

Answer 14

• cleft lip- cleft palate- congenital heart disease- neural tube defects

Question 15

unifactorial inheritance: examples (kind of definition too)

Answer 15

• autosomal dominant, recessive inheritance- inborn errors of metabolism- x-linked dominant, recessive inheritance

Question 16

Tay Sachs

Answer 16

• lipid-storage disease, deficiency in hexosaminidase- until 4 to 6 months old, appear normal- THEN: apathy, regression in motor and social development, decreased vision- death between 3 and 4 yo- no treatment exists- common in Ashkenazi Jews, Quebecois French Canadians

Question 17

phenylketonuria (PKU)

Answer 17

• autosomal recessive disorder- relatively uncommon- deficiency of phenylalanine hydroxylase (liver enzyme) = phenylalanine metabolism failure = metabolites accumulate in blood- screening routinely performed/US state mandated- 1/10000 to 1/20000- highest incidence: Caucasians

Question 18

inborn errors of metabolism

Answer 18

• gene mutation reduces efficiency of encoded enzymes such that normal metabolism cannot occur- defective enzyme action interrupts normal series of chemical reactions from the affected point onward

Question 19

x-linked dominant inheritance

Answer 19

mimics autosomal dominant inheritance, except that male-to-male transmission cannot occur unless the father has Klinefelter syndrome due to XY disomy

Question 20

x-linked recessive inheritance

Answer 20

• females may be heterozygous or homozygous -males may be hemizygous - most commonly manifested in the male, with the abnormal gene on his single X chromosomedisorders ex: hemophilia, Duchenne muscular dystrophy, color blindness

Question 21

ovum

Answer 21

unfertilized (by sperm) egg- considered fertile for 24 hours after ovulation- zona pellucida (inside layer, thick, acellular)- corona radiata (outer layer, elongated cells)

Question 22

zygote

Answer 22

fertilized egg

Question 23

morula

Answer 23

fertilized ovum –> 16 cells- produced within 3 days- still surrounded by zona pelludica- free floating in uterus

Question 24

blastocyst

Answer 24

morula –> defined structure, the blastocyst cavity- outer layer called trophoblast, surrounding hollow sphere

Question 25

embryo

Answer 25

fertilized ovum --> day 15 through 8 weeks after conception- 3cm from end to end at the end of period

Question 26

fetus

Answer 26

8 weeks since fertilization

Question 27

amnion

Answer 27

forms at implantation; develops from interior cells of blastocyst; grows with fetus and will surround umbilical cord

Question 28

chorion

Answer 28

forms at implantation; developed from trophoblast and contains chorionic villi on surfacefetal side of the placenta- contains major umbilical blood vessels

Question 29

conception

Answer 29

sequential process by which egg and sperm unite; the beginning of pregnancy. two week period.- gamete formation- ovulation- fertilization- implantation

Question 30

fertilization

Answer 30

physical union of egg and sperm- occurs in ampulla (outer third) of uterine tube

Question 31

implantation

Answer 31

- trophoblast implants in endometrial cells- between 6 to 10 days

Question 32

primary germ layers (3)

Answer 32

ectoderm, mesoderm, endoderm

Question 33

ectoderm*

Answer 33

gives rise to: - epidermis*- glands (ant. pit, cutaneous, mammary)- nails & hair*- central & peripheral nervous systems*- lens of eye- tooth enamel- floor of amniotic cavity

Question 34

mesoderm*

Answer 34

gives rise to:- bones and teeth*- muscles (skeletal, smooth, cardiac)*- dermis & connective tissue*- cardiovascular system & spleen*- urogenital system

Question 35

endoderm*

Answer 35

gives rise to:- epithelium lining respiratory and digestive tracts*- glandular cells of associated organs (oropharynx, liver*, pancreas*, urethra, bladder*, vagina)- roof of the yolk sac

Question 36

oligohydramnios

Question 37

polyhydramnios

Answer 37

> 2L amniotic fluid- associated with GI and other malformations (stricture of GI means fluid being swallowed, not filtered, comes back out and builds up)

Question 38

umbilical cord

Answer 38

- link between fetus and placenta (filter)- transports O2 and nutrients to fetus FROM placenta, returns waste products from fetus TO placenta- 2 arteries, 1 vein, filled with Wharton's Jelly- no pain receptors

Question 39

placenta not fully functional until...

Answer 39

...end of first trimester

Question 40

placenta

Answer 40

- produces hormones that regulate maternal pregnancy symptoms (subside by end of first trimester)- FILTER-- diffusion: gases, water, electrolytes-- facilitated: glucose, amino acids, minerals-- pinocytosis: minute particle movement- mother transmits IgG to fetus- leakage is defect, may allow maternal/fetal blood mixing

Question 41

Shiny Schultz

Answer 41

placenta attached to baby, usually comes out this way

Question 42

Dirty Duncan

Answer 42

placenta attached to mom, make sure all lobes of placenta are present if it comes out this way; not abnormla but pieces can be left in uterus

Question 43

respiratory distress syndrome (RDS)

Answer 43

results from decreased pulmonary gas exchange- retention of CO2 (increased arterial PCO2)most common neonatal causes:- prematurity- perinatal asphyxia- maternal DM- hyaline membrane diseaseinsufficient surfactant!

Question 44

fontanel

Answer 44

where >2 bones meet

Question 45

omphalocele

Answer 45

hernia of abdominal contents through navel; present at birth if midgut does not return to abdomen during week 10 after projecting into cord week 5

Question 46

meconium

Answer 46

dark green to black tarry waste accumulated in fetal intestine near term

Question 47

viability

Answer 47

capability of fetus to survive outside uterus at the earliest gestational age: 22-24 weeks

Question 48

fetal/infant survival depends on

Answer 48

- maturity of fetal central nervous system- maturity of lungs

Question 49

only immunoglobulin that crosses the placenta

Answer 49

IgG - passive acquired immunity to specific bacterial toxins

Question 50

associated with neural tube defects

Answer 50

inadequate folic acid intake- NTD could be decreased 50-70% with adequate folic acid intake during periconception period