Genetics, Conception, and Fetal Development

Question 1

genes

Answer 1

basic physical units of inheritence; determine traits

Question 2

chromosome

Answer 2

made up of proteins and DNA organized into genes; most cells have 23 pairs

Question 3

sex chromosomes vs autosomes

Answer 3

sex = determine gender (XX vs XY)
all other pairs are autosomes (1-22)

Question 4

haploid

Answer 4

having a single set of unpaired chromosomes; gametes

Question 5

diploid

Answer 5

having 2 complete sets of chromosomes; often homologous/matching (autosomes)

Question 6

karyotype

Answer 6

photo of all a person’s chromosomes

Question 7

trait

Answer 7

determined by a gene’s allele

Question 8

dominant vs recessive

Answer 8

dominant alleles/genes prevent other from showing
recessive alleles only show if not dominant

Question 9

homozygous vs heterozygous

Answer 9

homo = 2 identical alleles
hetero = 2 different alleles

Question 10

what can we figure out with genetic counseling?

Answer 10

probability! estimation of risk

Question 11

chromosomal mutations

Answer 11

less common than gene mutations; more drastic, caused by failure of proper separation of homologous chromosomes during meiosis

Question 12

down syndrome

Answer 12

trisomy 21l mental retardation, cardiac defects, variable in severity, immune deficiencies, hypotonia/motor dysfunction

Question 13

turner’s syndrome

Answer 13

monosomy 23 (X only)

girls - short, slow growth; cardiac issues, learning disabilities; generally infertile

Question 14

mosaicism

Answer 14

different cells in the body have different numbers of chromosomes. can have higher or lower percentage of abnormal cells; less abnormal cells = less severity of condition

Question 15

sex-linked recessive inheritance

Answer 15

carried on X chromosome. Males don’t have the protective 2nd X, meaning they are more likely to exhibit it.

Question 16

sex-linked recessive diseases

Answer 16

hemophilia A + B; color blindness; fragile X syndrome

Question 17

autosomal recessive inheritance

Answer 17

must have two copies of recessive allele; someone can be a carrier with only one.

Question 18

autosomal recessive diseases

Answer 18

PKU, CF, sickle cell anemia

Question 19

autosomal dominant inheritance

Answer 19

only 1 dominant gene needed to exhibit disease

Question 20

autosomal dominant diseases

Answer 20

Huntington’s, polycystic kidney disease, polydactyly, achondroplasia, neurofibromatosis

Question 21

fertilization - where and what?

Answer 21

outer 1/3 of fallopian tube; sperm and egg (haploid) bind and become zygote (diploid)

zygote undergoes cleavage to become morula and then blastocyst

Question 22

Implantation – when and what does each part become?

Answer 22

occurs between days 5-9

outer blastocyst -> placenta and amnion

inner blastocyst -> fetus

Question 23

what are the three parts that develop from a balstocyst?

Answer 23

placenta
fetal membrane
embryo

Question 24

fetal circulation loop

Answer 24

placenta sends O2 through ONE umbilical vein –> goes through Inferior Vena Cava to R atrium of fetus –> TWO PATHS:

1) most blood goes through foramen ovale to L atrium -> L ventricle -> ascending aorta -> heart, brain, and arms; –> superior vena cava -> R atrium, mixing with oxygenated blood
2) lesser foes to R ventricles, through pulmonary arteries, bypass lungs to ductus arteriosus -> Inferior Vena Cava, oxygenating lower body –> inferior vena cava fuses to 2 umbilical arteries –> return to placenta

Question 25

Fetal Oxygenation Dissociation Curve

Answer 25

left shift – fetal HCT is 15 g/dL compared to maternal 12 g/dL

hgb binds and releases oxygen easier in fetus :)