Genetics, Conception, and Fetal Development Flashcards
genes
basic physical units of inheritence; determine traits
chromosome
made up of proteins and DNA organized into genes; most cells have 23 pairs
sex chromosomes vs autosomes
sex = determine gender (XX vs XY)
all other pairs are autosomes (1-22)
haploid
having a single set of unpaired chromosomes; gametes
diploid
having 2 complete sets of chromosomes; often homologous/matching (autosomes)
karyotype
photo of all a person’s chromosomes
trait
determined by a gene’s allele
dominant vs recessive
dominant alleles/genes prevent other from showing
recessive alleles only show if not dominant
homozygous vs heterozygous
homo = 2 identical alleles
hetero = 2 different alleles
what can we figure out with genetic counseling?
probability! estimation of risk
chromosomal mutations
less common than gene mutations; more drastic, caused by failure of proper separation of homologous chromosomes during meiosis
down syndrome
trisomy 21l mental retardation, cardiac defects, variable in severity, immune deficiencies, hypotonia/motor dysfunction
turner’s syndrome
monosomy 23 (X only)
girls - short, slow growth; cardiac issues, learning disabilities; generally infertile
mosaicism
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
sex-linked recessive inheritance
carried on X chromosome. Males don’t have the protective 2nd X, meaning they are more likely to exhibit it.
sex-linked recessive diseases
hemophilia A + B; color blindness; fragile X syndrome
autosomal recessive inheritance
must have two copies of recessive allele; someone can be a carrier with only one.
autosomal recessive diseases
PKU, CF, sickle cell anemia
autosomal dominant inheritance
only 1 dominant gene needed to exhibit disease
autosomal dominant diseases
Huntington’s, polycystic kidney disease, polydactyly, achondroplasia, neurofibromatosis
fertilization - where and what?
outer 1/3 of fallopian tube; sperm and egg (haploid) bind and become zygote (diploid)
zygote undergoes cleavage to become morula and then blastocyst
Implantation – when and what does each part become?
occurs between days 5-9
outer blastocyst -> placenta and amnion
inner blastocyst -> fetus
what are the three parts that develop from a balstocyst?
placenta
fetal membrane
embryo
fetal circulation loop
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
