Chapter 2: Prenatal Development Flashcards
How many chromosomes are there in humans
23 pairs or 46 chromosomes
What’s Genotype and what’s phenotype
Genotype is The genetic makeup (Genes) and Plenotype is the expression of the genes
Unit of heredity is
Gene
differentiate mitosis from meiosis
mitosis isthe diving of the cel into two identical copies (somatic cells), while meiosis is the division of the cell intro two where the daughter cells receive half of the chromosomes, this results in high genetic variation and cellular uniqueness
differentiate monozygotic twins from dizygotic
monozygotic twins are identical twins, where the zygote splits into 2 distinct but identical zygotes, and share 100%of their genes, while dizygotic twins or fraternal twins there are 2 separate eggs, fertilized by separate sperm
what’s the dominant recessive inheritance
is when the dominant allele is always expressed either heterozygous or homozygous while recessive only expressed when it’s paired with another recessive gene
incomplete dominance
genetic inheritance pattern in which both genes influence the characteristic. eg: blood, sickle cell trait
polygenic inheritance
a trait is a function of the interaction of many genes. eg: height, intelligence, and temperament
genomic imprinting
the instance when the expression of a gene is determined whether it is inherited from the mother or father. eg: prader-willi syndrome and algeman syndrome
genetic disorders
disorders and abnormalities that are inherited through the parent’s genes
definitions of dominant recessive disorders (phenylketonuria, huntingtons, cystic fibrosis, tay-sachs)
PKU (phenylketonuria) - common recessive disorder that prvents the body from producing an enzyme that breaks down the amino acid phenylalanine from proteins causing damage to the central nervous systems
huntington’s disease - dominant, degerative brain disorder that affects muscular coordination and cognition
cystic fibrosis - recessive, abnormal thick mucus clogs the lungs and digestive system, leading to respiratory infections and digestive difficulty
Tay-sachs - recessive, degenerative brain disease
how can the disorder PKU confirm the gene-environment interaction
The intellectual disability resulting from PKU results from the interaction of the genetic predisposition and exposure to phenylalanine from the environment
what are some examples of x-linked disorders
hemophilia - blood does not clog normally, recessive
fragile X syndrome - dominant disorder carried on the X chromosome
colorblindness - difficulty distinguishing red from green (blue from green)
duchennes muscular dystrophy - weakness and wasting of limb and trunk muscles; it progress slowly and affect involuntary muscles
give some examples of chromosomal abnormalities
trisomy 21 (down syndrome)
turner (X0)
triple X (XXX)
Klinefelter (XXY)
jacobs syndrome (XYY)
how to detect and predict genetic disorders
genetic counseling - conducting family history of heritable disorders
prenatal diagnosis - testing done to assess genetic defects on fetus
prenatal treatment - therapies administered prenatal to reduce effects of genetic abnormalities; example of CRISPR
name advantages and disadvantages of prenatal diagnosis
ultrasound
advantage: fully see the fetus
disadvantage: many abnormalities cannot be easily observed
amniocentesis
advantage: thorough analysis of fetus genotype
disadvantage: greater risk to fetus
CVS (chronic villus sampling)
advantage: genotype of fetus, painless, can be conducted earlier
disadvantage: can cause spontaneous abortion if done before 10 weeks
noninvasive prenatal testing (NIPT)
advantage: no risk to fetus, can diagnose several chromosomal abnormalities
disadvantage: not thorough and less accurate
examples of gene-environment interaction
range of reaction- genetic trait may be expressed in a wide range of phenotypes dependent on environmental opportunities and conditions
canalization - the trend of a trait that is biologically programmed to only a few outcomes
gene-environment correlation - many individuals’ traits are supported by genes and the environment
what are the 3 types of gene-environment correlation
passive - parents pass to child through environment and genes (passively receives)
evocative - child evokes change through others (their genetics influence the environment and the environment reciprocates)
active - child acts on their environment
what’s epigenetics? epigenome
epigenbtics is the strudy of genetic expession in connection with environment
epigenome is the molecule that dieects genes to turn on and off based on development and environment. eg: nutrition, trauma, injuries, responsive parenting, toxins
what are the patterns of genetic inheritance
dominant recessive
incomplete dominance
polygenic inheritance
genomic imprinting
Assisted reproductive technology (cost/benefit, success rate, and complications)
vitro fertilization (outside woman’s body)
cost/benefit: $12k not including medication, multiple cycles, financial burden, cells are screened for genetic problems
success rate: 50% depending on woman’s age
complications: no difference in development, but multiple gestations can cause increase risk for low birthweight, prematurity
surrogacy (surrogate)
cost/benefit: $30k-$55k
success rate: most surrogacies are successful
complications: no psychological differences to fetus, but mental and physical health risks to surrogate
what are the periods of fatal development
germinal period (weeks 1 and 2)
= cell division (30h after fertilization)
=cell differentiation (72h after)
=blatocyst (day 4) - fluid-filled sphere containing an inner mass of cells from which the embryo will develop
=implantation (day 6-11) - process in which blastocyst becomes attached to uterine wall
embryonic period (weeks 3- 8)
= neural tube - develop into the central nervous system
= development of major body systems
= risk of miscarriage
= sensitive to teratogens
=cephalocaudal and proximodistal
fetal period (weeks 9-40: 7 months, appearance of bones)
=end of first semester (9-13)
- spontaneously movement
-differentiation of sex organs
=second semester (14-26)
-development of lanugo (first hair) and vernix caseosa (greasy material covering the fetal skin and have a protective function, like for hardening that can occur with exposure to amniotic fluid)
-age of viability
=third semester (27-40)
-baby grows (5 pounds, 7inches)
-37 weeks is considered full term
high change of survival
what are the 2 ways of childbirth
childbirth- a surgical procedure that removes the fetus from the uterus through the abdomen
natural birth
what are the influences on prenatal development
teratogens
prenatal care
parental characteristics
