Development and Genetics Flashcards
What is the end product when a sperm and ovum combine?
Zygote
When a zygote is formed, it splits. When there are 8 cells, they each have equal potential. What does this mean?
They can all become everything a person needs for a body; if a cell is lost, a person can still fully develop from the 7 remaining cells
Term for inner cell mass (embryo) and trophoblast (placenta).
Blastocyst
What are the three germ layers?
- Ectoderm
- Mesoderm
- Endoderm
Germ layer that becomes the skin and nervous system
Ectoderm
Germ layer that becomes the muscles and bones
Mesoderm
Germ layer that becomes the GI tract
Endoderm
Occurs during organogenesis; time where organs are particularly susceptible to injury, cells are rapidly dividing, cells are migrating, and important interactions between cells are occurring
Critical periods
When do most critical periods occur?
First 3 months of pregnancy
Fetal RBC contain fetal Hb which are replaced by adult Hb after birth. What is the difference between the two Hb’s? Why does it make the switch after birth?
Fetal Hb has a higher affinity to O2; because of the higher affinity, it is also harder for the O2 to get to the baby’s body tissue
What is the importance of surfactant and gestational age?
Surfactant isn’t produced by the baby’s body until later pregnancy; premies don’t have enough surfactant to aid with breathing when born
Where are fetal RBC’s made?
Liver
Study of birth defects
teratology
Anything that can produce a birth defect?
teratogen
What are physical teratogens?
- X-rays
2. Other forms of irradiation
What are chemical teratogens?
- Alcohol
- Illegal drugs - cocaine
- Thalidomide - limb deficiencies
- Diethylstilbestrol (DES) - reproductive tract abnormalities and cancers
What are microbial teratogens?
- Direct effects:
1. Toxoplasma (cat and cat litter)
2. Other
3. Rubella
4. Cato megalovirus
5. Herpes virus - Indirect effects:
Weakening of the mother cause fetal weight reduction, growth retardation, premature birth
The DNA sequence determines the sequence of proteins
DNA base pair
All of the DNA that determines a protein, along with the regulation of the synthesis of that protein
Genes
Structures that contain multiple genes and DNA regulatory regions
Chromosomes
What are the types of chromosomal abnormalities?
- Structural
- Numerical
- Sex aneuploidy
Structural chromosomal abnormality where there is a loss of part of a chromosome
Deletion
Structural chromosomal abnormality where part of a chromosome is moved to another chromosome; may be moved to regulatory elements and turn expressions on or off
Translocation
What are 2 common diseases that are examples of structural chromosomal abnormalities?
- Fragile X
2. Philadelphia chromosome (associated with myelogenous leukemia)
Numerical chromosomal abnormality that has the wrong number of chromosomes
Aneuoploidy
Numerical chromosomal abnormality where where there is a loss of one chromosome; incompatible with life
Monosomy
Name the numerical chromosomal abnormality where there is a gain of one chromosomes; most are lethal, but some will result in birth defects if they survive. Which chromosomes result in abnormalities, not death?
Trisomy; 13, 19, and 21
Numerical chromosomal abnormality where there is a loss of an X chromosome (OX)
Turner’s syndrome; females only
Numerical chromosomal abnormality where there is a gain of an X chromosome (XXY)
Klinefelter’s syndrome; males
Changes in DNA sequence that produce a change in function
Gene mutation
Different versions of the same gene; code for different characteristics
Allele
Alleles on different chromosomes are the same
Homozygous
Alleles on different chromosomes are different
Heterozygous
The genetic make up of a person’s DNA; the alleles in their DNA
Genotype
How the genes are expressed in the individual; what you see
Phenotype
Trait that is expressed water homozygous or heterozygous; overshadow recessive genes
Dominant
True or false:
Not all people with an autosomal dominant gene will have the same S&S.
True; relates to penetrance and expressivity
Measure of whether the gene is expressed; a person may have the gene but not the disorder
Penetrance
Measure of how well the trait is expressed; how severe the disease is
Expressivity
Trait where both alleles are expressed
Codominant (blood types - AB)
Trait where only expressed of dominant alleles are not present; need to be homozygous
Recessive
What are 4 examples of recessive trait diseases?
- Cystic fibrosis (1 in 25 whites are carriers)
- Tay-sachs disease
- Sickle cell anemia
- Thalassemia
Disorders not linked to a single gene; involve several genes and exogenous factors
Multifactorial inheritance
Effect where persons with a more severe form of the disease have a greater chance of transmitting the disease
Dose effect
