Genetics intro Flashcards
Who was the Australian monk and founder of modern genetics?
Gregor Mendel
Before Gregor Mendel, how did scientists think traits were inherited?
by blending of parents’ traits
What were the results of the DNA analysis on Gregor Mendel when his body was exhumed?
-very large brain
-neurologic disease genes identified
What did Gregor Mendel experiment with?
pea plants
What are the names of Mendel’s Laws?
- law of segregation
- law of independent assortment
- law of dominance
What is the law of segregation?
each person has two alleles for each gene and only one is contributed to a gamete in a random manner with equal frequency
What is the law of independent assortment?
alleles for different genes are sorted into gametes independently of each other, therefor one allele of a gene does not affect a different allele of a different gene
What is the law of dominance?
in a heterozygote, one trait will conceal the other and the presence of a dominant allele will conceal the trait of the recessive allele
What is it called when alleles of a gene are identical (AA or aa)?
homozygous
What is it called when alleles of a gene are different (Aa)?
heterozygous
What is the location of a gene on a chromosome called?
locus
What is the individuals collection of genes, or can reference to two alleles that code for a gene (AA, Aa, aa)?
genotype
What is the observable trait or set of traits that is created from your genetic makeup–hair color, flower color, wrinkled seeds?
phenotype
Genotype determines ___________
phenotype
What is is called when a disease is expressed in 100% of people with a particular genotype, incomplete or complete?
penetrance
most diseases are _______
polygenic
What does it mean when it is said that most diseases are polygenic?
several or many alleles of several genes are interacting
How many chromosomes do humans have?
46 chromosomes
-22 pairs of autosomes
-1 par of sex chromosomes
During cell division, what can lead to an abnormal number of chromosomes?
nondisjunction
What is nondisjuction?
failure of chromosome pairs to separate
What are examples of nondisjunction that occurs during cell division?
monosomy
trisomy
polysomy
What is it called when only one member of chromosome pair is present?
monosomy
What is it called when three chromosomes are present?
trisomy
What is it called when one chromosome is present 4 or more times?
polysomy
What can occur in a chromosomal region that can cause no or severe changes in a phenotype?
deletions and inversions
What is the most common trisomy?
down syndrome (trisomy 21)
The risk of having a child with down syndrome increases with _______
maternal age
Women who become pregnant at 35 or older are considered high-risk for what?
down syndrome and other malformations due to increased age
What tests are beneficial for diagnosis of down syndrome during pregnancy?
labs and ultrasounds
What are these facial characteristics associated with?
-flat facial features
-upward slant of eyes
-brushfield spots on iris of eyes
-changes to ear structure
-small nose
-enlarged and protruding tongue
down syndrome
These abnormalities can be present in individuals with what?
-deep palmar crease (simian crease)
-extra space between first and second toe
-hyper flexibility of joints
-decreased muscle tone (hypotonia)
Down syndrome
What are the organ manifestations of down syndrome?
*cardiac defects:
-most common cause of mortality in DS
-atrioventricular septal defects
*gastrointestinal malformations
*vision and hearing loss
*pulmonary infections
What are the growth feature manifestations of Down syndrome?
*short stature
*short fingers