Exam 1: Genetics Flashcards
Another name for base pair substitution:
Single nucleotide polymorphism
Most catastrophic form of genetic mutation:
Frameshift mutation
Three types of single gene disorders:
Dominant
Recessive
X-linked
X-linked recessive disorders predominantly affect which gender? Why?
Men, because with only one X gene, any inheritance will be expressed; for women, takes two
X-linked dominant disorders are:
Rare and few in number
Define aneuploidy. Which type is better?
Monosomy or trisomy of a chromosome
Trisomies are less devastating than monosomies
Which is the only monosomy which people typically survive?
Turner syndrome (female with only one X)
Give the aneuploidy for each disease: Down syndrome Edward syndrome Patau syndrome Turner syndrome Klinefelter syndrome
Down: trisomy 21 Edward: trisomy 18 Patau: trisomy 13 Turner: 45:X Klinefelter: 47:XXY
XXX females and XYY males:
Typically pretty normal
Define polyploidy:
69 instead of 48 chromosomes
Define penetrance:
The chance that phenotype follows genotype
Define haplotype:
Alleles on a single chromosome
What is nondisjunction?
When chromosomes don’t separate during meiosis
Which cells are more likely to experience nondisjunction? Why?
Oocytes; proteins are older at time of replication and less reliable
At what maternal age does the incidence of Down syndrome begin to rise?
35ish
Relationship between X and Y chromosome:
Part of Y is homologous with X; this part is needed for fertility
S/s of Turner syndrome:
Menopause before menarche
Webbed neck
“Less female” features
Short stature
S/s of Klinefelter syndrome:
Nonfunctional spermatagonia
Infertile
Mostly normal development
Small testes, long limbs
Is extra genetic material better or worse tolerated than missing genetic material?
Better tolerated
Types of errors with crossover:
Deletion when a chromosome segment is lost
Unequal crossing over leads to duplication on one side and deletion on the other
What is chromosome translocation?
Crossover between non-homologous chromosomes
Result of chromosome translocation:
Unbalanced gametes result in zygotes that are partially trisomic and partially monosomic
High rate of spontaneous abortion and cancer in survivers
Name six dominant single gene disorders:
Familial hypercholesteremia Huntington disease Achondroplasia Marfan's syndrome Retinoblastoma La-Fraumeni
Name five recessive single gene disorders:
Sickle cell anemia Cystic fibrosis Lysosomal storage diseases (Tay-Sachs, Gaucher, Niemann-Pick) Phenylketonuria Glycogen storage diseases
Name two X-linked recessive diseases:
Duchenne muscular dystrophy
Hemophilia A, B
Hemophilia A and B - which factor is missing?
A: VIII
B: IX
