Untitled Deck Flashcards
A, B, and C are linked genes. Recombination between A and B is 3%; between A and C is 6%; and between B and C is 9%. The order of these genes on the chromosome is
B-A-C
What is a trait caused by an environmental influence that appears to be inherited?
Phenocopy
How many genes does the human mitochondrial genome consist of?
37 genes (that encode 13 proteins, 22 tRNAs, and 2 rRNAs.)
What gene controls X inactivation?
XIST gene
What is the probability that June transmits colorblindness and ichthyosis to his son?
0% (sons inherit X-chromosome from the mother)
What type of mutagens are acridine dyes?
Mutagens that disrupt the reading frame of the gene
What is the characteristic shape of the mathematical plot for a multifactorial, polygenic trait?
Bell-shaped curve
What are traditional ways of evaluating multifactorial traits?
Empiric risk and heritability
What are DNA sequences that contribute to polygenic traits called?
Quantitative trait loci (QTLs)
What are the human equivalent of opiates
endorphin and enkephalin
Which neurotransmitters might contribute to causing autism if levels are abnormal?
Serotonin and GABA
What does schizophrenia mean?
“Split mind”
What condition may cause a person with narcolepsy to suddenly collapse?
Cataplexy
What does it indicate if a cancer cell is injected into a healthy mouse and develops tumors?
Cancer is heritable/transplantable
Where do mutational hot spots occur most often?
Regions where the DNA is repetitive/symmetrical
What was the first single-gene disorder for which the mechanism of mutation was understood?
Sickle cell disease
What term describes cancer cells that have lost their specializations?
Dedifferentiation/dedifferentiated
What is a passenger mutation?
A mutation that does not cause or propel a cancer’s growth and spread
What are genes that normally prevent cell division called?
Tumor suppressor genes
What causes osteogenesis imperfecta?
A mutation in a gene that encodes collagen
In a heterozygote for two linked genes, what arrangement are the alleles in if both dominant alleles are on one chromosome?
Cis arrangement
What does genetic heterogeneity refer to?
Mutations in different genes that cause the same symptoms
What type of mutation causes sickle cell disease?
Missense mutation
How is a mitochondrial trait passed?
From mothers to sons
What affects the phenotype when one allele is imprinted?
Imprinting
When can direct repeats cause mutation?
When homologs duplicate during meiosis
In human males, genes on the X chromosome are expressed
true
How many genes affect skin, hair, and eye color in humans?
More than 10 genes (nearly 170 genes)
Do people with light skin have the same number of melanocytes as those with very dark skin?
Yes
What type of mutation changes the codon GAA to UAA?
Nonsense mutation
Where was the first narcolepsy gene discovered?
In dogs (canines)
What is it called when GGG increasingly consumes more cocaine to get the same effect?
Tolerance
Myotonic dystrophy worsens with each generation because of the increasing number of repeated long DNA sequences
true
What do all cancers reflect at the most general level?
A defect in DNA repair and cell cycle regulation
What do sporadic cancers result from?
Somatic cells (somatic mutations)
What are traditional cancer treatments?
Surgery, chemotherapy, and radiation
Why are mutations more likely to occur in repeated DNA sequences?
Because the bases can form base pairs by generating loops that interfere with DNA repair
What is a tautomer?
An alternate structure of a molecule
What is the proportion of shared genes between a grandparent and grandchild?
25 percent
What is a source of gamma radiation?
Cesium isotope
