Exam 1 - Quiz Questions Flashcards
When a person has two alleles for a gene that are the same (BB, bb), what do we call this?
Homozygous
When a person has two alleles for a gene that are different (Bb), what do we call this?
Heterozygous
What is a single nucleotide polymorphism?
When a gene differs by one nucleotide base
The central dogma of molecular biology is that DNA is ———- into RNA, and then RNA is ———- into protein.
Transcribed, translated
Definition
Phenotype results from interactions between many genes
Polygenic
Definition
Phenotype of allele only expressed because dominant allele is not present
Recessive
Definition
Gene 1 influences the expression of gene 2
Epistasis
Definition
Phenotype of one allele is expressed over the other
Dominant
What enzyme is mutated in PKU?
Phenylalanine Hydroxylase (PAH)
Phenylalanine is unable to turn into Tyrosine due to this enzyme missing
Results in other pathways being utizlized, and metabolic toxicity
True/False
A sex-linked gene carried on the Y chromosome is always expressed in females
False
Never expressed in females (XX), where as males (XY)
Sex chromosomes are know as ——— and all other chromosome are known as ———
Allosomes, Autosomes
Definition
Changes the # of nucleotides and shifts the reading of codons, changing all amino acids downstream of mutation
Frame Shift Mutation
Definition
An entire section of DNA is reversed
Inversion
Definition
Changes one nucleotide in DNA, same number of nucleotides
Point Mutation
Describe the type of hemoglobin and phenotype seen in each of the 3 possible genotypes for sickle cell trait (SS, Ss, ss)
SS - normal hemoglobin, not resistant to malaria
Ss - 50% sticky cell hemoglobin, resistant to malaria
ss - 100% Sticky cell hemoglobin, resistant to malaria
Describe the difference between genotype and phenotype
Genotype (Bb,aa) is the specific DNA sequence of an allele, gene, cell, or organism where as the phenotype is the physical characteristic of the genotype (ex: brown hair)
——— is the rate-limiting enzyme in cholesterol synthesis
HMG CoA Reductase
If hemochromatosis is left untreated, which of the following may occur?
a) Diabetes
b) Cirrhosis
c )Skin pigmentation
d) All of the above
D) All of the above
Which protein is mutated in familiar hypercholesterolemia?
LDLR (Low density lipoprotein receptor)
True/False
For individuals homozygous for familiar hypercholesterolemia, statins are the best treatment option
False - Statins aren’t usually beneficial for homozygous individuals, although they can be helpful for those that are heterozygous
What serum cholesterol levels would someone heterozygous for familial hypercholesterolemia present with? How about those who are homozygous?
Heterozygous - Cholesteral levels >300 mg/dL
Homozygous - Cholesteral levels >600 mg/dL
Explain on a molecular level why a mutated HFE protein causes hemochromatosis to occur.
HFE protein regulates the transcription of hepcidin, and hepcidin regulates turning on/off ferraportin (allows the intake of Iron from cell into blood stream)
If HFE is mutated then it is unable to distinguish low versus high levels of Iron from the Iron transferrin receptor, and won’t turn on the genes to make Hepcidin. This leads to the ferraportin allowing an infinite amound of iron into the bloowsteam and liver –> too much iron
