medical genetics

• What is the genetic makeup of an organism called?

  Genotype
• What is the physical appearance of an organism called?

  Phenotype
• What does the term "heterozygous" mean in genetics?

  Having two different alleles for a trait
• How many types of nucleic acid bases are there in the genetic code?

  4
• How many amino acids are encoded by the genetic code?

  20
• What is a codon in the genetic code?

  A sequence of three nucleotides

  
• How many codons are there in the genetic code?

  64
• Why is the genetic code considered degenerate?

  Multiple codons can code for the same amino acid

  
• How many amino acids can humans produce on their own?

  10
• What determines protein folding and stability?

  Amino acid charge, size, shape, reactivity, and hydrophobicity
• What is the origin of all genetic variation?

  Mutation
• What is a gene mutation?

  A change in a single base pair

  
• What is a chromosome mutation?

  A visible change in chromosome structure
• What is the difference between a spontaneous and an induced mutation?

  Spontaneous mutations have no known cause, while induced mutations result from external factors
• What type of mutation affects only germ cells?

  Gamete mutation
• What is a point mutation?

  A change in a single nucleotide
• What is a frameshift mutation?

  Insertion or deletion of nucleotides altering the reading frame

  
• What is a silent mutation?

  A base pair substitution that does not change the amino acid

  
• What is a missense mutation?

  A base pair substitution that changes the amino acid

  
• What is a nonsense mutation?

  A base pair substitution that creates a stop codon

  
• What is a transition mutation?

  Purine to purine or pyrimidine to pyrimidine substitution

  
• What is a transversion mutation?

  Purine to pyrimidine or pyrimidine to purine substitution

  
• What is the molecular consequence of a gain-of-function mutation?

  Abnormal protein product enhances normal protein function
• What is the molecular consequence of a loss-of-function mutation?

  Loss of protein function
• What is haploinsufficiency?

  Loss of function where 50% of the gene product is insufficient
• What is a dominant negative mutation?

  Abnormal protein product interferes with normal protein function
• What is the most common deletion causing cystic fibrosis?

  DF508
• What is the effect of the DF508 mutation in cystic fibrosis?

  Protein does not fold and is degraded
• What is the characteristic genetic feature of Huntington's disease?

  Increased CAG repeat length in the huntingtin gene
• What is the effect of a splice site mutation?

  Alters the splicing signal necessary for proper intron excision
• What are the two main types of splice site mutations?

  Donor site and acceptor site mutations
• What is the effect of a mutation in a promoter or enhancer region?

  Affects the quantity but not the quality of the gene product
• What is the effect of a mutation at a ribosome binding site?

  Affects translation initiation
• What is the effect of a mutation at an exon-intron junction?

  Alters the splicing of the mRNA
• What is the effect of a mutation at a cryptic splice site?

  Excision occurs within the next exon
• What is the effect of a mutation in a non-coding sequence?

  No phenotype is observed
• What is the effect of a mutation in a transcription factor binding site?

  No response to environmental cues
• What is the effect of a mutation in a suppressor binding site?

  Constitutive activation of the gene
• What is the effect of a mutation in an RNA polymerase binding site?

  Blocking of gene expression
• What is the effect of a mutation in a ribosome binding site?

  Affects translation initiation