Post-translational + mutations

• What occurs to the ribosome after termination?

  The small and large subunits separate

  
• What is the wobble effect in genetics?

  Redundancy in the genetic code
• How many amino acids are coded by the genetic code?

  20 amino acids
• How many codons code for amino acids?

  61 of the 64 possible codons

  
• What is the significance of the first two nucleotides in a codon?

  They are always identical for each amino acid

  
• What does the third nucleotide in a codon do?

  It can change without affecting the amino acid

  
• Why do cells not need 61 different tRNA molecules?

  The third nucleotide can wobble

  
• What is the role of inosine in tRNA anticodons?

  It can bind with A, C, and U

  
• How does the wobble effect protect against mutations?

  It can turn mutations into silent ones
• What must happen to a polypeptide chain after translation?

  It must be folded into a functional shape
• Where does most protein folding occur?

  In the endoplasmic reticulum
• What are chaperonins?

  Proteins that assist in folding polypeptides

  
• What are the types of post-translation modifications?

  • Glycosylation: Addition of carbohydrates
  • Lipidation: Addition of lipids
  • Phosphorylation: Addition of phosphate groups
  • Ubiquitination: Addition of ubiquitin for degradation
• What are mutations?

  Changes in the nucleotide sequence

  
• What can cause mutations?

  Errors in DNA replication or mutagens
• What are mutagens?

  Factors that change nucleotide sequences
• Give examples of mutagens.

  Ultraviolet radiation, cigarette smoke
• What are point mutations also known as?

  Substitutions
• What happens in silent point mutations?

  No change in the amino acid sequence
• What are missense point mutations?

  They replace one amino acid with another
• What disease is caused by a missense mutation?

  Sickle Cell Anemia

  
• What is a nonsense point mutation?

  It creates a stop codon prematurely
• What are frameshift mutations?

  Insertions or deletions not in multiples of three
• What is Tay Sachs Disease caused by?

  A frameshift mutation in the HEXA gene
• What happens due to the frameshift mutation in Tay Sachs Disease?

  The enzyme hexosaminidase A becomes nonfunctional
• What are gametic mutations?

  Mutations in germ cells passed to offspring

  
• What are somatic cell mutations?

  Mutations in normal body cells not passed on

  
• How do mutations relate to natural selection?

  They can lead to changes in phenotype
• What is an example of natural selection in rock pocket mice?

  Dark mice survive better on dark lava
• What causes antibiotic resistance in bacteria?

  Mutations that provide survival advantages
• How do pesticides lead to resistance in insects?

  Individuals with resistance genes survive and reproduce
• What are the mechanisms that can change genotype or phenotype?

  • Errors in mitosis or meiosis
  • Horizontal gene transfers
  • Transformation
  • Transduction
  • Conjugation
  • Transposition

  
• What can errors in meiosis lead to in humans?

  Conditions like Down Syndrome or triploidy
• What is horizontal gene transfer?

  Transfer of genetic information outside reproduction

  
• What is transformation in horizontal gene transfer?

  Uptake of naked DNA from the environment

  
• What is transduction in horizontal gene transfer?

  Viral transmission of genetic information between bacteria

  
• What is conjugation in horizontal gene transfer?

  Direct transfer of DNA between prokaryotes

  
• What is transposition in horizontal gene transfer?

  Movement of DNA segments within DNA molecules

  
• How can related viruses increase genetic variation?

  By combining genetic information in host cells