BIO 184 Laboratory
CSU, Sacramento
Fall 2008
EXAM 2 STUDY GUIDE – GENERAL CONCEPTS
Single-Gene Mutations
Point mutations (transitions vs transversions)
Structural Gene Mutations (silent, missense, nonsense, frameshift)
Supressor mutations (intragenic vs intergenic) vs Reverse mutations
Spontaneous mutations (DNA replication, depurination of purines, deamination of
cytosines, tautomeric shifts)
Induced Mutagens
Chemical (base modifiers, base analogues, intercalating agents)
Physical (Ionizing radiation very potent – able to break bonds; non-ionizing
radiation such as UV causing thymine dimmers)
Ames Test
Repair mechanisms (methyl-directed mismatch repair, photolyase removal of thymine dimers
caused by UV irradiation; Xeroderma pigementosum is caused by the lack of a repair
mechanism)
Prokaryotic Gene Regulation
Transcriptional regulation
Repressors/ activators
Catabolic regulation uses induction= Positive control (lac operon)
Anabolic regulation uses repression =Negative control (trp operon)
Inducers, Corepressors, Inhibitors
Lac Operon (a polycistronic mRNA)[Positive control regulation]
Promoter, Operator, CAP site, lac Z (B-galactosidase), lac Y (permease) and
the lac I (repressor)
regulation by repressor (inducer is allolactose)
regulation by activator protein (CAP plus the inducer cAMP)
Induction in the presence of Glucose and/or Lactose
Trp Operon (another polycistronic mRNA) [negative control]
trp R is the repressor protein; corepressor is trypotophan itself (feed-back
regulator)
Attenuation (coupled transcription & translation allows for tryptophan to feedback and cause premature termination of transcript)
Translational Regulation (inhibitors that prevent translation)
Antisense RNA
Eukaryotic Gene Regulation
Transcription factors and regulatory elements
Chromatin compaction changes
DNA Methylation (expression, repair, imprinting & disorders)
Alternative splicing
Stability of mRNA
BIO 184 Laboratory
CSU, Sacramento
Fall 2008
Meiosis and Mitosis
Chromosomes vs chromatids
Homologous chromosomes
Non-disjunction
Chromosome number variations (genome mutations)
Euploidy (variation of complete sets)
Polyploidy
Aneuploidy (variation of particular chromosomes within a set)
Sex Chromosomes vs Autosomes
Natural Mechanisms to Produce Chromosome Number Variations
Meiotic Nondisjunction (difference between nondisjuction in meiosis 1 vs 2)
New Species Formation (autopolyploid, allopolyploid)
X-inactivation (Barr bodies)
Chromosome Structure & Recombination (rearrangements)
Types of Mutations that Alter Chromosome Structure
Deletions/Defiencies (pseudodominance)
Duplications (creation of gene families)
Inversions (pericentric, paracentric, inversion heterozygotes)
Translocations (reciprocal, simple or unbalanced; meiotic segregation of
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can lead to balanced or unbalanced gametes)
Familial Down Syndrome