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Review Sheet for Exam #4 (Morris Chapters 13-17)
Dr. Solti
This review is meant to serve as a guide to ensure your notes are complete. You will need to be able to
do/understand and READ YOUR BOOK! Simply filling out this review sheet will not be enough to earn a good
grade.
Chapter 13--Genomes
 Definition of genome
 No relationship between genome size and complexity of eukaryote
 Why are there differences between large and small genomes? polyploidy and amount of repetitive DNA
 Definition of polyploidy
 Humans have 2 sets of 23 chromosomes/total 46
 Transposable elements: "selfish DNA", inserts itself into new positions in genome; about 45% of human DNA
 Bacterial genomes are 1 long, circular chromosome in the nucleoid region
 Know 6 levels of eukaryotic chromosome packing
 Mitochondria and chloroplasts have a little bit of their own DNA supercoiled
 Virus: also called a virion; not a living organism.
o Why? Obligate intracellular parasite, cannot independently have life, not a cell, inactive outside of host cells
 Baltimore system of virus classification
 Basic structure, only 2 necessary pieces: genome (either SS or DS- DNA or RNA) and capsid (protein coat)
 Viral replication: viral DNA  viral RNA  viral protein
 Know about specific host range
 Know 2 reproductive cycles: lytic and lysogenic
 Retrovirus: “backward” virus….goes from RNA to DNA; uses reverse transcriptase enzyme; have extremely
high rates of mutation; ie. HIV, the virus that causes AID
 Emerging viruses: new viruses develop from cross-species jump…. from their natural hosts to humans (HIV,
dengue, Ebola, hanta, West Nile, etc)
o Causes: mutation of existing virus, change in human activity, natural disasters that put viruses with
humans, cross-species jumping, etc.
 Viruses and Cancer: 20% of all human cancers are viral, called Persistant Viral Infections
 Tumor viruses transform normal cells by inserting viral NA into host cell DNA…..this alters host cell’s
DNA: called Integration
 Proto-oncogenes: normal genes that can be transformed into oncogenes
 Oncogenes: cancer-causing gene
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Chapter 14--Mutations and DNA Repair
Understand what mutations are and their results
Mutation rates & how mutation rates depend on cell type
Germ-line versus somatic-line mutations
Somatic mutation and cancer
2 repair enzymes during replication
Point mutations--nonmutant gene, silent mutations, missense mutation, nonsense mutation
Sickle Cell results from missence mutation
Cystic Fibrosis in-frame deletion of 3 nucleotides; symptoms of CF
Transposable elements (transposons): moveable DNA sequences; can insert into a gene and disrupt its function
Mutations caused by mutagens
Chapter 15--Genetic Variation
Know definitions of: genotype, phenotype, polymorphisms, allele
Know that the effects of mutation depend up : whether mutation is homozygous or heterozygous & the
environment
Understand the heterozygote advantage of sickle cell trait (AS) versus sickle cell disease (SS) versus normal
hemoglobin (AA)
Understand that harmful mutations are often eliminated in 1 or few generations: (1). decreased survival, and (2).
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Review Sheet for Exam #4 (Morris Chapters 13-17)
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Dr. Solti
decreased reproduction
Know about emphysema and harmful mutations: understand the interaction between the alpha1AT gene and
smoking
Neutral mutations
Beneficial mutations: know about HIV and AIDs
Know what VNTR is (new genetic fingerprinting) and how it can be visualized by PCR and gel electrophoresis
Understand RFLPs
Know SNPs: commmon point mutations; i.e. eye color; there are 3 milliion SNPs between one human and
another
Understand nondisjunction: causes cancer if happens in anaphase of mitosis; causes gametes with extra or
missing chromosome in meiosis
Most human fetuses with extra or missing chromosomes miscarry, but some live: Down's Syndrome, 47
chromosomes, Trisomy 21
Know about sex chromosomal abnormalities: Turner, metafemale, Kleinfelter, Jacobs
Chapter 16--Mendel
Know the Blending Theory versus the Particulate Theory of Heredity
Hereditary factor detected: called “gene”
Two or more variations: can be called “traits” or “alleles”
True breeding: always producing offspring with the same alleles as the parents when the parents self-fertilize (
AA or aa)
F1: hybrid result of crossing the P generation: 1st generation offspring
Dominant trait: expressed trait in hybrid F1
Recessive trait: unexpressed (masked) trait in F1
Phenotype: how it looks
Genotype: the actual genes
Locus: specific location of a gene on the homologous chromosomes
Homozygous: same alleles on homologous chromosomes ( either AA homozygous dominant or aa homozygous
recessive)
Heterozygous: different alleles on homologous chromosomes (Aa; also called hybrid)
Know Law of Segregation and Law of Independent Assortment
Monohybrid Cross: cross looking at one gene (know how to do the Punnett Squares)
YY x yy
F1 result:
Genotype: 100% heterozygote (Yy)
Phenotype: 100% dominant phenotype
F2 result:
Genotype: 1 YY: 2 Yy: 1 yy
Phenotype: 3 yellow (dominants): 1 green (recessive)
Dihybrid Cross: in Genetics Lab Homework…know how to do FOIL to get gamete possibilities
Test Cross: when you have a dominant phenotype, but an unknown genotype (is it AA or Aa?); test it by
crossing the dominant phenotype with a homozygous recessive (aa)
Range of dominance: know complete dominance, incomplete dominance (snapdragons), and codominance
(blood types)
Incomplete dominance: problems with snapdragon flowers
P generation: RR (red) x rr (white)
F1 genotype: 100% Rr
F1 phenotype: 100% pink
F2 genotype: 1 RR: 2 Rr: 1 rr
F2 phenotype: 1 red: 2 pink: 1 white
Blood Type: AB…….example of codominance since both markers show up on the person’s RBC
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Review Sheet for Exam #4 (Morris Chapters 13-17)
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Dr. Solti
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Understand dominantly inherited disorders: Aa, i.e. brachdactyly, achondroplasia (a type of dwarfism, Dd);
Huntington’s Disease: a late-acting lethal dominantly inherited disorder: degenerative disease of nervous
system; first symptoms appear at age 35-45 when already passed allele on to next generation
Understand recessively inherited human disorders:i.e. albinism, CF, Tay Sachs Sickle Cell
Parents will be carriers (Aa x Aa)
Offspring: 1 normal AA: 2 normal carriers Aa: 1 recessive disorder aa
Cystic fibrosis: most common lethal genetic disease in US; defective chloride channels; leads to accumulation
of mucus in lungs, other organs
Tay Sachs: lipid accumulation in babies’ brains
Sickle Cell Disease: most common inherited disease of African-Americans in US; single amino acid
substitution leads to sickling of RBC in blood hemoglobin
Know incomplete penetrance versus variable expressivity
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Chapter 17--Sex Chromosomes
Know human sex chromosomes
Understand sex-linked inheritance....X-linked genes
Commonly applied only to genes on X chromosome
Mainly seen in males, but females can also have sex-linked recessive disorders
Examples: color blindness, male pattern baldness Duchenne’s muscular dystrophy, hemophilia
Know genetic linkage and genetic maps
Understand Y-linked genes
Understand maternal inheritance
Understand how to do the genetics problems we discussed in the Genetics Problems
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