BIO 325 Study Guide - Final Guide: Growth Medium, Tata Box, Ribonucleoprotein
Review Outline for Final Exam Summer 2017
• Focus on the lecture slides, and remember to check the updated slides on Canvas to see
which topics were excluded.
• Questions will be straightforward, no tricks, so don't overthink them!
• Majority of questions will be multiple choice.
PLEASE CONTRIBUTE :-) It builds good karma
Chapter 2
• Understand both Mendel's laws (Equal Segregation and Independent Assortment).
● Alleles of a gene segregate so that each gamete receives one copy.
● Alleles of different genes display independent assortment during gamete formation.
• Phenotype and genotype ratios resulting from different types of crosses, like monohybrid,
dihybrid and testcross.
● Monohybrid ratio: 3:1 or 1:2:1 (incomplete/codominance)
● Dihybrid ratio: 9:3:3:1
● Testcross ratio
○ If all 1 phenotype, then the unknown is homozygous dominant
○ If 1:1 ratio, then the unknown is heterozygous
Chapter 3
• Difference between codominance, incomplete dominance, complementation, pleiotropy,
epistasis.
● Codominance
○ F1 hybrids express phenotypes of both parents equally
○ Ex: Red flower X White flower → Striped flower with red and white stripes
● Incomplete dominance
○ F1 hybrids differ from both parents and express an intermediate phenotype
○ Ex: Red flower X White Flower → Pink Flower
● Pleiotropy
○ A single gene determines more than one distinct and seemingly unrelated
characteristics
○ Ex: Sickle-Cell Syndrome
■ Hbßs allele affects multiple traits: sickling of red blood cells, resistance to
malaria, recessive lethality
● Epistasis
○ An allele of one gene masks the effects of another gene’s alleles
○ Ex: Coat Color in Labrador Retrievers
■ Homozygous ee hides effects of black (B-) or brown (bb) alleles and
results in a golden coat color
■ The e allele is epistatic to the B locus
● Complementation
○ When one dominant allele of each of two genes is necessary to produce a
phenotype
○ Example: Deafness Inheritance Patterns
■ Two genes control whether the person will be deaf or not, being
homozygous recessive in any of the two genes or both will result in the
deaf phenotype
■ AAbb X aaBB → AaBb Unaffected offspring
■ AAbb X AAbb → AAbb Deaf offspring
● When the two deaf parents are homozygous recessive in one of
the two genes, the offspring will all be affected (deaf).
○ When the two deaf parents are homozygous recessive in
different genes, the offspring will all be unaffected
• Penetrance and expressivity
● Penetrance
○ Percentage of a population with a particular genotype that show the expected
phenotype
○ If some people of a certain genotype do not always express the respective
phenotype of that genotype, the trait is an example of reduced penetrance
● Expressivity
○ Degree or intensity with which a particular genotype is expressed in a phenotype
○ A phenotype expressed at different levels in different individuals with the same
genotype is an example of variable expressivity
Chapter 4
• Know the parts of a chromosome, homologous and nonhomologous chromosomes,
autosomes and sex chromosomes
● Parts of a chromosome
○ Centromere
■ The middle part of a chromosome where the two sister chromatids
connect
■ Different positions of centromere
● Metacentric: Centromere is more or less in the middle
● Acrocentric : Chromosome is very close to one end
● Telocentric : Near end at telomere
● Homologous vs nonhomologous chromosomes
○ Homologous chromosomes contain the same set of genes, size, shape, and
banding patterns
■ Genes may carry different alleles of the same genes
○ Nonhomologous chromosomes carry completely unrelated sets of genes
● Autosomes
○ All the chromosomes that are not sex chromosomes
○ Human have 23 pairs of chromosomes
■ 22 of the chromosomes are autosomes and one pair are sex
chromosomes
● Sex chromosomes
○ The pair of chromosomes that determine gender
■ XX is the female genotype
■ XY is the male genotype
• Mitosis and meiosis – what happens in the different stages of each and how alleles behave
through these processes.
● Meiosis
○ Meiosis produces our gametes
○ Results in four haploid daughter cells after two rounds of meiosis
● Mitosis
○ Ensures that every single somatic cell in the body carries the same set of
chromosomes
○ Results in two daughter cells identical to the parent cell
● Steps of Mitosis
○ Interphase
■ Period of cell cycle between divisions/cell growth and replicate
chromosomes
■ G1 - birth of cell → beginning of chromosome replication/cell growth
■ S - duplication of DNA (synthesis phase)
■ G2 - end of chromosome replication → beginning of mitosis
○ Prophase
■ Chromosomes condense (DNA is packaged)
○ Metaphase
■ Chromosomes move towards an imaginary equator line
■ Homologous chromosomes arrange themselves in a line next to their
homologs
○ Anaphase
■ Homologous chromosomes are pulled apart by spindles towards opposite
sides of the cell
■ Separation of sister chromatids allows each chromatid to be pulled
towards spindle pole connected by kinetochore microtubule.
○ Telophase/Cytokinesis
Document Summary
Chapter 2: understand both mendel"s laws (equal segregation and independent assortment). Alleles of a gene segregate so that each gamete receives one copy. Alleles of different genes display independent assortment during gamete formation: phenotype and genotype ratios resulting from different types of crosses, like monohybrid, dihybrid and testcross. If all 1 phenotype, then the unknown is homozygous dominant. If 1:1 ratio, then the unknown is heterozygous. Chapter 3: difference between codominance, incomplete dominance, complementation, pleiotropy, epistasis. F1 hybrids express phenotypes of both parents equally. Ex: red flower x white flower striped flower with red and white stripes. F1 hybrids differ from both parents and express an intermediate phenotype. Ex: red flower x white flower pink flower. A single gene determines more than one distinct and seemingly unrelated characteristics. Hb s allele affects multiple traits: sickling of red blood cells, resistance to malaria, recessive lethality. An allele of one gene masks the effects of another gene"s alleles.
