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Study Guide

[BI111] - Final Exam Guide - Comprehensive Notes fot the exam (88 pages long!)


Department
Biology
Course Code
BI111
Professor
Tristan Long
Study Guide
Final

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WLU
BI111
FINAL EXAM
STUDY GUIDE

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Buy SimBio for Tutorials ($5 US)
Biology Journal (about 59 cents)
Read units 36-39, 32, 45, 46 and 48 for this week
DNA as repository of genetic information
DNA is a language, every cell contains info how they build, copy, prepare themselves
Encoded in a polynucleotide chain in a "language" with 4 "letters
Linked by a sugar phosphate backbone, adenine with thymine, guanine with cytosine
DNA replication is quite accurate- instructions aren't corrupted from one sequence to another
Mutations are not necessarily a bad thing
Mutation Rates
Vary within and between taxa
Vary with environmental conditions
o In some environments mutation rates are higher
Higher in RNA viruses (10-3 to 10-5 mutation base -1 generation01) than in DNA viruses (10-6 to 10-8)
Higher in mitochondrial DNA (3x10-6 to 2.7x10-5) than in genomic DNA (2.5x10-8)
Higher in asexual species than sexual species
In humans 1.1x10-8 mutations, per site per generation
On the Road to the Phenotype
Introns removed from Pre-mRNA before translation
Alternate mRNA transcripts created by selective slicing/arrangement of exons
Translation involves taking particular string of letters and reading them 3 letters at a time
The genetic code has both specificity and redundancy
Genetic code was established very early in the evolution of life and has remained unchanged
Nonsense mutation means a mutation occurs that results in a stop codon being prematurely called
upon(missing a big part of sequence)
Silent mutation codons call for the same amino acid and switching one letter does not change the
amino acid being called for
Frameshift mutation which involves the deletion or addition of one or more base pairs into a
particular sequence
Mutations can affect phenotypes
Sometimes even a very simple mutation can have a huge impact on a phenotype
In hemoglobin which is made up of many proteins, single mutation is responsible for sickle celled
anemia
Many alleles, varying affects on phenotype
Two copies of the same allele, mother and father both donated either big a or little a and are
Homo(same)zygous(sperm or egg)
Two copies of different alleles, small a and big A are Heterozygous because there is a mismatch
between the two matches
Manx cats
Mutation originated in populations of cats on the Isle of Mann
Tailless mutation is dominant and homozygous lethal
Different Types of Genes
1)All white fur controlled by "White Masking" gene
W-dominant all white hair
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w-recessive, colored hair possible
W allele has 'epistatic' and 'pleiotropic' properties
2)Pleiotropic effects on phenotype
Altering shape of hemoglobin
The "dense pigment" gene, "D" codes for melanophilin, a protein involved in the transportation and
deposition of pigment into a growing hair
3)Piebald Spotting gene "S" is responsible for whether coat has white patches
2 alleles:
s(recessive)-homozygous have no white hair
S(incomplete or partial dominance)- some white hair
No white hair(ss), some white hair (Ss), lots of white hair (SS)
4)The "red" gene, "O", located on the X-chromosome determines whether or not there will be red
variation in fur color
2 Alleles:
O(dominant)-production of phaeomelanin(red)
o(recessive)- production of eumelanin(browns and blacks)
5. The "Agouti" gene, "A" influences where pigment is deposited. Non-agouti (aa) are
hypermelanistic and mask tabby patterns
At Tabby pattern gene(Taqpep)
o 2 alleles:
Mc(dominant)-Mackerel striped phenotype
mc(recessive)-'classic' tabby when homozygous
6. The "TYR" gene (aka"C") contains instructions on how to produce the enzyme tyrosinase
"Wild-type" allele is dominant, C, produces functional tyrosinase
Recessive allele, c is recessive, results in albinism when homozygous
Burmese cbcb, Siamese cat cscs, Tonkinese cat cbcs (genotype by environment interaction)
Phenotype produced by different alleles depend on the environment (GxE)
Sex Chromosomes
Homogametic-homo meaning the same
Heterogametic sex
o Sex chromosome often*(not always, can be determined by environment) determine sex
o X and Y chromosomes in some species
o XX:female;XY:male
o W and Z chromosomes in others (birds, Lepidopterans)
o WZ: Female; ZZ:male
o Other chromosomes are called autozoic
Consequences of Sex Chromosomes
Heterogametic sex has only one copy of each type of sex chromosome
o One copy of a recessive allele results in expression of the trait
Homogametic sex have two copies of sex chromosomes
o Heterozygote: recessive allele hidden (carrier)
o Homozygote recessive: trait expressed
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