BIOL 142 Study Guide - Spring 2018, Comprehensive Midterm Notes - Gene, Dna, Messenger Rna
BIOL 142
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Tuesday, January 23, 2018
BIOL142
•What makes us unique? Different versions of genes#
•Instructions are not always available - nucleus is the first line of defense#
•Can instructions be changed - mutations#
What is a gene?#
•Gene: a unit of heredity that is transferred from a parent to offspring and is held to
determine some characteristic of the offspring#
•Technical definition: a sequence if nucleotides forming a part of a chromosome, the
order of which determines the order of monomers in a polypeptide or nucleic acid
molecule which a cell may synthesize#
•What does a gene need to function?#
•Carry information/code#
•Regulation - on/off switch#
•Withstand errors#
•Mendel - alleles are associated with specific traits which are transmitted to offspring#
•Theodor Boveri and Walter Sutton - chromosomes occur in matched pairs which
separate during meiosis. #
•Watson&Crick&Rosalin Franklin - used previous an new observations to model
secondary structures of double stranded DNA#
•Post-transcriptional control: mRNAs can be modified and/or degraded#
•mRNA is read from 5’-3’ for translation#
•Start codon = AUG#
•Stop codon = UGA, UAA, UAG#
•Redundancy - the code can withstand errors
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Thursday, January 25, 2018
BIOL 142
•Coding sequence is read in 5’-3’ direction"
•Copy is complementary and anti-parallel"
•Mutations"
•Silent - does not change the aa specified by the codon"
•Missense - change in nucleotide sequence that changes the aa specified by the
codon"
•Nonsense - change in nucleotide sequence that results in a early stop codon
(changes it to a stop codon)"
•Frameshift - addition or deletion of nucleotide"
•Mutation categories"
•Beneficial mutations - increase the fitness"
•Neutral mutations - Do not affect fitness (silent)"
•Deleterious mutations - decrease the fitness"
•Most mutations are neutral or slightly deleterious"
•Things we need for transcription"
•Template"
•Initiation"
•Separation of strands"
•Polymerase activity"
•Termination "
•Start and stop codons are not relevant here"
•Sense strand (non-template, coding strand) & anti-sense strand (template strand)"
•Sense strands looks like how the RNA would look (except there are Us instead of Ts)"
•RNA polymerase (sigma a holoenzyme) - holoenzyme meaning the enzyme complex"
•Sigma (interface with the substrate) - initiation/promoter recognition"
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Document Summary
Di erent versions of genes: instructions are not always available - nucleus is the rst line of defense, can instructions be changed - mutations. : a cell"s ploidy indicates the number of each type of chromosome present (n,2n,3n, etc) - 2n in humans, diploid, organisms with two of each type of chromosomes are termed diploid. Tuesday, february 6, 2018: crossing over, random combination of egg and sperm (out crossing) #2: sticky ends may have 5" - or 3"- overhangs, the average distance between cutting sites is determined by how long the recognition sequence is and the probability of nding each nucleotide. Biol 142: the genome is the genetic material of an organism. The genome includes both the genes and the non-coding sequences: there are approximately 25000 genes in human beings, signi cantly more segmental duplications (nearly identical, repeated sections of.
