DNA
What Is DNA Deoxyribonucleic acid Molecule of heredity Constitutes our genes Genes are stretches of DNA sequence DNA is present in each cell Passed on to gametes and into progeny
What is DNA, Really Polymer of nucleotides Polymer? Nucleotides? A large molecule that is a series of joined smaller molecules Nucleotides The small molecules that make up the large DNA polymer
DNA Concepts Genes Chromosomes Complementary base-paired double helix Polymer of nucleotides The sequence of nucleotides is the information of DNA
DNA Concepts DNA controls traits of organism Traits pass from parent to offspring DNA is copied during cell division DNA is present in sex cells DNA is passed from parent to offspring
Nucleotides The building blocks of DNA
Nucleotides Adenosine monophosphate Cytidine monophosphate Figure: 10-08 Caption: Structures & names of the nucleosides & nucleotides of RNA & DNA. Adenosine monophosphate Cytidine monophosphate Guanosine monophosphate Uridine monophosphate Deoxyadenosine monophosphate Deoxycytidine monophosphate Deoxyguanosine monophosphate Deoxythymidine monophosphate
Order of Nucleotides As nucleotides join the strand they generate a sequence Inherent fidelity of DNA replication TAAGTGTACACGTA ATTCACATGTGCAT TAAGTGTACACGTA TCACATCG TAAGTGTACACGTA TCACATCG TCACATCG AGTCCGATCGTAACTGGGTCACATCGTAAGTGTACACGTA TCAGGCTAGCATTGACCCAGTGTAGCATTCACATGTGCAT |||||||||||||||||||||||||||||||||||||||| AGTCCGATCGTAACTGGG TCACATCG TAAGTGTACACGTA |||||||||||||||||| |||||||||||||||||||||| TCAGGCTAGCATTGACCC AGTGTAGC ATTCACATGTGCAT AGTGTAGC AGTGTAGC ATTCACATGTGCAT TAAGTGTACACGTA ATTCACATGTGCAT
DNA Sequence Human Genome Project What does “sequencing” mean? sequencing the human genome What does “sequencing” mean? To determine the order of the nucleotides in the human DNA molecules Human DNA molecules are our chromosomes Each chromosome is a DNA double helix Each DNA double helix is two single DNA molecules intertwined Each single DNA molecule is a chain of nucleotide units Sequencing is the method to determine what the exact order of units is in this chain
Gene Expression DNA Gene Transcription RNA (messenger RNA) Translation Protein (sequence of amino acids) Functioning of proteins within living cells influences an organism’s traits.
Overview of gene expression A C
The code is 3 letter words, but what about punctuation? GROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW c b a b Code written in three letter words - codons Ribosomes must start at the right place to read the message There are three frames, but only one is read to give an intelligible message Need a start codon (NOW) and a stop codon (END) to define the frame to use frame b NOW THE CAT SAW THE DOG BUT DID NOT RUN
Reading Frames & Mutation Types Frame shift mutations Original reading frame is frame a Insertions or deletions shift the reading frame ROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW a b c ROWNDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW a b c ^
Reading Frames & Mutations ROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW a b c Once a ribosome begins translation in a particular frame (a) it does not shift frames Therefore, if a mutation shifts the reading frame in the mRNA, the ribosome will read the wrong frame. ^ ROWANDNOWTHECATSAWTHEADOGBUTDIDNOTRUNENDSEW a b c NOW THE CAT SAW THE ADO GBU TDI DNO TRU NEN DSE W..
Reading Frames & Mutations ROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW a A change that creates a stop codon is a non-sense mutation Generates a truncated protein ^ ^ ROWANDNOWTHECATSAWTHEDOGBUTENDNOTRUNENDSEW a NOW THE CAT SAW THE DOG BUT END
Reading Frames & Mutations ROWANDNOWTHECATSAWTHEDOGBUTDIDNOTRUNENDSEW a A change that creates a different codon is a mis-sense mutation Generates a protein with an altered sequence ROWANDNOWTHECATSAWTHEHOGBUTDIDNOTRUNENDSEW a ^ NOW THE CAT SAW THE HOG BUT DID NOT RUN END
Molecular Basis of Phenotype
Effect of Mutations Sickle cell disease single nucleotide change AT