Transcript
Launch
•What are some differences between autosomal and sex-linked traits?
•The offspring of two individuals produce 775 children with a dominant phenotype and 236 children with a recessive phenotype. What are the genotypes of the parents?
Molecular Genetics, Review7 March 2010
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Molecular Genetics
•Molecular Genetics is the study of how DNA is changed into workable substances that control our bodies
Molecular Structures
•The three structures that we work with the most are DNA, RNA and Protein
DNA Structure
•The structure of DNA is a double helix▫The strands of the helix are made of sugar
and phosphates▫Nitrogenous Bases (Adenine, Guanine,
Cytosine and Thymine) connect the strands of the helix
Central Dogma
•The central dogma states that DNA is changed into RNA and then into protein
DNA RNA Protein
Transcription Translation
Complimentary Base Pairing
•When converting DNA to DNA we use the following base pairing rules:▫A pairs with T▫T pairs with A▫G pairs with C▫C pairs with G
Complimentary Base Pairing
•When converting DNA to RNA, we use the following base pairing rules:▫A pairs with U▫T pairs with A▫G pairs with C▫C pairs with G
CFU
Translation
•Translation is the process of converting RNA into proteins
Codons
•Three nucleotides (bases) on an mRNA sequence form a codon
•One codon codes for one amino acid
•Ex: mRNA: AUG-CUU-CUC
Codons
•Because codons come from RNA and RNA is determined by DNA, the order of nitrogenous bases determines what proteins are produced
CFU
Codons
•Using a codon chart, find the amino acid sequence using the following DNA sequence
DNA: TAC-GTC-CCC-AAA-ATT-TTTmRNA: AUGProteine MET
Codons
Why is it important that different codons can produce the same amino acid?
UCCUCA Ser Ser
The reason for this is so that proteins wont be changed in the case of mutation!
CFU
Mutations
•Mutations are the result of one or more nucleotide (base) changes in DNA
Mutations
•All mutations happen in DNA but they also effect the amino acid sequence
Types of DNA Mutations Amino acid effects
FrameshiftPoint
SilentMissenseNonsense
Mutations
•A frameshift mutation results in either the addition or deletion of bases
•A pointmutation results in the change of one amino acid to another
Mutations
•A silent mutation does not change the protein being made
•A nonsense mutation results in an early stop for the protein
•A missense mutation results in a different protein being made
CFU
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