BIO SCI 98 Lecture Notes - Lecture 1: Alpha Helix, Beta Sheet, Transfer Rna
19 Jun 2018
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The Central Dogma Of Molecular Biology
DNA → RNA → protein
What you need to know about proteins
-Proteins are chains of amino acids joined
together
-20 different amino acids
-Features
-Amino group (N)
-Carboxyl group (C)
-R group (side chain)
-Each amino acid has 3 letter and 1 letter
nickname (Phenylalanine, Phe, P)
-Peptide bond joins two amino acids together
-Proteins also called polypeptides
-N-terminus = front of polypeptide = 5' on RNA/DNA
-C-terminus = back of polypeptide = 3' on RNA/DNA
-4 levels of structure
-Primary = linear sequences of amino acids
-Secondary = alpha helices and beta sheets
-Tertiary = 3D structure of folded protein
-Quaternary = subunits
find more resources at oneclass.com
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Translation in a nutshell
1. Processed mRNA shuttled from nuclear
2. Ribosome assembled onto mRNA
3. tRNA with bound amino acid enters ribosome, base pairs with codon sequence on
mRNA
4. Ribosome catalyzes formation of a peptide bond between two amino acids bound to
tRNA
5. Ribosome moves along mRNA, 3 nucleotides at a time
a. New tNRAs enter and have their amino acids attached to the growing
polypeptide
The Central Dogma is the Engine of Evolution
Classical definition of a gene: genes are discrete, heritable elements that control an observable
phenotype or biological property
Modern biochemical definition: genes are pieces of DNA that direct protein synthesis
Genotype determines Phenotype
-Gregor Mendel → discrete inheritable units that give rise to observable physical
characteristics
-Dominant + recessive traits
-Traits sort independent of one another
-2 versions of each trait (alleles) passed down by each parent
-Wilhem Johanssen → coined terms "gene", "genotype", "phenotype"
-Genotype: genetic constitution of an organism
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Proteins are chains of amino acids joined together. Each amino acid has 3 letter and 1 letter nickname (phenylalanine, phe, p) Peptide bond joins two amino acids together. N-terminus = front of polypeptide = 5" on rna/dna. C-terminus = back of polypeptide = 3" on rna/dna. Primary = linear sequences of amino acids. Tertiary = 3d structure of folded protein. Translation in a nutshell: processed mrna shuttled from nuclear, ribosome assembled onto mrna. The central dogma is the engine of evolution. Classical definition of a gene: genes are discrete, heritable elements that control an observable phenotype or biological property. Modern biochemical definition: genes are pieces of dna that direct protein synthesis. Gregor mendel discrete inheritable units that give rise to observable physical characteristics. 2 versions of each trait (alleles) passed down by each parent. Wilhem johanssen coined terms gene, genotype, phenotype Based on observations of segregation patterns of chromosomes during division. White eye trait only segregated with males.
