Bio 2 exam 2 notes

Bio 2 exam 2 notes - Bio 2 Midterm #2 Lecture Notes...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Bio 2 Midterm #2 Lecture Notes Molecular Genetics 1. One Gene-one Polypeptide Hypothesis a. This hypothesis was based on Beadle and Tatum’s original work Used mutations in bread mold to deduce gene-protein relationship Each gene was blocked by an early stem - From this they proposed a biochemical pathway - If some precursor blocks the conversion of a compound to another compound then it must lack an enzyme needed for that conversion - The enzyme that this biochemical pathway lacks is the one that much have a mutation in its gene One gene – one pathway - One defective gene produces a mutated protein which causes a block in the biochemical pathway b. Extension to Polypeptides Many proteins contain several polypeptides which are encoded by different genes c. Exceptions and Modifications Control sequences and introns - Noncoding sequences - See later notes tRNAs and rRNAs - non-proteins coded by genes - used in protein synthesis overlapping reading frames - some genes overlap with other genes d. Definition of “gene” A region of DNA whose final end product is a polypeptide or RNA 2. Overview a. Transcription The conversion of DNA into mRNA intermediate product or a tRNA or rRNA final product mRNA stands for messenger (intermediates) mRNA carries information to the ribosomes b. Translation The process in which mRNA information is read and translated into amino acid sequences Involves protein synthesis This process takes place on the ribosomes Language of nucleic acid language of proteins c. Posttranslational Modification Occurs after protein synthesis Process in which some proteins are modified - such as, the addition of a
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
sugar group Central Dogma: refers to the pattern of flow of information 3. The Genetic Code Metaphorically speaking, the dictionary that links the DNA/RNA information with amino acids Takes the form of a dictionary because information is being translated into different codes a. Codons (words in the dictionary) Sets of 3 RNA nucleotides Read left to right and is listed in the 5’ to 3’ direction Total possible codons = 64 Basically all organisms use this code Stand for - 20 amino acids - 1 start translation signal (AUG) - 3 stop translation signals (UAA, UAG, UGA) - fig. 12.6 shows all the combinations of possible codons and the amino acids they code for - stop codons do not code for amino acids - many codons encode the same amino acid b. Reading Frame Sending the right messages Start signal establishes the reading frame, otherwise the it would produce a nonsense protein There is no overlap in codons The start codon begins and sets the reading frame (sets of 3 bases) A frame shift, such as a mutation or deletion, can drastically change the framing of the protein Redundancy: different codons that code for the same amino acid c. Redundancy 2 aminos have only one codon - tryptophan - methionine other 18 have several condons
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/07/2008 for the course BIOSC 0160 taught by Professor Bledsoe during the Spring '08 term at Pittsburgh.

Page1 / 14

Bio 2 exam 2 notes - Bio 2 Midterm #2 Lecture Notes...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online