Biological Principles 1 -- HW#2.1

translation
1. ribosome binds 5' end and finds 1st AUG = start CODON
2. tRNA with appropriate amino acid and complementary anticodon binds mRNA
3. 2nd tRNA binds 2nd Codon
4. ribosome cleaves 1st amino acid off of 1st tRNA
5. ribosome continues to march down the mRNA taking the last amino acid off of the last tRNA and attaching it to the amino acid of the next tRNA.
6. stop codon, stops.

Promoter -- signals beginning of transcription

eukaryote transcription
--pre-mRNA contains "intron" that are spliced out to leave "exons" in the mature mRNA

a gene is OFF
--no transcription because a protein blocks promoter
--negative control: a repressor inhibits transcription

a gene is ON
--transcription occurs
--RNA polymerase binds with mRNA

LAC OPERON
--regulatory system
--single promoter for 3 genes
--OPERON: some genes in bacteria are regulated together in a single transcript (mRNA)
--LAC: lactose: genes cooperatively are used to utilize sugar lactose
--gene 1: lac Z: encodes B-galactosidase
--gene 2: lac Y: encodes lactose permease
--gene 3: lac A: encodes galactosidase transacetylase

allolactose -- binds with repressor protein so transcription occurs

negative control -- repressor protein binds operator, no transcription, no gene expression

positive control -- CAP transcription: catabolite activator protein

mutation
--change in DNA
--spontaneous (errors of replication)
--radiation: UV and gamma
--chemicals

change in DNA
1. silent - no change in polypeptide chain
2. neutral - amino acid sequences changed but function is same
3. beneficial - better (rare)
4. deleterious - worse (common)

STR
--variable DNA
--unique patterns; identifiable

PCR -- polymerase chain reaction

telomerase -- enzyme that prevents chromosome shortening by attaching many copies of a DNA repeat sequence to the ends of chromosomes

histones
--group of proteins
--first way DNA is compacted by wrapping itself around histones

nucleosomes
--repeating structural unit of eukaryotic chromatin
--DNA wrapped around an octamer of histone proteins

DNA repair -- nucleotide excision repair (NER) removes segments of damaged DNA

CODON -- 3 nucleotides on mRNA that signify the code for an amino acid

Anti-Codon -- 3 complementary nucleotides on a tRNA that base pairs with the codon

mRNA
--messenger
--formation molecule
--sequence of nucleotides dictates sequence of amino acids in a protein

tRNA
--transfer
--RNA transports amino acids to the ribosome

rRNA
--ribosomal
--enzymatic
--couples amino acids together to form the peptide bond