Biological Principles 1 -- HW#2

single strand unwinding proteins -- stabilizes single strands
topoisomerase -- relieves torsional stress
helicase -- unwinds the double helix
DNA polymerase -- continues DNA synthesis from a RNA primer
DNA primase -- synthesizes a small RNA primer

three parts of a nucleotide
1. phosphate
2. deoxyribose
3. nitrogenous base

sugar in DNA nucleotide -- deoxyribose
sugar in RNA nucleotide -- ribose

nitrogenous bases in DNA -- adenine, thymine, guanine, cytosine
nitrogenous bases in RNA -- adenine, uracil, guanine, cytosine

enzyme responsible for transcribe -- RNA polymerase

enzyme responsible for translate of an mRNA -- ribosome

binding sequence in front of a gene
attracts RNA polymerase -- promoter

mRNA
--sequence of nucleotides on this RNA "calls" for a particular sequence of amino acids to be put together
--RNA molecule has a codon

tRNA
--RNA molecule has an anti-codon
--RNA molecule "carries" an amino acid with it

rRNA
--RNA associates with proteins to form a unit that has an enzymatic function

Portion of the pre-mRNA is discarded -- intron

enzymatic apparatus responsible for translation -- ribosome

binding site for RNA polymerase -- promoter

binding site for allolactose (lactose) -- repressor protein

binding site for repressor protein -- operator

binding site for cAMP -- CAP

binding site for CAP -- CAP site

under conditions lac operon to be expressed
--lactose present, glucose is not

under conditions expect high ATP concentrations -- glucose concentration is high

lac operon is regulated at -- transcription level

DNA
--storage molecule of information to make proteins
--polymer molecules (nucleotides)
--double stranded
--anti-parallel
--contains: phosphate, deoxyribose, nitrogenous base

Nitrogenous base
--in DNA: Purine [ Adenine, Guanine], Pyrimidine [ Thymine, Cytosine]
--in RNA: Adenine, Uracil, Guanine, Cytosine

RNA contains: phosphate, ribose, nitrogenouse base

Base-pairing rules
--in DNA: A-T, G-C
--in RNA: A-U, G-C

DNA replication
1. helicase proteins pull strands apart
2. single stranded binding proteins stabilize
3. topoisomerase relieves torsional stress
4. DNA primase synthesizes a small anti-parallel, complementary RNA
5. DNA primase "pops" off, DNA polymerase "pops" on, DNA polymerase continues synthesis

DNA synthesis 5' --> 3'
--as replication bubble opens there will be continuous synthesis on one strand in one direction but discontinuous synthesis on other strand in same direction

DNA polymerase III -- DNA polymerase that synthesizes from RNA primer

DNA polymerase I -- digest away the RNA primer and "fills" with DNA

DNA ligase -- fuses (forms covalent attachment) adjacent DNA fragments (OKAZAKI)

Instructions on DNA to produce gene product, protein?
--transcription: DNA is transcribed into an RNA copy
--translation: mRNA is translated into a polypeptide at the ribosome

Transcription -- RNA polymerase binds promoter region of gene, unwinds, synthesizes a complementary, anti-parallel RNA

tRNA -- transfer RNA; transport molecule for amino acids

rRNA
--ribosomal RNA
--in nucleolus rRNA and rProteins form subunits of ribosomes
--enzymatic

mRNA
--messenger RNA
--information specific amino acid sequence for the polypeptide chain

translation
--ribosome binds 5' end of mRNA
--ribosome identifies the first AUG triplet on mRNA -- 1st AUG = start CODON

tRNA -- has anti-codon