Biology Review 8-11
~DNA STRUCTURE AND REPLICATION~
DNA is the genetic material
--some viruses can infect the host cell by injecting their DNA
Phage reproductive cycle
--attaches to bacterial cell, injects DNA, makes more phages, cell lyses and releases
DNA and RNA are polymers of nucleotides
--DNA is a nucleic acid made up of nucleotide monomers.
--Pyrimidines = T&C, Purines = A&G
--RNA uses U instead of T, HCNOP
DNA is a double stranded helix
--Found by Watson and Crick based by Franklin, Three dimensional, two polynucleotide
strands wrapped around each other.
--hydrogen bonds hold bases together, A pairs with T, C pairs with G
--depends on base pairing, starts with separation of DNA strands, each strand becomes a
--is a complex process b/c DNA must unwind.
--happens quickly. With few errors-proofread and repair.
The flow of genetic information
--genotype is the genetic makeup, phenotype is the expression, genotype is expressed
though proteins, a gene is a line of nucleotides, genes specify how to build polypeptides.
From DNA to protein
--DNA is transcribed to RNA and translated into a polypeptide.
--produces messages in RNA form, the DNA unzips and RNA nucleotide bases pair up
on one side, the RNA peels off and the DNA rejoins.
--has 3 steps 1. Initiation 2. Elongation 3. Termination
Eukaryotic RNA is processed before leaving the nucleus
--transcription~ RNA is used to make proteins = mRNA, mRNA carries the message
to…, Translation~ ribosome attaches to mRNA, tRNA translates the message to a
--genetic info written in codons is translated to amino acid sequences, triplets of bases are
codons, they specify the amino acid sequence of a polypeptide, almost all organisms use
the exact same genetic code.
The genetic code
--each codon is translated into an amino acid, start=AUG, stop=UAA, UAG, UGA.
--DNA>RNA>Protein, the codon sequence in DNA spells out structure of polypeptide.
Mutations can change the meaning of genes