Genome consists of DNA that contains one complete copy of all the genetic information of that organism.
(eukaryotic cells have a nuclear genome (multiple DNA molecules dispersed among haploid or diploid set of chromosomes,) mitochondrial genome (single, usually circular DNA molecules resembling those of bacteria,) and in the case of plants and algae, a chloroplast genome (same as mitochondrial.) Bacterial genome consists of one circular (ds) DNA molecule (a chromosome) in the nucleoid as well as circular plasmid DNA that carry genes for cellular replication and other functions.
Genome size is expressed as the number of base pairs (bp) (or Kb, Mb, and Gb).
Genome size increases with the complexity of the organism: viruses: contain enough nucleic acid to code for a dozen or so proteins, bacteria can code for a few thousand, and eukaryotic cells - hundreds of thousands of proteins. (there are exceptions to this rule within the eukaryotes, though.).
How large is the human genome? About 3.2 billion bases (about 1000x more DNA than E. coli) of which 90% was sequenced by 2001 and 100% is expected by 2003!.
Approx. what percent of the human genome codes for something functional? 1-2%.
Chapter 17:.
Foci: PCR, and cancer:.
PCR:.
Polymerase Chain Reaction.
(pp. 533-534).
A method to rapidly (in a few hours) amplify selected DNA segments that are present only in small amounts in a sample (less than 1 µg of DNA; the amount in a small drop of blood) (e.g. a few skin cells).
Billions of copies can be made of a particular DNA sequence, producing enough genetic material for DNA fingerprinting (note: DNA fingerprinting can be used with as little as 1 µg DNA; see pp. 502-503.) Both techniques can be used in forensic studies.
Simplicity: a DNA polymerase.
Required: .
1) DNA sequence with a known base sequence.
2) short ss DNA primers (chosen based on DNA sequence).
15-20 nucleotides long (complementary to the two ends of the DNA being amplified) (synthetic) (responsible for selecting the DNA sequence to be amplified).
