Nucleic Acids B.8

Structure of DNA/RNA (B.8.1-3)

long polymers (thousands) of nucleotidestherefore, sometimes called polynucleotides

each nucleotide consists of 3 parts1. a phosphate group2. a pentose sugar called deoxyribose in DNA (or

ribose in RNA)3. in DNA/RNA, five nitrogen bases (only need to

recognize these)DNA - thymine(T), cytosine(C), adenine(A) and guanine(G)RNA – uracil(U) is substituted for thymine

Warning: Lots of pictures of nucleotides

DNARNA

Condensation reactionthe joining of nucleotides with a phosphodiester bond (a covalent bond) to form a sugar-phosphate backbone

RNA DNAsugar is ribose (OH is on 2’ carbon)

sugar is deoxyribose (H is on 2’ carbon)

contains the base uracil

contains the base thymine

single stranded two strands forming a double helix held together by hydrogen bonds

Distinguish between RNA and DNA

complementary base pairingthe size and shape of the bases is such that hydrogen bonds can only form at specific sitesadenine only forms two hydrogen bonds with thymineguanine only forms three hydrogen bonds with cytosine

why twisting/spiraling of DNA?it minimizes the repulsion between negatively charged phosphates

DNA as information (B.8.4)

inherit genetic material from parentsgenetic info. on DNA allows proteins to be made through the process of transcription and translation

Replicationhttp://highered.mcgraw-hill.com/sites/0072437316/student_view0/

chapter14/animations.html

http://www.johnkyrk.com/DNAreplication.html

Transcription and Translation

http://highered.mcgraw-

hill.com/sites/0072437316/

student_view0/chapter15/

animations.html

64 codons that code for 20 amino acids or to stop

DNA profiling steps and uses (B.8.5)

commonly known as ‘DNA fingerprinting’method used to identify individuals by similarities or differences in their DNA

isolation of the DNA from a sample sourceblood, semen, skin cells, hair or saliva

DNA is the cut up with restriction enzymes and replicated

these DNA fragments are then separated into bands according to size using gel electrophoresis

the resulting pattern is transferred to a nylon membrane, labeled with radioactive 32P, and exposed to x-ray filmfilm is finally compared to other samples of DNA

done