12.1 DNA: STRUCTURE & FUNCTION DNA—deoxyribonucleic acid

BACKGROUND INFO--NUCLEUS -NUCLEUS is control center of the cell— -NUCLEUS controls all cell activities including: cell reproduction & heredity storage of genetic information DNAGENESCHROMOSOMESNUCLEUSCELLS

BACKGROUND INFO--PROTEINS -building blocks for every structure in your body -control chemical processes in the cell

DNA FUNCTION DNAStorage/Transmit genetic information DNA’s primary function – code for PROTEINS

DNA BLUEPRINT of LIFE— ALL body cells (except sex cells) have same copies of DNA to produce protein structures…. all 70 BILLION of them!! DNA is found in other organelles— mitochondria & chloroplasts

DNA STRUCTURE 1953—James Watson & Francis Crick discovered -double helix = twisted staircase -unwound resembles a ladder

DNA STRUCTURE

copyright cmassengale DNA Double Helix Nitrogenous Base (A,T,G or C) “Rungs of ladder” “Legs of ladder” Phosphate & Sugar Backbone copyright cmassengale

NUCLEOTIDES -repeating sub-units of DNA 1 nucleotide = 1 sugar, 1 phosphate, 1 base

NUCLEOTIDES stack on top of each other to form sides of DNA NUCLEOTIDE INFO: 1 nucleotide : 1 sugar, 1 phosphate 1 base NUCLEOTIDES stack on top of each other to form sides of DNA 1side of DNA upside down--“anti-parallel” 2 bases attached with hydrogen bonds

-A = Adenine -G = Guanine NITROGENOUS BASES PURINES – 2 rings of C and N -A = Adenine -G = Guanine *2 rings--each has 2 n’s *both end in “nine” Double ring has nine sides

T=Thymine C = Cytosine NITROGENOUS BASES PYRIMIDINE – single ring of C and N T=Thymine C = Cytosine *1 ring--each has 1 n* *both have a “y” – so does pyrimidine

DNA STRUCTURE *CHARGAFF’S RULE THYMINE = ADENINE GUANINE = CYTOSINE CREATE: memory device for pairing nitrogenous bases T A G C

copyright cmassengale DNA STRUCTURE P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A copyright cmassengale

ANTIPARALLEL SET 2 PENCILS PARALLEL TO EACH OTHER --POINT 1ST PENCIL UP --POINT 2ND PENCIL DOWN  = ANTI-PARALLEL One strand of DNA runs from 5’ to 3’ (sugars) The other strand runs in opposite direction - 3’ to 5’ (sugars)

Nucleotides THINK – PAIR – SHARE -What are the repeating units in DNA called? Nucleotides -What 3 things make up a DNA nucleotide? Sugar Phosphate Nitrogen containing base

NITROGENOUS BASE PAIR RULES CREATE a matching (complementary) DNA sequence for the following strand: A T G A A G T T T T T GG C T G G C T A G

DNA: Blueprint of Life -ANALYZE why DNA is called the “BLUEPRINT of LIFE” -every cell in your body has the same copies of DNA –pattern to produce protein structures

NUCLEUS: Control Center of the Cell -INFER why the nucleus is called the “CONTROL CENTER” of the cell -controls all activities of the cell including cellular reproduction and heredity

APPLY: COMPLETE the DNA CONCEPT MAP nucleotides twisted ladder produce proteins double helix nitrogenous base phosphate group Watson & Crick deoxyribose guanine adenine thymine cytosine 1953

MODEL structures of DNA by labeling & coloring SUGAR--pink PHOSPHATE--green CYTOSINE--grey GUANINE--orange THYMINE--blue ADENINE--yellow

copyright cmassengale NUCLEOTIDE O=P-O O Phosphate Group N Nitrogenous base (A, G, C, or T) O CH2 O C1 C4 C3 C2 5 Sugar (deoxyribose) copyright cmassengale