DNA Proteins are found in all ________ ________ Are species specific/ individual specific (transplant rejections) Importance of DNA Chromosome: DNA + ____ __________: 5 carbon sugar, nitrogen base and phosphate Cut and paste a nucleotide here 1953 Watson and Crick – model of DNA molecule as a spiral helix living things RNA nucleotide

Double helix (like a ladder twisted on its long axis) Side of ladder – sugar and phosphate Rungs = _________ ______ pairs (draw here) Only _____ nitrogen bases in DNA: Purines: adenine and guanine Pyrimidines:thymine and cytosine Arranged in complementary base pairs: A------TAll Teachers G------CGo Crazy nitrogen base four

Replication of DNA Replication = ________________________________________________ ________________________________________________ DNA ladder unzips at base pairs Free nitrogen bases assemble on the open strands, forming two new complete strands. Occurs with a great degree of accuracy Requires enzymes called DNA polymerases the process of making an identical copy of a section of double stranded DNA

Transcription: copies the information of DNA Transcription = making complementary copy of _________ segment Is it an exact copy? Explain why or why not ? Made inside the nucleus Leaves nucleus and goes to ribosome in cytoplasm to direct synthesis of protein RNA differs from DNA. RNA has: One strand Ribose sugar Uracil replaces __________ as fourth nitrogen base RNA is smaller than DNA Three types of RNA 1: mRNA – carries “recipe” from protein to ____________ 2: tRNA – carries amino acids to ribosomes 3: rRNA – in ribosome mRNA transcribes in nucleus: mRNA leaves nucleus and moves to ribosome to direct protein synthesis DNA thymine ribosome

Codons determine amino acid sequence Codon = group of three nitrogen bases on ________ that codes for an amino acid. Also called triplets. 2-3 codons for each amino acid (20 -22). 1 codon (_______) is start codon. Several stop codons. PROTEIN SYNTHESIS Translation: proteins are synthesized mRNA moves to _____________. Acts as a template for protein synthesis. tRNA has anticodon that will match mRNA codons. As ribosomes move across mRNA, tRNA brings appropriate amino acids to it. __________ acids bond together forming a peptide chain, which forms a polypeptide, which, when reaching macromolecular size, is a ______________. mRNA AUG ribosome Amino protein