Nucleic Acid and Protein Synthesis 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 Draw a nucleotide here 1953 Watson and Crick – model of DNA molecule as a spiral helix living things RNA nucleotide

Structure of DNA 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------T All Teachers G------C Go Crazy nitrogen base four

The Roles of DNA and RNA Replication of DNA ________________________________________________ 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

RNA 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 Codons determine amino acid sequence PROTEIN SYNTHESIS 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