Post on 02-Jan-2016
DNA
Chapter 12
DNA• DeoxyriboNucleic Acid• Sugar = deoxyribose• Adenine + Thymine• Guanine + Cytosine• Double-stranded helix with alternating
sugars and phosphate groups• Only found in the nucleus
DNA Replication• Takes place in nucleus
• Uses enzyme polymerase
• Separates double-strand….produces two single strands
• Complimentary strands are made using the original DNA strands as templates
• A + T, C + G
Transcription
• RNA Polymerase – separates complimentary DNA and original strand
• Complimentary strand is used as a template to make an RNA strand...Uracil replaces thymine
• DNA-GCATTAGC = • RNA-CGUAAUCG
RNA
• RiboNucleic Acid• Sugar = ribose• Single-stranded• Uracil + Adenine
–(There is NO thymine in RNA)• Cytosine + Guanine • Found in nucleus and outside nucleus
mRNA• Messenger RNA (carries a message)• Made during transcription inside
nucleus• Thymine is replaced with uracil in order
to fit outside the nuclear membrane• mRNA carries a message out the
nucleus to the ribosomes, where it is called rRNA (ribosomal RNA)
Translation
• In ribosomes…where proteins are made• Codon – group of 3 bases (AAT) that is found
on the rRNA…every 3 bases acts as a codon• A tRNA (transfer RNA) carries an amino
acid…tRNA are groups of three bases…this is called an anti-codon.
• An anticodon fits into specific codons that match the base sequences and brings along specific amino acids
Protein Synthesis
• The amino acids bond together with peptide bonds
• Amino acids are the building blocks of all proteins
• Every variety of amino acids codes for a different trait
• If the order of bases gets mixed up, the codon will change, changing the matching anti-codon, changing the amino acid, changing the protein it codes for, changing the trait