Biology Unit 3 DNA

• <S>:DNA replication produces an exact copy of a cell's DNA during cell division.
• Dna is composed of adenine, thymine, guanine, uracil
• pentise sugars have 5 carbon atoms
• ribose and deoxyribose are pentose sugars
• nucleic acids are polymers of nucleotides
• nucleic acids have a backbone of phosphate - sugar - phosphate - sugar
• backbones are formed when nucleotides combine in a condensation reaction
• Dna has a double helix backbone RNA has one backbone
• DNA = Deoxyribo Nucleic Acid
• the bases on the outside of the strand are called purines (adenine, guanine)
• RNA = ribonucleic acid
• nucleic acid functions: pass information between generations + code for protein production
• drawing DNA

  structure of DNA

  
• Dna has 2 antiparallel strands of DNA double helix running in opposite directions
• DNA features: double helix, formed by deoxyribose nucleotides, nitrogenous base=thymine, found in nucleoid of prokaryote cells
• RNA features: single strand, formed of ribose nucleotides, nitrogenous base: uracil, found in cytoplasm of prokaryote
• RNA and DNA both: have sugar-phosphate backbone, are nucleic acids, formed by condensation
• base pairing occurs before cell division
• DNA polumerase III: builds new strand by 'reading' the template and adding nucleotides onto strands
• transcription is the synthesis of RNA using DNA template which results in the RNA strand having the complementary sequence of basis as the DNA
• translation is the synthesis of a polypeptide from mRNA
• translation occurs as a ribosome builds up a polypeptide by reading the mRNA template + binding the coded amino acid to the polypeptide chain
• DNA stores information in the sequence of the nitrogenous bases
• structure of DNA allows for unlimited replications
• Conservative DNA is the first step of replication producing one exactly the same as one of the parent and one different
• Semi-conservative DNA in the first step produces 2 strands that are 50% from the parent 50% different
• Semi-conservative DNA in the second step produces 4 strands, 2 being 50% parent 50% different and the other 2 being 100% new
• dispersive DNA is in both first and second steps of replication where parental and new DNA are randomly dispersed
• double helix needs to unwind + disperse
• complementary base pairing ensures that two DNA molecules from DNA replication are identical in base sequences
• helicase is a ring-shaped protein that separates two strands of a DNA molecule by breaking down hydrogen bonds between nitrogenous bases
• DNA polymerase: assembles new strands of DNA using the leading + logging strands linking the nucleotide to the end of the new strand by making a covalent bond
• Replisome contains separate DNA polymers for each strand
• PCR - polymerase chain reaction
• PCR and gel electrophoresis are used to replicate DNA
• steps of a PCRcr

  1. melting/denaturing: heating it to 95°C for 30-60s, hydrogen bonds that hold the DNA strands are broken down but the covalent bonds remain
• steps of PCR

  2. annealing: cooking it to 54° for 30-60s allowing the primers to bind
• steps of PCR

  3. elongation: binding together single-stranded DNA adjacent to the primer then assembling new DNA strands in the 30-60s
• DNA bases: T,A,G,C are important for the synthesis of a new strand
• double helix is important for protecting the code + provides template for new DNA