DNA HistoryContributions Rosalind Franklin and Maurice Wilkins She
DNA History/Contributions Rosalind Franklin and Maurice Wilkins She took the picture of the ‘X’ shape which revealed the helix shape using X-ray crystallography. Erwin Chargaff Found that the amounts of A = T and the amounts of C = G in all organisms; means they pair together James Watson and Francis Crick Discovered the structure of DNA; used Franklin’s and Chargaff’s research.
DNA Why is it important? DNA provides the genetic information that is passed from parent to child and codes for all of an organism’s traits. What is DNA? Deoxyribonucleic Acid *Remember: Nucleic Acids are made of nucleotides *Nucleotides are made of a 5 -Carbon sugar, phosphate, and a nitrogen base
DNA 4 DNA nucleotides Since there are 4 different nitrogen bases in DNA, there are 4 DNA nucleotides possible: Adenine P sugar Cytosine P sugar Guanine P Thymine P sugar
DNA Nucleotide bonding The phosphate of one nucleotide bonds to the sugar of another nucleotide.
DNA Base Pairing Rule Adenine bonds with Thymine Guanine bonds with Cytosine
DNA Structure DOUBLE HELIX – two strands, twisted *like a twisted ladder* The sides of the ladder are made of the sugar and phosphate. The rungs of the ladder are made of the nitrogen bases. The two strands of the double helix are complementary – they pair together.
DNA Replication Process of copying DNA – required before a cell can divide. * Remember: DNA is copied during the S phase of interphase so each new cell can have the full set of DNA
DNA Steps of Replication 1. Enzyme 2. Complementary 3. The two strands DNA Ligase nucleotides of DNA connects must are unwind the added backbone and by DNA separate polymerase of the new(unzip). nucleotides. to make Helicase new strands, is the enzyme based that on pairing does this. rules. Hydrogen Bonds – very weak DNA Replication is SEMICONSERVATIVE: each molecule contains one old strand one new strand.
DNA is anti-parallel. The two strands of DNA are parallel, but they go in opposite directions (like a road).
DNA Protein Synthesis The two process which use the information in DNA to make proteins: Transcription then Translation Transcription Occurs in the nucleus Uses the DNA sequence to make an RNA copy Differences between DNA and RNA DNA RNA Sugar deoxyribose Bases A, C, T, G A, C, U, G Strands double stranded single stranded
DNA Different types of RNA m. RNA – messenger RNA, brings the message (sequence) from the DNA to the ribosome; has the codon. t. RNA – transfer RNA, brings the amino acids to the ribosome to be made into proteins; has the anticodon. r. RNA – ribosomal RNA, majority of the ribosome is made of RNA.
DNA Steps of Transcription 3. 2. 1. After RNA Section the nucleotides of copy DNA is made, ispair unzipped upthe with DNA is nucleotides zipped revealing back themaking up sequence and an the. RNA of bases. copy can leave of the DNA. the nucleus. * Any place that there would normally be a Thymine, it is replaced with a Uracil.
DNA Translation Steps of Translation (after RNA has left the nucleus) 2. 3. 1. t. RNA After m. RNA Occurs the molecules attaches t. RNA in the molecule bring tocytoplasm, thethe ribosome. delivers appropriate on the ribosomes. Theamino ribosome acid, acidreads the to the 3 ribosome. letters at Uses a connects Ittime knows the (3 m. RNA letters which it to the sequence amino onprevious the acid m. RNA (from amino to bring strand Transcription) acids, based is acreating codon) onto acode three chain. complementary for. The an amino bond connecting acid letters sequence onthe theamino –t. RNA to make acids (anticodon) proteins. is called a peptide bond. Each codon codes for one amino acid * We use a coding dictionary to determine which amino acid each codon codes for.
DNA Central Dogma Representation of the flow of genetic information DNA Transcription RNA Translation Protein
Random changes in DNA Mutation in. Affect the sequence entire sections of DNAof chromosomes Chromosomal Gene Mutations
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