DNA Replication, Transcription and Translation

Structure of DNA and RNA DNA Deoxyribonucleic Acids are nucleotides made of: –Base pairs (Adenine, Thymine, Guanine, Cytosine) –Deoxyribose sugar group –Phosphate group –Double stranded, in helix coil form RNA Ribonucleic Acids are nucleotides made of: – Base pairs (Adenine, Uracil, Guanine, Cytosine) – Ribose sugar group – Phosphate group – Single stranded

Base pairs come in two combinations: C bonds to G A bonds to T RNA uses Uracil, in place of Thymine. (A bonds to U)

DNA structure Makes a ladder shape Phosphates bond to Sugars ( uprights ) Base pairs bond A to T, and C to G between sugars The two strands twist into double helix form

DNA structure compared to RNA Both have a ladder shape made when Phosphates bond to Sugars (uprights or backbone) Both Base pairs are attached to this backbone Both the strands of DNA or strand of RNA twist

DNA Replication - “Xeroxing” - Happens in the nucleus 1.DNA unzip - with help of enzymes 2.Two strands DNA form (sense and anti-sense) 3.Enzymes help new nucleotides pair with free ends on single strand of DNA: A-T and C-G 4. A-T and C-G form hydrogen bonds between new nucleotide and the strand of DNA Sense Anti- sense

DNA Replication Final Product: 2 double helix DNA formations that are exact copies of the original DNA strand

Transcription of DNA- monks re-writing manuscripts letter by letter (messenger writing down the plans before they are carried away) Happens in nucleus Then mRNA exits into cytoplasm carrying message Involves DNA and mRNA, and enzymes (polymerase)

Transcription 1. DNA "unzips " - enzyme breaks double and triple bonds between nitrogen base pairs (A-T, C-G) 2. Two strands DNA formed (sense and anti-sense) 3. Enzyme reads DNA base pairs and adds new nucleotides to match base pair (Uracil in place of Thyamine) (A-U, C-G)

Transcription - Final stages 4. The nucleotides are bonded at the phosphate and sugar creating the new strand of RNA. 5. RNA introns spliced out, leaving mRNA. Final Product: coded strand of mRNA

Occurs in the cytoplasm (Endoplasmic reticulum) Molecules involved mRNA, tRNA, codons (3 bases), ribosomes, amino acids, and enzymes Translation of mRNA- deciphering the code, like spies in WWII (builders building the structure, using plans carried by messenger) = Protein!

Translation - begins 1. First codon of mRNA strand attaches to a Ribosome (codon is 3 base pair combination) 2. tRNA carrying a specific amino acid, approaches ribosome. 3. Enzyme helps tRNA anti-codon to pair with codon on mRNA. 4. tRNA remains with amino acid attached to it.

Translation - continued 5. Next codon on mRNA slides along to ribosome, New tRNA anti-codon with specific amino acid is paired with codon on mRNA. 6. Amino acid is bonded with previous amino acid. (peptide bonds) tRNA breaks off, leaving bonded amino acids.

Translation - Finale 7. Process continues as each codon is paired with anti-codon, until STOP codon on mRNA is reached. Final Product: Polypeptide chain also known as Protein!

Summary of Transcription and Translation