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So Just How Does DNA Copy Itself and Get It Right??? • Words to know before we start: • Mutation: Change • Spontaneous: Without any reason • Protein synthesis: Making proteins STUDENTS: NOTE- YOU WILL BE RECEIVING CREDIT FOR YOUR NOTES BEING COMPLETE AND READABLE – WORK WITH CARE
DNA REPLICATION • Replication of DNA occurs to create new strands of DNA or to correct or replace mutated DNA sections.
Just What is a Mutation? • A Mutation is a change in the nitrogen bases (A,T,G,C) which then cause some change in how an organism looks or works. • Mutations are mostly lethal…(causing the death of an organism).
DNA Replication • DNA replication starts with an enzyme called Helicase, The Helicase separates the Hydrogen bonds that are in between the two complementary bases. • The point at which the separation occurs is called the replication fork.
DNA Replication • The DNA polymerase binds to a single stain of the old (parent) DNA, and uses it as a template to make a new chain. • The result is a new strain that is half old half new.
DNA Replication • Replication takes place on the leading strain in a 5’ to 3’ prime direction and is continuous. However on the lagging strain the DNA is replicated in segments (pieces). • DNA strands are very long so DNA Replication can be occurring at many points at the same time, and does not occur at one end at a time.
Accuracy and Repair • DNA replication increases accuracy, there is only one error ever 10,000 per nucleotide. • Errors cause mutations • Mutations may have serious effects of cells. • With in Replication the DNA is proofread and repaired, this bring the errors to one error in one billion nucleotides. (this takes place by specific enzymes)
RNA • Ribonucleic acid – Its Function/Job is to store and transfer genetic information essential for manufacturing of proteins. • Nucleic Acid made of repeating nucleotides • Sugar phosphate backbone (sugar = ribose) • Four bases • Adenine, Guanine, Uracil, Cytosine
RNA – copy of DNAIt can leave the Nucleus of a Cell Notice there is URACIL instead of Thymine NOW!
STUDENTS:COPY THIS ON BLANK LAST SHEET OF NOTES DNA Vs. RNA • Can move out of • nucleus to cytoplasm • Single (one) strand • A-U • G-C Pairs • Has URACIL instead • Of thymine • Goes to ribosome • To make proteins • Are Nucleic Acids • Have Nitrogen Bases • Have genetic • Information • Found in cells • Stays in Nucleus • Double strand • A-T • G-C pairs • Has all heredity • Information for an • organism RNA DNA SAME
Types of RNA • Three types of RNA • Messenger RNA(mRNA) carries genetic information from the DNA in the nucleus to the cytosol of a eukaryotic cell. • Transfer RNA(tRNA) hairpin shape, used to bind to specific amino acids. (45 varieties of tRNA) • Ribosomal RNA(rRNA) is the most abundant of the RNA. Globular shape. With the help of other proteins it makes up the ribosome where proteins are made.
Transcription • This is the process that RNA copies the genetic information from DNA and transfers it to the cytosol where it can be used to produce proteins.
Remember: Proteins are made in the ribosomes found in the cytoplasm outside of the nucleus.