DNA Replication
What is DNA? Deoxyribonucleic Acid (DNA) DNA is a NUCLEIC ACID The sugar is DeoxyRibose DNA is a NUCLEIC ACID
Why is DNA important? DNA is like the blueprint for your body! It is an extremely long strand of directions for all of the proteins that allow living things to function Think of DNA as the recipe for making proteins
Where is DNA found? PROKARYOTES: Found in the cytoplasm EUKARYOTES: Found in the nucleus
How SIMILAR are you to the person sitting next to you? You are 99% identical to the person sitting next to you!! The only difference it the ORDER of your NITROGEN BASES!
How is DNA STORED in eukaryotes? The DNA is compacted in the CHROMOSOMES and stored in the nucleus
What is DNA made of (the subunits)? NUCLEOTIDES!!
What are the main parts of a NUCLEOTIDE? Phosphate Sugar Nitrogen Base (A, T, C, G)
Label the parts of a Nucleotide
What are the FOUR NITROGEN BAES? A = Adenine T =Thymine C =Cytosine G = Guanine
What is COMPLIMENTARY BASE PAIRING? The same bases will ALWAYS pair together! A pairs with T C pairs with G ALWAYS!!! (Unless there is a mutation)
TRY IT! ATT ATC GTA TCT CAT ATG TCG GAT
How is a DNA molecule MADE? Nucleotides come together Then, HYDROGEN bonds form between the nitrogen bases This makes TWO strands of nucleotides which twist into a DOUBLE HELIX
What is the SHAPE of DNA? DOUBLE HELIX It looks like a twisted ladder OR, a spiral staircase
What are HYDROGEN BONDS? The bonds that form between the nitrogen bases They are very WEAK and break easily This is how DNA is able to make new copies of itself!
What is DNA REPLICATION? NEW cells are made by copying OLD cells Before a cell divides, you have to copy or REPLICATE the DNA REVIEW! What stage of the cell cycle does DNA Replication happen in?
When does DNA Replication occur? During S –Phase of INTERPHASE S-Phase = Synthesis Phase The DNA Replicates (copies itself ) to prepare for cell division (MITOSIS!!!)
Why does DNA REPLICATE? To get ready for cell division So each new cell has the same exact DNA!
What are the STEPS for DNA Replication? An Enzyme “UNZIPS” the 2 strands of DNA by breaking the weak Hydrogen bonds New nucleotides are added to the old stand REVIEW: A = T and C = G Another Enzyme “ZIPS” the strands back up DNA Polymerase (an enzyme) “proofreads” the strands to make sure there are no MISTAKES! What do you think might happen if there are mistakes?!
What is the ROLE of ENZYMES? Enzymes help to: 1. Split the DNA in half Put DNA back together Proofread for any mistakes in the base pairs
How is DNA Replication SEMI-CONSERVATIVE? When the DNA copies itself, it always has HALF of the parental (OLD) strand and HALF of the daughter (NEW) strand In other words: the DNA is HALF OLD and HALF NEW
What are MUTATIONS? Changes in the genetic code (DNA) Can be: positive, negative or neutral Causes: UV radiation, chemicals, bad DNA proofreading Can lead to CANCER