DO NOW HMMM If there is 16 Thymine

DO NOW: HMMM…. . If there is 16% Thymine and 34% Cytosine in a DNA strand, what percent would be Adenine and Guanine?

If there is 24% Cytosine, there would be an equal amount of Guanine (24%) If there is 26% Thymine, there would be an equal amount of Adenine (26%) Since Adenine pairs with Thymine and Cytosine pairs with Guanine the percentages equal. All percentages equal to 100%

DNA and Chromosomes • When cells get ready to divide, they pack up all their DNA into chromosomes • Humans have 46 chromosomes located in the nucleus of every cell http: //www. youtube. com/watch? v=E 8 NHc. Qes. Yl 8

DNA Wrapping • A lot of DNA must be tightly packed into the nucleus • CHROMOSOMES are made of CHROMATIN, which is DNA wrapped around PROTEINS called HISTONES

DNA Replication • Make a copy of its DNA. • DNA unwinds and “unzips” splits down the middle • DNA polymerase (an enzyme) joins new nucleotides using base-pairing rules to http: //www. phschool. com/ats chool/phbio/active_art/dna_r eplication/index. html • make complementary strands of DNA: one strand makes two identical strands. • DNA polymerase also “proofreads” the code to make sure it makes exact copies. http: //www. youtube. com/watch? v=hf. Z 8 o 9 D 1 tus http: //www. youtube. com/watch? v=7 wh 0 m 5 WRLSU&feature=relmfu http: //www. youtube. com/watch? v=bee 6 PWUg. Po 8&feature=relmfu

Think Pair Share What does “COMPLEMENTARY” mean? Complementary means things that go well together. In DNA, this refers to the two strands and their bases: A always goes with T C always goes with G http: //johnkyrk. com/DNAreplication. html

Quickcheck: What are the two types of nucleic acids? DNA and RNA

Risk Box: The second type of nucleic acid is RNA or ribonucleic acid. Using the diagram, compare and contrast DNA and RNA Fill in the table on your guided notes sheet DNA RNA

RNA= Ribo. Nucleic Acid RNA is a nucleic acid and it is made of long strands of nucleotides like DNA, but there are important differences: DNA RNA Type of Sugar deoxyribose # of Strands 2 (double-stranded) Bases A, T, C, G 1 (usually singlestranded) A, U, C, G (Uracil instead of Thymine)

There are 3 types of RNA: 1. m. RNA- messenger RNA carries a copy of the DNA code from the nucleus to the ribosome 2. r. RNA- ribosomal RNA is what ribosomes are made of 3. t. RNA- transfer RNA carries amino acids to the ribosomes according to the 3 -letter code RNA has a very important role in the cell: Protein Synthesis (building proteins)

Protein Synthesis means building proteins • DNA is divided into segments called genes • Genes can be 100 or more than 1000 base pairs long • Each gene is a coded instruction for building a protein • Proteins do all the jobs in the cell/body

Step #1: Transcription (making m. RNA) First the cell must make a copy of the DNA because DNA never leaves the nucleus

Risk Box: Hmmm… DNA never leaves the nucleus. Why do you think that is?

Safe inside the nucleus… • DNA unwinds and unzips • Transcription starts at a site on DNA called a promoter • RNA polymerase (an enzyme) uses the template strand of the DNA to make m. RNA (messenger RNA) from free-floating nucleotides RNA Polymeras e

• • In RNA, A—U , C—G m. RNA is single stranded (only one strand) the m. RNA is a copy of the gene when the gene is completely copied, the m. RNA leaves the nucleus http: //www. youtube. com/watch? v=5 Mf. SYn. It. Yvg&NR=1 http: //www. youtube. com/watch? v=Ot. Yz_3 rkv. Pk&feature=related

http: //johnkyrk. com/DNAtranscription. html Sometimes the m. RNA needs to be edited a little before it’s ready to go to work. INtrons are pieces that are taken OUT and EXons are pieces that are left IN

http: //johnkyrk. com/DNAtranscription. html m. RNA editing: INtrons are taken OUT and Exons are left IN

What is one difference between DNA and RNA? Record your response on a seperate sheet of paper.