8.2 Structure of DNA Intro to DNA Topic: 8.2 Structure of DNA Essential Question: Explain the base-pairing rules. How many types of nucleotides are there? How do they differ? Key Concept:DNA structure is the same in all organisms

8.2 Structure of DNA Participation Guide (True or False) – Copy the statements and determine if its True or False 1.DNA is the hereditary material in humans and almost all other organisms. 2. Nearly every cell in a person’s body has the same DNA. 3.Most DNA is located in the cell nucleus, but a small amount of DNA can also be found in the mitochondria. 4.DNA bases pair up with each other, Adenine with Thymine and Cytosine with Guanine. 5.Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases.

8.2 Structure of DNA KEY CONCEPT DNA structure is the same in all organisms.

8.2 Structure of DNA DNA is composed of four types of nucleotides. Each nucleotide has three parts. 1. a phosphate group 2. a deoxyribose sugar 3. a nitrogen-containing base phosphate group deoxyribose (sugar) nitrogen-containing base Covalent bonds base backbone

8.2 Structure of DNA The nitrogen containing bases are the only difference in the four nucleotides. Thymine- T Adenine- A Guanine- G Cytosine-C BASES

8.2 Structure of DNA

Watson and Crick determined the three-dimensional structure of DNA by building models. They realized that DNA is a double helix –backbone on the outside –bases on the inside. backbone bases

8.2 Structure of DNA Watson and Crick’s discovery built on the work of Rosalind Franklin and Erwin Chargaff. –Franklin’s x-ray images suggested that DNA was a double helix of even width. –Chargaff’s rules stated that A=T and C=G.

8.2 Structure of DNA T A C G Nucleotides always pair in the same way. the helix has a uniform width. –Ex: ladder – A pairs with T – C pairs with G

8.2 Structure of DNA The backbone is connected by covalent bonds. hydrogen bondcovalent bond The bases are connected by hydrogen bonds. backbone Hydrogen bond Bases (A,T,G,C)

8.2 Structure of DNA A T C C G A T G A T GC

GATTACAATCGATCGAT CTAATGTTAGCTAGCTA TAGGACTACTAGTCGTA ATCCTGATGATCAGCAT Using the base pairing rules- complete the DNA strand:

8.2 Structure of DNA Let’s Review – Summary Questions Answer in complete sentences. What is the structure of DNA? How do the nitrogen bases pair? What is a nucleotide? (Draw one and label)

8.2 Structure of DNA Adenine (A) = Green Thymine (T) = Pink Cytosine (C) = Yellow Guanine (G) = Orange Have Your DNA & Eat It Too * I need to check your work before you eat the DNA!!!!!

8.2 Structure of DNA RNA RNA (Ribonucleic Acid) Job: act as a messenger carrying instructions for the synthesis of proteins. Three Types –Messenger RNA (mRNA) Contains genetic information. A copy of a portion of DNA. –Ribosomal RNA (rRNA) Part of the ribosomes. It does not contain a genetic message. –Transfer RNA (tRNA) Transfer RNA functions to transport amino acids to the ribosomes during protein synthesis.

8.2 Structure of DNA Checkpoint Are you smarter than a 5 th grader? Think-Pair-Share 15 mintues