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•Humans share 50% of their DNA with bananas. •Cells can contain 6-9 feet of DNA. If all the DNA in your body was put end to end, it would reach to the sun and back over 600 times. •DNA in all humans is 99.9 percent identical. It is about one tenth of one percent that makes us all unique, or about 3 million nucleotides difference. •DNA can store 25 gigabytes of information per inch and is the most efficient storage system known to human. So, humans are better than computers!! •In an average meal, you eat approximately 55,000,000 cells or between 63,000 to 93,000 miles of DNA. •It would take a person typing 60 words per minute, eight hours a day, around 50 years to type the human genome. In the next 60 seconds your body will produce enough new DNA that if it was linked together, it would stretch 100,000 km Big Idea: Characteristics from parents are passed to offspring in predictable ways. Unit 2 Lesson 6 DNA Structure and Function Essential Question: What is DNA? Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function Cracking the Code What is DNA? • The genetic material in cells is contained in a molecule called deoxyribonucleic acid, or DNA. • Scientists describe DNA as containing a code. A code is a set of rules and symbols used to carry information. • To understand how DNA functions, you first need to learn about the structure of the DNA molecule. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function How was DNA discovered? P = phosphate S = Sugar A = Adenine Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function How was DNA discovered? Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function How was DNA discovered? • Many scientists from all over the world contributed to our understanding of DNA. • Some scientists discovered the chemicals that make up DNA, and others learned how these chemicals fit together. • Still others determined the three-dimensional structure of the DNA molecule. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function Unraveling DNA What does DNA look like? • Experiments and imaging techniques have helped scientists to infer the shape of DNA. • The structure of DNA is a twisted ladder shape called a double helix. • The two sides of the ladder are made of sugars and phosphate groups. • The rungs of the ladder are made of pairs of bases. Unit 2 Lesson 6 DNA Structure and Function What does DNA look like? • A base, a sugar, and a phosphate group make a building block of DNA called a nucleotide. • There are four different nucleotides in DNA. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function What does DNA look like? • The bases in nucleotides are paired, or complementary. • Adenine always pairs with thymine (A-T). • Cytosine always pairs with guanine (C-G). • The order of the nucleotides in DNA is a code that carries information. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function What does DNA look like? • Genes are segments of DNA that relate to a certain trait. • The code in the nucleotide order has information about which proteins the cells should build. • The types of proteins that your body makes help determine your traits. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function Replication and Mutation How are copies of DNA made? • The cell makes copies of DNA molecules through a process known as replication. • During replication, the two strands of DNA separate. • The bases on each side of the molecule are used as a pattern for a new strand. • As bases on the original molecule are exposed, complementary nucleotides are added. • When replication is complete, there are two identical DNA molecules. 1. UNZIPPING: The DNA molecule opens up, separating into two strands 2. COMPLEMENTARY BASE PAIRING: Nucleotides move into position to bond with the complementary bases on the DNA chain. This process continues along the primary chain until we have 2 IDENTICAL STRANDS of DNA molecules (assuming there have been no errors made). Unit 2 Lesson 6 DNA Structure and Function p152 How are copies of DNA made? Nucleotides DNA 2 Strands Identical Molecules Unit 2 Lesson 6 DNA Structure and Function When are copies of DNA made? • Before a cell divides, it copies its DNA so that each new daughter cell has a complete set of instructions • Our cells can replicate DNA in just a few hours, because replication begins in many places along a DNA strand. • Many groups of proteins are working to replicate your DNA at the same time. What are mutations? DNA has the ability to mutate (change). This allows for new characteristics and abilities to appear which may help an individual to survive and reproduce (EVOLUTION). Unit 2 Lesson 6 DNA Structure and Function What are mutations? • Mutations are changes in the number, type, or order of bases on a piece of DNA. • There are three main kinds of mutations: • Deletion - a base is left out. • Insertion - an extra base is added. • The most common mutation – Substitution - when one base replaces another. Copyright © Houghton Mifflin Harcourt Publishing Company GENE MUTATIONS Deletion: one nucleotide base is left out. All of the amino acids after a deletion will be wrong, so SHAPE and FUNCTION of protein are altered. Serious. Insertion: one extra nucleotide base is added. This will also change the entire amino acid sequence of the protein, so SHAPE and FUNCTION of protein are altered. Serious. Substitution: when single bases or short pieces are replaced with one another. Example: Sickle-Cell Anemia, only one nucleotide base is switched. This causes only 1 amino acid to change, but it is an important one. This type of mutation is usually not as serious as the 1st two. It just depends on which amino acid is affected Unit 2 Lesson 6 DNA Structure and Function What are mutations? • Which type of mutation is shown in each row? Unit 2 Lesson 6 DNA Structure and Function What are mutations? Mutations can occur naturally, randomly or through environmental factors. Environmental mutagens include some chemicals (food additives, pesticides, plastics) and radiations (X-rays to UV light). •Cells make proteins that can fix errors in DNA, but sometimes the mistake is not corrected. •The mistake then becomes part of the genetic code. Unit 2 Lesson 6 DNA Structure and Function What are mutations? • A genetic disorder results from mutations that harm the normal function of the cell. • Some genetic disorders are inherited, or passed on from parent to offspring. • Other disorders result from mutations during a person’s lifetime. Most cancers fall in this category. Unit 2 Lesson 6 DNA Structure and Function Protein Factory What is the role of DNA and RNA in building proteins? • Some of the information in the DNA is copied to a separate molecule called RNA, or ribonucleic acid. • RNA is used to build proteins. • Like DNA, RNA has a sugar-phosphate backbone and the bases adenine (A), guanine (G), and cytosine (C). • Instead of thymine (T), RNA contains uracil (U). Unit 2 Lesson 6 DNA Structure and Function Unit 2 Lesson 6 DNA Structure and Function Protein Factory What is the role of DNA and RNA in building proteins? • Three types of RNA have special roles in making proteins. • mRNA – Messenger RNA: Provides instructions for building proteins • rRNA – Ribosomal RNA: Makes up the ribosome • tRNA – Transfer RNA: Transfers amino acids to the ribosome during translation Unit 2 Lesson 6 DNA Structure and Function What is the role of DNA and RNA in building proteins? • When a cell needs to make a protein, it makes an RNA copy of a section of the DNA. This is called transcription. • In transcription, DNA is used as a template to make a complementary strand of messenger RNA (mRNA). Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 6 DNA Structure and Function What is the role of DNA and RNA in building proteins? • The information in the mRNA is then used to build proteins. This is called translation. • In translation, the mRNA passes through a protein assembly line within a ribosome. Unit 2 Lesson 6 DNA Structure and Function What is the role of DNA and RNA in building proteins? • A ribosome is a cell organelle made of ribosomal RNA (rRNA) and protein. • As mRNA passes through, transfer RNA (tRNA) delivers amino acids to the ribosomes. • The amino acids are joined together to form a protein. Process Transcription Translation What molecules are involved DNA, mRNA tRNA, ribosome (rRNA), mRNA Product Complimentary Strand Protein