Life Science In Class –Collect Field Trip Permission Slips –Return Graded Material Create Portfolio –Record Work –Warm Up –Introduction to Protein SynthesisIntroduction Homework: –The Master Molecule of Life Crossword Puzzle

How DNA Works Name __________________ Warm Up Unscramble the two words below. Then, use both of them in one sentence. tpsoneirneesg

Complementary Base Pair Answer Key 1.CGTAAGCGCTAATTA GCATTCGCGATTAAT 2.TCTTAAATGATCGATC AGAATTTACTAGCTAG 3.AATGAATAGCTAGCTT TTACTTATCGATCGAA 4.GGCATTCGCGATCATG CCGTAAGCGCTAGTAC 5.CGTTAGCATGCTTCAT GCAATCGTACGAAGTA 6.ACTAACGGTAGCTAGC TGATTGCCATCGATCG

Chapter 7 Section 1 What Does DNA Look Like?

Chapter 7 Section 1 What Does DNA Look Like?

Chapter 7 What You Will Learn DNA is bundled with proteins to form chromosomes. DNA stores genetic information in the form of a code. Cells use the DNA code to make proteins. –Proteins affect traits. A mutation is the result of a change in the genetic code. Section 2 How DNA Works

Chapter 7 Unraveling DNA The total length of DNA in a single human cell is about 2 m. This is true for nearly every one of your cells. The long molecules fit within the nucleus because they are wrapped tightly around proteins. Together, the DNA and proteins are called chromosomes. Section 2 How DNA Works

Chapter 7 Most of the time, chromosomes exist as loosely packaged strands called chromatin. Before a cell divides, the chromatin is bundled into smaller shapes to allow for mitosis. Section 2 How DNA Works Unraveling DNA, continued

Chapter 7 Unraveling DNA, continued The unique structure of DNA contains codes for making proteins. The order of bases on a strand of DNA can code for certain proteins. These codes are called genes. A gene is a string of nucleotides that give the cell information about how to make a specific trait. Section 2 How DNA Works

Chapter 7

As you look at Figure 1 answer the following questions: 1.Where is the DNA in your cell? 2.How much DNA fits into the nucleus? 3.What is the name for strands of DNA wound around proteins? 4.When do chromosomes become visible in cells? 5.What are chromatids?

As you look at Figure 1 answer the following questions: 1.Where is the DNA in your cell? In the nucleus 2.How much DNA fits into the nucleus? 2 meters 3.What is the name for strands of DNA wound around proteins? Chromatin 4.When do chromosomes become visible in cells? When the cell is about to divide 5.What are chromatids? Two identical copies of a chromosome in a cell that is about to divide

Chapter 7 Genes and Proteins The DNA code is read in a single direction. Each gene has a starting point and a stopping point. The code works in groups of three. Three bases code for a single amino acid. As the code is read, amino acids are added in a long chain to form a protein. Section 2 How DNA Works

Chapter 7 A typical cell has thousands of genes that code for thousands of proteins. Proteins are responsible for most of the differences between organisms. Proteins act as chemical triggers, as messengers, and as parts of structures. Proteins determine the texture of your hair and the colors you can see, among other things. Section 2 How DNA Works Genes and Proteins, continued

Chapter 7 RNA, or ribonucleic acid, is another molecule that helps to make proteins. RNA serves as a copy of DNA outside the nucleus. RNA copies of DNA genes are made, then sent to the cytoplasm to code for proteins. RNA is very much like DNA, except it has the base uracil (U) instead of thymine. Section 2 How DNA Works Genes and Proteins, continued

Chapter 7 The mirror-like RNA copies are called messenger RNA (mRNA) because it carries the message from the DNA. mRNA is sent through a ribosome “protein factory.” Ribosomes are organelles made of RNA and protein. Section 2 How DNA Works Genes and Proteins, continued

Chapter 7 Genes and Proteins, continued The mRNA code is read by transfer RNA (tRNA). The transfer RNA carries specific amino acids from the cytoplasm. The bases of tRNA fit into the bases of mRNA, ensuring that the proper amino acids are put into place. The growing chain of amino acids folds into a protein molecule. Section 2 How DNA Works

Chapter 7

Section 2 How DNA Works Chapter 7

Changes in Genes Like a change in the letters of a sentence, a change in the sequence of bases in DNA can change the meaning of the code. A change in the nucleotide-base sequence of DNA is called a mutation. Mutations occur due to errors during replication. Exposure to mutagens, like cigarette smoke or ultraviolet radiation, can also cause mutations. Section 2 How DNA Works

Chapter 7 Changes in DNA may cause no change in a trait, or it may cause a harmful trait or an improved trait. Some mutations do not change the protein that a gene codes for, so there is no effect. A mutation that improves a trait makes the organism more likely to survive. Section 2 How DNA Works Changes in Genes, continued

Chapter 7 Changes in Genes, continued Mutations are rarely helpful, so cells make proteins that detect and repair mutations. If a mutation occurs in a sex cell (egg or sperm) it can be passed on to offspring. Section 2 How DNA Works