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Chapter 6 life science

Chapter 6 life science. Genes and DNA. Section 1 what does DNA look like?. Inherited characteristics are determined by genes Genes are found on the chromosomes Chromosomes are made of Proteins and DNA DNA (deoxyribonucleic acid) contains the information that determines traits of organisms.

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Chapter 6 life science

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  1. Chapter 6 life science Genes and DNA

  2. Section 1what does DNA look like? • Inherited characteristics are determined by genes • Genes are found on the chromosomes • Chromosomes are made of Proteins and DNA • DNA (deoxyribonucleic acid) contains the information that determines traits of organisms. • DNA is made of subunits called nucleotides. • A nucleotide consists of a sugar, a phosphate, and a base. • The four bases are adenine thymine, guanine, and cytosine. • Each base has a different shape. • The bases are referred to by their first letter A,T, G, and C. • In the 1950’s, Erwin Chargaff found that the amount of adenine always equals the amount of thymine and the amount of cytosine always equals the amount of guanine. • later the structure of DNA was discovered through X ray diffraction by Rosilind Franklin.

  3. Section 1 page 2 • James Watson and Francis Crick concluded that DNA was shaped like a twisted ladder. • Using simple materials, the two built a double helix model of DNA. • The two sides of the ladder represent alternating sugar and phosphate parts. • The rungs of the ladder represent paired bases. • Adenine (A) always pairs with thymine (T) • Cytosine (C) pairs with guanine (G). • This made the strands complimentary: CGAT would be paired with GCTA. • Copying of DNA strands is called replication, (the DNA strands splits and the bases make a complimentary copy to form a new strand) • DNA is copied each time a cell divides.

  4. DNA models

  5. Section 2how DNA works • Each gene is usually a set of instructions to make a specific protein. • Proteins act as chemical triggers and messengers for many of the processes of a cell. • Proteins help determine how tall you are , what color hair and eyes you have, and how well you see. • Another material that helps make proteins is ribonucleic acid (RNA). • RNA is very similar to DNA and can serve as a temporary copy of a DNA sequence. • The factory that runs the copying process is a ribosome. • RNA is what allows these puzzle pieces to match up when a cell divides and copies itself to be passed on to another organism. • During replication, changes can occur in a gene. These changes are called mutations. Mutations can be helpful or harmful. • One mutation is called insertion. An extra base is added in the stand.

  6. Section 2 page 2 • If a base is left off the code, it is called deletion. • If a mutation is found on a sex cell, it is passed to the next generation. And example in humans is albinism ( the lack of pigment in skin) • Mutations happen randomly or can be caused by a mutagen. • Mutagens include radiation or exposure to chemicals. • Another mutation called substitution occurs if the wrong base is inserted into a sequence. • Sickle cell anemia is an example that causes blood cells to have an abnormal shape. This disorder can cause severe and painful blood clots to form. • Scientists have learned to manipulate genes through genetic engineering. • DNA fingerprinting allows people to be identified through crime scene investigations and also is used in the process of creating organism called cloning.

  7. Daily assignment Page 147 # 3-8 Page 155 # 3-5, 7-11 Pages 158 – 159 # 2-14, 16-22

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