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Changes in Matter - PowerPoint PPT Presentation

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Changes in Matter. Chapter Eighteen: The Chemistry of Living Systems. 18.1 The Chemistry of Carbon 18.2 Protein, Fats, and Nucleic Acids. Investigation 18B. The Structure of DNA. How does a DNA molecule carry information?. 18.2 Proteins, fats and nucleic acids.

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Chapter eighteen the chemistry of living systems
Chapter Eighteen: The Chemistryof Living Systems

  • 18.1 The Chemistry of Carbon

  • 18.2 Protein, Fats, and Nucleic Acids

Investigation 18b
Investigation 18B

The Structure of DNA

  • How does a DNA molecule carry information?

18 2 proteins fats and nucleic acids
18.2 Proteins, fats and nucleic acids

  • Proteins, fats, and nucleic acids are complex molecules, containing thousands of individual atoms in a single molecule.

  • Nucleic acids found in DNA are at the core of genetics, an active area of scientific research.

  • Fats are large molecules that take much longer to break down.

18 2 fats
18.2 Fats

  • Fats are high-energy molecules that plants and animals use to store energy.

  • A fat molecule has a two-part structure.

18 2 proteins
18.2 Proteins

  • Proteins are basic molecular building blocks of cells and all parts of animals.

  • Proteins are among the largest organic molecules.

Why is the shape of a

protein important?

18 2 saturated and unsaturated fats
18.2 Saturated and unsaturated fats

  • In a saturated fat, carbon atoms are surrounded by as many hydrogen atoms as possible.

  • An unsaturated fathas fewer hydrogen atoms than it could have.

18 2 enzymes
18.2 Enzymes

  • Thousands of chemical reactions are going on in your body each second, involving thousands of chemicals.

  • Catalystshelp control chemical reactions.

  • You can think of catalysts as helper molecules that allow a reaction to proceed in many small steps instead of all at once.

18 2 enzymes1
18.2 Enzymes

  • Enzymesare special proteins.

18 2 enzymes2
18.2 Enzymes

  • Enzymesallow your body to initiate chemical reactions at a low temperature and to control the rate of reactions.

The body has thousands of different enzymes.

Each one is specific and matched with its target molecule.

18 2 dna and nucleic acids
18.2 DNA and nucleic acids

  • Cells must continually create the proteins they need.

  • In the process called protein synthesis, proteins are made using the instructions found in DNA molecules.

Where does the energy needed for this process come from?

18 2 dna and nucleic acids1
18.2 DNA and nucleic acids

  • DNA is a nucleic acid .

  • A DNA molecule is put together like a twisted ladder.

*This model shows a short piece of the flattened DNA ladder.

A DNA molecule is usually twisted and much longer.

18 2 dna
18.2 DNA

  • Each side of the ladder is made of:

    • 5-carbon sugars called deoxyribose

    • and phosphate groups.

18 2 dna1
18.2 DNA

  • There are four nitrogen bases in two matched pairs.

18 2 dna and amino acids
18.2 DNA and amino acids

  • The assembly of proteins is coded by a certain sequence of nitrogen bases.

  • The sequence: thymine + thymine + adenine would code the amino acid leucine.

What sequence stops the assembly of proteins?

Can you name the bases involved?

18 2 dna and replication
18.2 DNA and replication

  • When an organism reproduces, the DNA molecule is able to make exact replicas of itself.

18 2 dna and replication1
18.2 DNA and replication

  • Special enzymes play a role when DNA copies itself:

    • Helicase enzymes untwist the DNA helix.

    • Ligase enzymes unzip the DNA.

    • Polymerase enzymes rebuild nitrogen bases on the open strands.

18 2 dna and reproduction
18.2 DNA and reproduction

  • Changes in DNA are called mutations.

  • Mutations lead to new proteins, and the resulting changes in living organisms are passed on in successive generations.

Health connection
Health Connection

Good Fats vs. Bad Fats

  • We need a reasonable amount of fat in our diets.

  • Fat helps support cell function and helps our bodies absorb vitamins.

  • But a diet too high in certain fats can lead to many health problems, including obesity, diabetes, and heart disease.


The Scoop on Nutrition Labels

  • A nutrition label shows the amount of calories, fat, cholesterol, carbohydrates, protein, and several vitamins and minerals in one serving of the food.

  • The exact amount of each nutrient a person needs depends on gender, age, activity level, and weight.