Carbon-organic Compounds

Transcription

1 Elements in Cells The living substance of cells is made up of cytoplasm and the structures within it. About 96% of cytoplasm and its included structures are composed of the elements carbon, hydrogen, oxygen, and nitrogen. 3% from phosphorus, potassium and sulfur 1% from calcium, iron, magnesium, sodium, chlorine, copper, manganese, cobalt, zinc and minute quantities of other elements

2 Elements in Cells When a plant first absorbs these elements from the soil or atmosphere, or when it breaks down products within the cell, the elements are in the form of simple molecules or ions. These simple forms may be converted to very large, complex molecules through the metabolism of the cells. The large molecules have backbones of carbon atoms within them and are said to be organic. The countless number of chemical reactions of living organisms is based on organic compounds.

3 Carbon-organic Compounds In their outer shells, carbon atoms have four electrons that can bond with other atoms. When carbon is bonded to hydrogen, which is common in organic molecules, the carbon atom shares an electron with hydrogen, and hydrogen likewise share an electron with carbon. Carbon-hydrogen molecules are referred to as hydrocarbons. Nitrogen, sulfur, and oxygen also are often joined to carbon in living organisms.

4 Building Cells from Four Types of Molecules The cells of all living things, including plant cells, are primarily made of four types of big molecules, called macromolecules: Carbohydrates Lipids Proteins Nucleic acids

5 Carbohydrates Carbohydrates, commonly called sugars, are the most abundant organic compounds in nature. Carbohydrates contain carbon, hydrogen, and oxygen in a ratio of 1C:2H:1O. The formula can be multiplied, for example, glucose has the formula C 6 H 12 O 6. The basic ratio is the same. Cells use carbohydrates for: Storing energy and Building materials and To provide structure to the cell.

6 Carbohydrates Monosaccharides - Simple sugars with backbones of three to seven carbon atoms. (Glucose and Fructose) Glucose fast source of energy

7 Carbohydrates Monosaccharides may form bonds with each other to form larger structures. Disaccharides - Formed when two monosaccharides (simple sugars) bond together by dehydration synthesis. (glucose + fructose = sucrose) Polysaccharides - Formed when several to many (some thousands) of monosaccharides bond together. (Cellulose)

8 Carbohydrates Carbohydrates are in nearly every food, not just bread and pasta, which are know for carbo loading. Fruits, vegetables, and meats also contain carbohydrates. Any food that contains sugars contains carbohydrates. Most foods are converted to sugars when they are digested. Plants and animals both store sugars. In animals it is glycogen The storage form of glucose in plants is starch.

9 Lipids Lipids are fatty or oily substances that are mostly insoluble in water. (Fats and Oils) Glycerol (or other alcohol) + three fatty acids Typically store twice as much energy as carbohydrates. Most consist of chain with carbon atoms. Saturated - No double bonds, H atoms attached to every available bond of their C atoms Unsaturated - At least one double bond between carbon atoms.

10 Saturated - No double bonds, H atoms attached to every available bond of their C atoms Unsaturated - At least one double bond between carbon atoms. Glycerol (or other alcohol) + three fatty acids

11 Lipids Lipids serve many important functions. Store energy Protection against dehydration and pathogens Carry electrons and absorb light Contribute to structure of membranes Agricultural commodities important to the food, medical, and manufacturing industry

12 Lipids Because plants can t control their temperatures, they contain much more oil than fats. Waxes - Lipids consisting of long-chain fatty acids bonded to long chain alcohol other than glycerol. Example: In plants, waxes, cutin, and suberin protect against dehydration and pathogens. Phospholipids - Constructed like fats, but one of the fatty acids is usually replaced by a phosphate group. Example: found in cell membranes

13 Proteins, Polypeptides, and Amino Acids Proteins perform essential jobs in cells. Help chemical reactions Support the cell Move materials around Control information flow Send signals

14 Proteins, Polypeptides, and Amino Acids Proteins are usually very large and consist of one or more polypeptide chains. Polypeptides are chains of amino acids. 20 different amino acids. Each amino acid has two functional groups plus an R group. Amino group (-NH 2 ) Carboxyl group (-COOH)

15 Proteins, Polypeptides, and Amino Acids

16 Proteins, Polypeptides, and Amino Acids Polypeptide Structure- To make a protein amino acids bond with covalent bonds called peptide bonds Primary Structure - A sequence of amino acids fastened together by peptide bonds. Secondary Structure - Coiling of polypeptide chains. Tertiary Structure - Maintained by coils between R groups. Quaternary Structure - Occurs when a protein has more than one kind of polypeptide.

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18 Proteins, Polypeptides, and Amino Acids Structural proteins support the cell. Cytoskeletal proteins provide supportive scaffolding from the inside of the cell. Outside the cell, proteins are woven into the cell wall, a protective layer that encases a plant cell.

19 Proteins, Polypeptides, and Amino Acids Transport proteins move materials into and within plant cells. Proteins located at the boundary of the cell help create passageways for materials. Inside the cells, structures may use cytoskeletal proteins as tracks that allow them to move around the cell.

20 Proteins, Polypeptides, and Amino Acids Enzymes are proteins that speed up chemical reactions. Enzymes are mostly large, complex proteins that function as organic catalysts under specific conditions. Work by lowering energy of activation. Temporarily bonds with potentially reactive molecules at a surface site. Names end in =ase.

21 Nucleic Acids Nucleic acids are very large, complex polymers. Vital to internal communication and cell functioning. Two types of nucleic acids. Deoxyribonucleic Acid (DNA) and ribonucleic acid (RNA) are composed of nucleotides. Three parts- nitrogenous base, five-carbon sugar, and a phosphate. DNA does not leave the nucleus of the cell.

22 Nucleic Acids DNA stores the information that determines the structure and function of all cells on earth. DNA determines the traits of plants. When cells reproduce, they copy their DNA molecules and pass them on to the new cells. RNA is similar to DNA in structure, but more flexible in its functions. Different types perform different functions. Some carry information around the cell. Some help build proteins. Some control when proteins are made. RNAs contain information, but they can move around and cause things to happen.

23 Review Attributes of Living Organisms Chemical and Physical Bases of Life Molecules Bonds and Ions Acids and Bases Carbohydrates, Lipids, Proteins Enzymes Nucleic Acids

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