Carbon Compounds in Cells

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Carbon Compounds in Cells

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life
• Chapter 3

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Key Concepts

• Organic compounds have carbon atoms to which
  hydrogen, oxygen, nitrogen, and other atoms are
  attached
• Cells put together large biological molecules,
  such as carbohydrates, lipids, proteins, and
  nucleic acids
• Glucose and other simple sugars are carbohydrates

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Key Concepts

• Complex carbohydrates are polysaccharides
• Lipids dissolve in nonpolar compounds
• They include neutral fats, phospholipids, waxes,
  and sterols
• Cells use carbohydrates and lipids as building
  blocks and as their major energy source

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Key Concepts

• Proteins have many roles forming structures,
  enzymes, transporters, body defenses, and help in
  movement
• ATP is crucial in metabolism. DNA and RNA are the
  basis of inheritance and reproduction

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Carbon

• Can form covalent bonds with up to four other
  atoms

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Carbon
Carbons versatile bonding
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Hydrocarbons and Functional Groups

• Hydrocarbons
• Hydrogen atoms attached to a carbon backbone
• Functional Groups
• Single or cluster of atoms covalently bonded to
  the carbon backbone
• Hydroxyl (OH-)
• Amino (NH2)
• Phosphate (PO4)

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Examples of Functional Groups
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How Cells Use Organic Compounds

• Enzymes
• Mediate reactions
• Speed up the rate
• Classes of Reactions
• Functional-group transfer
• Electron transfer
• Rearrangement
• Condensation
• Cleavage

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Condensation and Hydrolysis

• Condensation
• Two molecules
• combine
• Hydrolysis
• A molecule
• splits into two
• smaller ones

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The Molecules of Life

• Living cells synthesize
• Carbohydrates chains of simple sugars
• Lipids chains of fatty acids (except sterols)
• Proteins chains of amino acids
• Nucleic acids chains of nucleotides

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Carbohydrates

• Contain an aldehyde or a ketone group and one or
  more hydroxyl groups
• Main types
• Monsaccharides
• Oligosaccharides
• Polysaccharides

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Carbohydrates

• Monosaccharides
• 6 Carbon sugars
• Glucose
• Fructose
• Galactose
• 5 Carbon sugars
• Deoxyribose
• Ribose

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Carbohydrates

• Oligosaccharides
• Disaccharides
• Sucrose
• Lactose
• Maltose
• Formed by condensation
  reactions

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Carbohydrates

• Complex
• Polysaccharides
• Starch
• Cellulose
• Glycogen
• Chitin

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Lipids

• Largely hydrocarbon
• Do not dissolve in water
• Dissolve in nonpolar substances
• Lipids with fatty acids
• Glycerides
• Phospholipids
• Waxes
• Lipids with no fatty acids
• Sterols

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Fatty Acids

• Carbon backbone
• Carboxyl group (- COOH)
• Unsaturated
• One or more double bonds in backbone
  
• Saturated
• All single bonds in backbone

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Triglycerides

• Neutral fats
• Three fatty acids
  and a glycerol
• Condensation
  reaction
• Bodys most abundant
  lipid
• Functions
• Energy reservoir
• Insulation

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Phospholipids

• Glycerol backbone
• Two fatty acid tails (hydrophobic)
• Phosphate-containing head (hydrophilic)
• Main materials of cell membranes

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Sterols

• Sterols
• No fatty acid tails
• Four carbon rings
• In eukaryotic cell membranes
• Cholesterol in animals tissues
• Vitamin D
• Steroids (hormones)
• Bile salts

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Waxes

• Long-chained fatty acids linked to alcohols or
  carbon rings
• Cover plant parts
• Help conserve water
• Fend off parasites
• Animals
• Protect
• Lubricate
• Impart pliability to skin and hair
• Repel water

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Amino Acids and the Primary Structure of Proteins

• Proteins
• Enzymes
• Structures
• Transport
• Nutritious
• Hormones
• Immune system
• Proteins are made from a pool of 20 amino acids

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Structure of Amino Acids

• Central carbon atom
• An amino group
• A carboxyl group
• A hydrogen atom
• One or more atoms
  R Group

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Structural Formulas for Some Amino Acids
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Structural Formulas for Some Amino Acids
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Peptide Bond Formation

• A type of condensation reaction

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Second Level of Protein Structure

• Hydrogen bonds
• Helical coiling
• Sheet-like pattern

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Third Level of Protein Structure

• Additional folding of secondary structure
• R Group interactions
• Hydrogen bonds
• Disulfide bridges

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Fourth Level of Protein Structure

• Two or more polypeptide chains joined by
• Weak bonds (Hydrogen bonds)
• Covalent bonds between sulfur atoms and R groups
• Collagen
• Keratin
• Hemoglobin

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Structure of Hair

• Keratin
• Fibrous structural protein

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Structural Changes by Denaturation

• Disruption of three-dimensional shape of protein
• Changes in temperature and pH
• Loss of function
• Some proteins have organic compounds attached
• Glycoproteins
• Lipoproteins

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Nucleotides and The Nucleic Acids

• Nucleotides
• Sugar
• Ribose or Deoxyribose
• Phosphate group
• Bases
• Single or double carbon rings with nitrogen
• Subunits of coenzymes
• NAD and FAD
• ATP
• Energy source for chemical reactions

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Structure of ATP

• ATP
• Three phosphate groups

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Nucleic Acids - DNA and RNA

• Building blocks
• Four kinds of
  nucleotides
• Differ only in component bases

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Single Strand of Nucleic Acid

• A series of
• covalently
• bonded
• nucleotides

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DNA

• Double stranded
• Hydrogen bonds between strands
• Twisted helically
• Four kinds of nucleotide monomers (A, T, C, G)
• Encodes protein-building instructions

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RNAs

• Single stranded
• Four kinds of nucleotide monomers (A, U, C, G)
• Do not encode protein-building instructions
• Key players in the protein-building processes
• mRNA, tRNA, rRNA

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In Conclusion

• Organic compounds have elements covalently bonded
  to carbon atoms
• Living cells assemble organic compounds lipids,
  carbohydrates, proteins, and nucleic acids
• The building blocks are amino acids, nucleotides,
  simple sugars, and fatty acids
• Complex carbohydrates are energy storage forms
  and structural materials

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In Conclusion

• Lipids are used as energy storage and structural
  components
• Proteins are made of amino acids. They form
  structures, enzymes, transport, movement, and are
  part of the immune system
• Nucleic acids are the basis of inheritance and
  reproduction