Biology Chapter 3 Biochemistry

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Biology Chapter 3 Biochemistry
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Ch 3 Biochemistry

• Section 1 Carbon Compounds
• Section 2 Molecules of Life

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Section 1 Carbon Compounds Objectives

• Distinguish between organic and inorganic
  compounds
• Explain the importance of carbon bonding in
  biological molecules
• Identify functional groups in biological
  molecules
• Summarize how large carbon molecules are
  synthesized and broken down.
• Describe how the breaking down of ATP supplies
  energy to drive chemical reactions.

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Carbon Bonding

• Inorganic compounds do not contain chains or
  rings of carbon
• Organic compounds
• Made primarily of carbon atoms
• Most of the matter in living organisms that is
  not water
• Carbons ability to form large and complex
  molecules has contributed to the great diversity
  of life

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Carbon

• 4e- in outermost energy level
• Most atoms become stable when their outermost
  energy level contains 8e-
• Carbon atoms readily form 4 covalent bonds
• Can bond with the other atoms of other elements
• Readily bonds with other carbon atoms forming
  straight chains, branched chains, or rings (Fig
  3-1 p51)

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• Bond is represented by a line joining 2 atoms
  sharing a pair of electrons.
• Can also form double and triple bonds (Fig 3-2
  p52)

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Functional Groups

• Clusters of atoms
• Influence the characteristics of the molecules
  they compose and the chemical reactions the
  molecules undergo

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• Hydroxyl Group (-OH)
• Can make the molecule it is attached to polar
  (partially charged on each end due to unequal
  electron sharing)
• Polar molecules are hydrophilic (water-loving)
  or soluble in water
• Alcohol an organic compound with a hydroxyl
  group attached to one of its carbon atoms
• Table 3-1 Common Functional Groups p52

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Large Carbon Molecules

• Monomers smaller, simpler molecules
• Monosingle or alone Merosa part (Greek)
• Polymers a molecule that consists of repeated
  and linked units. The units may be identical or
  structurally related to each other
• Macromolecules large polymers. Ex carbohydrates,
  lipids, proteins, and nucleic acids

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• Condensation Reaction chemical reaction that
  links monomers to form polymers releasing a water
  molecule. (Fig 3-4 p53)

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• Hydrolysis the breakdown of some complex
  molecules such as polymers.
• Water is used to break down a polymer by breaking
  the bond linking each monomer
• Reverse of a condensation reaction
• Fig 3-4 p53 in reverse

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Energy Currency

• Life processes require a constant supply of
  energy
• Certain compounds store a large amount of energy
  in their overall structure

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• ATP adenosine triphosphate
• Ribose 5-carbon sugar
• Adeninenitrogen-containing compound
• 3 Phosphate groups (-PO4)
• Connected by covalent bonds that easily break
  because they have negative charges.
• Energy released when bonds between phosphate
  groups are broken

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ATP Video Clip

• Hydrolysis of ATP is used by the cell to provide
  the energy needed to drive the chemical reactions
  that enable an organism to function. Figure 3-5
  p54

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Section 2 Molecules of LifeObjectives

• Distinguish between monosaccharides,
  disaccharides, and polysaccharides.
• Explain the relationship between amino acids and
  protein structure.
• Describe the induced fit model of enzyme action.
• Compare the structure and function of each of the
  different types of lipids.
• Compare the nucleic acids DNA and RNA

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Molecules of Life

• The 4 main classes of organic compounds are
  essential to the life processes of all living
  things.
• Built primarily from carbon, hydrogen, and oxygen
• Atoms occur in different ratios in each class,
  producing different properties

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Carbohydrates
Carbohydrate Narration

• 1C2H1O
• Some carbohydrates serve as energy sources.
• Some carbohydrates are used as structural
  materials.

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Monosaccharaides

• Monomer
• Simple sugar
• General formula (CH2O)n 121
• nany whole number from 3 to 8
• Ex. (CH2O)6 ? C6H12O6

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• Most common
• Glucose main source of energy for cells
• Fructose sweetest. Found in fruit
• Galactose milk sugar
• Isomers all have the same molecular formula but
  different structures with slightly different
  properties. (Fig 3-6 p55)

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Disaccharides

• Double sugars
• 2 monosaccharides combined during a condensation
  reaction. (Figure 3-4 p53)

Disaccharide Narration
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Polysaccharide

• Complex molecule composed of 3 or more
  monosaccharides

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Glycogen

• Polysaccharide in which animals store glucose in
  liver and muscles.
• 300 molecules strung together in a highly
  branched chain
• Ready to be used for quick energy

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Starch

• Plants store glucose
• 2 basic forms
• Highly branched chains (similar to glycogen)
• Long, coiled unbranched chains

Corn starch
Starch granules under microscope
Potatoes
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Cellulose

• Also in plants
• Gives strength and rigidity to plant cells (cell
  walls). Makes up 50 of wood
• In a single cellulose molecule, thousands of
  glucose monomers are joined in a long straight
  chain.
• Chains tend to form hydrogen bonds with each
  other resulting in a strong structure

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Proteins

• Organic compounds composed mainly of C, H, O, N
• Made of linked monomers called amino acids
• Hair, horn, skin, muscle, and biological
  catalysts (enzymes)

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Amino Acids

• 20 different types with the same basic structure
  (Figure 3-7b p56) but differing by the R-group
• Can be simple or complex. Gives different shapes
  to proteins which allows them to carry out many
  different activities.

Amino Acid Narration
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• Amino acids are commonly shown in a simplified
  way in illustrations such as a ball. Proteins are
  shown as a chain of balls

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Dipeptides

• 2 amino acids joined in a condensation reaction
  forming a covalent bond called a peptide bond. A
  water molecule is released. (Fig 3-8 p57)

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Polypeptides

• Amino acids formed in very long chains
• Proteins are composed of one or more
  polypeptides.
• Some proteins are very large molecules containing
  hundreds of amino acids
• Long proteins are bent and folded with hydrogen
  bonding between individual amino acids in
  different parts of the chain.

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• Shape is also influenced by conditions such as
  temperature and the type of solvent in which the
  protein is dissolved.
• Ex. Boiling an egg changes it from runny to solid

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Enzymes

• Biological catalysts essential for the
  functioning of any cell
• Many enzymes are proteins

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• Induced Fit Model of Enzyme Action (Fig 3-9 p57)
• Enzyme can attach only to a substrate (reactant)
  with a specific shape (puzzle piece)
• The enzyme then changes and reduces the
  activation energy of the reaction so the
  reactants can become products.
• The enzyme is unchanged and is available to be
  used again.

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• An enzyme may not work if its environment is
  changed.
• Ex. Temperature or pH can change the shape of the
  enzyme substrate.

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Lipids

• Large, nonpolar organic molecules
• Do not dissolve in water
• Includes triglycerides, phospholipids, steroids,
  waxes, and pigments
• Higher ratio of C and H atoms to O than in
  carbohydrates. Store more energy per gram than
  carbs.

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Fatty Acids

• Unbranched carbon chains that make up most lipids
• Structure
• Long carbon chain (12-28C) nonpolar component.
  Hydrophobic (water-fearing)
• Carboxly group(-COOH) attached to chain at one
  end. Polar. Hydrophilic (attracted to water)

Fatty Acid Narration
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• Saturated Fatty Acids (Figure 3-10 p59)
• Ex. Palmitic Acid
• Each C is covalently bonded to 2 C and 2H.
  (saturated with Hs)
• Unsaturated Fatty Acids
• Ex. Linoleic acid.
• Some C atoms are not bonded to maximum number of
  Hs, instead form double bonds within the chain.

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Triglycerides

• Composed of 3 molecules of fatty acid joined to
  one molecule of the alcohol glycerol.
• Saturated Triglycerides composed of saturated
  fatty acids.
• High melting points
• Hard at room temp.
• Ex. Butter, fats in red meat

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• Unsaturated Triglycerides composed of
  unsaturated fatty acids.
• Usually soft or liquid at room temp.
• Found primarily in plant seeds where they serve
  as an energy source during germination.

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Phospholipids

• 2 rather than 3 fatty acids attached to a
  molecule of glycerol
• Phosphate group attached to the 3rd carbon of the
  glycerol

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• Ex. Cell membrane is made of 2 layers of
  phospholipids called the lipid bilayer.
• The inability to dissolve in water allows the
  membrane to form a barrier between the inside and
  outside of the cell

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Waxes

• A type of structural lipid consisting of a long
  fatty acid chain joined to a long alcohol chain
• Waterproof
• In plants form a protective coating on the outer
  surface
• Form protective layers in animals. Ex. Earwax
  prevents microorganisms from entering ear canal

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Steroids

• Composed of 4 fused carbon rings with various
  functional groups attached to them
• Examples
• Male hormone testosterone
• Cholesterol needed by the body for nerve and
  other cells to function normally. Also a
  component of the cell membrane.

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Nucleic Acids

• Very large and complex organic molecules that
  store and transfer important info in the cell.
• 2 Types
• DNA deoxyribonucleic acid. Contains info that
  determines the characteristics of organisms and
  directs its cell activities
• RNA ribonucleic acid. Stores and transfers info
  from DNA that is essential for the manufacturing
  of proteins. Also can act as enzymes

DNA Video Clip
DNA and RNA Video Clip
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• Both are polymers composed of thousands of linked
  monomers called nucleotides.
• 3 main components of a nucleotide (Fig 3-12 p60)
• Phosphate group
• 5 carbon sugar
• Ring-shaped nitrogenous base

Nucleic Acid Narration
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