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Lipids, proteins, and nucleic acids

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Lipids, proteins, and nucleic acids Biological molecules, continued Lipids are hydrophobic Lots of nonpolar bonds (C-H) Tend to cluster in water If the molecule has ... – PowerPoint PPT presentation

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Title: Lipids, proteins, and nucleic acids


1
Lipids, proteins, and nucleic acids
  • Biological molecules, continued

2
Lipids are hydrophobic
  • Lots of nonpolar bonds (C-H)
  • Tend to cluster in water
  • If the molecule has polar (hydrophilic) regions,
    they are exposed on the surface

3
Triglycerides
  • Glycerol covalently linked to three fatty acids
  • Fatty acids may be saturated or unsaturated
  • Affects the melting point of the triglyceride

4
Saturated and unsaturated lipids
5
Other types of lipids phospholipids
6
Steroids
  • Four fused rings with functional groups
  • Found in cell membranes of animal cells
  • Cholesterol is a precursor for several hormones

cholesterol
7
Prostaglandins
  • Formed from fatty acids
  • Are derived from membrane phospholipids
  • Help regulate responses to stimuli

8
Functions of proteins
9
continued
10
Why are proteins so versatile?
  • Twenty different amino acids (with a few
    variants)
  • Amino acids have many different properties
  • Proteins vary in number, sequence of amino acids
  • This affects the structure and function of the
    protein

11
Amino acids are joined by peptide bonds
12
Categories of amino acids
13
Levels of protein structure primary
  • Length and order of amino acids in the chain is
    genetically determined
  • Basis for all further levels of protein structure

14
Levels of protein structure secondary
  • Regions of amino acid chain may be coiled or
    flattened
  • Achieved through hydrogen bonding

15
Tertiary structure
  • Interactions between R groups
  • Remember protein has three-dimensional structure
  • In cells, proteins are formed in an aqueous
    environment

16
Quaternary structure
  • Some proteins are formed with more than one chain

17
Protein structure is determined genetically
18
Motifs and domains
  • Protein structure is extremely complex
  • Studying protein structure is complex, too
  • X-ray crystallography
  • NMR
  • Modeling
  • Proteins with similar activities have some common
    features

19
Proteins are helped to fold correctly
  • Chaperone proteins are found throughout nature
  • Misfolded proteins are usually degraded
  • Changes in the environment can also affect
    protein folding

20
Protein sequence information is contained in DNA
  • DNA contains the genetic information
  • DNA can replicate itself
  • RNA is required for actual protein synthesis

21
Nucleic acids are made of nucleotides held
together by a sugar-phosphate backbone
22
DNA vs. RNA
  • Thymine vs. uracil
  • Double-stranded vs. single stranded
  • Deoxyribose vs. ribose
  • Stability
  • Function

23
Structures of DNA and tRNA
24
ATP contains adenine
  • High-energy bonds are formed and broken
  • Energy from ATP is used to drive energy-requiring
    reactions
  • Energy from ATP hydrolysis is used to do cellular
    work

25
Summary
  • Molecules are made of atoms, and acquire new
    properties based on their structure
  • Molecular structure and function are affected by
    their behavior in water
  • Carbohydrates, lipids, proteins and nucleic acids
    all contain C, H, and O- but have unique
    functions in cells
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