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RNA World Hypothesis

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Title: Slide 1 Author: NSSD Last modified by: Andrew Coffin Created Date: 10/6/2008 1:19:46 AM Document presentation format: On-screen Show (4:3) Company – PowerPoint PPT presentation

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Title: RNA World Hypothesis


1
RNA World Hypothesis
  • The RNA world hypothesis proposes that
    self-replicating ribonucleic acid (RNA) molecules
    were precursors to current life, which is based
    on deoxyribonucleic acid (DNA), RNA
    and proteins. It is generally accepted that
    current life on Earth descends from an RNA
    world, although RNA-based life may not have been
    the first life to exist.

2
Assignment
  • Take 10 minutes and write out in a paragraph what
    the basic idea of the RNA World Hypothesis is.
    Use your own words in an original way. Read the
    previous paragraph again, roll it around in your
    head, then write your own fresh version.

3
Chemistry of Cells
  • Objectives
  • Summarize the characteristics of organic
    components
  • Distinguish between carbohydrates, lipids, and
    proteins
  • Describe the structure and function of nucleic
    acids and ATP.

4
Organic Compounds
  • Organic compounds contain carbon atoms that are
    covalently bonded to other elements, typically
    Hydrogen, oxygen, and other carbon atoms.

5
There are four principal classes of organic
molecules found in living things
  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
  • Without these cells couldnt function.

6
Carbohydrates
  • Carbohydrates are organic compounds made of
    carbon, hydrogen, and oxygen, and are found in
    the proportion 121

7
Carbohydrates are a key source of Energy
  • They are found in large quantities in fruits,
    vegetables, and grains.

8
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9
Monosaccharide
  • Monosaccharides are the simplest of sugars.
  • Larger sugar molecules are built up by adding
    monosaccharides together to form longer chains.

10
Disaccharides
  • Disaccharides are double sugars formed when two
    monosaccharides are attached together.
  • Such as sucrose and glucose, or common table
    sugar.

11
Polysaccharides
  • Polysaccharides are chains of 3 or more
    monosaccharides such as starch, which is an
    example of a macromolecule (a large molecule made
    up of smaller molecules).
  • In organisms, polysaccharides function as store
    houses of energy.

12
Glycogen and Starch
  • Glycogen is the polysaccharide that animals use
    to store energy
  • Starch is the polysaccharide that plants use to
    store energy

13
Lipids
  • Lipids are also molecules composed of Carbon,
    hydrogen, and oxygen.
  • These include molecules such as fats,
    phospholipids, steroids, and waxes.

14
Phospholipids
  • Phospholipids are important in the function of
    cell membranes, and create a lipid bilayer.

15
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16
Steroids
  • Steroids such as cholesterol are also found in
    cell membranes.
  • The plant pigment chlorophyll is also a lipid.

17
FATS
  • Fats are lipids that store energy
  • A typical fat contains 3 fatty acids bonded to a
    glycerol molecule.

18
Saturated Fats
  • Saturated fats, are saturated with hydrogen
    atoms.
  • Each carbon is bound to 2 hydrogens, the end
    carbons have 3 hydrogens attached.

19
Saturated Fats
  • Most animal fats such as butter, lard, and the
    fatty part of steaks are saturated fats.
  • They are typically solid at room temperature.

20
Unsaturated fats
  • Unsaturated fats some of the carbon atoms form
    double bonds, each with only one hydrogen atom,
    producing kinks in the molecule

21
Unsaturated fats
  • Unsaturated fats mainly come from plants, and are
    usually liquid at room temperature.

22
Proteins
  • Proteins are long chain molecules.
  • They are made up of chains of amino acids strung
    like pearls on a necklace.
  • The amino acids are connected by peptide bonds.

23
Amino Acids
  • Amino acids are the building blocks of proteins.
  • There are 20 different amino acids found in
    proteins, each with a different chemical
    structure.

24
Primary, Secondary, and Tertiary Structure of
Proteins
25
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26
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27
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28
Proteins have a variety of functions in living
organisms
29
Enzymes
  • Enzymes promote chemical reactions, such as
    amylase which breaks down starches, and DNA
    synthase which builds DNA molecules.

30
Nucleic acids
  • Nucleic acid is a long chain of smaller molecules
    called nucleotides.

31
Nucleotides
  • Nucleotides have three parts a sugar, a base,
    and a phosphate group.

32
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33
RNA
  • RNA- ribonucleic acid, consists of a single
    strand of nucleotides, and plays several roles in
    cell function, including the manufacture of
    proteins.

34
DNA
  • DNA- Deoxyribonucleic acids- consists of two
    strands of nucleotides that spiral around each
    other forming a double helix.
  • This molecule stores hereditary information that
    can be used to make proteins.
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