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MOLECULAR BIOLOGY BASICS

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MOLECULAR BIOLOGY BASICS CISC 4020 Bioinformatics Spring 2013 Department of Computer and Information Science Outline DNA RNA Protein Gene Cell Theory All organisms ... – PowerPoint PPT presentation

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Title: MOLECULAR BIOLOGY BASICS


1
MOLECULAR BIOLOGY BASICS
  • CISC 4020 Bioinformatics
  • Spring 2013
  • Department of Computer and
  • Information Science

2
Outline
  • DNA
  • RNA
  • Protein
  • Gene

3
Cell Theory
  • All organisms are made up of cells
  • The cell is the smallest living unit of all
    organisms
  • All cells come from pre-existing cells

4
What is a cell?
  • In its simplest description, a cell has 3
    essential parts
  • a membrane that defines the boundary of the cell
  • inner material called cytoplasm
  • DNA that contains the information that the cell
    requires to live and reproduce.

5
Nucleotide
  • Nucleotides are molecules that, when joined
    together, make up the structural units of RNA and
    DNA.
  • DNA has 4 different types of nucleotides
  • Adenine (A) and Guanine (G)
  • Cytosine (C) and Thymidine (T)

6
DNA
  • The two chains of a DNA molecule run in opposite
    directions, and twist around each other to form a
    double helix.
  • Base pairing
  • A T
  • C G

7
How to see DNA?
  • There are 3 common ways to view DNA in the lab
  • Direct view in a gel with Ethidium Bromide and UV
    light
  • Radioactive probe - image on X-Ray film
  • Fluorescent prove - image with digital camera

8
Raw Genome Data
9
Outline
  • DNA
  • RNA
  • Protein
  • Gene

10
RNA
  • RNA molecules are very similar to DNA, except
    that instead of Tyhmine, RNA uses the base Uracil
  • RNA is single stranded.
  • RNA form a double helix with complementary
    strands of DNA.
  • RNA molecules are much less chemically stable
    than DNA.

11
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12
The central dogma of Molecular Biology
  • DNA is transcribed into RNA which is then
    translated into protein.

13
Outline
  • DNA
  • RNA
  • Protein
  • Gene

14
What is a Protein?
  • Protein is in food
  • Silk and hair are protein
  • Enzymes are proteins
  • Proteins are molecules

15
Proteins
  • Proteins are the most structurally and
    functionally diverse group of biomolecules. They
    also make up the majority of the dry weight of
    all living cells.
  • Proteins are used as motors, structural elements,
    enzymes, receptors, channels through membranes,
    intra-cellular transporters, regulatory switches,
    and much more.

16
Molecular structure
  • Proteins are polymers - chains of smaller
    molecular units called Amino Acids.
  • A protein is a chain of different amino acids.

17
Amino Acids
  • There are 20 kinds of amino acids.
  • How DNA/RNA are translated to protein?
  • A three base sequence in DNA or RNA is known as a
    codon (genetic code).
  • Each codon corresponds to one amino acid.

18
The standard genetic code (DNA codon table)
19
The standard genetic code (RNA codon table)
20
Protein Sequence
  • Proteins are generally described as a string of
    letters GCVFRTLLSAGR that represent
    abbreviations for the 20 amino acids
  • Since a protein can have any amino acid at each
    position in the chain, and proteins may be many
    hundreds of amino acids long, the potential
    number of different proteins is huge (20300
    for a 300 amino acid protein)
  • The chemical diversity of the 20 amino acids
    means that different proteins can have vastly
    different biochemical properties.

21
Start and stop codons
  • The stop codons in the RNA table (UAA, UAG and
    UGA) serve as a signal that the end of the chain
    has been reached during protein synthesis.
  • The codon that marks the start of a protein chain
    is AUG. If you check the table, that's the amino
    acid, methionine (Met). That ought to mean that
    every protein chain must start with methionine.
    That's not quite true because in some cases the
    methionine can get chopped off the chain after
    synthesis is complete.

22
Protein Structure Function
  • Although proteins are synthesized as linear
    chains of amino acids, they do not remain flat
    and stretched out.
  • Under biological conditions, proteins fold up
    into complex 3-dimensional shapes.
  • These 3-dimensional shapes play a major role in
    determining the interactions of proteins with
    other molecules.
  • Lock and key model of enzyme function

23
Structure -gt Function
  • Proteins are an illustration one of the most
    important principles in biology
  • Structure determines function
  • The molecular shape of each protein molecule is
    perfectly suited for its function.

24
Example - Hemoglobin
  • One of the first proteins to be studied (1830s
    and 1840s)
  • The main oxygen carrier in the red blood cells of
    vertebrates.
  • A tetramer of four globin subunits (aß)2
  • alpha globin, beta globin,
  • Globin family has hemoglobin, myoglobin, etc.

(aß)2
25
Outline
  • DNA
  • RNA
  • Protein
  • Gene

26
Gene
  • The fundamental physical and functional unit of
    heredity.
  • A gene is an ordered sequence of nucleotides
    located in a particular position on a particular
    chromosome that encodes a specific functional
    product (i.e., a protein, or RNA molecule).
  • Consisting of regulatory regions, protein-coding
    exons, and introns.
  • There are now about 22,000 human genes and human
    genes are 10 100 kb in size. (1 kb is 1000 bp)

27
Gene Expression
  • The process by which a genes coded information
    is converted into the structures present and
    operating in the cell.
  • Expressed genes include those that are
    transcribed into mRNA and then translated into
    protein and those that are transcribed into RNA
    but not translated into protein.

28
Gene Mapping
  • Determination of the relative positions of genes
    on a DNA molecule (chromosome or plasmid) and of
    the distance, in linkage units or physical units,
    between them.
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