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Nucleic acids (DNA and RNA)

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Introduction Nucleic acids are macromolecules made up of smaller nucleotide subunits. They carry genetic information, form specific structures in a cell or carry out ... – PowerPoint PPT presentation

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Title: Nucleic acids (DNA and RNA)


1
Nucleic acids (DNA and RNA)
2
Introduction
  • Nucleic acids are macromolecules made up of
    smaller nucleotide subunits.
  • They carry genetic information, form specific
    structures in a cell or carry out specific roles
    in a cell.
  • Found in all living things and viruses.
  • The two most common are deoxyribonucleic acid
    (DNA) and ribonucleic acid (RNA).

3
Structure
  • Nucleotides consist of
  • A nitrogenous base
  • A pentose sugar
  • A phosphate group

4
DNA
  • Used primarily for the carrying of hereditary
    information and the recipe for making proteins.
  • DNA contains four different types of nucleotides
    that differ in their nitrogenous base only.
  • The four bases are Adenine, Guanine, Cytosine
    and Thymine.

5
DNA
  • The shape of DNA is a double helix, where two
    nucleotide strands run anti-parallel to each
    other.
  • It looks like a twisted ladder where the sugar
    and phosphate groups make up the sides and the
    nitrogenous bases make up the rungs.

6
DNA
  • The nucleotides are held together by two types of
    bonds.
  • Phosphodiester bonds link the phosphate group of
    one nucleotide to the sugar of an adjacent
    nucleotide along the side of the double helix.
  • The nitrogenous bases are held together by
    hydrogen bonds across a rung.

7
DNA
  • In DNA, Adenine will only bind with Thymine and
    Guanine will only bond with Cytosine based on the
    number of hydrogen bonds each can form.
  • A and T each form 2 while C and G each form 3.

8
RNA
  • Unlike DNA, RNA is single stranded and generally
    much shorter in length.
  • RNA uses nucleotides Adenine, Cytosine and
    Guanine, but instead of Thymine, it uses another
    pyrimidine, Uracil.
  • There are three different types of RNA. They all
    play important roles in protein synthesis.

9
mRNA
  • 1) Messenger RNA decodes the DNA code (protein
    recipe) and takes it from the nucleus to the
    ribosome.

10
tRNA
  • 2) Transfer RNA brings amino acids to the
    ribosome to be incorporated into the newly
    forming polypeptide chain.

11
rRNA
  • 3) Ribosomal RNA is what makes up the ribosomes,
    where proteins are made in the cell.

12
Other Important Nucleic Acids
  1. Adenosine Triphosphate (ATP) which is the energy
    currency of the cell.
  2. NAD, FAD, GDP and NADP, which are high energy
    electron carrying molecules used in cellular
    respiration or photosynthesis.

13
Protein Synthesis
14
Introduction
  • Protein production relies on complex interactions
    among organelles.
  • Protein synthesis is important because nearly all
    cell processes require proteins.
  • Ex A spider produces proteins in order to spin
    a web and humans produce hemoglobin in order to
    transport oxygen to all the cells and take carbon
    dioxide away.

15
Protein Synthesis
  • Protein synthesis refers to making proteins. It
    occurs in a 6 step process in all cells
  • The DNA that codes for a protein is copied onto a
    similar molecule called messenger RNA (mRNA).
    This happens in the nucleus and is called
    transcription.

16
Protein Synthesis
  • Remember RNA uses Uracil instead of Thymine, so
    when DNA has an Adenine molecule, the RNA
    molecule will have a Uracil bound to it.

17
Protein Synthesis
  • The messenger RNA carries the coded message from
    the nucleus to ribosomes in the cytoplasm. It
    exits the nucleus through the nuclear pore.

18
Protein Synthesis
  • A ribosome clamps onto the mRNA and the code for
    protein (codons) begins to get translated into
    amino acids, the building blocks of protein.

19
Protein Synthesis
  1. Special molecules called transfer RNA (tRNA)
    bring the amino acids the recipe calls for to the
    ribosome in the correct sequence specified by
    mRNA.

20
Protein Synthesis
  • Two tRNAs can be at the ribosome at one time.
    When two are there, one will attach its amino
    acid to the amino acid of the other one, creating
    a chain of amino acids. Once this happens, that
    tRNA leaves and the one with the chain moves to
    its place.

21
Protein Synthesis
  • Once the entire mRNA is read by the ribosome all
    the parts will separate. The amino acid chain
    will then fold into a functional protein. The
    others will wait for another chance at
    translation.
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