Chapter 13 .Chemicals of life

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Chapter 13 .Chemicals of life

• No molecule in a living organism is a permanent
  resident. Within 7 years, most of the molecules
  in a human body have been replaced by new one!
• Individual? Decided completely by the genetic
  code? No! An individuals identity is continually
  re-established each and every moment.

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13.1 Biomolecules are produced and utilized in
cells

• Plasma membrane ???
• Cell wall ???
• Cell nucleus???
• Cytoplasm ???
• Organelles ???
• Carbohydrate ?????
• Lipid ??
• Protein ???
• Nucleic acid ??

Plant cell
Animal cell
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13.2 Carbohydrates give structure and energy

• Carbohydrates are molecules of carbon, hydrogen
  and oxygen produced by plant through
  photosysthesis (????).
• Saccharide ??
• Glucose ???
• Fructose ??

Honey
Glucose Fructose
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Sucrose ??
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Lactose ??Lactase ???
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Polysaccharides (??) are complex carbohydrates
Hyaluronic acid ???? Glucuronic acid
???? Chitin ???
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The polysaccharides of the human diet are made
only of glucose. These polysaccharides include
starch (??), glycogen (??) and cellulose (???),
which differ from one another in how the glucose
units are chained together.
Amylose ????20
Amylopectin ????80
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Glycogen is found in animal tissue
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Cellulose is consisted of ßglucose and has a
straight conformation.Cellulose is by far the
most abundant organic compound on earth. But most
animals, including humans, are not able to break
cellulose down to glycose.
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13.3 Lipids are insoluble in water

• Fats are used for energy and insulation
• A fat is any biomolecule formed from the reaction
  of a glycerol molecule, attached to three fatty
  acid molecules. Fatty acid can be saturated or
  unsaturated.
• Fats are used to reserve energy. 1 gram of fat
  contains about 9 calories of energy, while a gram
  of carbohydrate and protein contains only 4
  calories of energy.
• Fats are also used to insulate us from cold.

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Saturated fat and unsaturated fatThe molecules
of saturated fats can pack together, leading to
high melting points.The molecules of unsaturated
fats can not pack together, leading to low
melting points.
stearic acid,m.p.69?
oleic acid,m.p.13?
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Fats from animals and plants are mixture of
different fat molecules
Table 13.1 degree of unsaturation in some common
fats
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Steroids (???) contain four carbon rings

• Cholesterol ???
• Testosterone ??
• Estradiol ????

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13.4 Proteins are polymers of amino acids (???)

• 20 amino acids differ from one another by the
  chemical identity of their side groups.

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• Amino acids are linked through peptide bonds
  (??). A group of amino acids linked together
  through peptide bonds is called peptide. Peptides
  containing more than ten amino acids are
  generally called polypeptides.

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There are many kinds of proteins
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Protein structure is determined by attractions
between neighboring amino acids
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The proteins in hair and fingernails contain a
lot of disulfide bonds
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Many proteins consist of two or more polypeptide
chains.

• ????

The proteins can be denatured with the change in
conditions.
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Enzymes are biological catalysts
Figure 13.25 Upon binding to the receptor site
on the enzyme sucrase, the substrate sucrose is
split into its two monosac-charide units, glucose
and fructose.
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13.5 Nucleic acids code for proteins

• Our bodies are built of proteins. Our bodies are
  able to assemble amino acids in just the right
  order to build proteins that have highly
  functional structures.
• A nucleotide (??) consists of a phosphate (??), a
  ribose sugar (??), and a nitrogenous base (??).
• A nucleic acid is a polymer made up to nucleotide
  monomers.

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• Two types of nucleic acids deoxyribonucleic acid
  (??????) and ribonucleic acid (????).
• Deoxyribonucleic acids are the primary source of
  genetic information and are found in the cell
  nucleus.
• Ribonucleic acids occur mostly outside the cell
  nucleus in the cytoplasm, where they piece
  together amino acids to make proteins.

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DNA is the template of life

• Gregor Mendels work rose the idea of heredity.
  The unit containing the heritable information is
  called genes. In 1900s, genes have been related
  to chromosomes (???), which consist of DNA and
  proteins.

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• In 1953, James Watson and Francis Crick proposed
  the double helix structure of DNA. The most
  critical point of double helix model is the
  hydrogen bonding between guanine and cytosine,
  and also between adenine and thymine.

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Replication of DNA
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• One gene codes for one polypeptide
• Gene controls the proteins amino acid sequence.
  Each gene codes for the synthesis of a particular
  protein.
• The number of human gene is 30000-100000.
• Each chromosome contains 1000-2000 genes.
• Each DNA molecule contains about 3.1 billion base
  pairs.
• Genes make up only about 20 of a DNA molecule.

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• RNA is largely responsible for protein synthesis
• The manufacturing of proteins involves two
  processes transcription (??) and translation
  (??).
• These steps are mediated by the three forms of
  RNA messenger RNA (??RNA,mRNA), ribosomal RNA
  (???RNA,rRNA) and transfer RNA (??RNA,tRNA).

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Codon (???????)
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Translation
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Ribosome
Ribosome
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• Genetic engineering
• Restriction enzyme (???) ban cleave long strands
  of DNA into small fragments.
• Gel electrophoresis is used to separate
  fragmented DNA.

Gel electrophoresis
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Recombinant (??)DNA
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Gene cloning (????)
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13.6 Vitamins are organic, minerals are inorganic

• Lipid-soluble vitamins and water-soluble vitamins
• Lipid-soluble vitamins can be stored in body for
  long time, but not for children.
• Over-dose of vitamins A and D are harmful.
• Vitamins B and C are washed away by water.

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Table 13.2 Some Vitamins Needed by the Human Body
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Minerals
Table 13.3 Some Macrominerals Needed by the Human
Body
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ATPADP
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13.7 Metabolism (??) is the cycling of
biomolecules through the body catabolism and
metabolism
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13.8 The food pyramid summarizes a healthful diet
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CarbohydratesGlycemic Index (????)
Table 13.4 Glycemic Index for Select Foods
source Jennie Brand Miller et al., the Glucose
Revolution the authoritative guide to the
Glycemic index. Sydney Marlowe company, 1999
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• Unsaturated fats are generally more healthful
  than saturated fatsSaturated fats are used to
  synthesize cholesterol.Fats are also packaged
  with water soluble proteins (Lipoproteins) to
  move through bloodstream.
• Hydrogenation of unsaturated fats can be used to
  prepare margarine and also in the process of
  making chocolates.

Table 13.5 The Classification of Lipoproteins
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Essential for children
Essential for adults