Download Section 2 Molecules of Life

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Carbohydrates
 Organic compounds composed of carbon,
hydrogen, and oxygen in a ratio of 1:2:1
 Carbohydrates can exist as
1) monosaccharides (simple sugar)
2) disaccharides (double sugar)
3) polysaccharides (“many” sugars)
Glucose is a very important sugar
to living things.
 Glucose, hence
carbohydrates,
are the most
important
source of
energy for our
cells.
Monosaccharides- simple sugars
 Glucose
 Fructose
 Galactose
 They can be combined to form a
disaccharide by a ? reaction.
CONDENSATION
Isomers- same formula but slightly
different structure
 glucose
C6H12O6
Polysaccharides & examples
 Composed of three or more
monosaccharides
especially glucose
1) glycogen
2) starch
 Animals store glucose as glycogen.
Plants store
glucose as starch.
Another large
polysaccharide is
cellulose
Proteins
 Compounds made of carbon, hydrogen, oxygen,
and nitrogen
Proteins make up hair, skin,
muscles, enzymes, and horns
Amino acids- the building block or
subunit of proteins
 There are 20 amino acids and they are linked together
by peptide bonds to form proteins.
A
?
together.
reaction is the process that links them
CONDENSATION
A peptide bond forms between 2 amino
acids…
 The peptide bond forms between the C, H, N, O.
Happy Halloween!!!!
Amino acids are linked together to
form a protein chain
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alanine
arginine
asparagine
aspartic acid
cysteine
glutamic acid
glutamine
glycine
histidine
hydroxyproline
isoleucine
leucine
lysine
methionine
phenylalanine
proline
serine
threonine
tryptophan
tyrosine
valine
Almost all
of them
end in ‘ine’
The chain then folds into various shapes.
The Structure of One Amino Acid
 Each amino acid has a
different “R” group. The
“R” group gives different
proteins different shapes
and therefore different
functions.
Enzymes are Protein
 Enzymes are molecules that catalyze reactions in
living systems
 They make reactions go faster by reducing
activation energy
 They lower activation energy by linking to a
substrate and weakening the bonds within that
substrate
Induced Fit Model (shows how
enzymes work)
Another view…
There are 3 basic steps of enzyme
action:
 1) A substrate attaches to the active site of an
enzyme.
 2) The enzyme changes shape weakening
the bonds of the substrate.
 3) The substrate turns into something
different (products) and is released from the
enzyme.
About enzymes
They may not work if the temperature or
the pH is not right.
 Enzymes are very specific for the
reactions they control.
 Without enzymes, reactions would go
too slowly to support life processes.