Carbohydrates (cont.)
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Transcript Carbohydrates (cont.)
3-2: MOLECULES OF LIFE
There are 4 classes of organic compounds
essential to life:
Carbohydrates
Proteins
Lipids
Nucleic Acids
Each
of these compounds are made up of C, H,
+ O atoms; but occur in different ratios
Carbohydrates
Organic compounds composed of C, H, + O
Found in ratios of 2H:1O; the # of C varies
Carbohydrates (cont.)
Monosaccharides
Monomer – a simple sugar (1C:2H:1O ratio)
Formula = (CH2O)n ; where n = 3-8
Common types:
Glucose - - used in cells
Fructose - - found in fruits
Galactose - - found in milk
All have same formula = C6H12O6
Isomers = same formula, different structures
Examples
Carbohydrates (cont.)
Disaccharide – “double sugar” – combination of
2 monosaccharides from a condensation rxn
Ex. Sucrose
Carbohydrates (cont.)
Polysaccharide – complex molecules composed
of 3 or more monosaccharides
In animals, glucose is stored as glycogen
Found in branched chains
Stored in liver + muscles
Carbohydrates (cont.)
In plants, glucose is stored as starch or
cellulose
Starch – found as branched or unbranched chains
Cellulose – gives strength + rigidity to plant cell
walls
Proteins
Organic compounds composed mainly of C, H,
O, + N
Formed from monomers
Found in skin, hair, nails + muscles
Proteins (cont.)
Amino Acids (AA)
Building blocks of proteins – monomer
20 different AA in living things
Difference = functional groups attached to C
R. Groups can be simple or complex
Can take on a variety of shapes, thus carrying out different
activities in living things
Proteins (cont.)
Dipeptide – the bonding of 2 AAs
Forms a peptide bond
Proteins (cont.)
Polypeptide – a long chain of AA’s
Chain folds or bends based on certain conditions
( i.e. Temperature increase/decrease) – ex. egg
When polypeptide folds, takes on a globular shape
Enzymes
Proteins (cont.)
RNA or protein molecules that act as biological
catalysts
Work by a “lock-and-key” method with its
substrate – the reactant being catalyzed
Substrate will only “fit” if shape of active site is a
match
Once enzyme is done, it releases the product(s) and
can be used over + over again
Mail fail to work if environment changes (temp or
pH)
How an enzyme works…
Lipids
Large, nonpolar organic molecules that do not
dissolve in water
Higher ratio of C + H atoms to O atoms
C-H bonding (stores more nrg)
Lipids (cont.)
Fatty acids – monomer of a lipid – unbranched
chains
Contain a carboxyl group, -COOH, at one end
Hydrophilic
Hydrocarbon
end – attracted to water (polar)
at other end
Hydrophobic
end – “afraid” of water (nonpolar)
Saturated vs. Unsaturated
Saturated – all C atoms are “full”
Unsaturated – has double bond(s) between C
atoms
Lipids (cont.)
Triglyceride – 3 fatty acid molecules + glycerol
Functions:
NRG, insulation + protection, nutrition
(vitamins ares stored in fats in body)
Types:
Saturated
High melting point, solid @ room temp.
Examples: shortening (Crisco), animal fats
Unsaturated
Low melting point, liquid @ room temp.
Examples: plant seed oils, fruits
Lipids (cont.)
Phospholipids – 2 fatty acid molecules +
glycerol
Forms lipid bilayer for cell membranes
Lipids (cont.)
Wax – long fatty acid chain + long chain of
alcohol
Highly waterproof
Used as a protective coating
Lipids (cont.)
Steroids – molecules of 4 fused C-rings with
different functional groups
Common types:
Hormones – testosterone
Cholesterol – needed by nerves + cells
Nucleic Acids
Very large, complex organic molecules that store
important information in cells
Two types:
DNA – deoxyribonucleic acid – determines characteristics
of organism and directs cells activities
RNA – ribonucleic acid
Stores + transfers info. essential to make proteins
Can also act as an enzyme
Nucleotides – monomers of Nucleic Acid
5-C sugar
Phosphate group
Nitrogen-base
What a nucleotide looks like…
DNA vs. RNA