Transcript Carbohydrates , lipids, and proteins

Carbohydrates, lipids, and
proteins
IB Topic 3.2
Pages 56-61
Introduction
 Living things are composed of an array of molecules
 We need to classify them
 Certain qualities
 The more common biochemically important molecules
are:
Molecule (polymer)
Carbohydrates
Lipids
Proteins (polypeptides)
Nucleic acids
Subcomponents
(monomer)
Monosaccharides
Glycerol & fatty acids
Amino acids
Nucleotides
Common biochemicals & their structure
Classified as organic or inorganic
All organic molecules contain the element
carbon
However, not all carbon-containing
molecules are organic
Example = carbon dioxide (not organic)
Carbohydrates, lipids, proteins ARE organic
Some of the most important categories …
Category
Subcategory
Example molecule
Carbohydrates
Monosaccharides
Glucose, galactose,
fructose
Disaccharides
Maltose, lactose,
sucrose
Polysaccharides
Starch, glycogen,
cellulose
Proteins
X
Enzymes, antibodies
Lipids
X
Triglycerides,
phospholipids
Nucleic Acids
X
DNA, RNA
You should learn to recognize the
structures of common molecules
BUT you do not need to draw them (yea!)
Wait till organic chemistry …
Open your book to page 57
Look at figures 3.2, 3.3, 3.4, and 3.5
Answer question 4
Carbohydrates
Different “sizes”
Monosaccharides, disaccharides,
polysaccharides
All serve many functions in living
organisms
Short term energy
Because they carbohydrates are soluble
Contain only three elements: C, H, O
Hydrogen and oxygen in a 2:1 ratio
Monosaccharide – simple sugar
Relatively small; taste sweet and soluble
in water
Examples:
Glucose: made by green leaves using light
energy, our bodies transport it in our blood,
respiration (chemical fuel), building block for
larger molecules
Galactose
Fructose (found in fruits – makes them sweet)
Disaccharides
Made of 2 monosaccharide molecules
Examples:
Sucrose (glucose + fructose)
Maltose (glucose + glucose)
Lactose (galactose + glucose)
Polysaccharides
Built from many monosaccharide
molecules connected by glycosidic links
Examples
Starch (polymer of glucose)
Glycogen (polymer of glucose)
Stores glucose in liver and muscles
Cellulose (polymer of glucose)
Component of cell walls
Lipids
Lipids occur in living things as animal fats,
plant oils, phospholipids of cell
membranes, and steroids
Contain C, O, and H (like carbs), but
proportion of oxygen is much less
Insoluble in water; hydrophobic
Long term energy storage
Can be dissolved in organic solvents (alcohol)
Lipids
 Fats and oils are compounds called triglycerides
Formed when water is removed between fatty acids and
glycerol
 Long hydrocarbon tails
The Role of Lipids
Energy storage
Lipids store about twice as much chemical
energy as carbohydrates
If you eat more food than you burn, your
body will store much of the excess as fat
in adipose tissue
Other important roles of lipids
1. Energy storage
Less oxygen atoms/more concentrated source
2. Metabolic water source
3. Thermal insulation and buoyancy
4. Water proofing of hair and feathers
5. Electrical insulation
Myelin sheath
Homework
Due Tuesday
#4-7 page 61
Bell Ringer:
Take out your homework (#4-7 page 61)
Take out your PowerPoint questions from
yesterday
Homework for tonight: amino acids
worksheet (will be passed out at the end of
class) & bring your book the rest of the
week.
Topic 3.1 and 3.2 quiz Thursday
Answers to #4-7 page 61
 4) a. glucose + fructose  sucrose + water
 4) b. condensation reaction
 5) a. glycerol + 3 fatty acids  triglyceride + 3
water
 5) b. condensation enzyme
 5) c. product
 5) d. three (b/c three condensation reactions
occurred)
Answers to #4-7 page 61
6) a. amino acids
6) b. glycerol and fatty acids
6) c. nucleotides
7) a. nucleotides
7) b. amino acids
7) c. glucose (a monosaccharide)
Amino Acids, peptides, and proteins
 Contain nitrogen, sulphur, hydrogen, carbon and
oxygen
Amino group: NH2
Carboxyl group: COOH
 Amino acids  peptides and proteins
Polypeptide and protein are used interchangeably
 Once the chain is constructed, it takes a specific
shape – shape matters with proteins
Shape  function
Amino acids
 Proteins are made from 20 amino acids
 Also attached is an R group
Differ  different chemical characteristics
Most macromolecules are polymers
Carbohydrates, lipids, and proteins are
chainlike molecules called polymers
Polymer is a long molecule consisting of many
similar or identical building blocks linked by
covalent bonds
Monomers
Condensation and hydrolysis
Many organisms rely on food to gain the
building block molecules
When animals eat, food is digested (or
hydrolyzed) into the building blocks
Going from polymers to monomers
These building blocks are transported to
body cells and bonded together to form
larger molecules
What happens when you eat?
Foods are chemically digested in your
alimentary canal
Hydrolyzing enzymes are required
Each reaction is called a hydrolysis and
requires a molecule of water as a reactant
Think about the word hydrolysis:
Hydro = water
Lyse = split
Examples of hydrolysis
 Hydrolysis of a
disaccharide in two …
 Hydrolysis of a
triglyceride lipid to …
 Hydrolysis of a
polypeptide to …
Condensation reactions
Are the reverse of hydrolysis
Condensation reactions occur to re-form
larger biochemical molecules
Water molecules are products rather than
reactants
Also requires a different type of enzyme
Condensation Reaction (or Dehydration
Synthesis)
 The process of
connecting monomers to
create a polymer
 This process requires
energy and is aided by
enzymes
 Removes water
molecules
 One monomer provides a
hydroxyl group and the
other provides a hydrogen
Wrap Up
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All organic molecules contain the element _________
Carbohydrates exist as _______, _______, & _______
The smallest carbohydrates are ___________
The subcomponents of other biochemically important
organic molecules are:
 _____________, which make up proteins
 _____________, which make up lipids (fats and oils)
 _____________, which make up nucleic acids (DNA and RNA)
 Subcomponents are bonded together by ___________
 Larger molecules are split by ____________
 Although carbohydrates and lipids are used for energy
storage …