Food CH3 Flashcards
Nutrition
The way in which an organism obtains and uses food.
Nutrients
The substances in food that are used by organisms.
What are nutrients necessary for
Growth and repair
energy
metabolic reactions
How many elements are food mainly made of
14
Apart from hydrogen, carbon and oxygen, they are called minerals.
6 Common elements
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
Sulfur
Dissolved salts
Sodium
Magnesium
Chlorine
Pottassium
Calcium
Trace elements
Iron
Copper
Zinc
Biomolecules
Chemicals made inside a living thing
4 biomolecules in food
Carbohydrates
Lipids
Proteins
Vitamins
Elements in carbohydrates
Carbon,
Hydrogen
Oxygen
Element ratio for carbohydrates
Cx(H2O)y
(twice as much hydrofen as oxygen or carbon)
Types of carbohydrates
Monosaccharides
Disaccharides
Polysaccharides
Monosaccharides
-Single sugar unit
-Smallest type of carbohydrate
-Sweet taste and soluble in water
Examples of monosaccharides
Glucose - found in sweets, fruits and made by plants
Fructose - found in fruits
Disaccharides
-Made of two sugar units joined together
-Sweet tasting and soluble in water
Examples of disaccharides
Maltose - found in germinating seeds (2glucose molecules)
Sucrose - table sugar (a glucose joined to a fructose)
Polysaccharides
-Made of many sugar units ( often thousands )
-Insoluble or slightly in water
-not sweet tasting
Examples of polysaccharides
Starch
cellulose
glycogen
Starch
-Made of many glucose molecules joined together
-Is the carb stored by plants
-easily digested as only two chemical bonds must be broken to release glucose
Cellulose
-Made of many glucose molecules joined together by cross-bonding
-very strong
-difficult to digest
Glycogen
-Made of large numbers of glucose arranged in branch chains
-Animals store glycogen in their livers and muscles.
Sources of carbohydrates
Bread, pasta, rice, potatoes, sugars, fruits, sweets, cakes
structural role of carbohydrates
Cellulose used to form plant cell walls
Metabolic role of carbohydrates
Glucose broken down in respiration to release energy
glucose made in photosynthesis
Lipids
Fats and oils
Fats
Lipids solid at room temp
oils
lipids liquid at room temo
Elements of lipids
Carbon, hydrogen, oxygen
Structure of lipids
1 molecule of glycerol linked to 3 fatty acid molecules (triglycerides)
Phospholipids
fat-like substances, in which one of the fatty acids is replaced by a phosphate group or has a phosphate group added to it.
Key component of cell membranes
Source of lipids
Butter oils margarine cream fat on meats dried food
Structural role of lipids
Heat insulation + protection of organs
Energy stores in planta and animals
Combine with phosphorus (phospholipids) and proteins (lipoproteins0 to form cell membrane.
Metabolic role of lipids
Can be broken down in respiration to release energy
Elements in proteins
carbon, hydrogen, oxygen nitrogen
(sometimes small amts of sulfur, phosphorus and other elements.)
Structure of proteins
-Composed of amino acids
-amino acids are joined together by peptide bonds.
How many types of amino acids are there
peptide
less than 20 amino acids
polypeptide
more than 20 amino acids
protein folding
Determines how a protein will work
- fibrous and globular
Fibrous proteins
Little or no folding, are strong and tough
eg keratin in hair nails and feathers.
Globular proteins
Lots of folding and form rounded shapes
eg. egg whites (albumin)
enzymes
What does incorrect protein folding cause
prions- eg BSE in cattle and CJD in humans
Sources of proteins
Meat, fish, eggs, milk, nuts, peas, beans
what happens to excess amino acids
Our body does not store amino acids.
Excess amino acids are converted to urea in the liver in a process called deamination
How is urea transported
Urea is carried in the blood to the kidneys and excreted in urine.
Structural role of proteins
-Fibrous proteins eg keratin is found in skin and hair
-Myosin found in muslces
Metabolic role of proteins
-Used as enzymes to control reaction
- Form antibodies to fight infection
- Hormones regulate body reactions.
Vitamin c
Water soluble vitamin
Sources of vitamin c
veg, fresh fruit, limes, guava, peppers, grapefruit
Metabolic role of vitamin c
- Forms connective tissue, bones and teeth, and is involved in wound healing and the immune system.
Deficiency in vitamin c
Scurvy - bleeding gums, loose teeth, poor skin healing, bleeding under the skin
Vitamin d
Fat soluble vitamin
Sources vitamin d
Fish oils, liver, milk, egg yolk, made when uv light shines on skin
Metabolic role of vitamin d
- Helps absorb calcium from intestine
- Needed for healthy bones and teeth
Deficiency in vitamin d
Rickets / osteomalacia - weak deformed bones that break easily
Name two minerals plants need, why and where they get it
magnesium- salts in the soil, helps form chlorophyll
calcium - salts in the soil, holds cell walls together
Name two minerals animals need, why and where they get it
Iron- liver, meat, green veg, helps form haemoglobin
Calcium- milk, cheese Dairy, Helps form bones and teeth
5 reasons why water is important
- Component of cytoplasm, tissue fluid and blood plasma
- good slovent, allows chemical reactions to take place and transports materials.
- Participates in chemical reactions
4.Moves in and out of cells to give them the correct shape
- A good absorber of heat, provides a stable temperature for living things and their reactions
Anabolic reaction
Uses energy to convert smaller molecules to larger molecules
eg. formation of muscle from amino acids
photosynthesis - cellulose made from co2 and glucose
Catabolic reactions
Releases energy whe a larger molecule is broken down into smaller ones
