Transcript File - King`s General Science

Carbohydrates
Carbohydrates contain the elements carbon, hydrogen
and oxygen. Come from plants in the form of sugar (glucose) and
starch (how plants store glucose).
Carbohydrates provide the main source of
energy for respiration in living organisms.
Sources:
•
Sugars: honey, jam, molasses, candy,
table sugar
•
Starch: breads, cereals, pasta, potatoes
Glucose C6H12O6
C
HO
C
HO
C
H
C
HO
C
H
C
C
C
H
C
OH
H
C
OH
C H2OH
A glucose molecule as a
straight chain
O
C
5 of the carbon atoms may
be arranged in a ring
This molecule is often represented
simply as a hexagon
Other carbohydrates
Glucose is a ‘simple’ sugar. Fructose (fruit sugar), maltose and
sucrose are more ‘complex’ sugars.
2 molecules of glucose can
join together to form a
molecule of maltose
maltose
Starch and cellulose are formed from
hundreds of glucose molecules joined to
form a long chain
one sugar molecule (glucose)
carbohydrate molecule
The body breaks down long chains of carbohydrates into the smaller sugar
molecules. These small sugar molecules are used by the body to release energy
and make the body work.
PROTEIN
Proteins
Proteins are made up of carbon, hydrogen and
oxygen molecules but with the addition of nitrogen
Most proteins are very large molecules, made up of hundreds of
amino acids.
Enzymes are proteins which carry out specific reactions in cells.
What are proteins?
Proteins, like carbohydrates, are made of long chains of small
molecules. In proteins, these small molecules are not
identical.
one amino acid
protein molecule
Proteins are made up of chains of small molecules called amino
acids. There are over 20 different kinds of amino acid.
Proteins are used by the body for growth and repair.
•
•
•
Builds and repairs muscles and cell tissues
Helps the body make important substances
Regulates body processes & supplies energy
Complete proteins:
• dairy products,
eggs, fish, meat and
poultry.
Incomplete proteins:
• beans, grains and
nuts.
Lipids
Lipids are fats and oils
They are made up from glycerol and fatty acids
Examples of fatty acids are stearic acid, oleic acid and
palmitic acid
H2 C
O
stearic acid
H
C
O
oleic acid
H2 C
O
palmitic acid
glycerol
fatty acids
A simple lipid
What are fats?
Fats are made up of fat molecules, which contain fatty acids
and glycerol.
fatty acids
glycerol
fat molecule
Fat molecules have to be broken down by the body so that
they can be used for energy storage.
Fats are also used by the body to keep heat in and to make
cell membranes.
Function
•
•
•
•
•
Supply energy
Carry fat-soluble vitamins
Insulate the body
Protect organs
Provide essential fatty
acids
Sources
Types of Fats
• Saturated: dairy products, meats, lard,
coconut and palm oils
• Unsaturated: fish, nuts, vegetable oils
Matching exercise- Connect the statements correctly!
Carbon
Hydrogen
oxygen
Protein
Carbon
Hydrogen
oxygen
nitrogen
Simple sugars e.g. glucose
Fat
Amino acid
Carbon
Hydrogen
oxygen
Carbohydrate
e.g.
Starch/cellulolse
Glycerol and fatty acid
9
Salts and water
In addition to proteins, carbohydrates and lipids, cytoplasm
contains salts and water
Water makes up the bulk of cytoplasm
All the chemical reactions in cytoplasm take place in
solution, i.e. in water
Water itself takes part in many of these chemical reactions
Salts of sodium, potassium and calcium and many others
play an important part in these reactions
Vitamins and minerals boost the immune system, support normal
growth and development, and help cells and organs do their jobs.
Nutrient
Functions
Sources
Vitamin D
Builds strong bones and teeth
Vitamin C
(ascorbic acid)
Helps wounds heal
Oranges, grapefruits, tangerines
(citrus fruits), cantaloupe, broccoli,
Helps fight infection
Helps promote healthy gums and tissues, tomatoes and raw cabbage
Promote absorption of iron
Nutrient
Functions
Egg yolk; fortified butter,
margarine, and milk; the sun
Sources
Calcium
Builds bones and teeth
Helps muscles and nerves work
Milk, yogurt, cheese, broccoli,
salmon, dark veggies, esp. leafy
greens
Iron
Combines with protein to make
hemoglobin. Helps cells use oxygen
Liver, spinach, raisins and
molasses
Water Function
•
•
•
•
Aids digestion and cell growth and
maintenance
Facilitates chemical reactions
Lubricates joints and cells
Regulates body temperature
Fibre (roughage)
• Complex carbohydrates that the body cannot break down.
These help clean out the digestive system. Most plants are
high in fibre eg fruits, vegetables, whole grains
Write each of the following nutrients in the appropriate space below:
carbohydrate, fat (lipid), fibre, minerals, protein, vitamins, water.
Nutrient
Use
Fat (Lipids)
To store and provide energy. Insulates the
body.
Protein
To grow new tissue, repair damage and
provide energy
Carbohydrates
Water
Minerals
Vitamins
Fibre
To provide a supply of energy. The two
main forms are sugar and starch
To carry things round the body and
replace lost water (hydrate)
To make healthy blood, bones and other
tissues
To take part in important chemical
reactions in your body
To keep the digestive system healthy
10
Enzymes Review
Enzymes are special proteins
They are present in the cytoplasm of all cells
They help to speed up the chemical reactions in the cell
There are hundreds of different enzymes but each enzyme
speeds up only one kind of reaction
For example, glucose and fructose might join up slowly to
form sucrose
glucose--fructose
With the right enzyme present, the reaction happens faster
glucose--fructose
24
ENZYME ACTION
1
glucose
molecules
E
1. A glucose molecule combines
with the active site on an enzyme
25
E
2 A region of the active site is still available
26
3 One end of a growing starch
molecule combines with the
glucose molecule at the active
site
E
part of starch
molecule
27
4 The growing starch molecule
breaks free from the enzyme which
is now free to repeat the reaction
E
28
Enzyme action
11
glucose
molecules
E
E
2
E
E
3
E
E
part of starch
molecule
4
29
Question 1
The correct formula for glucose is
(a) C12H22O11
(b) C5H10O5
(c) C4H8O4
(d) C6H12O6
30
Question 2
Which is the most accurate description of a carbohydrate?
A carbohydrate contains
(a) carbon and oxygen
(b) carbon, oxygen and nitrogen
(c) carbon, hydrogen and oxygen
(d) carbon and hydrogen
31
Question 3
When two molecules of glucose combine, they form
(a) maltose
(b) sucrose
(c) fructose
(d) ribose
32
Question 4
Which is the most accurate description of a protein
Proteins contain
(a) carbon, hydrogen and oxygen
(b) carbon, hydrogen, oxygen and nitrogen
(c) carbon, hydrogen and nitrogen
(d) carbon, nitrogen and oxygen
33
Question 5
Which statements are correct?
Proteins are present in
(a) cell membranes
(b) cell walls
(c) cytoplasm
(d) nucleus
34
Question 6
High temperatures damage proteins by
(a) decomposing them
(b) changing their chemical composition
(c) changing their shape
(d) making them soluble
35
Question 7
A protein is made up of a series of
(a) glucose units
(b) fatty acids
(c) amino acids
(d) carbohydrates
36
Question 8
Lipids are made up of
(a) glycerol and amino acids
(b) glycerol and fatty acids
(c) protein and fatty acids
(d) starch and fatty acids
37
Question 9
Enzymes are
(a) proteins
(b) lipids
(c) carbohydrates
(d) a combination of these
38
Question 10
An enzyme can
(a) change a reaction
(b) prevent a reaction
(c) slow down a reaction
(d) speed up a reaction
39
Question 11
A substrate is a substance which
(a) an enzyme acts on
(b) is produced by an enzyme reaction
(c) is a particular kind of enzyme
(d) is any chemical substance in a cell
40
Question 12
An enzyme can
(a) combine with different substrates
(b) form different kinds of end-product
(c) function at temperatures above 90oC
(d) speed up a reaction in the cytoplasm
41
Question 13
The part of an enzyme which combines with the substrate
is called
(a) the reaction centre
(b) the active site
(c) the action centre
(d) the reaction site
42
Question 14
After being exposed to a high temperature an enzyme
cannot function because
(a) it has been broken down
(b) its shape has been changed
(c) its composition has been changed
(d) it cannot separate from its substrate
43
ANSWER
Correct
44
ANSWER
Incorrect