The sum of all the biochemical reactions in the body = metabolism
-
Building blocks of life
4 most common elements→ Hydrogen, carbon, oxygen, nitrogen. Carbon is the most important as it can join together to
form long chains or ring structures, which can be thought of as the basic skeletons of organic molecules to which
groups of other atoms are attached.
Organic molecules always contain carbon ie proteins, lipids + carbohydrates.
Monosaccharides Organic bases Amino acids Fatty acids + glycerol
- ↓ ↓
~
Nucleotides
↓
Polysaccharides Nucleic acids Proteins Lipids
water The most important biochemical for 2 reasons. 1 major component of cells (50% - 90% of moss of cell is
water) 2 provides an environment for those organisms that live in water. It's a simple molecule but doesn't naturally
exist as a gas at normal earth temperature, as a molecule of water binds with other water molecules by hydrogen
bonding to form a liquid. t
t
a water molecule has no overall charge but
Oxygen atom tends to pull e away from the
-
Oxygen
nucleus of the Hydrogen atom = a polar molecule.
L +
-
7
Hydrogen bond
L The hydrogen bonding makes the water molecules more difficult to
Hydrogen
t separate and affects the physical properties of water eg. more
-
energy is needed to break these bonds and convert water from a
liquid to a gas than in similar compounds
t
t
Water as a solvent
1. Most of a cell's reactions take place in an aqueous solution.
2. Acts as a transport medium in living organisms
3. Excellent solvent for ionic compounds eg. NaCl, Organic molecules that have charged groups e.g. glucose, AA,
glycerol and FA, and polar molecules, because the water molecules are attracted to them, collect around and
separate them. This is what happens when a chemical dissolves in water.
hydrophilic - water loving molecules e.g. giucose, AA
hydrophobic - water hating molecules e.g. - lipids
Once a chemical is in solution it is free to move about and react with other chemicals. Most processes in living
organisms take place in solution this way.
Non-polar molecules e.g. lipids are insolubie in water and if surrounded by water, tend to be pushed together by
the water since the water molecules are attracted to each other. This is important e.g. in hydrophobic
interactions in protein structures and in membrane structures and it increases the stability of these structures.
, Inorganic ions - many are highly soluble in water
Calcium - Ca ''
2t
Calcium phosphate is an important structural component of bones and teeth. Ca are impt. in transmission of
2t
electrical impulses across synapses and in contraction of muscles. Plants use calcium Pectate as a major
component of the middle lamella. If absent, the plants will have stunted growth. It's essential for blood
clotting.
Magnesium - Mg
27
Mg 2t are contained in Chlorophyll These molecules absorb light. If a plant is lacking in Mg it will have a yellow
appearance. Some enzymes that catalyse the breakdown of ATP called ATPases, have Mg at their active sites.
Potassium - K t
K are involved in maintaining nerve impulses across neurones. They contribute to the control of turgidity of guard
t
cells and therefore opening and closing of Stomata
Head
Nitrate - NO3 Found in cell membranes
Plants use the nitrogen from nitrate ions to make AA, nucleotides and chlorophyll Tails
Phosphate - PO
3-
4
Phosphate ions are used for making nucleotides including ATP (adenosine triphosphate). With calcium they form
calcium phosphate that gives bones their strength. The phosphate group makes up the hydrophilic head of a
water Tike
phospholipid which is an important component of cell membranes
Iron - Fe non-protein
2t
Haemoglobin molecules contain iron in their prosthetic haem groups. Oxygen binds here for transport in RBCs. Fe
2t
Is an important constituent of electron carriers in respiration.
Osmotic and Buffering Systems
• Are chemicals or substances that resist changes in pH and ensures that a particular environment maintains a
particular pH
Buffers are often used in experiments involving enzymes, because enzyme's specific 3D shape is affected by
changes in pH. Different enzymes have different optimum pH. So buffer help regulate the solution to ensure
the enzymes are operating at their optimum pH.
, Carbohydrates
Contain the elements carbon nitrogen and Oxygen -
Hydrogen and oxygen are present in the ratio 2;1
General formula is C (H O)y x2
Divided into 3 main groups, monosaccharides, disaccharides and polysaccharides
Single double many
Monosaccharides E.g.
Single sugars
-> mono 1 - -
=
3C= triose e.g. gycoraldehyde. Names of sugars all
Dissolve easily to form Sweet solutions 5C= pentose e.g. ribose, deoxyribose end in ose
General formula (CHZ 0)n 6C = hexase e.g. fructose, glucose
Consist of a single sugar molecule
Classified according to number of carbon atoms
Ring Structures
Important feature of pentoses and hexoses is that the chain of carbon atoms is long enough to close up on itself and
form a more stable ring structure.
In glucose the carbon 1 C1 and Carbon 5 C5 join to form a ring (removal of water) but carbon 6 C6 is not part of
the ring.
The Hydroxyl group (OH) may be above or below the ring on carbon 1 C1
When it is below the plane of the ring it is called a glucose (alpha glucose)
When it is above it is called the B glucose (beta glucose).
Two structural forms of the same chemical (same molecular formula) are known as Isomers e.g. glucose and
fructose.
Glucose =C6126
H O
alpha glucose - detailed structural formula alpha glucose - simplified
CH2OH
6 CH2OH
It O It O
Cs H H
H
Cu C
H
OH
HO OH HO OH
C
i
-
9
OH
OH =
hydroxyl -
different group
beta glucose B positions !! Fructose
CH2OH CH2OH
8 CHOH
H L OH
.
G
H8 It
It OH
-
Building blocks of life
4 most common elements→ Hydrogen, carbon, oxygen, nitrogen. Carbon is the most important as it can join together to
form long chains or ring structures, which can be thought of as the basic skeletons of organic molecules to which
groups of other atoms are attached.
Organic molecules always contain carbon ie proteins, lipids + carbohydrates.
Monosaccharides Organic bases Amino acids Fatty acids + glycerol
- ↓ ↓
~
Nucleotides
↓
Polysaccharides Nucleic acids Proteins Lipids
water The most important biochemical for 2 reasons. 1 major component of cells (50% - 90% of moss of cell is
water) 2 provides an environment for those organisms that live in water. It's a simple molecule but doesn't naturally
exist as a gas at normal earth temperature, as a molecule of water binds with other water molecules by hydrogen
bonding to form a liquid. t
t
a water molecule has no overall charge but
Oxygen atom tends to pull e away from the
-
Oxygen
nucleus of the Hydrogen atom = a polar molecule.
L +
-
7
Hydrogen bond
L The hydrogen bonding makes the water molecules more difficult to
Hydrogen
t separate and affects the physical properties of water eg. more
-
energy is needed to break these bonds and convert water from a
liquid to a gas than in similar compounds
t
t
Water as a solvent
1. Most of a cell's reactions take place in an aqueous solution.
2. Acts as a transport medium in living organisms
3. Excellent solvent for ionic compounds eg. NaCl, Organic molecules that have charged groups e.g. glucose, AA,
glycerol and FA, and polar molecules, because the water molecules are attracted to them, collect around and
separate them. This is what happens when a chemical dissolves in water.
hydrophilic - water loving molecules e.g. giucose, AA
hydrophobic - water hating molecules e.g. - lipids
Once a chemical is in solution it is free to move about and react with other chemicals. Most processes in living
organisms take place in solution this way.
Non-polar molecules e.g. lipids are insolubie in water and if surrounded by water, tend to be pushed together by
the water since the water molecules are attracted to each other. This is important e.g. in hydrophobic
interactions in protein structures and in membrane structures and it increases the stability of these structures.
, Inorganic ions - many are highly soluble in water
Calcium - Ca ''
2t
Calcium phosphate is an important structural component of bones and teeth. Ca are impt. in transmission of
2t
electrical impulses across synapses and in contraction of muscles. Plants use calcium Pectate as a major
component of the middle lamella. If absent, the plants will have stunted growth. It's essential for blood
clotting.
Magnesium - Mg
27
Mg 2t are contained in Chlorophyll These molecules absorb light. If a plant is lacking in Mg it will have a yellow
appearance. Some enzymes that catalyse the breakdown of ATP called ATPases, have Mg at their active sites.
Potassium - K t
K are involved in maintaining nerve impulses across neurones. They contribute to the control of turgidity of guard
t
cells and therefore opening and closing of Stomata
Head
Nitrate - NO3 Found in cell membranes
Plants use the nitrogen from nitrate ions to make AA, nucleotides and chlorophyll Tails
Phosphate - PO
3-
4
Phosphate ions are used for making nucleotides including ATP (adenosine triphosphate). With calcium they form
calcium phosphate that gives bones their strength. The phosphate group makes up the hydrophilic head of a
water Tike
phospholipid which is an important component of cell membranes
Iron - Fe non-protein
2t
Haemoglobin molecules contain iron in their prosthetic haem groups. Oxygen binds here for transport in RBCs. Fe
2t
Is an important constituent of electron carriers in respiration.
Osmotic and Buffering Systems
• Are chemicals or substances that resist changes in pH and ensures that a particular environment maintains a
particular pH
Buffers are often used in experiments involving enzymes, because enzyme's specific 3D shape is affected by
changes in pH. Different enzymes have different optimum pH. So buffer help regulate the solution to ensure
the enzymes are operating at their optimum pH.
, Carbohydrates
Contain the elements carbon nitrogen and Oxygen -
Hydrogen and oxygen are present in the ratio 2;1
General formula is C (H O)y x2
Divided into 3 main groups, monosaccharides, disaccharides and polysaccharides
Single double many
Monosaccharides E.g.
Single sugars
-> mono 1 - -
=
3C= triose e.g. gycoraldehyde. Names of sugars all
Dissolve easily to form Sweet solutions 5C= pentose e.g. ribose, deoxyribose end in ose
General formula (CHZ 0)n 6C = hexase e.g. fructose, glucose
Consist of a single sugar molecule
Classified according to number of carbon atoms
Ring Structures
Important feature of pentoses and hexoses is that the chain of carbon atoms is long enough to close up on itself and
form a more stable ring structure.
In glucose the carbon 1 C1 and Carbon 5 C5 join to form a ring (removal of water) but carbon 6 C6 is not part of
the ring.
The Hydroxyl group (OH) may be above or below the ring on carbon 1 C1
When it is below the plane of the ring it is called a glucose (alpha glucose)
When it is above it is called the B glucose (beta glucose).
Two structural forms of the same chemical (same molecular formula) are known as Isomers e.g. glucose and
fructose.
Glucose =C6126
H O
alpha glucose - detailed structural formula alpha glucose - simplified
CH2OH
6 CH2OH
It O It O
Cs H H
H
Cu C
H
OH
HO OH HO OH
C
i
-
9
OH
OH =
hydroxyl -
different group
beta glucose B positions !! Fructose
CH2OH CH2OH
8 CHOH
H L OH
.
G
H8 It
It OH
