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Topic Three Chemistry of Life
Unicellular organisms must perform all cellular functions at the cellular level.
Multicellular organism can differentiate or specialize and by doing this, there is a
division of labor. This allows the cell to form tissues organs and organ
systems.
A cells job is determined by its genetic make-up, its position in relation to others
and its chemical environment (stem cells ??)
Most common elements occurring in living things are; carbon, hydrogen, oxygen
and nitrogen.
C = 18.5% O = 65% H = 9.5% N = 3.5% Ca = 1.5% P = 1%
Other necessary elements are; sulfur, phosphorous, calcium, iron and sodium
Know functions; C, H, O makes up carbohydrates and lipids, C, H, O, N make up
Element Plants
Animals
Prokaryotes
S
Some amino acids/proteins and
vitamins
Bones, muscle fibers, blood
clotting, co-factor
ATP, bones
Electron transport molecule,
hemoglobin
Membrane function, nerves
Some amino acids/proteins
and vitamins
Co-factor
C
P
Fe
Na
Some amino acids/proteins
and vitamins
Cell wall, co-factor for
vitamins
ATP
Electron transport moleuces,
chlorophyll
Membrane function
ATP
Electron transport molecule
Membrane function
similarity between plants, animals and bacteria in that ATP is ATP, glucose is
glucose (universality of genetic code) also see page. 41 of text for specific
Atoms – neutral
Ions – charged particles
Acids, bases (alkaline), neutralize, pH scale (number gets larger)
Bromothymol blue is an acid indicator and is also a CO2 indicator???
CO2 + H2O  H2CO3 - carbonic acid is a buffer
H2CO3 ↔ HCO3 - + H+
Base
Million atoms can fill out a period
Person can only survive of a few minutes if pH drops below 7 or rises to
7.8. Blood is 7.4. pH – one number is 10 times greater than next. Ph is [H]
ion.
Water
Major molecule of the body, has unique properties
**Draw a label diagram showing polarity of water and hydrogen bond formation
and where it is specifically
Water has a slight –ve end, the O and a slight +ve end, the H. This gives it
charge separation or polarity. Water is a polar molecule. (like dissolves like).
Water’s –ve end is attracted to the +ve end of other, creating a hydrogen bond
between molecules – an intermolecular bond. The polarity with its hydrogen
bonds gives water unique properties. Some are;
1. Cohesion – attraction of like molecules. Water has high cohesion, which helps
explain transport up a tree.
2. Thermal properties – water stabilizes temperatures and can form a heat bank.
It takes a lot of heat to change its temperature – called specific heat capacity.
Large bodies of water take a lot of heat to heat up and resist change in
temperature. Evaporation cools the body of animals and plants.
Water’s specific heat capacity is 10 times greater than iron → so you can burn
your hand on a pot while the water inside the pot is still only warm.
3. Good solvent – dissolves many organics and inorganic molecules. Blood and
cytosol are mainly water. Allows ions dissolved in it to pass the bilipid
membrane. Because many things dissolve in it, is a good form of transport.
Most/to all reactions occur in water and metabolic rate would slow down without it
(particles can’t get to each other)
* Other properties
4. Transparency – allows water plants do photosynthesis
5. Solid less dense than liquid
Cotton is polar – adheres to water so does a good job of drying you off.
Organic compounds – contain carbon, covalently bonded but not CO2 or
carbonates and oxides of carbon, makes up living things
CO2 is most abundant carbon compound in world
Poly or polymer – many repeating units bonded together
Monomer or mono – one unit that is repeated
*Condensation – the process of connecting 2 or more monomers by a covalent
bond. Involves loss of water. Requires energy.
* Hydrolysis – breaking apart of polymers, uses water to break bonds
Show kids each holding a different ball, pull ball away and have them join
*Oxidize – to lose an electron or hydrogen
* reduce – to gain an electron or hydrogen LEO says GER
NH2 – Amino group COOH – carboxyl group –
Main Organic Compounds
1. Carbohydrates – soluble in water, made up of C, H and O in a certain ratio.
The monomer is called a saccharide. If only made up of one saccharide, called a
monosaccharide. Many types of monosaccharides – know glucose, galactose
and fructose all C6H12O6 but different isomers
Function – main form of energy in cellular respiration
Fructose – main energy molecule for plants
** be able to identify diagrams of glucose. Different forms.
Brain can only use glucose for energy, not fat so need breakfast as can’t
use stored energy.
**must be able to identify amino acids, glucose, ribose, and fatty acid –
also HL will have to draw amino acids. Always done in m.c. fatty acid is
the problem
Disaccharide – 2 monos joined by condensation, a covalent bond called
glycosidic linkage. Eg. Sucrose  glucose + fructose
Maltose  glucose + glucose
Lactose  glucose + galactose
Sucrose – plants transport carbohydrates from leaves to roots in this form.
Lactose – milk sugar **lactose intolerant
Polysaccharide (macromolecule) – many monomers, function is storage of
energy and building materials for cells. Three types
a) starch – storage for plants, made up of glucose monomers is bulky but
plants don’t move, is a carbohydrate bank, can draw out when needed
b) glycogen – storage for animals, glucose monomers, hydrolysis of glycogen
releases glucose for energy, not very soluble, stored in liver and muscle cells
glycogen bank depleted in one day
c) cellulose – structural use for cell walls, is held together by hydrogen bonds and
linked by microfibrils, not soluble, strong links, tend to form parallel structures like
cables for strength – would require different enzymes. we don’t have enzymes
to break the bonds. But cows have bacteria in stomach that can
All three macromolecules are chemically similar but structural different – different
isomers
Another polysaccharide is chitin found in arthropods used to make
exoskeleton and surgical thread, strong but will decompose.
*relate above with condensation and hydrolysis, equations – see Allott
2. Lipids – hydrophobic, contains C, H, O but in different ratio than carbs, not
soluble. Three types; **drawing was hard
a) fats – large molecules but not polymers, made up of glycerol and fatty acids.
Three fatty acids are attached to glycerol by condensation. Absorbed into
lacteals first then into blood stream.
***recognize fatty acid by diagrams showing structure, very hard, see Allott
Also called triglyceride or triacylglycerol – three acids to a glycerol
There are two types of fats
i) saturated – no double bonds in fatty acid, has more hydrogens because of
single bonds, animal fat, solid at room temperature, harder to digest, requires
cholesterol, animals store their fat in adipose cells
ii) unsaturated – has one or more double bonds, plant fats or oils, liquid at room
temperature, easier to digest, less hydrogens hydrogenated oils have had
double bonds removed
Function is for energy storage, fats yield twice as much energy as carbs, also
cushions and insulate organs.
1 g of carbs = 17 kJ while fat gives 39 kJ, is more compact so easier to
carry around, fats have long hydrocarbon tails with hydrocarbon bonds –
just like petroleum and can store a lot of energy – and not soluble in water
When fats are metabolized for energy, it releases a lot more water than if
you use glucose. Desert camels can live off that water when they use the
fat in their hump.
*condensation and hydrolysis equations with words or formulas
b. phospholipids – only two fatty acids and other is replaced by phosphate group
c. steroids – has four fatty acids, form a ring. Cholesterol is a type of steroid
need for cell membrane and precursor of sex hormones. Cholesterol is also
needed to emulsify fats (found in bile) Cholesterol is carried through the blood by
two types of molecules; low density and high density lipoproteins. LDL and HDL.
LDL takes cholesterol to arteries and lines the walls with it to form plaque. This
can lead to atherosclerosis or hardening of the arteries. HDL take cholesterol to
the liver to be excreted and helps clean out the arteries . Saturated fats stimulate
LDL and inhibit HDL. Unsaturated stimulate HDL and excrete cholesterol.
Carbohydrates are the main form of energy and are stored as lipids.
Anabolic steroids are tissue builders, a version of the male hormone
testosterone. Males will turn excess into estrogen  breasts testes
reduce, aggression; women  infertile, menstrual cycle stops.
3. Proteins – made up of C, H, O, N, S. Are large molecules made up of the
same 20 amino acids, but in various combinations - yielding a lot of different
types of proteins. Amino acids are made up of an amino group (NH2) and a
carboxyl or organic acid group (COOH). These groups are attached to the same
carbon, also attached is a molecule called the ‘R group’ (which makes the amino
acids different and will determine whether it is polar or not)
Polymers of amino acids called a polypeptide. The bond that joins the amino
acids is called a peptide or dipeptide bond. A covalent bond. Polypeptides are
not proteins yet – just like one strand of wool is not a sweater but the terms
are used interchangeable – generally, if the polypeptide has more than 50
amino acids we will call it a protein (when do we call you an adult???)
More than 50% of the dry weight of cells is protein, have tens of thousands
of proteins all doing different jobs.
*Be able to identify an amino acid and outline how condensation and hydrolysis
are involved. HL must be able to draw – comes in DNA and know where peptide
bond is.
Proteins are affected by pH, [salt], and temperature. At high temperatures, over
45°C, disrupts hydrogen bonds, starts to unravel and lose configuration.
Denatured – breaking of weak intramoleular bonds, affecting the shape. Proteins
have optimum temperatures.
H.L only
Many functions – don’t use membrane proteins
1. structural support – collagen, tendons, ligaments
2. transport of substances – hemoglobin
3. make up some hormones – insulin
4. receptor for hormones and other chemicals
5. defense of the body – antibodies
6. contractions of muscles – actin and myosin
7. enzymes for catalyzing reactions –
A protein is usually made up of many polypeptides twisted together. How it is
physically made up and twisted together determines its function.
There are four levels of structure that a protein can have
1. primary structure– all have, is the unique amino acid sequence, is determined
by genetic code and will determine everything else – ie its structure and function.
2. secondary structure – polypeptide chains start to coil or fold. This causes
hydrogen bonds to form between. The pattern it makes determines its function.
Two main patterns are helix and pleated. Helix – hair, feather, fur, structural.
Pleated – antibodies, silk *Note where the hydrogen bonds are**
3. tertiary – the 3-D conformation, some proteins further refine or twist their
polypeptides into more shapes. This irregular bending causes the ends to get
close together and form extra bonds – ionic and disulfide bonds plus more
hydrogen. Gives more strength.
4. quaternary – going even further for some proteins, made up of more than one
polypeptide string. A prosthetic group (helper molecule) is included to enable all
the parts to function together. These large proteins have a lot of twists and turns,
allowing for more bonds and more strength. Not all proteins go to this level.
In the tertiary structure, proteins can take up two different shapes – form =
function. They are; globular and fibrous.
(i)Globular proteins – the proteins found in the cell membrane, have a pleated
secondary structure but the tertiary structure is more important to them. Easily
soluble. Enzymes are globular with tertiary structure to give it many active sites
and many shapes for substrates. Antibodies, insulin
(ii)Fibrous proteins have helix secondary structure and this secondary structure is
most important to them, are more structural proteins. Insoluble in water,
physically tough. Hair, fur, collagen, myosin in muscle fiber
* The physical and chemical properties of the R side chain determine the unique
characteristics of the amino acid and thereby the proteins. You have both polar
and non-polar amino acids.
Polar amino acids are hydrophilic, soluble in water, can make hydrogen bonds,
found in the hydrophilic part of the cell membrane and on the surface of watersoluble proteins. They are polar and therefore hydrophilic – they are not
hydrophilic amino acids
Non-polar are hydrophobic, not soluble in water, form VanderWaals, found in
interior of membrane and interior of water-soluble proteins.
Some big globular proteins can be both polar and non-polar like the integral
membrane proteins
See diagram of cell membrane and where the polar and non- polar are.
Polar amino acids needed to enter the membrane?
4. Nucleotides and nucleic acids
Nucleotides consist of a nitrogen base, a 5-carbon sugar and one or more
phosphates. .
Functions
a) ATP is a nucleotide
b) combine to form co-enzymes
c) signaling molecules
d) are the building blocks of DNA and RNA
Nucleic acids are polymers of the monomer nucleic acid
DNA is not directly involved in running the cell, just like software can not
do anything by itself, its needs a printer. Proteins are like the printer of the
cell.
***Know shape of ribose – one of the 5-carbon sugars.