Chapter 2- The chemical composition of cells
Cell Environments
All cells exist in a very watery environment. Eg blood, water etc
Extracellular fluid
• As the plasma
membrane is semipermeable the
extracellular fluid is
critical for all cells.
Intracellular fluid
The environment
within a cell.
External
environment
Internal environment
• Because multicellular
organisms are part of a larger
organisation they are able to
have an extra barrier against
the external environment.
• For unicellular
organisms the
extracellular fluid is
the extracellular
environment it lives in. • This creates an internal
environment that can be
• It can’t control the
controlled.
extracellular fluid, it
can only move to a
different environment.
• More or less independent of
external environment

Regulated so that cells can function at their optimum
levels
◦ Aspects regulated: -ion concentration
-temperature
-pH
-Nutrients, water and waste levels and removal
What happens when the above aspects are not regulated?
 Some of the major bodily systems are involved in
this regulation process:
• Respiration
• Digestion
• Circulation
Plants and Animals

Compounds are
organized into 2 types:
◦ Organic compounds –
These are complex
chemical compounds
which contain Carbon and
Hydrogen.
◦ Inorganic compoundsThese are all non-organic
compounds. e.g. water,
oxygen, nitrogen.
Water- most organisms are 7090% water
 Surface tension
 Heat capacity
 Cohesiveness
Oxygen and carbon dioxide
 Oxygen is needed for cells to release
energy from food molecules
 Carbon is the key molecule in
organic molecules.
Nitrogen
 Nitrogen is needed to make
proteins.
Minerals
 Are needed for the structural part of
cells, the body and in enzymes and
vitamins
Carbohydrates
 Important source of energy
 Made of carbon, hydrogen and oxygen
Lipids
 fats and oils important for energy stores and some structures.
Proteins
 Vital for all sorts of functions!
Nucleic Acid
 Genetic material for all organisms
Vitamins
 Required for normal functioning.


These are really big molecules that make up
99% of most organisms.
These are:




LIPIDS
CARBOHYDRATES
PROTEINS
NUCLEIC ACID

Biomacromolecules are made up of subunits;
meaning they are made of smaller parts that can be
broken down or built up. The smaller parts are
called subunits.
Why do you think they need to be built up or
broken down?

Lipids are made of a glycerol and 3 fatty acids

Carbohydrates are made of glucose chains

Proteins are made of amino acid chains

Nucleic acids are made of nucleotide chains
• The most
important
functions of
lipids
•Storage of
energy
• The plasma
membrane is
made up of
lipids.


Most lipids are made of fatty acids tails and
one glycerol.
Lipids can either be saturated or unsaturated.
Saturated Fats
Unsaturated fats
•Coconut oil
•Butter
•Beef
•Pork
•Cheese
•Olive oil
•Peanut oil
•Almonds
•Sunflower oil
•Corn oil
•Fish
•Mayonnaise
•Margarines


Special types of lipids, that
have a phosphate head and 2
fatty acid tails.
The phosphate head is
hydrophillic (water loving)
and the fatty acid tails are
hydrophobic (water hating)
• The plasma membrane
separates the cells
internal environment
from the external
environment.
•Controls the movement
of substances into and
out of the cell.
•The membrane that
surrounds cell organelles
controls the movement
of substances into and
out of different
organelles.
Lipids are
important
components of
membranes.
Lipids are the fluid
part of the
membrane.
Cholesterols give
flexibility when
cold and stability
when hot.

Fats are needed in our diet for the absorption
of many vitamins.

Proteins are made up of subunits called amino acids.
There are 20 different types of amino acids. Different
combinations can made different types of proteins.
CLASS
FUNCTION
Catalytic proteins
Catalytic proteins (enzymes) control and
regulate chemical reactions in the cell
Structural proteins
Proteins provide support and shape the cell.
They are components of many structures.
Mobility proteins
Proteins are involved in the movement of
cells.
Regulatory proteins
Proteins regulate the movement of substances
across the plasma membrane, act as signals
between cells, are components of the immune
response.
AA
AA
AA
AA
AA
AA
Keratin and Collogen

Catalasts- meaning they speed up chemical
reactions!
Enzymes break
things down or
build things up.
http://www.youtub
e.com/watch?v=CZ
D5xsOKres



These are made up of sugar chain. They can be 1
sugar – monosaccharide, 2 sugar- disaccharide or
longer – polysaccharide.
Carbohydrates are the biggest source of energy.
Cells break down carbs into glucose and use it to
make ATP.

The mitochondria is the site where
carbohydrates or glucose is used to make
ATP. It is the power supply of the cell.
WHAT IS THIS PROCESS CALLED?
TRANSPORTATION


Folded membranes and
tubules within the
cytoplasm.
2 kinds of endoplasmic
reticulum rough ER and
smooth ER.
▪ Rough ER is caused by the
ribosome being present on the
surface
Proteins produced by the ribosomes
enter the ER and are then transported
about the cell, they are finally
exported out of the cell.

Recieves protein products via the ER. Protein
products are modified and stored in this
structure before they are placed in vesicles for
transport to the plasma membrane and released
from the cell.



DNA and RNA
They are information
molecules. The hold
the instructions for
everything that is made
by an organism’s body.
The DNA is located in
the Nucleus of a
eukaryotic cell. Why?

Complete a DNA model.

Water is the main liquid in your body
because:
◦ It doesn’t boil at low temperatures or freeze at
higher temperatures.
◦ It keeps the temperature stable enough for
chemical reactions.
◦ It has a high surface tension meaning all the
molecules stick together this allows cells to hold
their shape by being filled up with water. Water is
INCOMPRESSIBLE!

Pigments in animal and plant cells provide
the colours in the world around us.
Chlorophyll
WHERE DOES THE ENERGY
COME FROM?



All cells use a form
of energy called ATP.
Adenosine
Triphosphate is
when this molecule
is fully loaded with
energy.
Adenosine
Diphosphate is when
it is not fully loaded
with energy.

ATP is made from glucose in a process called
CELLULAR RESPIRATION.
Glucose
Cellular respiration
ATP

Autotrophs make their own glucose from
sunlight. They undergo a process called
photosynthesis (some bacteria undergo
chemosynthesis instead).
Heterotrophs
get their
energy from
...
BOTH
Autotrophs
and Heterotrophs
must undergo
cellular respiration
to make ATP!
Aerobic respiration
Occurs in the
MITOCHONDRIA
Anaerobic respiration
LACTIC ACID STITCH

20 Questions! Chapter 1 and 2