Download Ch 1 - Composition of cells

Chemicals that make up
cells
Chemicals are made up of atoms
Everything that exists in the
universe is made up of tiny
particles called atoms
These atoms are so small that
they cannot even be seen
under the microscope
Atoms make up chemicals and
chemicals make up living
things
Atoms
Different
substances are
made up of
different types of
atoms
There are 92
different types of
naturally occurring
atoms, known as
elements
Elements
Nitrogen
Oxygen
Hydrogen
Carbon
Phosphorous
Elements Name
Symbol
Carbon
C
Hydrogen
H
Oxygen
O
Nitrogen
N
Sulfur
S
Sodium
Na
Potassium
K
Chlorine
Cl
Atoms
Chemical bonds
Atoms are able to combine and
link with one another to form
the vast array of chemical
compounds
These linkages between atoms
are called bonds
There are many different types
of chemical bonds
Chemical bonds
Ionic bonds
Occur between ions (+ or charged particles)
Eg. Salt (sodium
chloride Na+Cl-
Covalent
Very strong bonds which
occur when atoms share
electrons. Sometimes
electrons are shared
unequally producing polar
molecules
Eg the bonds
between O and H
in water.
Hydrogen
Weak attractions between
polar molecules that
contain H
Eg the bonds
between water
molecules
Hydrophobic
Weak attractions between
Eg interactions
hydrophobic molecules that between
are repelled by water
hydrophobic R
groups of AAs
Covalent Bonds
Electrons are
shared
between atoms
Very strong
bonds
Ionic Bonds
When an
electron leaves
an atom to
become part of
another
This forms
charges that
attract each
other (+,-)
These bonds are
weaker than
covalent bonds
Hydrogen Bonds
Weak bonds
between
slightly
positive
hydrogen
atom and the
negative
region of
another
molecule (only
between H and
N,O or F)
Organic Vs. Inorganic
Organic chemicals contain carbon and
hydrogen in them. They make up living
things
– Eg. proteins, carbohydrates, lipids, DNA
Inorganic chemicals do not contain
carbon and hydrogen
– Eg. Water, oxygen, carbon dioxide
Biological Compounds
Carbohydrates - CHO
In cells:
– usually stored in vacuoles as starch
– make up cell walls as cellulose
– Glucose is used by cells for cellular
respiration
Carbohydrates
Simple
Complex
Monosaccharides
Disaccharides
Polysaccharides
Contain a
single sugar
unit
Contain
two sugar
units
Contain
many
sugar units
Glucose
Sucrose
Starch
Carbohydrates
2 main types:
– Simple
Monosaccharide
Disaccharide
– Complex
Polysaccharide
Simple Carbohydrates
Monosaccharide – 1 unit of glucose
Glucose
Disaccharide – 2 units of glucose =
sucrose
Glucose
Glucose
Complex Carbohydrates
Polysaccharide – many units of
glucose. 2 examples are:
Glucose
Glucose
Glucose
Glucose
Storage
in plant
cells
Starch
Glycogen
Glucose
Glucose
Glucose
Glucose
Glucose
Storage
in
animal
cells
Complex Carbohydrate
Another example of complex carbohydrate is
cellulose.
Cellulose makes up plant cell walls.
Cellulose is a polysaccharide made up of
glucose also but the bonds that hold glucose
units together are of a different form than
starch or glycogen
The human digestive system does not
produce any enzymes that can break down
these bonds
Glucose
Glucose
Glucose
Glucose
Protein - CHON
In the cell protein can be found as
part of the cell membrane
Used for building eg. muscle
Protein is also found within the
cytosol in the form of enzymes
Protein
Made of Amino Acids (AA)
There are 20 different types of AA
Our bodies can only produce 11 of these
The rest we get from our diet. These are
called ‘essential’ amino acids.
Peptide bond
Amino acid
Amino Acids
The general structure of an amino is as
follows
R
H2N
Amino
Group
C
H
The ‘R’ group is the
part of the amino acid
that varies amongst
the 20 amino acids
COOH
Carboxyl
group
Amino Acids
When two amino acids come together,
a peptide bond is formed and water is
released
This reaction requires energy
Peptide
bond
R
H2N
C
H
COOH
CO
H2N
HN
R
C
H
COOH
Proteins
Proteins are very long polymers (more
than 50 amino acids long) that become
folded up to form 3D shapes
This folding occurs in a series of steps:
– Primary - 1˚
– Secondary - 2˚
– Tertiary - 3˚
Primary
structure refers
to the order of
amino acids
that make up
the chain
Tertiary
structure refers
to how the
helices and
pleats interact to
make the protein
fold in to a 3D
globular shape.
This is due to
many different
types of bonding
such as
covalent, ionic,
hydrogen and
hydrophobic
interactions
Secondary
structure refers
the folding of
the structure
into coils
(helix) or
pleated sheets.
This is caused
by hydrogen
bonds between
the amino
acids
Quaternary
structure refers
to the interaction
of one
polypeptide
chain with
another
Protein Roles
Structural
Enzymes
Contractile
Support tissue in skin
and other connective
tissue
Catalyse (speed up)
reactions
Keratin, collagen
Chlorophyll,
lipase, pepsin
Cause muscles to move Actin & myosin
Immunoglobulin defence against disease Antibodies
Hormones
Chemical messengers
Insulin, Thyroxin
Receptor
Detect
messages/changes in
environment
Insulin and
thyroxin
receptors
Transport
Carry other molecules
haemoglobin
Proteome
The total variety of proteins produced by
a single cell or organism in a particular
environment is called a proteome
The study of a proteome is called
proteomics
Studying the human proteome can help
to understand how cells function, how
diseases affect cell functioning and can
speed up the design of drugs
Lipids – Fat - CHO
Lipids are found in vacuoles of animals
cells as energy stores and in the cell
membrane
Lipids - Fats
G
l
y
c
e
r
o
l
Fatty Acid
Fatty Acid
Fatty Acid
This diagram
represents a type of fat
called a triglyceride
It is made up of a
glycerol and 3 fatty
acids
There are
approximately 20
different fatty acids
‘Water
loving’ Hydrophilic
Phosphat
e+
glycerol
Lipids - Fats
Fatty Acid
Fatty Acid
This diagram represents a type of
fat called a phospholipid
It is made up of a glycerol, 2 fatty
acids, and a phosphate group
These make up the majority of the
cell membrane
Fats usually don’t mix well with
water
Phospholipids are unusual in this
way
‘Water hating’ Hydrophobic