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PROTEINS
LIFE
IS AN
ORGANIZED
SYSTEM OF
COMPLEX
CHEMICAL
REACTIONS
THE FOUR MOST
IMPORTANT
MACROMOLECULES
IN A LIVING SYSTEM
ARE:
NUCLEIC ACIDS:
Such as DNA and RNA
Nucleic Acids store and
transfer chemical
information needed by the
cell.
CARBOHYDRATES
Such as
glucose and sucrose
Carbohydrates
provide the energy to
the cell to make ATP
Lipids
Lipids
Long–term Energy
storage molecules
and membranes
PROTEINS
Proteins control the
chemical activity of the
cell and provide the
structure of the cell
THERE MAY BE AS
MANY AS 60,000
DIFFERENT
PROTEINS IN THE
HUMAN BODY
Some proteins, such
as these collagen
fibers, give strength
to structures in the
body
This genetic
condition
involving
extra stretchy
collagen is
known as
EhlersDanlos
Syndrome
Hair is made of
the protein
keratin
The protein melanin gives skin the various
shades of color
The protein
hemoglobin is in red
blood cells and
transports oxygen to
the cells of the body.
Some hormones are
proteins, such as
insulin which
controls the uptake
of glucose by the cells
Beta cells produce the hormone insulin
and release it into the blood
Cells have insulin receptors
transmembrane proteins that
are activated by insulin to
allow glucose to move into the
cell by facilated difussion
If the cells of the pancreas do not
produce insulin, then the person
has diabetes and must take insulin
produced by other organisms
Other proteins
called antibodies
protect the body
from foreign
substances
Such as these
antibodies
attacking a virus
in the blood
Muscles are
mostly protien
Both of the muscle fibers,
actin and myosin, are proteins
Proteins in the cell membrane
allow substances to move into and
out of the cell
Perhaps the most
important
proteins in
organisms are
enzymes.
Enzymes are
proteins that
control the rate
chemical reactions
in the cell
Enzymes do not
cause a reaction
they make the
reaction easier to
happen
The enzyme amylase in
saliva breaks down
starches in the mouth
PROTEINS
All proteins are chains of
amino acids
Such as the protein insulin,
which is two strands of about
fifty amino acids in a chain.
There are about 20
different amino acids.
Proteins are different
because they have
different orders of
amino acids.
Amino acids
have the same
basic structure
but the side
chains are
different, giving
them different
chemical
properties
The
sidechains
of an
amino
acid is
referred
to as an
R-group
The R-group is in white.
Some R-groups are polar
Some polar groups have stronger positive
or stronger negative areas
The
primary
structure of
a protein is
the type
and order
of the
amino acids
Amino
acids are
linked
together by
peptide
bonds
Peptide
bonds are
another
example of
dehydration
synthesis
Short chains of amino acids
are termed Polypeptides
The
secondary
structure
of a
protein is
the folding
of the
amino
acid chain.
Tertiary
structure is the
actual folded
structure of the
protein
Primary structure is the
sequence of amino acids
The secondary is the
sheet and helix
structures that gives the
protein rigidity.
The tertiary structure is
the folding of the
protein to give it shape
The quaternary
structure is the final
shape of the protein
after it is assembled
with other polypeptides
The primary structure is the sequence of the
amino acids
Amino acids are connected by
covalent peptide bonds
SECONDARY
STRUCTURE
Alpha Helix
The alpha
helix
sections of
transmembrane
proteins
often form
the channel
in facilitated
transport
proteins,
such as this
glucose
transport
protein
Beta
sheets
give a
protein
rigidity
Cystine
bonds form
between the
sulfur
atoms in
the Rgroup of
the cystine
Disulfide bonds are
important in determining
the tertiary structure
Disulfide
bonds
form
where
the
amino
acid
cystine
are
brought
close
together
The difference
between curly and
straight hair is the
the number of
disulfide bonds
between cystine
amino acids in the
keratin protein
These two
proteins are
different
because they
have a
different
number and a
different order
of amino acids.
Some proteins have less
than 100 amino acids
Most
proteins
have
many
hundred
amino
acids
The shape
of the
enzyme
proteins are
essential for
their
proper
function.
A mistake in the hemoglobin protein can
cause a condition called sickle cell disease.
Sickle cell
disease is
caused by one
amino acid
difference in
the 150 amino
acids that make
up the
hemoglobin
molecule.
How do the
cells make
proteins
We eat proteins in
our food.
In the stomach and
the small intestines
digestive enzymes
break down the
proteins into
separate amino
acids.
In the small intestines the amino acids
are absorbed through the villi into the
blood vessels of the circulatory system.
The circulatory
system carries the
amino acids to all
parts of the body in
the serum of the
blood.
In the capillaries amino acids diffuse into the cells.
In the cytosol
the amino
acids attach to
specific
transfer-RNA
Each
type of
t-RNA
combines
with a
specific
amino
acid
• You have to eat 8 of the amino
acids, your body can make the rest.
These are called the essential
amino acids.
In the cytoplasm of the cells,
amino acids are assembled
into the correct
order
to make
the right
protein
RIBOSOME
PROTEIN
Ribosomes
are very
small
structures
in the
cytoplasm
of all cells
including
bacteria
Proteins are made on the ribosomes
DNA has the
information for
the correct
order of the
amino acids to
make a working
protein
Ribosomes
Messenger-RNA
carries the
information from
the DNA in the
nucleus to the
ribosomes in the
cytoplasm
DNA
The information is carried to the
ribosomes by RNA
RNA is an
exact copy of
the
information
for the
sequence of
the amino
acids to make
the protein
DNA is made of four
different bases
connecting the two
sides of the spiraling
sides.
The order of the four bases are the
code for the order of the amino acids
in the protein. The four bases are
adenine (A), guanine (G), thymine
(T) and cytosine (C).
RNA copies the order of the complimentary bases
from the DNA
Each three bases of DNA is the
code of one amino acid
DNA
makes
RNA.
RNA
takes code
out of
nucleus to
the
ribosome
• The process of making RNA from DNA is called
Transcription
Transcription begins when RNA
polymerase attaches to a region of
DNA called a promoter
The promoter defines the start of a
gene, the direction of transcription
and the strand to be transcribed
RNA
Polymerase
binds to the
promoter and
binds
complementary
bases until it
reaches a stop
sequence
The
primary
RNA
molecule is
modified
and
prepared to
leave the
nucleus.
• 1. A cap is added to tell the molecule where to attach
to the ribosome
• 2. The introns are removed by
enzymes called spliceosomes
3. The mature RNA leaves the nucleus
through a nuclear pore
Introns- Sections of “junk DNA”
The functions of introns is truly unknown
but the thoughts are:
-Allow RNA to be spliced together in
slightly different orders
-Regulate gene feedback
-Allow for complexity in organisms
without increasing the amount of
DNA
Once the RNA has left the nucleus it
is taken to the ribosomes
Ribosomes are made of Ribosomal
RNA (rRNA) with a variety of
proteins and are broken into two
subunits
rRNA provides a binding site for the
mRNA and the tRNA once binded the large
molecule is called a polyribosome
When the mRNA binds to rRNA translation
can occur
Translation occurs
in three steps:
• Initiation- The
start codon of
the mRNA binds
to the small
subunit of the
rRNA, the
initiator tRNA
binds along with
the large subunit
2. Elongation
3. TerminationWhen the rRNA
reaches a stop
codon, the
polypeptide is
released, and the
rRNA breaks into
its two subunits
As the protein is being made, the first
couple amino acids act as a tag to
determine where the protein will end up.
When the protein is released from the
ribosome if needed, it will be taken to
the ER and/or golgi for folding,
processing, tagging and packaging
Review of
RNA
• How many
types?
Functions?
• What does the R
mean?
• What nucleotides
make up RNA?
Sickle Cell Disease is caused by a single
mutation in the gene for the globin part of
the hemoglobin molecule.
A hemoglobin molecule is made of four globin
molecules.
A change of one
base in the DNA,
will change the
base in the RNA,
which may
change the amino
acid, which may
change the
protein.
If the globin
molecules in
the
hemoglobin
protein have
the
mutation,
the cell
becomes
sickle shape.
If only one
of the the
globin
molecules
has the
mutation,
the cell
appears
normal..
The sickle-cell hemoglobin changes
shape when the oxygen is not attached.
This change causes a change in the shape
of the red blood cell to a crescent shape.
Under low
oxygen
conditions
the cells
with
mutated
hemoglobin
become
sickle
shaped
Round,
normal red
blood cells
easily pass
through the
junctions of
the
capillaries
Sickle red blood cells tend to become
trapped at these junctions causing
swelling and sometimes life
threatening clots
Sickle cell disease
is a painful
conditions but many
individuals, such as
this professional
model, can lead
normal lives with
precautions.