THE END!
*On Slide:Peptides to Proteins. Lesson 2
Voice:Peptides to Proteins. Lesson 2
*On Slide:PRESENTING.The World of PROTEINSWhat are proteins?Why
are proteins important?How are proteins made?How do proteins
fold?
Voice:The purpose of this lesson is to introduce The World of
Proteins. We will begin by learning What are proteins. Then we will
discuss protein formation and structure. So lets begin!*On
Slide:What are PROTEINS?Proteins are large, complex molecules that
serve diverse functional and structural roles within cells.
Voice:We know from our everyday lives that proteins are
necessary component of our diet. We need proteins to keep our
immune systems healthy, grow fabulous hair, bulging muscles, and
much more. Great source of protein include beans, meat, and diary
products. But exactly what are proteins? Proteins are large
biological molecules that serve diverse functional and structural
roles within the cell. *On Slide: Proteins are the ACTION FORCE in
the cell.
Voice:In cells, proteins are the biological action force that
completes vital functions. They do most of the work in cells and
are required for the structure, function, and regulation of the
cell.*On Slide:Proteins can be functionally classified.
Voice:Proteins can be classified according to a wide range of
functions in the cell. For examples, antibodies act in defense of
the cell. They bind to specific foreign molecules, such as viruses
and bacteria, to help protect the cell. Enzymes perform thousands
of chemical reactions. Regulator proteins control biological
processes within cells, tissues, and organs. Many proteins, like
keratin and actin, provide structure, support, and range of motion.
Transport and storage proteins, like hemoglobin, bind and carry
atoms and small molecules within cells and throughout the body.
*On Slide:How are Proteins Made?
Voice:To carry out all of these functions, proteins must be
synthesized and folded correctly. But, how are proteins made and
folded?*On Slide:Proteins are chains of amino acids.Short chains of
amino acids are called peptides.Proteins are polypeptide molecules
that contain many peptide subunits.
Voice:Proteins are large molecules made up of several building
blocks called amino acids. Short chains of amino acids are called
peptides. Proteins are made of many peptide subunits and are often
called polypeptide molecules. *On Slide:Amino acids have an amino
group, carboxyl group, R group and hydrogen.
Voice:Each amino acid contains an amino group, a carboxyl group,
hydrogen, and a R group all bound to a central carbon atom. *On
Slide:Each amino acid has unique chemical properties.
Voice:Each amino acid has a R group. The R group provides the
amino acid with unique chemical properties. *On Slide: Peptide
bonds form by dehydration synthesis.
Voice:To form a covalent link between amino acids, the carboxyl
group of amino acid 1 and the amino group of amino acid 2 must
undergo dehydration synthesis. Dehydration synthesis links the
amino acids and produces a molecule of water. *On Slide:
Voice:The covalent link between amino acids is called a peptide
bond. *On Slide:Translation is the synthesis of proteins in the
cell.
Voice:In the cell, proteins are synthesized during a process
called translation. There are 3 major steps in translation. In step
1, the small ribosomal subunit binds the mRNA sequence and is
joined by the large subunit. After ribosome formation, the
initiator transfer RNA or tRNA is bound to the amino acid
Methionine. The codon AUG codes for the Methionine amino acid tRNA
complex. This complex binds to the first site within the ribosome.
In the elongation step, tRNA with bound amino acids, here Alanine,
binds with next codon. The Methionine is covalently linked to
Alanine by a peptide bond. Then the ribosome moves one codon
downstream and the initiator tRNA is released. The elongation step
continues and Tryptophan is added to the amino acid chain. Once the
elongation step is completed, the termination step begins. In the
termination step, the ribosome reaches a stop codon which does not
encode a tRNA. During this step the protein chain is released. *On
Slide: How do Proteins Fold Voice?
Voice:We now have a complete amino acid chain. But how does it
fold?*On Slide:There are 4 basic Levels of Protein Structure
Voice:Proteins consist of a long amino acid chain folded into
complex shapes. Protein structure can be viewed at four levels:
primary, secondary, tertiary, and quaternary.*On Slide:The Primary
Structure is the sequence of amino acids.
Voice:The amino acid sequence of protein encodes its primary
structure. The primary structure is the linear chain of amino
acids. *On Slide:The secondary structure is primarily composed of
alpha helices and beta-pleated sheets.
Voice:Bonds may form between nearby amino acids within the
primary structure. The bonds may produce folds and coils. These
coils are called alpha helices. The folds are called beta pleated
sheets. The secondary structure is primarily composed of alpha
helices and beta-pleated sheets.*On Slide:The tertiary structure is
the proteins 3D shape.
Voice:The alpha helices and beta-pleated sheets fold together to
form a 3D shape or the tertiary structure.*On Slide:The quaternary
structure is the assembly of folded subunits.
Voice:Many tertiary structures or folded subunits may assemble
into a single cluster. These clusters are called quaternary
structure. *On Slide:Proteins must reach their final shape to
perform their functions.
Voice:It is important to remember that protein must fold
properly in order to perform their functions. Improperly folded
proteins may cause serious slow downs or ceases of functions. These
alterations in function may even cause diseases, such as Alzheimers
or Mad Cow Disease. Again, proteins are the workhorse of the cell
and perform many vital functions.*On Slide:SummaryProteins are
biological workhorses that carry out most of the functions within
the cell. Proteins are large biological molecules that serve
diverse functional and structural roles within cells. Proteins are
synthesized during the translation process.
Voice:Proteins are large biological molecules that serve diverse
functional and structural roles in the cell. They are biological
workhorses and carry out most of the cellular functions. Proteins
are synthesized during translation where amino acids are linked by
peptide bonds. *On Slide:Summary contdProteins are composed of
amino acids that are covalently linked by peptide bonds. Proteins
have four basic levels of structure. However, proteins fold
correctly in order to function properly.
Voice:These protein chains have four levels of structure.
However, proteins much form their correct structures in order to
function properly.*On Slide:THE END!Proceed to Lesson 3
Voice:Please proceed to Lesson 3.
