CHAPTER 8 - Protein functions and structure. Flashcards
What are the 6 roles that proteins play in living cells?
- Enzymes
- Movement
- Transport
- Signalling
- Defense
- Structure
What role do protiens play in enzymes?
Enzymes catalyze chemical reactions.
1) Enzymes can be secreted by cells (e.g. chief cells add pepsin into your stomach)
2) attached to a plasma membrane (e.g. lactase on your small intestine microvilli cells),
3) floating inside the cytosol (e.g. hexokinase for step 1 of glycolysis),
4) held within a lysosome (many digestive enzymes), etc.
What role do protiens play in Movement?
Movement: motor proteins use energy (e.g. from ATP) to produce movement
1) kinesin and dynein drag vesicles along microtubules in opposite directions
2) myosin produces muscle contraction by pulling along actin filaments
TRUE OR FALSE
a single missense mutation (single amino acid change) can make kinesin move vesicles in the wrong direction.
TRUE
What role do protiens play in Transport?
Transport: e.g. membrane channels & transport proteins/pumps for facilitated diffusion and active transport.
What role do protiens play in Signalling?
Signalling: e.g. between cells via direct contact or signalling molecules
What role do protiens play in Defence?
Defence:
- receptors and antibodies that recognize and bind to foreign molecules and cells to inactivate and/or destroy them as part of our body’s immune response.
What role do protiens play in Structure?
Structure:
- The microtubules (e.g. spindle fibres) & microfilaments of a cell’s internal cytoskeleton, the proteins in the complex extra-cellular matrix found outside the cell, and the membrane-bound proteins that these fibres are anchored to.
Describe at least one way in which carbohydrates, nucleic acids, and lipids are each necessary for making this cell recognition possible.
Carbohydrates:
-The red blood cell’s glycoproteins include oligosaccharides (polymers of a few sugars) that are important markers recognized by the WBC’s receptor protein. OR
-Glucose provides energy for synthesizing the receptor protein.
Nucleic acids:
-DNA holds the genetic info. Needed for synthesizing the receptor protein. OR
-mRNA must be translated to synthesize the receptor protein.
Lipids:
-The phospholipids bilayer of the rough ER is needed for these transmembrane proteins to fold correctly.
-Without phospholipids to make membranes, there would be no Golgi apparatus to join sugars and proteins to make a glycoprotein.
What are 3 components that Amino acids are comprised of.
-It has carbon in the middle, called ⍺ carbon.
-It has an Amine group (NH2) at its N-terminus end.
-It has a carboxyl group (COOH) at its C-terminus end.
What is the real name for Amino Acids?
⍺-amino carboxylic acid,
What makes each of the amino acids?
Different unique side chains or R groups which are attached to the side of the alpha carbon.
Do polypeptides have directionality?
Yes, they are always synthesized from the N-terminus to
the C-terminus (i.e. new amino acids are always added to the C-terminus)
During what does each amino acid get added to a growing polypeptide chain?
During translation, each amino acid is added to the growing polypeptide chain with a peptide bond (a covalent bond between amino acids), forming a repeating backbone of N-C-C-N-C-C-…, with the specific R groups sticking out the sides of the backbone.
What are the 4 types of amino acids?
1) NON-POLAR
2) POLAR
3) (+) CHARGE
4) (-) CHARGE
