biol235 Flashcards
What are the 2 classes of proteins?
Fibrous and globular
What’s a colloid?
Solute particles are big enough to scatter light (translucent or opaque)
What are fibrous proteins?
Insoluble, polypeptide chains are lone and parallel. Collagen (strenghtens bones, ligaments and tendons), elastin (stretches skin, blood vessels, lung tissue), keratin (forms structure of hair and nails, waterproofs), dystrophin (reinforces parts of muscle cells), fibrin, (forms blood clots) actin and myosin (contractions of muscles, division in cells, and trnsport of substances within cells)
What are globular proteins?
Soluble, polypeptide chains are spherical, metabolic functions. Enzymes, antibodies and complement proteins, hemoglobin (trnsports O), lipoproteins (transports lipids and cholesterol), albumins (help regulate blood pH), membrane proteins (transports substances out of cells)
What are nucleic acids?
Huge organic molecules that contain C, O, H, N, and P.
What’s a tertiary structure in a protein?
3D shape of a polypeptide chain. Unique structure determines how it will function. Folding pattern is determined by disulfide bridges (form between the sulfhydryl groups of 2 monomers of amino acid cysteine) and weak bonds like H bonds, ionic bonds, and hydrophobic interactions.
What are nucleotides?
The monomers that repeat in the nucleic acid chain. Each nucleotide has 2 parts: Nitrogenous base, pentose sugar, and phosphate group
What is the nitrogenous base part of a nucleotide?
All contain C, H, O and N. Adenosine (A), thymine (T), cytosine (C) and Guanine (G). A and G are large and called purines. T and C are small and called pyrimidines.
What is the pentose sugar part of a nucleotide?
A 5 carbon sugar called deoxyribose attaches to each DNA base
What are the 2 phases of cellular respiration?
1) Anaerobic phase: Reactions that don’t require O, glucose is partially broken down by a series of catabolic reactions into pyruvic acid. Each glucose molecule converted into pyruvic acid molecule yeilds 2 molecules of ATP. 2) Aerobic phase: in presence of O, glucose is completely broken down into CO2 and water. Generates heat and 30-32 ATP molecules.
Describe the basic structure of the lipid bilayer
2 back-to-back layers made up of 3 types of lipid molecules: Phospholipids (75%… contains phosphorus), cholesterol (20%… steriod with attached OH group) and glycolipids (5%… attahched carbohydrate group)
How do phospholipids orient themselves in the lipid bilayer?
Their hydrophilic heads face outward… the heads face a watery fluid on either side (cytosol on the inside and EC fluid on the outside). Hydrophobic fatty acid tails in each half of the bilayer point toward one another forming a nonpolar hydrophobic region in the membrane’s interior
What are integral proteins?
Extended into or through the lipid bilayer and firmly embedded in it. Most are transmembrane proteins so extend the entire width of the bilayer and portrude into both the cytosol and the EC fluid. Example are glycoproteins (proteins with carbohydrate groups attached to the ends that protrude into the EC fluid. The carbohydrates are oligosaccharides)
What is peripheral proteins?
Not as firmly embedded in the membrane. Attached to the polar heads of membrane lipids or integral proteins at the inner or outer surface of the membrane.
What is Glycocalyx?
Carbohydrate portions of glycolipids and glycoproteins that form an extensive sugary glyccalyx. Enables cells to recognize one another (ie WBCs ability to detect a foreign glycocalyx).
What’s a main function of glycoproteins and glycolipids?
Serve as identity markers. May enable a cell to 1) recognize other cells of the same kind during tissue formation and 2) Recognize and respond to foreign dangerous cells. Eg blood cells must be compatible or RBCs will clump together.
What does membrane fluidity depend on?
The number of double bonds in the fatty acid tails of the lipids in the bilayer. Each double bond puts a kink in the fatty acid tail which increases membrane fluidity by preventing lipid molecules from packing together
How does cholesterol’s affect on the lipid bilayer vary based on temperature?
Makes lipid bilayer stronger (and less fluidity) at normal temperature and weaker (and more fluidity) at lower temperature
What is selective permeability?
The plasma membrane allows some substances t pass more readily than others. Nonpolar molecules (CO2, O2, steriods) are highly permeable, moderately permeable to small uncharged polar molecules (water and urea) and impermeable to large uncharged polar molecules (like glucose). Transmembrane proteins that act as channels and carriers can increase the plasma membrane’s permeability to a variety of selective ions and uncharged polar molecules.
What are endocytosis and exocytosis?
They are active processes using the vesicles. In endocytosis, vesicles detach from the plasma membrane while bringing materials into a cell0. In exocytosis vesicles merge with the plasma membrane to release materials from the cell.
What is facilitated diffusion?
An integral membrane protein (either a membrane channel or carrier) assists a specific substance across a membrane. Usually solutes that are too polar or highly charged
What are the 2 ways in which water passes through a plasma membrane?
1) By moving between neighbouring phospholipids in the lipid bilayer via simple diffusion or 2) by moving through aquaporins (integral membrane proteins that function as water channels)
What is Tonicity?
A measre of the solution’s ability to change the volume of cells by altering their water content. An ISOTONIC SOLUTION is any solution in which a cell maintains its normal shape and volume
Define hypotonic solution
A solution that has a LOWER concentration of solutes than the cutosol inside the RBCs… water enters faster than it leaves. RBCs swell and may burst (hemolysis)
