celluar respiration(units 3&4) Flashcards
What do enzymes do?
Enzymes speed up biochemical reactions by lowering the activation energy required for the reaction.
What does activation energy mean in the context of enzymes?
Enzymes help reactions overcome activation energy by stabilizing the transition state, reducing the energy needed to initiate the reaction.
Are enzymes consumed in a reaction?
No, enzymes are not consumed and can catalyze many reactions repeatedly.
What fits into the active site of an enzyme?
A specific substrate fits into the active site; specificity is high due to precise molecular complementarity.
What can affect the rate of an enzyme?
Temperature, pH, substrate concentration, and the presence of inhibitors or activators.
What metal is found in the active site of catalase?
Iron (Fe).
What do coenzymes do?
Coenzymes assist enzymes by transferring chemical groups or electrons during reactions.
What vitamins are coenzymes?
B vitamins, such as B1 (thiamine), B2 (riboflavin), and B3 (niacin).
What is NAD used for?
NAD is used in redox reactions to carry electrons to the electron transport chain.
What is an enzyme inhibitor?
An inhibitor binds to the enzyme, reducing or blocking its activity.
What is the name of the site that can regulate the active site of an enzyme?
Allosteric site.
What are enzymes made of?
Enzymes are complex folded molecules made of proteins (amino acid chains).
What does denaturation mean?
Denaturation disrupts the enzyme’s structure, rendering it inactive.
Where does pepsin reside and what is the independent variable in its activity graph?
Pepsin resides in the stomach; the independent variable is pH.
What is Taq polymerase used for?
Taq polymerase is used in PCR for DNA replication; it is heat-tolerant due to its origin in Thermus aquaticus, a thermophilic bacterium.
What organism uses hydrogen peroxide and catalase to defend itself?
Bacteria like Staphylococcus aureus and some immune cells.
What fits into the active site of lactase and what are the products?
Lactose fits; products are glucose and galactose; ~35% of adults retain lactase.
What suffix is used for almost all enzyme names?
‘-ase.’
How is the head of a phospholipid different from the tail?
The head is polar (hydrophilic), and the tail is non-polar (hydrophobic); they form a bilayer with heads outward and tails inward.
Is a phospholipid amphiphilic?
Yes, because it has both hydrophilic and hydrophobic regions.
Why are cell and organelle membranes bilayers?
Bilayers provide structural stability and form selective barriers.
What do we call the diffusion of water across a selectively permeable membrane?
Osmosis.
What is a saltwater solution made of?
Water (solvent) and salt (solute); water is the solvent.
If you bathe a cell in a high salt solution, will the water enter or leave the cell?
Water will leave due to osmosis, as the solution is hypertonic.
Distinguish between hypotonic, isotonic, and hypertonic solutions.
Hypotonic: low solute, water enters; Isotonic: equal solute, no net movement; Hypertonic: high solute, water exits.
Is there water movement in an isotonic solution?
Yes, but it is balanced (no net movement).
Distinguish turgid vs plasmolyzed cell.
Turgid: swollen with water; Plasmolyzed: shrunken due to water loss.
How do marsh plants like pickleweed adapt to a high salt environment?
They sequester salt in vacuoles or excrete it.
What organ in your body uses osmosis to concentrate urine?
Kidneys.
Why does a diet high in salt increase your blood pressure?
Excess salt retains water, increasing blood volume and pressure.
What do cells use vesicle transport for?
To transport large molecules and particles.
What is it called when the vesicle is going INTO the cell?
Endocytosis.
What do we call the bulk transport OUT of a cell?
Exocytosis.
Why are vesicles spherical?
Spherical shapes minimize surface tension and are energetically favorable.
Why can’t ions freely move across a membrane?
Membranes are hydrophobic, and ions are charged.
What type of protein-mediated transport does not require energy?
Facilitated diffusion.
What are the two gradients that molecules will diffuse down?
Concentration gradient and electrochemical gradient.
Which type of transport uses energy?
Active transport; energy is ATP.
Distinguish uniport, symport, antiport.
Uniport: one substance, one way; Symport: two substances, same way; Antiport: two substances, opposite ways.
What is the name of the protein channel that moves water across a membrane?
Aquaporin.
