BIO k101 IU Indy EXAM 2

What is a ligand?

Molecule that binds a target

What is a receptor?

Protein that binds a ligand

What is a substrate?

Reactant an enzyme acts on

What is an enzyme?

Catalyst; lowers activation energy

What is the active site?

Substrate-binding region

What is activation energy?

Energy needed to start reaction

How do enzymes affect activation energy?

Lower activation energy

Do enzymes change ΔG of a reaction?

No; only activation energy

What is ΔG?

Change in Gibbs free energy

What is an exergonic reaction?

Releases energy; ΔG < 0

What is an endergonic reaction?

Requires energy; ΔG > 0

What does ATP stand for?

Adenosine triphosphate.

What is ATP's major cellular function?

Transfers usable cellular energy

How does ATP energize cellular reactions?

Couples hydrolysis to cellular work

What is phosphorylation?

Addition of phosphate group

What can phosphorylation do to a molecule?

Increase reactivity/energy

What is ATP hydrolysis?

ATP → ADP + Pi + energy

What is energy coupling?

Exergonic drives endergonic reaction

What is competitive inhibition?

Competes for active site

Can competitive inhibition be overcome by increasing substrate?

Yes; add more substrate

What is a noncompetitive inhibitor?

Binds elsewhere; alters enzyme

What is an allosteric site?

Regulatory site away from active site

How can a noncompetitive inhibitor inhibit an enzyme?

Binds allosteric site; changes shape

Can increasing substrate usually overcome noncompetitive inhibition?

No

What does enzyme saturation mean?

All active sites occupied

If an enzyme is saturated, will adding more substrate greatly increase reaction rate?

No; enzyme is saturated

How can reaction rate increase when enzymes are saturated?

Add more enzyme

What is denaturation?

Loss of protein shape/function

How can high temperature affect an enzyme?

Denatures enzyme

What is a lyase?

Breaks/forms bonds without hydrolysis

What is a hydrolase?

Breaks bonds using water

What is a ligase?

Joins molecules; often uses ATP

What is apoptosis?

Programmed cell death

What is necrosis?

Uncontrolled cell death

Apoptosis vs. necrosis

Programmed vs. uncontrolled death

What is Herceptin?

Trastuzumab; anti-HER2 antibody

What does Herceptin target?

HER2 receptor

What type of treatment is Herceptin?

Monoclonal antibody targeted therapy

What is an organelle?

Specialized cellular structure

What is the nucleus?

Contains most cellular DNA

What is the nucleolus?

Makes rRNA/ribosomal subunits

Where is ribosomal RNA synthesized?

nucleolus.

What are ribosomes?

Sites of protein synthesis

What is the rough endoplasmic reticulum?

Makes secreted/membrane proteins

Where are transmembrane proteins such as insulin receptors synthesized?

Rough ER ribosomes

What is the smooth endoplasmic reticulum?

Lipid synthesis and detoxification

Where are many steroid hormones synthesized?

smooth ER.

Where would testosterone synthesis be associated?

smooth endoplasmic reticulum.

What is the Golgi apparatus?

Modifies/sorts/packages proteins

Which organelle sorts proteins targeted for extracellular secretion?

Golgi apparatus.

What is a mitochondrion?

Site of aerobic respiration

Where does synthesis of ATP through cellular respiration primarily occur?

Mitochondria.

What is the mitochondrial matrix?

Pyruvate oxidation + Krebs cycle

What are mitochondrial cristae?

Inner-membrane folds with ETC/ATP synthase

What is the intermembrane space?

H+ reservoir during respiration

What is the plasma membrane?

Selective phospholipid bilayer

What is the fluid mosaic model?

Fluid bilayer with embedded proteins

Can phospholipids move laterally within a membrane?

Yes; laterally

Do phospholipids frequently flip-flop between membrane layers?

No; rarely

What is a phospholipid?

Hydrophilic head + hydrophobic tails

What does amphipathic mean?

Hydrophilic + hydrophobic regions

Which part of a phospholipid is hydrophilic?

phosphate-containing head.

Which part of a phospholipid is hydrophobic?

fatty acid tails.

How are phospholipids arranged in a membrane?

Heads outward; tails inward

What is an integral membrane protein?

Protein embedded in bilayer

What is a peripheral membrane protein?

Protein on membrane surface

What is a glycoprotein?

Protein + carbohydrate

What is a glycolipid?

Lipid + carbohydrate

What is an important function of membrane glycoproteins and glycolipids?

Cell recognition

What role does cholesterol play in animal cell membranes?

Regulates fluidity/stability

What is a saturated fatty acid?

No C=C double bonds

What is an unsaturated fatty acid?

One or more C=C bonds

Why do unsaturated fatty acids increase membrane fluidity?

Kinks prevent tight packing

Why can unsaturated fatty acids help membranes remain fluid at low temperatures?

Kinks prevent tight packing

What is diffusion?

High → low concentration

What is passive transport?

Down gradient; no energy

What is facilitated diffusion?

Down gradient through protein

What is active transport?

Against gradient; requires energy

What is osmosis?

Water diffusion across membrane

During osmosis, water moves toward which side?

Toward higher solute concentration

What is tonicity?

Effect on cellular water movement

What is a hypotonic solution?

Lower solute; water enters cell

What is a hypertonic solution?

Higher solute; water leaves cell

What is an isotonic solution?

No net water movement

What happens to an animal cell in a hypotonic solution?

Water enters and the cell swells; it may lyse.

What happens to an animal cell in a hypertonic solution?

Water leaves and the cell shrivels or crenates.

What happens to an animal cell in an isotonic solution?

Its volume remains relatively stable because there is no net water movement.

What is hypotonic lysis?

Rupture of an animal cell caused by excessive water entry in a hypotonic solution.

What is crenation?

Shriveling of an animal cell due to water loss in a hypertonic solution.

What is plasmolysis?

Loss of water from a plant cell causing the plasma membrane to pull away from the cell wall.

What does turgid mean?

A plant cell is swollen and firm because water has entered and created turgor pressure.

What is turgor pressure?

Pressure of the cell contents against the plant cell wall due to water uptake.

What happens to a plant cell in a hypotonic environment?

It takes up water and becomes turgid.

What does flaccid mean in a plant cell?

The cell has insufficient turgor pressure and is relatively limp.

If extracellular solute concentration is greater than intracellular solute concentration, the extracellular solution is what?

Hypertonic.

If a dialysis bag contains more solute than the surrounding solution, what happens to its mass?

Water tends to enter the bag, increasing its mass.

What is the first law of thermodynamics?

Energy cannot be created or destroyed, only transferred or transformed.

What is the second law of thermodynamics?

Every energy transfer increases the entropy of the universe.

What is entropy?

A measure associated with energy dispersal or the number of possible arrangements in a system.

How can organisms become more ordered without violating the second law?

They increase order locally while causing a greater increase in entropy in their surroundings.