Bio Exam 2

Plasma Membrane

A phospholipid bilayer with embedded proteins, serving as a barrier and regulating the movement of substances in and out of the cell.

Endomembrane System

A network of membranes and organelles that modify, package, and transport lipids and proteins, including the nuclear envelope, ER, Golgi apparatus, lysosomes, and others.

Vacuoles

Organelles in plant cells that store substances, maintain turgor pressure, regulate pH, and support growth and development.

Peroxisomes

Organelles involved in detoxification and metabolism.

Chromoplasts

Organelles responsible for pigment synthesis, storage, and coloration.

Leucoplasts

Organelles that store starch, lipids, and proteins, and are involved in biosynthesis.

Microfilaments

Cytoskeletal filaments made of actin that assist in muscle contraction, amoeboid movement, and maintaining cell shape.

Intermediate Filaments

Tough, ropelike protein structures in the cytoskeleton providing mechanical stability and anchoring cell structures.

Microtubules

Hollow tubes made of tubulin that provide a rigid internal skeleton and framework for motor proteins.

Cilia

Short, hair-like structures made of microtubules that beat in one direction and assist in movement.

Flagella

Long, whip-like structures made of microtubules that facilitate snake-like movement.

Kinesin

A motor protein that drives vesicles along microtubules, powered by ATP hydrolysis.

Myosin

A motor protein that binds to actin filaments, generating force for movement.

Endosymbiosis Theory

The theory that mitochondria and chloroplasts originated from prokaryotes engulfed by larger cells.

Fluid Mosaic Model

A model describing the plasma membrane as a flexible structure with a mix of various proteins and lipids.

Saturated Fatty Acids

Fatty acids with straight tails and no double bonds, resulting in tight packing of phospholipids.

Unsaturated Fatty Acids

Fatty acids with kinks in their tails due to double bonds, causing loose packing of phospholipids.

Glycoproteins

Molecules consisting of carbohydrates attached to proteins that play roles in cell recognition and signaling.

Glycolipids

Molecules consisting of carbohydrates attached to lipids that contribute to membrane stability and cell recognition.

Tight Junctions

Cell junctions that form a seal to prevent the passage of materials through the space between epithelial cells.

Desmosomes

Structures that provide mechanical stability by linking adjacent cells while allowing materials to pass.

Gap Junctions

Cell junctions that allow for communication and the exchange of ions and small molecules between adjacent cells.

Diffusion

The process by which substances move from areas of higher concentration to areas of lower concentration.

Active Transport

The movement of molecules against their concentration gradient, requiring energy.

Endocytosis

The process by which cells take in large molecules by engulfing them with their membrane.

Exocytosis

The process through which cells release large molecules by vesicles fusing with the plasma membrane.

Anabolism

Metabolic processes that build larger molecules from smaller ones, such as amino acids to proteins.

Catabolism

Metabolic processes that break down larger molecules into smaller ones, such as carbohydrates to CO2.

Exergonic Reactions

Reactions that release free energy, typically associated with catabolic processes.

Endergonic Reactions

Reactions that consume free energy, typically associated with anabolic processes.

ATP (Adenosine Triphosphate)

The primary energy carrier in cells, capturing and transferring free energy to do work.

Enzyme

A biological catalyst that speeds up chemical reactions by lowering the activation energy.

Induced Fit Model

The model describing how enzymes change shape slightly to fit their substrates upon binding.

Competitive Inhibition

A type of enzyme inhibition where an inhibitor competes with the substrate for the active site.

Noncompetitive Inhibition

A type of enzyme inhibition where an inhibitor binds to an enzyme at a site other than the active site, changing the enzyme's shape.

Allosteric Regulation

Regulation of an enzyme's activity through binding of molecules at sites other than the active site.

Activation Energy

The minimum energy required for a chemical reaction to occur.

Temperature's effect on enzymes

Enzyme activity typically increases with temperature to an optimum point before denaturing.

pH's effect on enzymes

Each enzyme has an optimal pH range, deviating from which can decrease activity or denature the enzyme.

Substrate Concentration's effect on enzymes

Increasing substrate concentration generally increases enzyme activity until a saturation point is reached.