Biological Fundamentals: Cells, Membranes, and Energy

Comprehensive vocabulary flashcards covering cell structure (prokaryotic and eukaryotic), membrane transport, thermodynamics, and enzyme kinetics based on the lecture transcript.

Prokaryotes

Organisms belonging to the domains Bacteria and Archaea that lack a nucleus and have DNA located in a region called the nucleoid.

Eukaryotes

Cells characterized by a membrane-enclosed nucleus containing DNA and membrane-enclosed compartments called organelles.

Cytosol

The part of the cytoplasm consisting of water and dissolved material.

Ribosomes

The sites of protein synthesis found in both prokaryotic and eukaryotic cells.

Nucleoid

The region in a prokaryotic cell where the DNA is located, as it lacks a membrane-enclosed nucleus.

Organelles

Membrane-enclosed compartments in eukaryotic cells with specific roles, such as the nucleus, mitochondria, and Golgi apparatus.

Nuclear envelope

The membrane surrounding the nucleus, containing nuclear pores that regulate the movement of molecules in and out.

Endomembrane system

An interconnected group of membranes including the plasma membrane, nuclear envelope, endoplasmic reticulum, Golgi, lysosomes, and vesicles.

Rough endoplasmic reticulum (RER)

A network of interconnected membranes with attached ribosomes where proteins are modified, folded, and transported.

Golgi apparatus

An organelle composed of flattened sacs (cisternae) and vesicles that receives, concentrates, packages, sorts, and modifies proteins from the RER.

Smooth endoplasmic reticulum (SER)

Memsbrane network with no ribosomes that chemically modifies drugs/pesticides, hydrolyzes glycogen, and synthesizes lipids and steroids.

Lysosomes

Organelles containing digestive enzymes that hydrolyze macromolecules or digest food and cell materials.

Mitochondria

The organelle where energy in fuel molecules is transformed into the bonds of $ATP$ by Cellular Respiration.

Chloroplasts

The site of photosynthesis in plants and protists where light energy is used to make sugars.

Vacuoles

Organelles in plants and protists used for waste storage, maintaining turgor pressure, storing pigments (anthocyanins), or expelling excess water (contractile vacuoles).

Cytoskeleton

A structure that supports cell shape, holds organelles in position, is involved in cytoplasmic streaming, and interacts with extracellular structures.

Microfilaments

Cytoskeletal elements made from actin protein which form helical chains to determine cell shape and aid in movement.

Intermediate filaments

Tough, ropelike protein assemblages that anchor cell structures in place and resist tension.

Microtubules

Cytoskeletal components made of tubulin dimers that form a rigid internal skeleton and act as tracks for motor proteins.

Cilia

Short, numerous appendages used for motility in eukaryotic cells.

Flagella

Long appendages, present singly or in small numbers, used for cell motility.

Plasmodesmata

Channels that connect adjacent plant cells through their cell walls.

Endosymbiosis theory

The theory that mitochondria and plastids arose when one cell engulfed another cell in a symbiotic relationship.

Fluid mosaic model

The general structure of biological membranes where a variety of proteins "float" in a phospholipid bilayer.

Peripheral membrane proteins

Proteins that lack exposed hydrophobic groups and do not penetrate the phospholipid bilayer.

Integral membrane proteins

Proteins containing both hydrophobic and hydrophilic domains that penetrate the phospholipid bilayer.

Transmembrane proteins

Integral proteins that extend all the way through the phospholipid bilayer.

Tight junctions

Cell junctions that form a "quilted" seal to bar the movement of dissolved materials and ensure directional movement.

Desmosomes

Junctions that act like "spot welds" to link adjacent cells tightly while permitting materials to move around them.

Gap junctions

Hydrophilic channels that allow communication between adjacent cells by letting molecules pass through.

Diffusion

The passive process of random movement toward equilibrium down a concentration gradient.

Osmosis

The diffusion of water across a membrane from a region of higher water (lower solute) to lower water (higher solute).

Hypertonic solution

A solution with a higher solute concentration compared to the inside of the cell.

Hypotonic solution

A solution with a lower solute concentration compared to the inside of the cell.

Isotonic solution

A solution with an equal solute concentration compared to the inside of the cell.

Active transport

The movement of substances against a concentration gradient requiring energy ($ATP$) and specific membrane proteins (uniporters, symporters, or antiporters).

Phagocytosis

A type of endocytosis where molecules or entire cells are engulfed and fuse with a lysosome.

Pinocytosis

A type of endocytosis where a small vesicle forms to bring fluids or small dissolved substances into the cell.

Receptor mediated endocytosis

A process that depends on receptor proteins to bind and bring specific substances into the cell.

Exocytosis

The process by which indigestible material, proteins, or neurotransmitters are expelled from a cell via vesicles.

First law of thermodynamics

The principle stating that energy is neither created nor destroyed; total energy remains the same after conversion.

Second law of thermodynamics

The principle stating that during energy conversion, some energy becomes unavailable to do work, leading to an increase in disorder (entropy).

Entropy

A measure of the disorder in a system; it takes energy to impose order.

Free energy ($ΔG$)

The difference in free energy between products and reactants; a negative value indicates energy release, while a positive value indicates consumption.

Catabolic reactions

Exergonic reactions where complex molecules are broken down into simpler ones, releasing free energy ($-ΔG$).

Anabolic reactions

Endergonic reactions where complex molecules are made from simple molecules, requiring energy input ($+ΔG$).

ATP (adenosine triphosphate)

A nucleotide that captures and transfers free energy, releasing a large amount when hydrolyzed.

Activation energy ($E_a$)

The amount of energy required to start a chemical reaction by overcoming the energy barrier.

Substrates

Reactant molecules that bind specifically to the active site of an enzyme.

Induced fit

The phenomenon where an enzyme changes shape when binding to its substrate to facilitate catalysis.

Competitive inhibitors

Molecules that compete with the natural substrate for binding at the enzyme's active site.

Noncompetitive inhibitors

Molecules that bind to an enzyme at a site other than the active site, changing the enzyme's shape and altering the active site.

Feedback inhibition

A regulatory mechanism where the final product of a metabolic pathway acts as a noncompetitive inhibitor of the first enzyme in the pathway.