Biology Unit Two: Cells, Membranes, Transport, and Metabolism

Vocabulary practice flashcards covering cell structure and organelles, membrane structure and transport, osmosis, bulk transport, and enzyme kinetics from Biology Unit Two.

Prokaryotic Cells

Cells that lack a nucleus and membrane-bound organelles, represented by bacteria and archaea.

Eukaryotic Cells

Cells that possess a nucleus and membrane-bound organelles.

Nucleus

An organelle that houses DNA and directs gene expression, utilizing nuclear pores to regulate exchange with the cytoplasm.

Nucleolus

A structure within the nucleus that makes rRNA and assembles ribosomal subunits.

Ribosomes

Structures found in all cells that build proteins.

Rough Endoplasmic Reticulum (Rough ER)

Endoplasmic reticulum studded with ribosomes that makes and processes proteins entering the secretory pathway.

Smooth Endoplasmic Reticulum (Smooth ER)

Endoplasmic reticulum lacking ribosomes that synthesizes lipids, participates in detoxification, and stores calcium.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids.

Mitochondria

Organelles present in both plant and animal cells that produce much of a eukaryotic cell's ATP during cellular respiration.

Chloroplasts

Organelles that carry out photosynthesis in photosynthetic plant cells.

Lysosomes

Organelles that digest materials and worn-out cell parts.

Peroxisomes

Organelles that break down fatty acids and detoxify substances, including handling hydrogen peroxide.

Central Vacuole

A large plant cell organelle that stores water and other materials and provides cellular support.

Vesicles

Small cellular structures that transport or store materials.

Cytoskeleton

A cellular framework that supports cell shape, movement, and internal transport.

Fluid Mosaic Model

A membrane model describing a flexible phospholipid bilayer containing a mixture of proteins and other components, where many lipids and proteins move sideways.

Selectively Permeable

A membrane property allowing some substances to cross more easily than others (e.g., oxygen and carbon dioxide cross directly, while ions generally require transport proteins).

Diffusion

The net movement of a substance from an area of higher concentration to an area of lower concentration.

Diffusion Equilibrium

The state in which molecules continue moving, but there is no net movement.

Simple Diffusion

A passive process wherein substances move down a concentration gradient directly across the phospholipid bilayer.

Facilitated Diffusion

A passive transport process that moves substances down a concentration gradient using channel or carrier proteins.

Active Transport

The movement of a substance against a concentration or electrochemical gradient using transport proteins and energy directly or indirectly.

Osmosis

The net movement of water across a selectively permeable membrane, moving toward the higher concentration of nonpenetrating solute.

Hypotonic Solution

An external solution with a lower effective solute concentration than the cell, causing water to enter; animal cells swell and may lyse, while plant cells become turgid.

Isotonic Solution

An external solution with the same effective solute concentration as the cell, resulting in no net water movement; animal cells maintain normal size and plant cells are flaccid.

Hypertonic Solution

An external solution with a higher effective solute concentration than the cell, causing water to leave; animal cells shrivel and plant cells may plasmolyze.

Turgid

The firm state of a plant cell resulting from water entry in a hypotonic environment.

Flaccid

The state of a plant cell lacking firm turgor pressure when placed in an isotonic environment.

Lysed

The burst state of an animal cell caused by excessive water entry in a hypotonic environment.

Plasmolyzed

The state of a plant cell where the membrane and cellular contents pull away from the cell wall following water loss.

Endocytosis

An energy-requiring bulk transport process that brings material into a cell by forming vesicles.

Exocytosis

An energy-requiring bulk transport process that releases material when a vesicle fuses with the cell membrane.

Phagocytosis

A form of endocytosis commonly referred to as 'cell eating,' which takes in large particles.

Pinocytosis

A form of endocytosis commonly referred to as 'cell drinking,' which takes in extracellular fluid.

Metabolism

All chemical reactions occurring in a cell or organism, consisting of catabolism and anabolism.

Catabolism

Metabolic reactions that break molecules down.

Anabolism

Metabolic reactions that build molecules.

Enzymes

Biological catalysts that speed up reactions without being consumed overall; most are proteins, with catalytic RNA as an exception.

Substrate

The specific reactant upon which an enzyme acts.

Active Site

The specific region of an enzyme where substrate binding and catalysis occur.

Product

The substance formed as the result of an enzymatic reaction.

Activation Energy

The energy barrier a chemical reaction must overcome, which is lowered by enzymes.

Induced Fit

The conformational adjustment of enzyme and substrate shapes upon binding to support catalysis.

Denaturation

The disruption of a protein's normal structure, which potentially alters its active site and reduces or eliminates activity.

Cofactors

Inorganic helper ions, such as magnesium or iron, that assist enzyme function (or broadly used to include all enzyme helpers).

Coenzymes

Organic enzyme helpers that are frequently derived from vitamins.

Competitive Inhibitors

Inhibitors that bind directly to an enzyme's active site, whose effects can often be overcome by increasing substrate concentration.

Noncompetitive Inhibitors

Inhibitors that bind to an enzyme somewhere other than the active site to reduce activity, an effect that cannot be overcome by extra substrate.