Biology Unit 2: Cells, Transport, Energy, and Microscopes Study Guide

Vocabulary practice flashcards covering cell types, organelles, membrane transport mechanisms, energy transformations, photosynthesis, cellular respiration, and light microscopy.

Prokaryotic Cell

A simple, small cell lacking a true nucleus and membrane-bound organelles, where DNA floats in the cytoplasm (nucleoid region); characteristic of bacteria.

Eukaryotic Cell

A larger, complex cell that contains a nucleus enclosing its DNA along with membrane-bound organelles; includes plant, animal, fungal, and protist cells.

Nucleus

The 'control center' of a eukaryotic cell that houses the cell's genetic instructions (DNA), typically appearing as a large, dark spot under a microscope.

Ribosome

A structure found in all cells (both prokaryotes and eukaryotes) located on the rough ER and free in the cytoplasm that builds proteins.

Mitochondria

The 'powerhouse' organelle found in both plant and animal cells where cellular respiration takes place to produce $ATP$.

Chloroplast

An organelle found in plant and algae cells containing the green pigment chlorophyll that captures light energy to carry out photosynthesis.

Plasma Membrane

A selectively permeable phospholipid bilayer containing proteins and carbohydrates that regulates traffic of substances entering and leaving the cell.

Cell Wall

A rigid outer layer present in plants, fungi, and bacteria that gives shape, structure, and support, and prevents plant cells from bursting when water enters.

Central Vacuole

A large sack of water located in plant cells that maintains turgor pressure; when it loses water, the plant wilts.

Lysosome

A membrane-bound sac containing digestive enzymes that digests food, breaks down worn-out cell parts, and disposes of waste.

Cytoskeleton

An internal network of protein fibers that gives the cell its shape, provides internal structural support, and assists in cell movement.

Endoplasmic Reticulum (ER)

An internal transport network consisting of rough ER studded with ribosomes for protein synthesis and smooth ER that makes lipids.

Golgi Apparatus

An organelle that modifies, packages, and ships proteins into vesicles, often destined for exocytosis.

Passive Transport

The movement of substances across a cell membrane from high to low concentration (down the gradient) without requiring cellular energy ($ATP$).

Active Transport

The energy-requiring ($ATP$) movement of molecules across a membrane against the concentration gradient (from low to high concentration) using protein pumps or vesicles.

Simple Diffusion

The passive movement of small, nonpolar molecules (such as $O_2$ and $CO_2$) directly through the phospholipid bilayer from high to low concentration without helper proteins.

Osmosis

The passive diffusion of water across a selectively permeable membrane toward the region with a higher solute concentration.

Facilitated Diffusion

A form of passive transport where substances move down their concentration gradient (high to low) with the assistance of channel or carrier proteins without using energy.

Aquaporins

Specialized channel proteins embedded in the cell membrane that facilitate the rapid movement of water during osmosis.

Endocytosis

A form of active bulk transport where the plasma membrane engulfs external material to bring it inside the cell using vesicles.

Exocytosis

A form of active bulk transport in which vesicles fuse with the plasma membrane to release materials (such as hormones, mucus, or tears) outside the cell.

Hypertonic Solution

A solution that has a higher concentration of solute compared to the cell interior, causing net water movement out of the cell so that animal cells shrivel and plant cells wilt.

Hypotonic Solution

A solution that has a lower concentration of solute compared to the cell interior, causing water to flow into the cell until animal cells swell or burst and plant cells become firm/turgid.

Isotonic Solution

A solution that has an equal solute concentration relative to the cell's interior, resulting in equal movement of water in both directions with no net cell volume change.

Contractile Vacuole

A specialized organelle in freshwater protists (such as paramecia) that constantly pumps out excess water entering from a hypotonic environment to prevent cell bursting.

ATP (Adenosine Triphosphate)

The cellular energy currency composed of adenosine and three phosphate groups; breaking the bond to the terminal phosphate releases usable chemical energy to form $ADP$.

Photosynthesis

The light-driven chemical reaction ($6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$) in chloroplasts that converts solar energy into chemical energy stored in glucose.

Light-Dependent Reactions

The initial stage of photosynthesis occurring in the thylakoid membranes that splits water, releases $O_2$, and produces $ATP$ and $NADPH$ using sunlight.

Calvin Cycle

The light-independent stage of photosynthesis occurring in the stroma that utilizes $CO_2$, $ATP$, and $NADPH$ to synthesize glucose.

Cellular Respiration

The metabolic process ($C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$) occurring primarily in the mitochondria of living things that breaks down glucose to release energy as $ATP$.

Glycolysis

The first, anaerobic stage of cellular respiration that occurs in the cytoplasm, splitting glucose into two pyruvate molecules and yielding a net of $2\,\text{ATP}$.

Krebs Cycle

The second stage of aerobic cellular respiration occurring inside the mitochondria that breaks down pyruvate derivatives, releases $CO_2$, and yields $2\,\text{ATP}$ along with electron carriers.

Electron Transport Chain

The final, aerobic stage of cellular respiration situated in the inner mitochondrial membrane that utilizes oxygen as the final electron acceptor to generate the most $ATP$ ($\sim 32\text{--}34\,\text{ATP}$) and produce water.

Fermentation

An anaerobic cellular process that produces only $2\,\text{ATP}$ per glucose molecule in the absence of oxygen, yielding lactic acid in animal muscles or alcohol in yeast.

Eyepiece (Ocular Lens)

The microscope lens through which a viewer looks, providing a standard magnification of $10\times$.

Objective Lenses

Lenses mounted on a microscope's revolving nosepiece offering different powers of magnification: scanning ($4\times$), low ($10\times$), and high ($40\times$).

Coarse Adjustment Knob

The large knob on a microscope that moves the stage significantly; used exclusively for initial focusing on scanning or low power objectives.

Fine Adjustment Knob

The small knob that performs precise stage movements for sharp focusing; it is the only adjustment knob used on medium and high power objectives.

Diaphragm (Microscope)

The adjustable disc beneath the microscope stage used to regulate the amount of light that passes up through the specimen.

Total Magnification

The total power of specimen enlargement calculated by multiplying the ocular lens magnification by the objective lens magnification ($\text{Eyepiece} \times \text{Objective}$).