Cells · Topic 8 of 17

Cell Structure & Organelles

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Biology · the cell

Cell Structure & Organelles

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both. The nucleus holds DNA, ribosomes make proteins, mitochondria make ATP.

01 · Two cell typesProkaryote = no nucleus

02 · PowerhouseMitochondria make ATP

03 · Plant vs animalPlant: wall + chloroplasts + big vacuole

What it is

Every cell has a plasma membrane, cytoplasm, DNA and ribosomes

High-energy cells (muscle) are packed with mitochondria

Parts & jobs

Nucleus: holds the DNA and directs the cell's protein making must know

Mitochondria make ATP (cellular respiration), the cell's powerhouse must know

Ribosomes make proteins (free or on rough ER) must know

Nucleolus (inside the nucleus) assembles ribosomes

Rough ER (ribosome-studded): makes and modifies proteins

Smooth ER (no ribosomes): makes lipids, detoxifies, stores calcium

Golgi apparatus: modifies, sorts and packages proteins and lipids

Lysosomes digest wastes, worn-out parts and engulfed invaders

Vesicles and vacuoles store and transport; plant central vacuole → turgor

Chloroplasts (plants, algae) carry out photosynthesis

Cytoskeleton = protein fibers for shape, support and movement

Cell wall (plants, fungi, bacteria) protects and shapes; plant wall = cellulose

Don't confuse

Prokaryote: no nucleus or membrane-bound organelles; eukaryote: has both must know

Plant cells add wall, chloroplasts, big vacuole; animal cells add centrioles, lysosomes must know

Plant cell or animal cell?

Commonly confused

	Plant cell	Animal cell
Cell wall	Yes (cellulose)	No
Chloroplasts	Yes	No
Vacuole	One large central vacuole	Smaller vacuoles and vesicles
Centrioles / lysosomes	No	Yes
Mitochondria	Yes	Yes

Misconceptions

Trap: plant cells have mitochondria too, not just chloroplasts

More detail

Show 5 more facts

Prokaryote DNA sits in the nucleoid (no membrane around it)

Flagella (long, few) move the cell; cilia (short, many) sweep material

Peroxisomes break down fatty acids and detoxify (e.g. alcohol)

Size: prokaryotes 0.1–5 µm; eukaryotes 10–100 µm

Mitochondria and chloroplasts have their own DNA (endosymbiosis)

Pearl

Nucleus directs, ribosomes build proteins, mitochondria make ATP, and plant cells, unlike animal cells, add a wall, chloroplasts and one big vacuole.

Sources · OpenStax Concepts of Biology §3.2 Comparing Prokaryotic and Eukaryotic Cells · OpenStax Concepts of Biology §3.3 Eukaryotic Cells (organelles; plant vs animal cells; Table 3.1) · Union Test Prep — HESI A2 Biology study guide, p. 1: cells, organelles, membrane, respiration, photosynthesis · TSTC Library — HESI A2 guide (Biology: cell parts and organelles; compare photosynthesis and respiration) · Built from the verified NurseSavvy HESI A2 fact map (facts reviewed 2026-10-16). HESI is a trademark of Elsevier; NurseSavvy is not affiliated with Elsevier.

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