Prokaryotic cells
Bacteria and archaea lack a membrane-bound nucleus. Their DNA occupies a nucleoid region, while ribosomes operate in the cytoplasm.
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Biology · Unit 01
Cell biology: structure supports function.
Cells share basic components, but different cell types organize them in different ways. Eukaryotic organelles create specialized compartments, while the plasma membrane controls exchange with the environment.
15 cards4 exact referencesOriginal Lilerno wording
Practice one card at a timeEukaryotic cells
Animals, plants, fungi, and protists have a membrane-bound nucleus and specialized membrane-bound organelles.
Visual learning
See the organization
These original Lilerno figures simplify the structures so their relationships are easier to recognize. They are illustrative models, not microscope images and not drawn to scale.
Lilerno original illustration · not to scale
Prokaryotic and eukaryotic organization
The bacterial cell keeps its DNA in a nucleoid region and has no membrane-bound nucleus. The animal cell separates DNA inside a nucleus and organizes specialized work across membrane-bound organelles.
Scientific organization checked against:OpenStax, Rice University — Biology 2e, 4.2 Prokaryotic CellsOpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
Lilerno original illustration · not to scale
The plasma membrane as a fluid mosaic
Hydrophilic phospholipid heads face watery environments while hydrophobic tails point inward. Proteins, cholesterol, and exterior carbohydrate groups contribute to transport, stability, signaling, and recognition.
Scientific organization checked against:OpenStax, Rice University — Biology 2e, 5.1 Components and Structure
Retrieval practice
Cell-biology cards
Answer each question before opening the card. Every answer identifies the educational reference used for fact checking.
definition01What is the smallest unit that can carry out the basic processes of life?Reveal answer
A cell.
Organisms may contain one cell or many cells, but cellular organization is the basic structural level of living systems.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.1 Studying Cells
concept02Which four components are shared by all cells?Reveal answer
A plasma membrane, cytoplasm, genetic material (DNA), and ribosomes.
Prokaryotic and eukaryotic cells arrange these components differently, but both cell types depend on them.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.2 Prokaryotic Cells
comparison03What major structural feature separates eukaryotic cells from prokaryotic cells?Reveal answer
Eukaryotic cells have a membrane-bound nucleus; prokaryotic cells do not.
Prokaryotic DNA occupies a nucleoid region rather than a nucleus surrounded by a nuclear envelope.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.2 Prokaryotic CellsSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
concept04What does the nucleus contain, and what broad process does it help direct?Reveal answer
It contains the cell's DNA and helps direct gene expression, including the production of RNA and proteins.
The nuclear envelope separates the genome from the cytoplasm while pores regulate traffic between them.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
definition05What is the primary function of ribosomes?Reveal answer
They synthesize proteins by translating information carried by messenger RNA.
Ribosomes may be free in the cytosol or associated with the rough endoplasmic reticulum.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
concept06What is a central function of mitochondria in eukaryotic cells?Reveal answer
They produce much of the cell's ATP through aerobic cellular respiration.
ATP transfers usable chemical energy to many cellular processes; mitochondria are not simply storage containers for energy.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
comparison07Why does rough endoplasmic reticulum look rough, and what does it help produce?Reveal answer
Ribosomes attached to its surface create the rough appearance; it helps produce proteins destined for membranes or secretion.
New proteins enter or associate with the endoplasmic-reticulum system before further processing and transport.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
comparison08Name one major job of smooth endoplasmic reticulum.Reveal answer
It participates in lipid synthesis.
Smooth ER lacks surface-bound ribosomes and can also have specialized roles that vary by cell type.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
sequence09What does the Golgi apparatus do with many proteins and lipids received from the endoplasmic reticulum?Reveal answer
It modifies, sorts, and packages them for delivery to other cellular destinations.
The Golgi is part of the endomembrane trafficking system rather than the site where all proteins are initially synthesized.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
concept10Why is the plasma membrane described as selectively permeable?Reveal answer
It controls which substances cross between the cell and its environment.
The membrane forms a flexible boundary whose lipids and proteins support transport, communication, and recognition.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 5.1 Components and Structure
definition11What is a common function of lysosomes in animal cells?Reveal answer
They use digestive enzymes to break down macromolecules and worn cellular material.
The lysosomal membrane keeps these enzymes separated from most of the cytoplasm.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
definition12What process occurs in chloroplasts?Reveal answer
Photosynthesis.
Chloroplasts capture light energy to support the synthesis of energy-rich organic molecules in plants and algae.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
comparison13Where is a plant cell wall located relative to the plasma membrane?Reveal answer
Outside the plasma membrane.
The wall adds structural support, while the plasma membrane remains the selective boundary controlling molecular movement.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic CellsSource: OpenStax, Rice University — Biology 2e, 5.1 Components and Structure
concept14How can a plant cell's central vacuole contribute to structure?Reveal answer
Water in the vacuole helps maintain internal pressure against the cell wall.
The central vacuole also stores dissolved substances and occupies a large fraction of many mature plant cells.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
comparison15How do cytoplasm and cytosol differ?Reveal answer
Cytosol is the fluid portion; cytoplasm includes the cytosol and cellular structures between the plasma membrane and nuclear envelope.
Using the terms interchangeably can hide the distinction between the fluid medium and the larger cellular region.
Lilerno original · source-checked · High school / introductory collegeSource: OpenStax, Rice University — Biology 2e, 4.3 Eukaryotic Cells
Source transparency
Educational references
Lilerno wrote the lesson and cards in original language. These materials were used only to check scientific facts; their text, diagrams, and media are not reproduced.
Biology 2e, 4.1 Studying Cells
OpenStax, Rice University
Authors: Mary Ann Clark, Matthew Douglas, Jung Choi
Referenced for fact checking: OpenStax, Biology 2e, section 4.1, OpenStax at Rice University. Lilerno does not reproduce its text or media.
Biology 2e, 4.2 Prokaryotic Cells
OpenStax, Rice University
Authors: Mary Ann Clark, Matthew Douglas, Jung Choi
Referenced for fact checking: OpenStax, Biology 2e, section 4.2, OpenStax at Rice University. Lilerno does not reproduce its text or media.
Biology 2e, 4.3 Eukaryotic Cells
OpenStax, Rice University
Authors: Mary Ann Clark, Matthew Douglas, Jung Choi
Referenced for fact checking: OpenStax, Biology 2e, section 4.3, OpenStax at Rice University. Lilerno does not reproduce its text or media.
Biology 2e, 5.1 Components and Structure
OpenStax, Rice University
Authors: Mary Ann Clark, Matthew Douglas, Jung Choi
Referenced for fact checking: OpenStax, Biology 2e, section 5.1, OpenStax at Rice University. Lilerno does not reproduce its text or media.