Module 2: Eukaryotic Cell Structure

These free OCR A Level Biology Eukaryotic Cell Structure revision notes have been written for specification points 2.1.1(d), 2.1.1(g) and 2.1.1(j).

  1. Microscopy
  2. Microscopy Calculations
  3. Preparing Microscope Slides
  4. Eukaryotic Cell Structure
  5. Prokaryotic Cell Structure
  6. Organelle Involvement in Protein Synthesis
  7. Water
  8. Introduction to Macromolecules
  9. Carbohydrates
  10. Lipids
  11. Proteins
  12. Inorganic Ions
  13. Chemical Tests for Biomolecules
  14. Colorimetry
  15. Chromatography
  16. Nucleotides and Nucleic Acids
  17. DNA Replication
  18. Genetic Code
  19. Protein Synthesis
  20. Enzymes
  21. Biological Membranes
  22. Water Potential and Osmosis
  23. Eukaryotic Cell Cycle
  24. Mitosis and Cytokinesis
  25. Meiosis
  26. Stem Cells
  27. Organisation in Animals
  28. Organisation in Plants
Eukaryotic Cell Structure

The diagram below illustrates a generic eukaryotic cell structure.

Labelled diagram of a eukaryotic plant cell showing structures and organelles - OCR A Level Biology revision
Membrane-Bound Organelles

The table below outlines the structure and function of membrane-bound organelles:

OrganelleStructureFunction
Nucleus Double membrane (nuclear envelope) with nuclear pores.
Contains nucleolus (RNA & proteins).		 Stores DNA as chromatin.
Controls protein synthesis via mRNA.
Nucleolus makes ribosomes.
Rough ER (RER)Flattened sacs (cisternae) with ribosomes on the surface. Folds proteins.
Transports them via cisternae.
Sends them in vesicles to the Golgi.
Smooth ER (SER)Flattened sacs without ribosomes. Synthesises lipids, cholesterol, phospholipids, steroid hormones.
Golgi ApparatusStack of membrane-bound sacs. Modifies proteins/lipids.
Packages them into vesicles for transport.
Mitochondrion Double membrane.
Inner membrane folds to form cristae.
Fluid interior is called the matrix.		 Does aerobic respiration to make ATP.
Contains its own mtDNA.
Can self-replicate.
Chloroplast Double membrane.
Stacks of thylakoids (grana).
Stroma with enzymes.		 Does photosynthesis:
Thylakoids: light-dependent*.
Stroma: Calvin cycle*.
Contains its own cpDNA.
Permanent Vacuole Large fluid-filled sac (cell sap).
Tonoplast membrane.		 Maintains turgor pressure for structural support.
LysosomeMembrane sac with hydrolytic enzymes. Digests old organelles, pathogens or debris via enzyme breakdown.

*Stages of photosynthesis studied in A2.

Organelles Without a Membrane

The table below outlines the structure and function of organelles without membranes:

OrganelleStructureFunction
Cilia Short projections from the cell membrane.
Made of microtubules from centrioles.		 Move substances across the cell surface.
Some act as receptors in cell signalling.
UndulipodiaLong cilium.Moves the whole cell (e.g. sperm).
Ribosome (80s) Made of RNA & protein.
Made of two subunits.		 Synthesises proteins from mRNA.
Free in the cytoplasm or attached to the RER.
Centrioles / Centrosome Two microtubule cylinders at a right angle.
Centrosome is the centriole & surrounding matrix.		 Forms a spindle during cell division.
Forms cilia.
Cytoskeleton Network of protein filaments (microtubules, actin, etc.).
Has motor proteins which move along microtubules.		 Supports shape and strength.
Enables movement of organelles, vesicles and entire cells.
Used in cytokinesis.
Stabilises tissues.
Involved in cell signalling.
Cellulose Cell WallRigid outer layer made of cellulose fibres. Provides support; maintains shape.
Prevents lysis when the cell is turgid.
Chitinous Cell WallRigid outer layer of chitin and proteins. Provides support; maintains shape.
Prevents lysis when the cell is turgid.
PreviousFull NotesNext

Powered by  GDPR Cookie Compliance
Privacy Overview

This website uses cookies so that we can provide you with the best user experience possible. Cookie information is stored in your browser and performs functions such as recognising you when you return to our website and helping our team to understand which sections of the website you find most interesting and useful.