Cell structure and organization — A/L Biology

What must I remember about Cell structure and organization?

• Cell theory states that all living organisms are composed of cells, the cell is the structural and functional unit of life, and all cells arise from pre-existing cells.
• Prokaryotic vs Eukaryotic cells: Prokaryotes lack a membrane-bound nucleus and membrane-bound organelles, possessing 70S ribosomes and circular DNA; eukaryotes possess a membrane-bound nucleus, 80S ribosomes, and compartmentalized organelles.
• Endomembrane system consists of the nuclear envelope, rough endoplasmic reticulum (protein synthesis/folding), smooth ER (lipid synthesis/detoxification), Golgi apparatus (sorting/packaging), lysosomes (intracellular digestion), and vacuoles.
• Energy-transducing organelles: Mitochondria (sites of cellular respiration, ATP generation via oxidative phosphorylation) and Chloroplasts (sites of photosynthesis, carbon fixation in stroma, light reactions in thylakoids).
• Cytoskeleton comprises microtubules (tubulin, vesicle transport, cilia/flagella, spindle fibers), microfilaments (actin, cell motility, cleavage furrow), and intermediate filaments (tensile strength).

Test yourself (1 minute)

1. Organelle membrane counts

   Double-membrane organelles are Nucleus, Mitochondrion, and Chloroplast; single-membrane organelles are ER, Golgi apparatus, Lysosome, and Peroxisome; non-membranous structures are Ribosomes, Centrioles, and Cytoskeleton.

2. Plant vs Animal cell distinctions

   Plant cells possess rigid cellulose cell walls, large central vacuoles, and chloroplasts; animal cells possess centrosomes with centrioles and lysosomes.

3. Fluid Mosaic Model of plasma membrane

   Phospholipid bilayer with hydrophilic heads facing outwards and hydrophobic fatty acid tails inwards, studded with integral and peripheral proteins, glycoproteins, and cholesterol.

Practise Cell structure and organization questions today

Source: NIE G.C.E. (A/L) Biology Syllabus & Resource Book, Unit 2

What comes next?

Next in the syllabus

Where does Cell structure and organization fit in the syllabus?

Year 1 · Term 1