Study guide: Cell Structure and Organelles

📋 Course Outline

1. Cell Theory and Membrane Structure
2. Endoplasmic Reticulum and Golgi
3. Lysosomes and Cellular Renewal
4. Mitochondria and Chloroplasts
5. Plant and Animal Cell Features

📖 1. Cell Theory and Membrane Structure

🔑 Key Concepts & Definitions

• Plasma membrane: A selectively permeable phospholipid bilayer with proteins embedded in it.

★ Must-know

• Cell theory states that all living organisms are composed of cells, cells are the basic unit of life, and all cells arise from pre-existing cells.

• 🔄 Ribosome formation proceeds as follows: rRNA and proteins form small and large subunits in the nucleolus, The subunits exit the nucleolus into the cytoplasm, The small and large subunits assemble into ribosomes

Further detail

• Different organelles are surrounded by membranes, and each membrane has a unique composition of lipids and proteins.

• The nuclear envelope contains pores.

📖 2. Endoplasmic Reticulum and Golgi

🔑 Key Concepts & Definitions

• Endoplasmic reticulum: A network of membranous tubules and sacs called cisternae, with an internal compartment called the lumen or cisternal space.
• Transport vesicles: Vesicles in transit from one part of the cell to another.

★ Must-know

• The smooth endoplasmic reticulum synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, and stores calcium ions.

• Many cells secrete proteins made by ribosomes attached to the rough endoplasmic reticulum, and the secretory proteins leave the ER inside membrane-wrapped vesicles.

Further detail

• As ER products travel from the cis to the trans side of the Golgi, they are modified, new ER membranes are added, and the Golgi manufactures some macromolecules such as pectin.

💡 Memory Hook

ER products travel from the cis to the trans side of the Golgi.

📖 3. Lysosomes and Cellular Renewal

🔑 Key Concepts & Definitions

• Cell sap: The solution inside the central vacuole.

★ Must-know

• Lysosomes help the cell continually renew itself.

Further detail

• Macrophages, which are white blood cells, are human cells that carry out phagocytosis.

💡 Memory Hook

Lysosomes help the cell continually renew itself.

📖 4. Mitochondria and Chloroplasts

🔑 Key Concepts & Definitions

• Mitochondrial matrix: The space enclosed by the inner mitochondrial membrane that contains enzymes, mitochondrial DNA, and ribosomes.

• Intermembrane space: The narrow region between the outer and inner mitochondrial membranes.

★ Must-know

• Mitochondria occur in eukaryotes, including plants, animals, fungi, and protists, and their number depends on the cell's metabolic activity.

• A chloroplast is lens-shaped, has two membranes separated by an intermembrane space, and contains flattened interconnected sacs called thylakoids, stacks of thylakoids called grana, and fluid outside the thylakoids called stroma.

Further detail

• A mitochondrion is enclosed by two phospholipid bilayer membranes; the outer membrane is smooth and the inner membrane has convoluted infoldings called cisternae.

💡 Memory Hook

Mitochondrial matrix is inside the inner membrane; chloroplast stroma is outside the thylakoids.

📖 5. Plant and Animal Cell Features

🔑 Key Concepts & Definitions

• Plasmodesmata: Channels through perforations in many plant cell walls that connect adjacent cells.

★ Must-know

📌 Plant cells are usually larger and square or rectangular, with a cell wall and plastids; animal cells are comparatively smaller and irregular or round, with no cell wall or plastids.

📌 Plant cells usually have a side-positioned nucleus, few large vacuoles or one central vacuole, fewer mitochondria, rare lysosomes, and no centrosome; animal cells usually have a central nucleus, small and numerous vacuoles, numerous mitochondria, lysosomes, and a centrosome.

Further detail

• Both plant and animal cells have:
  • a plasma membrane
  • cytoplasm
  • a nucleus
  • endoplasmic reticulum
  • Golgi apparatus
  • ribosomes
  • mitochondria

💡 Memory Hook

Plant cells have a cell wall and plastids; animal cells have a centrosome and lysosomes.

📊 Synthesis Tables

Plant and Animal Cell Comparison

Feature	Plant cell	Animal cell
Size and shape	Usually larger; square or rectangular	Comparatively smaller; irregular or round
Cell wall and plastids	Present	Absent
Nucleus	Usually lies at the side	Usually lies in the centre
Vacuoles	Few large vacuoles or one central vacuole	Usually small and numerous
Lysosomes, mitochondria, and centrosome	Lysosomes rare; fewer mitochondria; centrosome absent	Lysosomes present; numerous mitochondria; centrosome present