علم وظائف الأعضاء للنباتات

Course Information

• Course title: General Botany I - Physiology
• Prepared by: Prof. assist Dr. Zeinab Ashour

What is Plant Physiology?

• The study of the function of plant cells, tissues, organs, and the chemistry behind these functions.
• Crucial to recognize that these functions depend on their structures.

Plant Anatomy

• Flower
• Leaf
• Fruit
• Stem
• Root

Plant Tissue Systems

• Diagrams of plant tissues are included (but no details are provided)

Plant Cell Diagram

• Chloroplast: Site of photosynthesis
• Nucleolus: Found inside the nucleus, plays a role in ribosome synthesis
• Ribosomes: Responsible for protein synthesis
• Large central vacuole: Maintains turgor pressure, stores substances
• Mitochondrion: Site of respiration
• Cell membrane: Outer boundary of the cell; controls permeability
• Cytoplasm: Site of many biochemical reactions

Course Outline

• Diffusion, osmosis, and permeability
• Plasma membrane
• Colloids in plants
• Cytoplasm
• Photosynthesis
• Chloroplast
• Respiration
• Mitochondria
• Enzymes in all compartments

Evaluation

• Midterm Exam (10 marks)
• Oral Exam and Assignments (15 marks)
• Practical Exam (20 marks)
• Final Written Exam (60 marks)

Plasma Membrane

• Encloses all cells, acting as the outer boundary.
• Separates the cytoplasm from the external environment.
• Allows selective uptake and retention of substances.
• Embedded transport proteins are responsible for selective transport of molecules across the membrane.

Biological Membranes (details)

• Composed of a phospholipid bilayer with embedded proteins.
• Phospholipids consist of two fatty acid tails (nonpolar) and a phosphate group head (polar), creating a hydrophilic-hydrophobic region.

Membrane Proteins (integral)

• Integral proteins are embedded in the lipid bilayer.
• Parts of these proteins interact with the outside environment, the hydrophobic core of the membrane, and the interior of the cell.

Membrane Proteins (peripheral)

• Attached to the membrane surface by non-covalent bonds.
• Involved in interactions between the plasma membrane and components of the cytoplasm (e.g., microtubules).

Permeability to Various Substances

• Non-ionized substances: Enter and leave by simple diffusion, a passive process.
• Size: Small non-polar substances diffuse directly, whereas large ones require membrane proteins (passive facilitated diffusion).
• Solubility: Substances with a high affinity for lipids (oily material) permeate quicker. Larger molecules, with equal lipid solubility, permeate slowly.
• Ions move slower through membranes due to charge interactions..

Active Transport

• Ions cross membranes against their concentration gradient.
• Requires energy (metabolic energy) and transmembrane protein pumps.
• Accumulation of ions or molecules in the cytosol happens through transport proteins.

Selective Uptake of Ions

• Living cells are selective in absorbing and accumulating versus rejecting ions.
• Monovalent cations, such as K+, are absorbed faster than polyvalent ones, such as Ca2+.
• Cells may favor certain ions over others, even with the same valence.