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.

تتناول هذه الاختبارات علم وظائف الأعضاء للنباتات، بما في ذلك وظائف الخلايا والنسيج والأعضاء. كما تغطي أيضًا بنية وخصائص الأنسجة المختلفة في النباتات وأهمية كل منها. ستكون هذه المعلومات ضرورية لفهم أداء النباتات في بيئتها.