The Structure of Animal and Plant Cells

I. STRUCTURE OF ANIMAL CELLS

Animal cells are eukaryotic, which means they have a nucleus and other specialised structures called organelles.
The nucleus contains genetic material (DNA) that controls the cell’s activities.
Cytoplasm is the jelly-like substance where most of the cell’s activities occur, including protein synthesis.
The cell membrane is semi-permeable and regulates the entry and exit of substances.
Mitochondria are the site of aerobic respiration, where energy is produced.
Ribosomes are the sites of protein synthesis.

II. STRUCTURE OF PLANT CELLS

Like animal cells, plant cells are also eukaryotic.
They also have a nucleus, mitochondria, ribosomes, and a cell membrane, serving similar functions as in animal cells.
In addition to these, plant cells also contain chloroplasts. These are organelles that contain chlorophyll for photosynthesis.
Plant cells have a cell wall made of cellulose, which helps to maintain the shape of the cell and support the plant.
They also have a large central vacuole filled with cell sap, which maintains the turgor pressure in the cell.

III. MOVEMENT ACROSS MEMBRANES

Small, uncharged molecules can diffuse directly across the cell membrane. This is called simple diffusion.
Osmosis refers to the movement of water molecules across the cell membrane, from a region of higher water concentration to a region of lower water concentration.
Larger or charged molecules require protein channels or carriers to help them travel across the cell membrane. This is facilitated diffusion.
Active transport is the movement of substances against a concentration gradient, from lower to higher concentration. It requires energy.

Remember to revisit diagrams of plant and animal cells to understand the spatial arrangement of different organelles. Practice drawing and labelling these diagrams yourself.

Regularly review different types of passive and active transport mechanisms, as these are key concepts in understanding the function of cell membranes. Understanding these mechanisms would also aid in comprehension of essential biological processes, like nutrient absorption and waste secretion.