Cells and Movement Across Membranes
Animal Cells
Animals and plants are multicellular organisms, consisting of many cells that work together. The main parts of an animal cell are the nucleus, cell membrane, cytoplasm, and mitochondria.
Plant Cells
Plant cells contain the same features as animal cells but also have additional ones such as chloroplasts, a cell wall made of cellulose, and a large central vacuole.
Cell Structures
The features of cells are essential for their function. Control of movement of substances, chemical reactions, genetic information, energy release for the cell, and support from tough substances such as cellulose are significant functions.
Microscopy
Microscopes are used to observe objects that are too small to be seen by the naked eye. The light microscope passes light through the object and uses lenses to magnify an image of the object.
Differentiation
Multicellular organisms begin life as a single fertilized egg cell called a zygote. The cells begin to adapt to specific functions through a process called differentiation, which is controlled by genes.
Differentiated Cells
Nerve Cell
A nerve cell is long and insulated with a fatty layer to carry electrical impulses around the body.
Sperm Cell
A sperm cell has a tail to swim to the egg.
Palisade Cell
A palisade cell is packed with chloroplasts for photosynthesis.
Xylem Cell
A xylem cell is a long, thin, straw-like waterproof tube carrying water from plant roots to leaves.
Red Blood Cell
Red blood cells are a biconcave shape, have no nucleus, and contain hemoglobin to carry oxygen around the body.
Transport and Concentration Gradients
The idea of concentrations and gradients is important when understanding the movement of particles or molecules across cell membranes. Concentration gradients exist when there is a region of high concentration leading to a region of low concentration.
Diffusion as Passive Transport
Diffusion is the movement of particles from a region of high concentration to a region of low concentration and is known as passive transport. Examples of diffusion in living organisms include the transfer of products of digestion and the exchange of oxygen and carbon dioxide in the lungs.
