Cell organelles

7- Peroxisomes: Functions of peroxisomes: contain enzymes that transfer hydrogen from various substrates to oxygen. Functions of peroxisomes: Hydrogen peroxide (H2O2) is a poison, but the peroxisome has enzyme that converts H2O2 to water. Some peroxisomes break fatty acids down to smaller molecules that are transported to mitochondria for fuel. They detoxify alcohol and other harmful compounds. Thus, it exists extensively in the liver cells

8- Mitochondria: They are the main energy transformers of cells as they convert energy to fuel that cells can use for work. Mitochondria are the sites of cellular respiration. Generating adenosine triphosphate ATP from the catabolism of sugars, fats, and other fuels in the presence of oxygen. Almost all eukaryotic cells have mitochondria. Mitochondria and chloroplasts are move around the cell along tracks in the cytoskeleton.

Mitochondria have a smooth outer membrane and a highly folded inner membrane forming cristae. The inner membrane encloses the mitochondrial matrix, a fluid-filled space with DNA, ribosomes, and enzymes.

The cytoskeleton: A network of fibres that provide structural support to the cell. The cytoskeleton also functions in cell motility and regulation. The cytoskeleton is a network of fibers extending throughout the cytoplasm. The cytoskeleton organizes the structures and activities of the cell.

Cytoskeleton Microfilaments Intermediate filaments Microtubules Thick Thin Middle Responsible for cell motility, and separation of chromosome during cell division. (Tubulin protein) Support cell motility and transport materials within the cell. (Actin protein) Reinforcing the cell shape and fixing position of organelles. (Fibrous protein)

Comparison between cilia and flagella: Microtubules are the central structural supports both cilia and flagella. Both can move unicellular and small multicellular organisms by propelling (Pushing) water outside the organism. Comparison between cilia and flagella: Cilia usually occur in large numbers on the cell surface. Flagella usually occur in just one or a few per cell. Cilia move more like oars with alternating power and recovery strokes. Flagella have an adulatory movement. So, they differ in their beating pattern.

Cilia Flagellum

Cilia and flagella are formed of arms of a motor protein (dynein). Dynein arms alternately grab, move, and release the outer microtubules. Protein cross-links limit sliding and the force is expressed as bending.

Many prokaryotes are motile About half of all prokaryotes are capable of directional movement by the following: By the flagella, scattered over the entire surface, is the most common method of movement. By two or more filaments. By threads that anchors (Link) the cells to the substratum. By cilia.

Cell membrane: The plasma membrane functions as a selective barrier that allows passage of oxygen, nutrients, and wastes for the whole volume of the cell.

Cell membrane: Composed of lipids (phospholipids) and proteins. Carbohydrate chains Hydrophilic Phospholipid Hydrophobic Proteins Composed of lipids (phospholipids) and proteins. Lipid layer contains hydrophilic and hydrophobic regions