Bio Lecture 10: Endomembrane System & Cytoskeleton Structure & Function

Endoplasmic Reticulum

interconnected system of membrane-enclosed compartments

Rough Endoplasmic Reticulum

composed of flattened sacks and cisternae. associated with ribosomes. help fold, glycosylate, and tag proteins for cellular delivery.

Smooth Endoplasmic Reticulum

tubular and lacks ribosomes. modifies small molecules, degrade glycogen in animals, store calcium, and synthesize steroids and lipids.

Golgi Apparatus

receives protein-containing vesicles from RER and modifies, concentrates, packages, and sorts proteins. Adds polysaccharides and modifies attached carbs added by RER. Site of synthesis of polysaccharides for cell wall in plants and fungi. involved in proteolysis and vesicular delivery.

Cis Golgi Apparatus

closer to nucleus or RER

Trans Golgi Apparatus

closer to plasma membrane

Lysosomes

have an acidic interior that contains hydrolytic enzymes that serve in cellular digestion/recycling of macromolecules to monomers. common in animals and serve roles in phagocytosis, exocytosis, and autophagy.

Mitochondria

the “powerhouse” of the cell which serves in cellular respiration and ATP production. composed of a matrix, an inner and outer membrane, and the cristae. the matrix contains ribosomes, DNA, and enzymes for energy conversion. the inner membrane is the selective barrier between cytosol and mitochondrial enzymes where ATP is produced. the outer membrane is non-selective and allows various materials across. the cristae contain key molecules for the ATP generation.

Chloroplasts

transform light into chemical bonds. composed of two membranes, stroma, and thylakoid membranes. stroma contain DNA and ribosomes. thylakoid membrane is composed of galactolipids and sulfolipids. overall, only 10% contain phospholipids.

Chromoplasts

store pigments

Leukoplasts

storage starch

Peroxisomes

made of roughly 50 enzymes. breaks down peroxides, oxidizes fatty acids, and lipid synthesis.

Glyoxosomes

only in plants. functions in converting lipids to carbohydrates.

Vacuoles

common in plants, fungi, and protists. rises from er or ga. structure is based on turgor pressure. Functions in reproduction of anthocyanins, pollination, and dispersal. Functions of digestion and storage of toxins, waste, and water.

Cytoskeleton

Made of microfilaments, intermediate filaments, and microtubules. Helps to support cell and maintain cell shape, hold organelles in place, facilitated movement of organelles within the cell, cytoplasmic streaming, and interacting with extracellular matrix.

Cilia

Propel the cells in protists and move fluid over stationary cell in respiratory system.

Flagella

push or pull a cell through an aqueous environment.