Animal Cell Structure

• Ribosome - The site where protein synthesis occurs.
• Nucleolus - A small structure within the nucleus responsible for producing ribosomes.
• Phospholipid bilayer= allows semipermeable texture (highly regulative)
• o   Polar phosphate head= hydrophilic
• Non-polar lipid tail= hydrophobic
• Cholesterol = stabilizes membrane, prevents it from becoming too fluid or too solid
• Cell Membrane maintains physical integrity of the cell and acts as barriers and gate keepers of the cell.
• Phospholipids of the cell membranes includes: Phosphatidylcholine, Phosphatidylethanolamine, Phosphatidylserine, Phosphatidylinositol, and

  Sphingomyelin
• The components of the cell membrane are glycerol, cholesterol, membrane proteins, and phospholipids.
• Glycolipids - carbohydrates attached to fatty acids
• Peripheral proteins: temporarily associated with the membrane.
• Integral proteins: permanently embedded within the plasma membrane.
• Channels: allow specific molecules or ions to pass through the membrane.
• Carrier Protein: binds to a substance on one side of the membrane and releases it on the other side.
• Channel: hydrophilic holes in cell membranes, facilitating transport of molecules down the concentration gradient.
• Carriers: transport chemicals across the membrane both down and up the concentration gradient.
• Cytoplasm is the second biggest organelle in terms of area and is a gelatinous liquid that fills the inside of a cell.
• Cytoplasm is composed of water, salts, and various organic molecules.
• Cytoplasm provides a platform upon which other organelles can operate within the cells.
• Nucleus is the most rigid and largest cell organelle
• Nucleus is programmed to control all the functions of the cell: acts as the brain.
• The heterogeneous structures of nucleus: heterochromatin and euchromatin
• Heterochromatin: tightly coiled inactive chromatin found in irregular clumps often around the periphery of the nucleus; electron dense
• Euchromatin: represents part of DNA that is active in RNA synthesis; electron lucent.
• Nucleolus: small non-membranous bodies known to be sites of ribosomal synthesis
• Ribosomes are composed of two subunits, one large (60S) and one small (40S).
• Messenger RNA (mRNA): molecules carry the coding sequences for protein synthesis and are called transcripts.
• Ribosomal RNA (rRNA) molecules form the core of a cell's ribosomes (the structures in which protein synthesis takes place).
• Transfer RNA (tRNA) molecules carry amino acids to the ribosomes during protein synthesis.
• Ribosomes synthesize proteins for the use, both within and outside the cell=protein factory
• Ribosome translates DNA to protein
• Endoplasmic reticulum is a membrane channel made up of cisterns or tubules
• Cytoplasm within tubules is vacuoplasm while outside tubules is hyaloplasm.
• The functions of endoplasmic reticulum: protein synthesis, steroid synthesis, lipid metabolism, and calcium storage.
• Golgi apparatus modifies and packages substances produced by the ER into vesicles that are transported out of the cell through exocytosis.
• Peroxisomes contain oxidative enzymes that produce hydrogen peroxide as a byproduct.
• Lysosomes contain enzymes that break down waste materials inside cells.
• Rough ER: modification of the synthesize proteins that are used up by the cells
• Smooth ER: produce the lipids and further processing of membrane proteins
• Golgi apparatus made up of stacks of cisternae and small rounded vesicles at the periphery.