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Biology of the Cell

Cells are the Fundamental Unit of All Living Things Prokaryotes  Single-cell organisms  Cells have no nucleus or membrane-bound organelles  Bacteria Eukaryotes (YOU-karyotes)  Multicellular organisms  Each cell has membrane-bound organelles, including a nucleus  Animals and plants

Prokaryotes vs. Eukaryotes

Tissues Are Composed of Cells

Chemical Constituents of Cells Carbohydrates  Sugars and starches Lipids  Fats and oils Proteins  Including enzymes Nucleic acids  DNA and RNA

Cell Structure and Components

Membrane-bound Organelles Nucleus Endoplasmic Reticulum  Smooth and Rough Golgi Complex Lysosomes and Peroxisomes Mitochondria

Nucleus Location of chromosomal DNA  DNA contains the “recipes” for making proteins  Proteins give cells their specific characteristics and functions Nucleolus  Site of ribosome production

Endoplasmic Reticulum Rough  Covered in ribosomes  Site of protein synthesis Smooth  Site of lipid synthesis

Ribosomes Scaffolding for protein synthesis Composed of RNA rRNA tRNA mRNA Growing protein

Golgi Apparatus Processing center Site of sugar synthesis Vesicles bud off of Golgi

Lysosomes and Peroxisomes Sacs of enzymes Lysosomes  Degrade cellular debris Peroxisomes  Degrade lipids and other biochemicals

Mitochondria Site of energy production Contains its own circular DNA Inherited from mom

Cytoskeleton Protein scaffolding Give cell its shape Transport cellular contents 3 major components  Microtubules  Intermediate filaments  Microfilaments

Microtubules Largest diameter Hollow tubes Composed of tubulin dimers Important for cell division Form cilia

Intermediate Filaments Smaller than microtubules Coiled rods Composed of dimers of different proteins depending on cell type Important for cellular attachments

Microfilaments Smallest component of the cytoskeleton Long, thin rods Composed of actin Important for stretching and compression of the cell Important for cell-cell interactions

Plasma Membrane Encompasses cytoplasm and organelles Phospholipid bilayer Regulates what enters and exits the cell Hydrophilic head Hydrophobic tail

Exocytosis and Endocytosis

Molecules in the Plasma Membrane Give cell its characteristics Glycoproteins  Proteins with sugar attached Glycolipids  Lipids with sugar attached Proteins  Receptors/Signal Transduction  Cell adhesion

Receptors Proteins embedded in the plasma membrane A ligand is a molecule that binds to a receptor Ionotropic  Allow direct passage of molecules into cell Metabotropic  Cause a cascade of events involving secondary messengers and enzymes

Signal Transduction Metabotropic receptors Outside stimuli (extracellular) changed into intracellular biochemical reaction Signal is changed and amplified Aris Q3

Cell Adhesion Cellular adhesion molecules (CAMs) Bind to adhesion receptor proteins Mouse embryonic neurons migrating up radial glia

Cell Adhesion and Schizophrenia Delusions Hallucinations Motor disturbances Inappropriate affect

Secretion “There are three reasons for breast- feeding: the milk is always at the right temperature; it comes in attractive containers; and the cat can't get it.” - Irena Chalmers