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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

CarbohydratesSugars and starches

LipidsFats and oils

ProteinsIncluding enzymes

Nucleic acidsDNA 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