C ELL S TRUCTURE AND O RGANELLES

A NIMAL C ELL Electron micrograph of a typical animal cell Note: mitochondria in red, nucleus in peach, endoplasmic reticulum in blue

a5b Structures in the animal cell nuclear pore chromatin nucleus nucleolus rough endoplasmic reticulum smooth endoplasmic reticulum ignore cytoplasm vacuole Golgi body cell membrane vesicle cytoskeleton lysosome mitochondria ribosome centriole microtubule

P LANT C ELL Electron micrograph of a typical plant cell Note: mitochondria in red, nucleus in green, plastids in yellow

Structures in the plant cell nuclear pore chromatin nucleolus vacuole chloroplast mitochondria microtubule cell wall Golgi body cell membrane vesicles endoplasmic reticulum nuclear membrane cell wall microtubule ribosomes cytoplasm lysosome

C ELL M EMBRANE Functions of cell membrane: protects cell from outside environment; keeps cell contents together; selectively allows materials to cross into & out of cell.

Cell membrane

C ELL M EMBRANE transmembrane protein glycocalyx

C ELL M EMBRANE Phospholipid: composed of a phosphate “head” and fatty acid “tails.” Hydrophilic head Hydrophobic tail Hydrophilic Head is “water loving” or soluble in water. Hydrophobic Tails are “water hating” or insoluble in water.

Proteins: functions include: structural support surface binding sites for molecules like hormones recognition sites for cell to cell communication & interaction transport molecules across the membrane transport electrons & protons within the membrane “float” around within the membrane or on its surface;

Glycocalyx: Cholesterol: carbohydrate chains attached to proteins (glycoproteins), involved in recognition & communication proteins, points for cell to cell attachment keeps the phospholipids stable and helps retain the membrane‘s shape Cell Membrane

M ITOCHONDRIA Mitochondria are the site of aerobic cellular respiration Cellular respiration is the process that converts sugar energy into adenosine triphosphate (ATP) for storage (overall reaction: glucose + O 2  CO 2 + H 2 O + ATP energy) ATP is used by other organelles & cell processes for energy

M ITOCHONDRIA outer membrane – protects and controls entry of materials inner membrane – folded into cristae intermembrane space cytosol containing ions

M ITOCHONDRIAL STRUCTURES Cristae: site of chemical reactions using embedded proteins Matrix: mitochondrion cytosol Mitochondrial DNA: self replicating organelle, produces its own unique proteins

C HLOROPLASTS Chloroplasts are found only in green plants They convert sunlight to chemical energy via photosynthesis (sunlight + CO 2 + H 2 O --> glucose + O 2 )

C HLOROPLAST STRUCTURES Stroma: chloroplast cytosol Lamella: membrane that attaches inner chloroplast structures Thylakoid disk: have a specialized membrane for photosynthesis Grana: stack of thylakoid discs Chloroplast DNA: self- replicating organelle

N UCLEUS Electron micrograph of a nucleus Note: nucleolus in center of nucleus, endoplasmic reticulum and ribosomes just outside of nucleus

C OMPONENTS OF THE N UCLEUS Nucleolus: the densest area within the nucleus; the location for production of ribosomes Chromatin: stringy material made of proteins and DNA that makes up the majority of the nucleus Chromosomes: just before the cell divides thechromatin condenses into chromosomes

N UCLEUS

C HROMATIN AND C HROMOSOMES chromosomes chromatin

R IBOSOMES Ribosomes are microscopic spheres attached to the ER or free- floating in the cytoplasm Ribosomes are protein factories

E NDOPLASMIC R ETICULUM The ER is a twisting network of canals and sacs extending through the cytoplasm and connecting the cell membrane to the nuclear membrane The ER may have ribosomes attached to it (rough ER) The ER serves to transport products (e.g. proteins) within the cell

G OLGI A PPARATUS The Golgi bodies are sacs of membranous plate-like bags which produce vesicles (sacs) They function to produce and store cellular secretions Many proteins and lipids undergo final processing in the Golgi complex

L YSOSOMES Membrane bound sacs that are used for digestion of various structures within the cell An acidic environment along with hydrolytic enzymes within lysosomes help to digest particles

C ILIA AND F LAGELLA Both are made of fine protein fibres Both can be used for locomotion Cilia: short, may be numerous on cell surface Flagella: long, usually few in number on cell surface

Questions from textbook Microscope drawings Microscope problems