SPM Biology 2 Cell Biology & Organization Part 2 Cell Structure & Functions

Mitochondrion

Mitochondrion (Plural: Mitochondria)

• Rod-shape / spherical
• 2 layers of membranes
• Functions: 
• A site that generates energy

Centriole

Centriole

• Small cylindrical components that exist in pairs in animal cells, X in plant cells
• Made up of microtubules 
• Functions:
• Forms spindle fiber during cell division

Golgi Apparatus

Golgi Apparatus

• Stack of parallel flattened sacs, single cell membrane
• Functions:
• Processes, modifies, packs and transports chemicals (protein, carbohydrate etc.)

Plasma Membrane

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  Plasma Membrane

  Outer membrane that surrounds the cell
• Made of proteins & phospholipids
• Thin, elastic
• Functions:
• Controls movement of substances into & out of the cell
• Separates content of cell from external environment
• Allows exchange of nutrients, gases and waste materials between cells & their surroundings

Lysosome

Lysosome

• Small spherical sac, single membrane
• Contains hydrolytic enzymes
• Functions:
• Hydrolyses complex organic molecules (protein, nucleic acid & lipid)
• Breaks down bacteria, damaged cells

Nucleus

Nucleus (Plural: Nuclei)

• Largest component in the cell
• Spherical, enclosed in nuclear membrane with many pores
• Double membrane
• Contains chromosomes, nucleolus and nucleoplasm 
• Functions:
• Controls all cell activities
• Chromosomes contain deoxyribonucleic acid (DNA)

Ribosome

Ribosome

• Small, compact, spherical granules
• Consists protein and ribonucleic acid (RNA)
• Present on the surface of rough endoplasmic reticulum / freely exist in cytoplasm
• Function:
• Site for protein synthesis

RER & SER

Endoplasmic Reticulum (ER)

• Folded flattened sacs
• Two types of ER
• Rough ER: has ribosomes attached on the surface
• Smooth ER: X ribosomes
• Functions:
• Act as transport system within the cell
• RER transports proteins synthesized by ribosomes
• SER synthesizes & transports glycerol and lipids, detoxify drugs and metabolic by-products 

Cytoplasm

Vacuole

Cytoplasm 

• Jelly-like medium that contains the components of cells
• Contain organic (protein, carbohydrate etc.) & inorganic (potassium ions) compounds 
• Functions:
• Medium for biochemical reactions in cells

Vacuole

• Liquid-filled sac, the liquid called cell sap
• Surrounded by tonoplast
• Exist in plant cells
• Small size in unicellular animals 
• Functions:
• Water is absorbed into the vacuole and the plant cell becomes turgid
• In unicellular animals, vacuole contracts during osmoregulation, osmosis and excretion

Chloroplast

Chloroplast

• Oval shaped
• 2 layers of membrane
• Contains chlorophyll
• Functions:
• Chlorophyll absorbs sunlight during photosynthesis

Cell Wall 

Cell Wall 

• Strong and rigid outer layer of plant cells
• Made from cellulose fiber
• Fully permeable
• Functions:
• Maintains the shape of plant cells
• Provides mechanical support to plant cells