Cell Structure and Organisation Flashcards
Cell theory
- All living organisms are composed of one or more cells
- The cell is the basic unit of life
- Cells can only arise from pre-existing cells
Eukaryotic Cells
-Contain a true nucleus and membrane bound organelles
E.g plant, animal, protocists and fungi cells
Prokaryotic Cells
-Do not contain a true nucleus or membrane bound organelles
Nucleus
Structure:
- Nuclear envelope encloses chromatin (DNA/RNA/Proteins)
- Nuclear pores perforating the nuclear envelope
- Nucleolus inside
Function:
- Contains the cell’s genetic material, regulating activity
- Nucleolus: Synthesis of ribosomal RNA (rRNA)
Rough Endoplasmic Reticulum
Structure:
- Ribosomes attached to surface
- Cisternae are flat
Function:
-Synthesis, folding and modification of proteins
Smooth Endoplasmic Reticulum
Structure:
- NO ribosomes attached
- Cisternae are more tubular
Function:
-Synthesis, storage and transportation of carbohydrates and lipids
Ribosomes
Structure:
- Comprised of 2 parts: 1 large subunit and 1 small subunit
- Made from ribosomal RNA
- 80s in Eukaryotes
- 70s in Prokaryotes, mitochondria and chloroplasts
Golgi Apparatus
Structure:
- Golgi Body: Series of curved membranes enclosing a series of stacks of flattened sacs
- Golgi Vesicles at end of stack
Function:
- Modification, sorting and packaging of proteins and lipids (e.g glycoproteins, glycolipids)
- Transportation of these materials through the cell
- Manufacture of macromolecules
Mitochondria
Structure:
- Inner and Outer membrane
- Intermembrane space
- Cristae (Folds)
- 70s ribosomes
- Mitochondrial matrix
- Circular DNA
Function:
- Site of aerobic respiration
- Synthesises ATP
- Found in abundance in metabolically active cells
Vacuoles
Structure:
- Membrane bound sac
- Large central vacuole in plants
- Small vacuole in animals
Function:
-Large central vacuole of plants provide cell volume and stores inorganic ions
Lysosomes
Structure:
- Spherical single membrane sacs
- Contain hydrolytic and digestive enzymes
Function:
- Digestion of macromolecules within the cell
- Transport hydrolytic and digestive enzymes
Centrioles
Structure:
-9 sets of triplet microtubules
Function:
-Used to form spindle fibres for nuclear division
Chloroplasts
Structure:
- Outer membrane
- Intermembrane space
- Inner membrane
- Stroma (fluid)
- Lamellae
- Thylakoid
- Grana (Thylakoid stacks)
Function:
-Site of photosynthesis
Cellulose Cell Wall
Structure:
-Made from long cellulose fibres
Function:
- Protects the cell
- Maintains shape
- Prevents bursting when water enters
Plasmodesmata
- Narrow strands of cytoplasm that pass through tiny pores in adjacent plant cell walls
- Used for cell to cell communication
Large Central Vacuole
Structure:
-Sac surrounded by membrane called Tonoplast
Function:
- Helps regulate the osmotic properties of cells
- Provides support
Prokaryotic Cells
- Circular DNA
- Cell Membrane
- Peptidoglycan Cell Wall
- 70s Ribosomes
- Cytoplasm
- Pilli
- Slime capsule
- Plasmids (Smaller loop of DNA)
- Mesosomes (site of respiration)
Endosymbiosis
- Mitochondria and chloroplasts were once free-living prokaryotes
- Engulfed into other cells by endocytosis
- Eukaryotic cells received source of sugar (chloroplast), and a way to break down the sugar to ATP (Mitochondria)
Viruses
- Capsid
- Nucleic Acid (DNA or RNA)
Organisation
Cell -> Tissue -> Organ -> Organ System
Tissue
An aggregation of SIMILAR cells with the same function:
- Epithelial tissue
- Connective tissue
- Muscle tissue
Tissue types
- Ciliated epithelium: Cells with hair-like cilia
- Columnar epithelium: Cells that are longer than wide
- Squamous epithelium: Thin cells
- Smooth muscle: Involuntary contractions (No striations)
- Striated muscle: Voluntary contractions (Striations)
- Cardiac muscle: Involuntary myogenic contractions (Striated)
- Connective tissue: Fills spaces with cells, collagen fibres and elastic fibres
