Cell Structure (1.2) Flashcards
Prokaryote Cells- General Information
- Unicellular bacteria eg. eubacteria and archaebacteria cells- 0.5 to 10 µm in size- The chromatin material and DNA are not held within a nuclear membrane or bound to proteins (histones)- The prokaryote chromosome is a simple DNA chain with its ends joined to form a circle- Prokaryote cells do not have membrane bound organelles like mitochondriaBacteria may be autotrophic (blue-green algae, cyanobacteria), heterotrophic (salmonella) or chemotrophic.
Prokaryote Cells- Structure
Cytoplasm: The internal fluid component of a cell.Cell membrane: The semi-permeable and selective layer surrounding a cell.Cell wall: A rigid outer covering made of peptidoglycan that maintains shape and prevents bursting (lysis).Plasmids: Autonomous circular DNA that can be transferred between bacteria by conjugation.Pili: Hair like extensions that enable adherence to surfaces (attachment pili) or meditate bacterial conjugation (sex pili).Ribosomes: Complexes of RNA and proteins that are responsible for polypeptide synthesis.Flagella: Long slender projections that contain a motor protein enabling movement (singular=flagellum).Slime capsules: A thick polysaccharide layer that is used for protection against dessication (drying out) and phagocytosis.
Give four examples of Eukaryote Cells
Animals Cells eg. muscle cells, skin cellsMulticellular and heterotrophic. Possess nucleus and membrane bound organelles but lack cell walls.Plant Cells eg. leaf cellsMulticellular and autotrophic (possess chlorophyll so photosynthetic). Their cell walls are made of cellulose. Protist Cells eg. chlorella, euglena, paramecium, amoebaMay be unicellular or multicellular.Fungal Cells eg. yeast, mushrooms, mouldUnicellular and heterotrophic (extracellular digestion). Cell walls made of chitin.
Animal Cells (Structures)
Able to be seen through a light microscope (400x magnification)Cytoplasm: Inner fluid component of a cell. Cell membrane: Semi-permeable barrier surrounding the cell. Controls which materials come in/out of the cell.Nucleus: Contains DNA and controls the cell’s activities. (The nucleolus works within the nucleus).Able to be seen through an electron microscope (100,000x magnification)Mitochondria: The site of respiration (where the cell converts its food into energy).Ribosomes: The site of protein synthesis (80S form)Lysosomes: Manages cell waste with enzymesSmooth endoplasmic reticulum: Transport system from nucleusRough endoplasmic reticulum: Transport system from nucleus with ribosomesGolgi bodies (apparatus): Packages proteins for secretion into vesiclesCentrioles: Makes spindles for cell divisionSmall vacuoles (vesicles): Stores food, chemicals and water.Microtubules: Control cell structure and shape
Plant Cells (Structure)
Able to be seen through a light microscope (400x magnification):Cytoplasm: Internal fluid component of a cellCell membrane: Semi-permeable barrier surrounding a cellCell wall: Rigid outer barrier made of cellulose. Helps to maintain cell shape.Nucleus: Contains DNA and controls cell’s activity. (Nucleolus works within the nucleus).Large vacuole: Storage (usually water)Able to be seen through an electron microscope:Mitochondria: Site of respiration (where the cell converts its food into energy)Ribosomes: Site of protein synthesis, 80S form.Smooth endoplasmic reticulum: Transport system from nucleus.Rough endoplasmic reticulum: Transport system from nucleus with ribosomes.Golgi bodies (apparatus): Packages proteins for secretion into vesicles.
Four main processes needed for the origin of life on Earth
1) The non living synthesis of simple organic molecules eg. amino acids, nucleotides, glucose2) The formation of these molecules into polymers eg. proteins, nucleic acid, starch3) The origin of self-replicating molecules that make genetic inheritance possible eg. DNA and RNA4) The packaging of all of these molecules into membranes with internal chemistry different to their surroundings eg. cells
