Chapter 1.2 - Reviewing Cells Flashcards
What are cells?
Cells are the basic structural and funcitonal units of living organisms
What are the 3 tenets of cell theory?
- All organisms are composed of cells
- All cells come from pre-existing cells (this is the principle of biogenesis)
- The cell is the smallest living organisational unit
What are prokaryotes?
Unicellular organisms that lack a membrane-bound nucleus
Examples of prokaryotes
Bacteria, archaea
What are eukaryotes?
Any cells or organisms with a membrane-bound nucleus and other membrane bound organelles.
Examples of eukaryotes
Protists, fungi, animals, plants
Key features of eukaryotic cells
- Membrane-bound organelles
- Chromosomes present as multiple linear DNA molecules
- Larger
- Contains cytoskeleton
- Usually multicellular
Key features of prokaryotic cells
- Single circular chromosome (genophore)
- Lacks membrane bound nucleus, has nucleoid instead
- Scattered ribosomes
- Smaller
- Small rings of DNA called plasmids found in cytoplasm
Features common to all cells
- Plasma membrane
- Cytoplasm
- Genetic material (DNA)
- Ribosomes
- Use ATP (adenosine triphosphate) as a source of energy
Gram-positive vs Gram-negative bacteria
Classification based on the composition of its outer layer.
Gram-positive bacteria have a thick peptidoglycan layer than can stain purple, while gram-negative bacteria have a thinner peptidoglycan layer than stains pink or red.
What is the nucleus?
Membrane-bound organelle that stores genetic material and controls cell activities/functions.
What is the nucleolus?
A small, dark, area in the nucleus that produces incomplete ribosomes
What are ribosomes?
Site where polypeptide chains are synthesised/assembled.
Can be free-floating or located on the rough ER.
What is the rough endoplasmic reticulum (ER)?
Network of membrane-enclosed flattened channels with ribosomes embedded. Involved in the synthesis and processing of specific proteins.
What is the Golgi body?
A stack of flattened sacs (cisternae), which further modifies and packages proteins for export via vesicles, which move to the plasma membrane and fuse with t to discharge their contents to the exterior via exocytosis.
What is the smooth ER?
Network of membrane-enclosed flattened channels involved in the synthesis of lipids.
What is a mitochondrion?
Site of cellular respiration, where ATP synthesis occurs
What is a chloroplast?
Site of photosynthesis in a plant and algal cells.
Most prominent plastid (double-membrane bound organelles unique to plant and algal cells, with photosynthesis and storage functions)
What are centrioles?
Small structures involved in cell division that are composed of microtubules
What are cilia and flagella?
External structures for cell movement. Composed of microtubules.
What is a lysosome?
Membrane-bound vesicle containing digestive enzymes. Serves purpose of digesting waste and foreign materials
What is a vacuole?
Large membrane-bound vesicle serving for storage and structure in plant cells/
What are peroxisomes?
Small organelles involved in metabolic reactions, including breaking down harmful materials
What is the cell wall?
External structure in plant cells that surrounds the plasma membrane, protecting and supporting the cell. Made of cellulose.
