Topic 1 | Cell Biology Flashcards
What are the main differences between eukaryotic and prokaryotic cells?
Eukaryotic cells (found in animals and plants) have a nucleus, membrane-bound organelles, and linear DNA. Prokaryotic cells (e.g., bacteria) are smaller, lack a nucleus, have circular DNA, and may contain plasmids.
What are the key structures in an animal cell and their functions?
Nucleus: Contains DNA and controls cell activities. Cytoplasm: Where chemical reactions occur; contains enzymes and organelles. Cell membrane: Controls what enters and leaves the cell. Mitochondria: Site of aerobic respiration, providing energy. Ribosomes: Site of protein synthesis.
What are the additional structures in plant cells compared to animal cells?
Chloroplasts: Site of photosynthesis, contain chlorophyll. Permanent vacuole: Contains cell sap, maintains cell rigidity. Cell wall: Made of cellulose, provides strength and support.
What are the key structures in a bacterial cell?
Cell wall: Made of peptidoglycan. Cell membrane: Controls entry and exit of substances. Cytoplasm: Contains enzymes and organelles. Circular DNA: Floats in the cytoplasm. Plasmids: Small rings of DNA.
What is cell specialisation and why is it important?
Cell specialisation is the process by which cells develop specific structures to perform specific functions. It allows organisms to have cells that are highly efficient at particular tasks, such as nerve cells transmitting electrical signals or muscle cells contracting.
How are sperm cells adapted for their function?
Streamlined head and long tail: Aid in swimming. Many mitochondria: Provide energy for movement. Acrosome: Contains enzymes to break down the egg cell membrane.
How are nerve cells adapted for their function?
Long axon: Allows transmission of electrical signals over long distances. Dendrites: Form connections with other nerve cells. Mitochondria: Provide energy for neurotransmitter production.
How are root hair cells adapted for their function?
Large surface area: Increases water and mineral ion uptake. Large permanent vacuole: Speeds up water movement. Mitochondria: Provide energy for active transport of mineral ions.
How are xylem cells adapted for their function?
Hollow and joined end-to-end: Form continuous tubes for water transport. Lignin: Strengthens cells and makes them waterproof. Spiral lignin deposits: Help withstand water pressure.
How are phloem cells adapted for their function?
Sieve plates: Allow movement of food substances between cells. Companion cells: Provide energy via mitochondria for phloem cells.
What is cell differentiation and how does it occur?
Cell differentiation is the process by which cells become specialised. It involves certain genes being switched on or off, leading to the production of specific proteins that allow the cell to perform a particular function.
What are the stages of mitosis?
Interphase: Cell grows, DNA replicates. Mitosis: Chromosomes line up and are pulled apart. Cytokinesis: Cytoplasm divides, forming two identical daughter cells.
What are stem cells and their types?
Embryonic stem cells: Can differentiate into any cell type. Adult stem cells: Found in bone marrow, can form specific cell types. Meristems in plants: Can differentiate into any plant cell type.
What is diffusion and what factors affect its rate?
Diffusion is the movement of particles from an area of high concentration to low concentration. Factors affecting its rate include: Concentration gradient: Greater gradient increases rate. Temperature: Higher temperature increases rate. Surface area: Larger surface area increases rate.
What is osmosis and how does it affect cells?
Osmosis is the movement of water across a partially permeable membrane from a dilute to a concentrated solution. In animal cells, it can cause cells to burst or shrivel. In plant cells, it affects turgor pressure and can lead to plasmolysis.
What is active transport and where does it occur?
Active transport is the movement of particles against their concentration gradient, requiring energy. It occurs in root hair cells (uptake of mineral ions) and in the gut (absorption of glucose and amino acids).
How are microorganisms cultured in the lab?
Microorganisms are grown in nutrient broth or on agar plates. Steps include sterilising equipment, inoculating with microorganisms, and incubating at 25°C to prevent harmful bacteria growth.
What is binary fission and how is it calculated?
Binary fission is the process by which bacteria divide. The number of bacteria after a certain time can be calculated using the formula: Bacteria at end = Bacteria at beginning × 2^(number of divisions)
How is the effectiveness of antibiotics tested?
Antibiotic-soaked paper discs are placed on an agar plate with bacteria. The size of the inhibition zone (clear area) indicates the effectiveness of the antibiotic.
Why is surface area to volume ratio important in cells?
A larger surface area to volume ratio allows for more efficient diffusion of substances. Single-celled organisms rely on diffusion, while multicellular organisms have specialised systems to overcome their smaller ratio.
