Biology Transport Mechanisms Quiz

Cell Structure and Proteins

• Cholesterol stabilizes the membrane's fluidity in response to temperature variations.
• Integral proteins facilitate transport of substances across the cell membrane.
• Peripheral proteins assist in cell-to-cell recognition and signaling.
• Carbohydrate chains are crucial for cell identification and communication.

Transport Mechanisms

• Passive transport moves molecules without energy input.
• Simple diffusion involves the movement of molecules from high to low concentration.
• Facilitated diffusion uses carrier or channel proteins for substance transport.
• Osmosis refers to water diffusion, classified into isotonic, hypotonic, and hypertonic states.
  • Isotonic: equal water concentrations inside and outside the cell.
  • Hypotonic: higher external water concentration, may cause cell lysis.
  • Hypertonic: higher internal water concentration, may lead to cell shrinkage (plasmolysis).
• Active transport requires energy to move molecules against their concentration gradient.
  • Sodium-potassium pump is an example of a protein pump.
• Bulk transport includes exocytosis (material exiting) and endocytosis (material entering).

Types of Endocytosis

• Pinocytosis: uptake of small droplets of extracellular fluid.
• Phagocytosis: ingestion of large particles by specialized cells.
• Receptor-assisted endocytosis: intake of specific substances that bind to membrane proteins.

Cell Division and Meiosis

• Meiosis produces 4 genetically diverse daughter cells, each with 23 chromosomes (haploid).
• Crossing over occurs between non-sister chromatids, enhancing genetic diversity.
• Synapsis involves the pairing of homologous chromosomes.

Applications of Mitosis

• Stem cells can differentiate into various cell types, such as blood or muscle cells.
• Cloning in agriculture uses mitosis to reproduce organisms.
• Tissue culture allows survival and function of plant or animal fragments in artificial environments.

Cell Theory

• Cells are the fundamental unit of all living organisms.
• All living beings consist of cells, forming from pre-existing cells.
• Hereditary information transfers from cell to cell during division.

Cell Types

• Prokaryotic cells lack a nucleus and organelles; eukaryotic cells have both.
• Prokaryotic: DNA is free-floating; eukaryotic: DNA is contained within a nucleus.

Cell Cycle

• Comprised of interphase (G1, S, G2) and mitosis (PMAT followed by cytokinesis).
• Checkpoints in the cycle monitor for size, DNA integrity, and chromosomal alignment before division.
  • G1 checkpoint checks cell size and nutrient availability.
  • G2 checkpoint ensures accurate DNA replication.
  • Metaphase checkpoint confirms attachment of chromosomes to spindle fibers.

Oncogenes and Tumor Suppressor Genes

• p53 is a critical tumor suppressor gene that prevents the propagation of damaged DNA.
• If DNA damage is irreparable, p53 can initiate programmed cell death (apoptosis) to prevent cancer.

Disorders Related to Cell Division

• Cancer results from uncontrolled cell proliferation.
• Down syndrome (trisomy 21) involves an extra chromosome 21.
• Turner syndrome features 45 chromosomes, usually in females.
• Alzheimer’s disease is characterized by neuron death and memory loss.
• Klinefelter syndrome (XXY) affects males, leading to physical and hormonal changes.
• XYY syndrome results in behavioral changes without distinct physical characteristics.

Test your understanding of biological transport mechanisms, including integral and peripheral proteins, and the role of carbohydrate chains in cell recognition. Explore concepts like passive transport and simple diffusion as you identify how cells manage substance movement. Perfect for biology students looking to strengthen their knowledge in cellular processes.