Chapter 4: Cell Structure Flashcards
What are the three tenets of cell theory?
All living organisms are composed of cells.
The cell is the basic unit of life.
All cells arise from pre-existing cells.
Compare light microscopy vs. electron microscopy (TEM/SEM).
Light: Live specimens, lower resolution (~200 nm).
Electron: Dead specimens, higher resolution (TEM for internal structures; SEM for surface).
What is cell fractionation?
Technique to separate cell components using centrifugation.
Label key structures of a prokaryotic cell.
Cell wall, plasma membrane, nucleoid, ribosomes, flagella, pili, capsule.
How do Gram-positive and Gram-negative bacteria differ?
Gram-positive: Thick peptidoglycan layer (stains purple).
Gram-negative: Thin peptidoglycan + outer membrane (stains pink).
Function of pili and flagella?
Pili: Attachment/DNA transfer.
Flagella: Motility.
What distinguishes eukaryotic from prokaryotic cells?
Membrane-bound organelles (nucleus, mitochondria, ER) and larger size.
Describe the nucleus structure and function.
Contains DNA; surrounded by nuclear envelope with pores.
What is the endosymbiotic theory?
Mitochondria/chloroplasts evolved from engulfed prokaryotes.
List components of the endomembrane system.
Nuclear envelope, ER, Golgi, lysosomes, vesicles, plasma membrane.
Compare rough ER vs. smooth ER.
RER: Protein synthesis (ribosomes attached).
SER: Lipid synthesis, detoxification.
Role of the Golgi apparatus?
Modifies, sorts, and packages proteins.
Name the three types of cytoskeletal filaments and their functions.
Microtubules: Cell shape, mitosis, transport.
Microfilaments: Muscle contraction, cytokinesis.
Intermediate filaments: Structural support.
What are motor proteins? Example.
Use ATP to move along filaments.
Structure and function of cilia vs. flagella.
Cilia: Short, numerous.
Flagella: Long, few.
Compare tight junctions, desmosomes, and gap junctions (animal cells).
Tight: Seal barriers.
Desmosomes: Anchor cells.
Gap: Allow communication.
What are plasmodesmata?
Channels in plant cell walls for transport/communication.
Why do cells have a size limit (surface area-to-volume ratio)?
Larger cells → lower SA:V ratio → inefficient nutrient/waste exchange.
Function of lysosomes? Example of dysfunction.
Digest macromolecules with enzymes. Dysfunction → lysosomal storage diseases.
What is the vacuole’s role in plant cells?
Stores water, nutrients, wastes; maintains turgor pressure.
