Cell Biology
89 flashcards by MentisLibrary
Tour the machinery inside every living thing, from the organelles that run the cell to the membranes that guard it. Covers transport, mitosis and meiosis, respiration, and photosynthesis in one clear pass.
- What is the smallest unit that can carry out all the processes of life?
- The cell
- What are the three main differences between prokaryotic and eukaryotic cells?
- Prokaryotes have no nucleus, no membrane-bound organelles, and a single circular chromosome
- Which organelle contains the cell's DNA and is bounded by a double membrane with pores?
- The nucleus
- What is made inside the nucleolus?
- Ribosomal RNA and ribosomal subunits
- Which organelle assembles amino acids into proteins?
- The ribosome
- What distinguishes rough endoplasmic reticulum from smooth ER?
- Rough ER is studded with ribosomes and makes proteins for secretion or membranes; smooth ER has none and makes lipids
- Which organelle modifies, sorts, and packages proteins into vesicles for shipping?
- The Golgi apparatus
- Which organelle is filled with hydrolytic enzymes that digest worn-out organelles and engulfed material?
- The lysosome
- What is autophagy?
- The process in which a cell digests its own damaged organelles inside a lysosome
- Which organelle breaks down fatty acids and detoxifies hydrogen peroxide using catalase?
- The peroxisome
- Which organelle carries out aerobic respiration and has its own circular DNA?
- The mitochondrion
- Which organelle captures light energy in plants and algae?
- The chloroplast
- What is the endosymbiotic theory?
- The idea that mitochondria and chloroplasts descend from free-living prokaryotes engulfed by an ancestral host cell
- What is the large fluid-filled organelle that maintains turgor pressure in a mature plant cell?
- The central vacuole
- What molecule makes up the plant cell wall?
- Cellulose
- What is the cytoskeleton made of?
- Microfilaments of actin, intermediate filaments, and microtubules of tubulin
- Which cytoskeletal element forms the tracks for motor proteins kinesin and dynein?
- Microtubules
- What structure organizes microtubules in an animal cell and contains a pair of centrioles?
- The centrosome
- What is the internal arrangement of microtubules in a motile cilium or flagellum?
- A 9 plus 2 arrangement of microtubule doublets
- What model describes the plasma membrane as a fluid bilayer with proteins drifting within it?
- The fluid mosaic model
- Why is a phospholipid described as amphipathic?
- It has a hydrophilic phosphate head and two hydrophobic fatty acid tails
- What does cholesterol do in an animal cell membrane?
- It buffers fluidity, reducing it at warm temperatures and preventing tight packing at cold ones
- What is the difference between an integral and a peripheral membrane protein?
- Integral proteins are embedded in the bilayer, often spanning it; peripheral proteins attach loosely to the surface
- Which molecules cross the lipid bilayer most easily without help?
- Small nonpolar molecules such as oxygen and carbon dioxide
- What is simple diffusion?
- Net movement of a substance down its concentration gradient without a transport protein or energy input
- What is facilitated diffusion?
- Passive movement down a concentration gradient through a channel or carrier protein
- What is osmosis?
- Diffusion of water across a selectively permeable membrane from lower to higher solute concentration
- Which channel protein dramatically speeds water movement across membranes?
- Aquaporin
- What happens to an animal cell placed in a hypotonic solution?
- Water enters and the cell swells and may burst, a process called lysis
- What happens to a plant cell placed in a hypertonic solution?
- The membrane pulls away from the wall as the cell loses water, which is called plasmolysis