Mitochondria, Chloroplasts, Cytoskeleton, Cell Adhesion

Q1: What are semi-autonomous organelles?

A: Organelles that grow, divide independently of the host cell, and have their own DNA (e.g. mitochondria, chloroplasts).

Q2: What two organelles are semi-autonomous?

A: Mitochondria and chloroplasts.

Q3: What kind of cells contain mitochondria?

A: All eukaryotic cells.

Q4: What are cristae and what is their function?

A: Folds of the inner mitochondrial membrane; increase surface area for ATP production.

Q5: What process happens on the inner mitochondrial membrane?

A: The electron transport chain, which synthesizes ATP.

Q6: What is the matrix of the mitochondria?

A: The inner compartment of the mitochondrion.

Q7: What are key features of mitochondria?

A: Has a double membrane, its own circular DNA, and produces energy for the cell.

Q8: Where are chloroplasts found?

A: In photosynthetic eukaryotic cells (e.g., plants).

Q9: What is the stroma in a chloroplast?

A: The inner compartment where CO₂ fixation and sugar production occur.

Q10: What are thylakoids and grana?

A: Thylakoids are membrane-bound disks; grana are stacks of thylakoids.

Q11: What is inside the thylakoid membrane?

A: Photosynthetic machinery for harvesting energy from the sun.

Q12: What does the endosymbiont theory state?

A: Mitochondria and chloroplasts originated from prokaryotes engulfed by early eukaryotic cells.

Q13: What kind of bacteria became mitochondria?

A: Aerobic proteobacteria.

Q14: What kind of bacteria became chloroplasts?

A: Photosynthetic cyanobacteria.

Q15: What evidence supports endosymbiont theory?

A: Circular DNA, double membranes, division by binary fission, similar size to bacteria.

Q16: Name two reasons mitochondria are thought to be from prokaryotic origin.

A: 1) Circular DNA. 2) Reproduce via binary fission like bacteria.

Q17: Which organelles have more than one membrane?

A: Mitochondria, chloroplasts, and the nucleus.

Q18: What is the cytoskeleton made of?

A: A dynamic network of protein filaments (intermediate filaments, microtubules, and microfilaments).

Q19: What do intermediate filaments do?

A: Provide mechanical strength; composed of keratin.

Q20: What are microtubules made of and what do they do?

A: Made of tubulin dimers; involved in organelle organization, mitotic spindle, and forming cilia/flagella.

Q21: What are actin microfilaments?

A: Helical polymers of actin; involved in movement, muscle contraction, and vesicle organization.

Q22: What is a centrosome?

A: A microtubule organizing center in animal cells; contains two perpendicular centrioles.

Q23: What are centrioles made of?

A: 9 triplets of microtubules.

Q24: What is a protofilament?

A: A single chain of tubulin dimers; 13 protofilaments form a microtubule.

Q25: What is dynamic instability?

A: The rapid assembly/disassembly of microtubules.

Q1: What are the three types of protein filaments in the cytoskeleton?

A1: Microtubules, intermediate filaments, and actin microfilaments.

Q2: What protein composes microtubules?

A2: Tubulin dimers (α- and β-tubulin).

Q3: What are the main functions of microtubules?

A3: Organize organelles and vesicles, form the mitotic spindle, and make up flagella and cilia.

Q4: What is dynamic instability in microtubules?

A4: The rapid assembly and disassembly of microtubules.

Q5: What are the two types of microtubules?

A5: Cytoplasmic (dynamic) and axonemal (stable, in cilia/flagella).

Q6: What is the microtubule organizing center (MTOC) in animal cells?

A6: The centrosome, containing a pair of centrioles.

Q7: What are centrioles made of?

A7: 9 triplets of microtubules.

Q8: What are intermediate filaments made of?

A8: Fibrous proteins like keratin; not defined by a single composition.

Q9: What is the main function of intermediate filaments?

A9: Withstand mechanical stress; maintain nuclear and cell structure.

Q10: What is their diameter (intermediate filaments)?

A10: About 10 nm.

Q11: What protein composes actin microfilaments?

A11: Actin (f-actin formed from g-actin monomers).

Q12: What are the functions of actin microfilaments?

A12: Cellular movement, structural support, vesicle movement, and cell division.

Q13: Are actin filaments polar?

A13: Yes, they have dynamic instability.

Q14: Which motor proteins move along actin?

A14: Myosin.

Q15: Which motor proteins move along microtubules?

A15: Kinesin (+ direction) and dynein (– direction).

Q16: What are the three ways motor proteins cause movement?

A16: Walk along cytoskeleton with cargo, push filaments by walking, and bend linked microtubules.

Q17: What is the 9+2 arrangement in cilia/flagella?

A17: 9 fused microtubule doublets around 2 central singlets.

Q18: How do flagella and cilia differ?

A18: Flagella are longer, used for locomotion; cilia move fluid across surfaces.

Q19: What is the basal body?

A19: The anchor of cilia/flagella, made of microtubule triplets.

Q20: What composes the extracellular matrix (ECM)?

A20: Proteins (collagen), carbohydrates, proteoglycans, and integrins.

Q21: What are proteoglycans?

A21: Proteins with attached carbohydrates forming complexes.

Q22: What do integrins do?

A22: Attach ECM to the cytoskeleton and neighboring cells.

Q23: What are gap junctions?

A23: Channels made of connexons that allow ions/molecules to pass between animal cells.

Q24: What are tight junctions?

A24: Seals between cells that block fluid/molecule passage.

Q25: What proteins make up tight junctions?

A25: Claudins and occludins.

Q26: What are desmosomes?

A26: Junctions connecting intermediate filaments of adjacent cells for strength.

Q27: What proteins are involved in desmosomes?

A27: Cadherins.

Q28: What are plasmodesmata?

A28: Channels between plant cell walls allowing cytoplasm sharing.