Cell Organelles and Cytoskeleton (Video Notes)

Flashcards covering key organelles and cytoskeleton concepts from the lecture notes (Pages 1–5).

What is the plasma membrane and its function?

A phospholipid bilayer that controls the movement of molecules into and out of the cell; composed of lipids, proteins, and carbohydrates, with phospholipids having hydrophilic heads and hydrophobic tails.

What is the nucleus and what does it contain?

The organelle that controls cell activities and heredity; contains DNA organized as chromatin and is enclosed by a double membrane called the nuclear envelope.

What is the nuclear envelope?

A double membrane surrounding the nucleus that regulates the flow of materials in and out of the nucleus.

What are ribosomes and where are they located?

Sites of protein synthesis; assembled in the nucleolus; found free in the cytoplasm and on the rough endoplasmic reticulum.

What is the endomembrane system?

A network of membranes including the nuclear envelope, rough and smooth ER, Golgi apparatus, lysosomes, vacuoles, and the plasma membrane that work together to modify, package, and transport proteins and lipids.

What are intermediate filaments?

Fibrous proteins that reinforce cell shape and anchor certain organelles; part of the cytoskeleton; are relatively permanent (keratin provides mechanical support in skin).

What are microtubules and what is their role?

Hollow tubes made of tubulin that can disassemble and reassemble; grow from the centrosome (centrioles); essential in cell division, move organelles with motor proteins, and form structures like cilia and flagella.

What is the centrosome (centrioles) related to microtubules?

Microtubule organizing center from which microtubules emanate; important during cell division in organizing the spindle.

What is the cytoskeleton and its function?

Network of protein filaments (microfilaments, intermediate filaments, microtubules) that provides structural support, organization, and motility; interacts with motor proteins for movement.

What are microfilaments and their role?

Solid rods of actin that support cell shape, enable movement, and participate in muscle contraction; can disassemble and reassemble.

What is a mitochondrion and its function?

Site of cellular respiration; converts energy from food into ATP; contains outer membrane, inner membrane, intermembrane space, and matrix; cristae increase surface area and there is own DNA/ribosomes supporting endosymbiosis.

What are cristae?

Folds of the inner mitochondrial membrane that increase the surface area for ATP production.

What is a chloroplast and its function?

Organelle where photosynthesis occurs in plants and algae; contains stroma (fluid with enzymes, ribosomes, and DNA), grana (stacks of thylakoids), thylakoid membranes, and double membranes.

What is the endosymbiotic theory?

Proposes that mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by a larger cell and evolved into organelles; supported by their own DNA and ribosomes and double membranes.

What is the Golgi apparatus and its function?

Receives vesicles from the rough ER, finishes, sorts, and ships modified products to their destinations; central to ER product processing.

What is the rough endoplasmic reticulum (RER)?

Region of the ER studded with ribosomes; synthesizes proteins and packages them into vesicles for transport.

What is the smooth endoplasmic reticulum (SER)?

Region of the ER without ribosomes; synthesizes lipids and participates in carbohydrate metabolism and detoxification processes.

What is a lysosome?

A sac containing digestive enzymes that break down bacteria, old organelles, and macromolecules.

What are vesicles and their function?

Small membrane-bound sacs that transport materials between organelles and to the cell membrane.

What is the central vacuole and its role in plants?

A large plant cell organelle that stores water and maintains turgor pressure; often contains pigments in flowers and other substances.