Cell Biology Quiz: Vacuoles and Protein Synthesis

Vacuoles

• Food Vacuole: Formed when protists use endocytosis to bring food into the cell.
• Contractile Vacuole: Collects and pumps excess water out of freshwater protists.

Protein and Lipid Synthesis

• DNA guides RNA synthesis; RNA exits the nucleus through nuclear pores.
• Ribosomes synthesize proteins, which enter the Rough Endoplasmic Reticulum (RER) for modifications; lipids are synthesized in the Smooth Endoplasmic Reticulum (SER).
• Vesicles bud off from the ER to merge with the Golgi apparatus, where proteins and lipids undergo further modifications.
• Modified products are tagged and sorted in Golgi vesicles for storage or export via the plasma membrane.

Mitochondria

• Size is approximately 1-5 microns; characterized by two membranes: outer and inner with folds called cristae.
• Contains intermembrane space and matrix with DNA and ribosomes.
• Primary function is ATP synthesis through glycolysis (cytoplasm), Krebs cycle (matrix), and electron transport system (intermembrane space).

Chloroplasts

• Site of photosynthesis within plant cells.
• Structure includes two outer membranes and thylakoid membranes organized into granum containing chlorophyll.
• Stroma is the fluid component inside chloroplasts.

Cytoskeleton

• Provides internal organization, shape, and movement ability in cells.
• Comprised of microtubules (thickest), microfilaments (thinnest), and intermediate filaments (medium diameter).
• Microtubules anchor organelles, assist in chromosome movement during cell division, and form cilia and flagella.

Microtubules

• Long, hollow tubes made of tubulin proteins.
• Serve as tracks for organelle movement and are essential for cilia and flagella structure.
• Centrosomes organize microtubules; centrosome contains centrioles with a 9 triplet microtubule arrangement.

Cilia and Flagella

• Cilia and flagella enable cell movement or surface material movement.
• Microtubules arranged in a 9 + 2 pattern wrapped in plasma membrane extensions.

Microfilaments

• Rod-like structures, the thinnest cytoskeletal elements enabling shape changes and movement.

Intermediate Filaments

• Diameter of 8-12 nanometers, provide structural support and anchor organelles more permanently than other cytoskeletal components.

Plant Cell Structures

• Unique to plant cells include chloroplasts, central vacuole, plastids (chromoplasts, amyloplasts), and cell wall.

Central Vacuole

• Functions as a storage area for water, sugars, ions, amino acids, and wastes; may perform specialized functions in some plant cells.

Plasma Membrane

• Comprised of a phospholipid bilayer with embedded proteins.
• Regulates substance entry and exit, and receives external signals.

Cell Structure

• All cells have a plasma membrane, genetic material in the form of DNA, and cytoplasm containing ribosomes.

Nucleus

• Isolates the cell's DNA, controlling cellular activities and RNA synthesis.
• Contains chromosomes (DNA fibers) and a nucleolus for ribosomal subunit production.

Ribosomes

• Composed of ribosomal RNA and protein, responsible for protein synthesis in cytosol (free ribosomes) or on the ER/nuclear envelope (bound ribosomes).

Endomembrane System

• Includes organelles that modify proteins, synthesize lipids, and package products into vesicles for export or cellular use.
• Key components are the endoplasmic reticulum (both rough and smooth), and Golgi apparatus.

Endoplasmic Reticulum (ER)

• Continuous with nuclear envelope; consists of Rough ER with ribosomes and Smooth ER lacking ribosomes.
• Rough ER modifies proteins as they move through its membrane sacs, while Smooth ER synthesizes various lipids.