Cell Organelles and Their Functions

Contractile Vacuoles

• Found in freshwater protists
• Pump excess water out of cells

Central Vacuoles

• Found in many mature plant cells
• Hold organic compounds and water

Mitochondria

• Found in nearly all eukaryotic cells
• Powerhouse of the cell
• Site of cellular respiration
• Contains its own DNA that is separate from that of the nucleus
• Divided into two compartments:
  • Intermembrane space
  • Matrix
• Inner membrane is folded into cristae, which increase the surface area for ATP production

Chloroplasts

• Found in plants and algae
• Site of photosynthesis
• Contains its own DNA distinct from the nucleus
• Enclosed by two membranes
• Contains a system of internal membranes called thylakoids
• Thylakoids are stacked into grana
• Surrounded by a fluid called stroma

Endomembrane System

• Regulates protein traffic and performs metabolic functions
• Consists of:
  • Endoplasmic reticulum (ER)
  • Golgi apparatus
  • Lysosomes
  • Vacuoles
  • Peroxisomes

Endoplasmic Reticulum (ER)

• Two Types:
  • Smooth ER
  • Rough ER

Smooth ER

• Lacks ribosomes
• Metabolizes carbohydrates
• Detoxifies drugs and poisons
• Stores calcium ions

Rough ER

• Studded with ribosomes
• Synthesizes proteins
• Modifies and packages proteins

Golgi Apparatus

• Organelle composed of flattened membrane-bound sacs
• Processes and packages proteins and lipids
• Sorts and ships proteins to their final destinations
• Modifies, stores, and ships products of ER

Lysosomes

• Membranous sacs of hydrolytic (digestive) enzymes that break down macromolecules
• Carry out intracellular digestion
• Digest worn-out organelles (autophagy)
• Digest engulfed bacteria (phagocytosis)

Peroxisomes

• Specialized metabolic compartments bound by single membrane
• Produce hydrogen peroxide (H2O2) as a byproduct of reactions
• Break down fatty acids
• Detoxify alcohol and other toxins
• Contain enzymes that break down H2O2

Plasma Membrane

• Selectively permeable membrane that controls the passage of substances into and out of the cell
• Composed of a phospholipid bilayer with embedded proteins

Cytoskeleton

• Network of fibers that extends throughout the cytoplasm of eukaryotic cells
• Provides structural support
• Aids in cell movement
• Controls the organization of the cytoplasm
• Has three main types of fibers:
  • Microtubules
  • Microfilaments
  • Intermediate filaments

Microtubules

• Hollow fibers composed of tubulin
• Function in maintaining cell shape, cell motility, and movement of organelles
• Help separate chromosomes during cell division
• Form tracks for the movement of vesicles and other organelles

Microfilaments

• Solid rods composed of actin
• Function in maintaining cell shape, muscle contraction, and cell motility
• Involved in cytoplasmic streaming

Intermediate Filaments

• Diverse group of fibers
• Function in maintaining cell shape, anchoring organelles, and forming nuclear lamina

Plant Cell Wall

• Provides support, structure, and protection to the cell
• Composed of cellulose, hemicellulose, and pectin

Cell Junctions

• Specialized structures that connect cells to each other
• Provide structural support
• Facilitate communication between cells
• Types:
  • Tight junctions
  • Desmosomes
  • Gap junctions

Nuclear Envelope

• Double membrane that encloses the nucleus
• Contains nuclear pores that regulate the passage of molecules between the nucleus and the cytoplasm
• Regulates the movement of molecules between the nucleus and the cytoplasm

Ribosomes

• Responsible for protein synthesis
• Composed of ribosomal RNA (rRNA) and proteins
• Found in cytoplasm and on the endoplasmic reticulum (ER)

Explore the vital organelles found in eukaryotic cells, such as mitochondria and chloroplasts, and their specific roles in cellular processes. This quiz delves into topics like the endomembrane system, contractile and central vacuoles, providing insight into cell structure and function.