Cell Structure

• What is a eukaryotic cell?

  A eukaryotic cell has DNA contained in a nucleus and contains membrane-bound specialized organelles.
• What is a prokaryotic cell?


  A prokaryotic cell has DNA that is 'free' in the cytoplasm and lacks organelles.
• What is the relationship between specialized cells and organ systems?

  Specialized cells form tissues that perform specific functions, which then combine to form organs and organ systems.
• Describe the structure of the cell-surface membrane.

  The cell-surface membrane is a 'fluid mosaic' phospholipid bilayer with extrinsic and intrinsic proteins embedded.
• What is the function of the cell-surface membrane?

  It isolates the cytoplasm from the extracellular environment, is selectively permeable, and is involved in cell signaling and recognition.
• What role does cholesterol play in the cell-surface membrane?

  Cholesterol connects phospholipids and reduces fluidity in the cell-surface membrane.
• What are the functions of glycoproteins in the cell-surface membrane?

  Glycoproteins are involved in cell signaling, cell recognition (as antigens), and binding cells together.
• What are the functions of glycolipids in the cell-surface membrane?

  Glycolipids are involved in cell signaling and cell recognition.
• What surrounds the nucleus?

  The nucleus is surrounded by a nuclear envelope, which is a semi-permeable double membrane.
• What is the function of nuclear pores?

  Nuclear pores allow substances to enter and exit the nucleus.
• What is the nucleolus made of?

  The nucleolus is made of RNA and proteins and assembles ribosomes.
• What is the function of the nucleus?

  The nucleus contains DNA coiled around chromatin into chromosomes and controls cellular processes such as gene expression and mitosis.
• What surrounds a mitochondrion?

  A mitochondrion is surrounded by a double membrane.
• What is the function of the cristae in mitochondria?


  The folded inner membrane forms cristae, which is the site of the electron transport chain.
• What does the fluid matrix of mitochondria contain?

  The fluid matrix contains mitochondrial DNA, respiratory enzymes, lipids, and proteins.
• What is the structure of a chloroplast?

  A chloroplast is a vesicular plastid with a double membrane and contains thylakoids stacked to form grana.
• What is the function of thylakoids in chloroplasts?

  Thylakoids contain photosystems with chlorophyll and are involved in photosynthesis.
• What is the function of mitochondria?

  Mitochondria are the site of aerobic respiration to produce ATP.
• What is the function of chloroplasts?

  Chloroplasts are the site of photosynthesis, converting solar energy to chemical energy.
• Describe the structure of the Golgi apparatus.

  The Golgi apparatus is a planar stack of membrane-bound, flattened sacs with a cis face aligning with the rough endoplasmic reticulum (rER).
• What is the function of the Golgi apparatus?

  The Golgi apparatus modifies and packages proteins for export and synthesizes glycoproteins.
• What is the structure of a lysosome?

  A lysosome is a sac surrounded by a single membrane that contains digestive hydrolase enzymes.
• What is the function of lysosomes?


  Lysosomes digest the contents of phagosomes and exocytose digestive enzymes.
• What are ribosomes made of?

  Ribosomes are formed of protein and rRNA.
• Where can ribosomes be found?


  Ribosomes can be free in the cytoplasm or attached to the endoplasmic reticulum (ER).
• What is the function of ribosomes?

  Ribosomes are the site of protein synthesis via translation.
• Describe the structure of the endoplasmic reticulum (ER).

  The endoplasmic reticulum consists of cisternae, a network of tubules and flattened sacs extending from the cell membrane through the cytoplasm and connecting to the nuclear envelope.
• What is the function of rough ER?

  The rough ER has many ribosomes attached for protein synthesis and transport.
• What is the function of smooth ER?

  The smooth ER is involved in lipid synthesis.
• What is the structure of the cell wall in bacteria?

  The cell wall in bacteria is made of the polysaccharide murein.
• What is the structure of the cell wall in plants?

  The cell wall in plants is made of cellulose microfibrils.
• What are the functions of the cell wall?


  The cell wall provides mechanical strength and support, acts as a physical barrier against pathogens, and is part of the apoplast pathway in plants to enable easy diffusion of water.
• What surrounds the plant cell vacuole?

  The plant cell vacuole is surrounded by a single membrane called the tonoplast.
• What does the cell vacuole contain?

  The cell vacuole contains cell sap, which includes mineral ions, water, enzymes, and soluble pigments.
• What is the function of the cell vacuole in plants?

  The cell vacuole controls turgor pressure and absorbs and hydrolyzes potentially harmful substances to detoxify the cytoplasm.
• What are some common cell adaptations?

  Common cell adaptations include folded membranes or microvilli to increase surface area, many mitochondria for ATP production, and walls that are one cell thick to reduce diffusion distance.
• What are plasmids in prokaryotes?

  Plasmids are small rings of DNA that carry non-essential genes.
• What is the role of plasmids in prokaryotes?

  Plasmids can be exchanged between bacterial cells via conjugation.
• What is the role of flagella in prokaryotes?

  Flagella are rotating tails that propel usually unicellular organisms.
• What is the role of the capsule in prokaryotes?

  The capsule is a polysaccharide layer that prevents desiccation, acts as a food reserve, provides mechanical protection against phagocytosis and external chemicals, and helps stick cells together.