cell structure

• What is the structure of the cell membrane?

  It consists of a phospholipid bilayer with embedded integral and peripheral membrane proteins
• What is the function of the cell membrane in terms of compartmentalization?

  It allows specialized activities to be independently regulated
• How does the cell membrane regulate the passage of specific solutes?

  It is a selectively permeable membrane
• What role does the cell membrane play in signal transduction?

  It responds to and transmits stimuli
• How does the cell membrane facilitate intercellular interaction?

  It allows cells to recognize and signal each other
• What is the role of the cell membrane in cell adherence?

  It can bind to cells to cause cell death
• What are the characteristics of lipids in the bilayer?

  They are amphipathic with polar heads that are hydrophilic and fatty acid chains that are hydrophobic
• What is the function of cholesterol in the cell membrane?

  It regulates fluidity between phospholipids
• What types of movement can lipids in the bilayer perform?

  They can rotate, move laterally, and move transversely
• What are the functions of proteins in the cell membrane?

  Transporters, anchors, receptors, and enzymes
• How does the membrane appear under transmission electron microscopy (TEM)?

  It appears as two electron-dense layers separated by an intermediate, electron-lucent layer
• How many nuclei are typically present in a cell?

  One per cell
• What is contained within the nucleus?

  Genetic information
• What is the function of the nuclear envelope?

  It has pores and contains the nucleolus and chromatin
• What is chromatin composed of?

  It is a highly folded nucleoprotein complex made of DNA and structural proteins
• What distinguishes heterochromatin from euchromatin?

  Heterochromatin is dense staining and highly condensed, while euchromatin is light stained and stretched
• What is the function of the nucleolus?

  It is the site of rRNA synthesis and ribosome assembly
• What is the structure of the nuclear envelope?

  It is a double membrane with a perinuclear space
• How is the outer nuclear membrane related to the endoplasmic reticulum?

  It resembles the ER and is continuous with the rough endoplasmic reticulum
• What is the role of the nuclear lamina?

  It supports the nuclear envelope and is essential in DNA replication, transcription, and gene regulation
• What is the function of nuclear pores?

  They mediate active transport of proteins, ribonucleoproteins, and RNAs between the nucleus and cytoplasm
• How many nuclear pores are typically found per nucleus?

  3000 to 4000
• What is the relationship between nuclear activity and the number of nuclear pores?

  A more actively transcribing nucleus has more nuclear pores
• What is the structure of mitochondria?

  They have a double membrane with phospholipids and proteins, forming a rod-like structure
• What is the function of the inner mitochondrial membrane?

  It contains ATP synthase to generate ATP in the matrix
• What are cristae in mitochondria?

  They are infoldings of the inner membrane that increase surface area
• What is the matrix in mitochondria?

  It is the space within the inner membrane
• What is the primary function of mitochondria?

  They produce ATP through aerobic respiration
• How does the number and position of mitochondria depend on the cell?

  They depend on the energy needs of the cell
• What additional roles do mitochondria play in the cell?

  They are involved in cell signaling, cell death, and maintaining cell cycle and growth control
• What is the structure of the endoplasmic reticulum?

  It is a membrane continuous with the nuclear envelope, consisting of cisternae and tubules with a fluid-filled lumen
• What distinguishes rough endoplasmic reticulum (RER) from smooth endoplasmic reticulum (SER)?


  RER has ribosomes on its membrane, while SER does not
• What is the primary function of the smooth endoplasmic reticulum (SER)?

  It synthesizes lipids
• Where is the smooth endoplasmic reticulum commonly found?

  It is common in glands
• What role does the smooth endoplasmic reticulum play in striated muscles?

  It serves as a calcium store
• What enzymes are found in the smooth endoplasmic reticulum?

  Enzymes that help eliminate toxins, drugs, and alcohol in hepatocytes
• What is the function of the rough endoplasmic reticulum (RER)?

  It synthesizes secretory and membrane proteins
• How are polypeptides assembled in the rough endoplasmic reticulum?

  They are assembled on bound ribosomes and threaded into the ER lumen
• What happens to polypeptide chains in the Golgi apparatus?

  They undergo folding and addition of carbohydrates
• What is proteostasis in the context of the rough endoplasmic reticulum?

  It refers to quality control of proteins