lecture 3

• What are the common features present in human cells?

  Plasma membrane, nucleus, cytoplasm
• How many types of tissue are there in the human body?

  Four types
• What is the main function of the plasma membrane?

  It acts as a selectively permeable barrier
• What role does the nucleus play in a cell?

  It contains the genome for cellular functions
• What is the approximate number of cells in an adult human?

  Around 50 trillion cells
• How do cells arise?

  Through cell division
• Why are cells specialized despite having identical genomes?

  They differ based on their function
• What is the main structure of the plasma membrane made of?

  Phospholipids
• What role does cholesterol play in the plasma membrane?

  It provides stability and increases stiffness
• What are carbohydrate tails on the plasma membrane used for?

  They act as recognition motifs
• What is the primary function of proteins in the plasma membrane?

  Transport of molecules
• How do molecules move via diffusion?

  Down their concentration gradient
• What type of molecules can cross the membrane by simple diffusion?

  Small and lipid-coated molecules
• What is channel-mediated transport?

  Transport using aqueous channels in proteins
• What is required for active transport across the plasma membrane?

  Energy (ATP)
• What is secondary active transport?

  Transport requiring cotransport of two molecules
• What is the control center of the cell?

  The nucleus
• What is the function of nucleoli in the nucleus?

  Involved in translation of proteins
• What is chromatin?

  Densely packaged DNA structures
• What is the composition of chromatin?

  30% DNA, 60% histones, 10% RNA
• What is the cytoplasm?

  Material between the cell membrane and nucleus
• What are organelles?

  Machinery of the cell performing metabolic functions
• What is the function of mitochondria?

  Generate ATP for energy
• What is the rough endoplasmic reticulum (ER) responsible for?

  Protein synthesis
• What do lysosomes contain?

  Digestive enzymes
• What are the four primary tissue types in the human body?

  Epithelial, connective, muscle, nervous
• What is the function of epithelial tissue?

  Forms a covering layer and boundary
• What are the two forms of epithelial tissue?

  Covering/lining and glandular epithelium
• What is the role of microvilli in epithelial cells?

  Increase surface area for absorption
• What is the regeneration capacity of epithelial cells?

  High regeneration capacity
• What are the two types of simple epithelia?

  Single-layer and thin permeable layer
• What is a gland?

  A cell or group of cells that secretes
• What are the five main roles of connective tissue?

  Binding, support, protection, insulation, transport
• What are the four classes of connective tissue?

  Connective tissue proper, cartilage, bone, blood
• What is the primary function of muscle tissue?

  Responsible for movement
• What are myofilaments?

  Networks of actin and myosin filaments
• What are the three types of muscle tissue?

  Skeletal, cardiac, smooth
• What characterizes skeletal muscle cells?

  Long, striated, multiple nuclei
• What is the function of cardiac muscle?

  Pumping blood around the body
• What are intercalated discs?

  Specialized junctions connecting cardiac muscle cells