biology- cells and tissues

• What is the main component of the cell membrane?


  Phospholipid bilayer
• What does it mean for a membrane to be selectively permeable?


  It allows some substances to pass through while blocking others
• What is a phospholipid composed of?


  A glycerol molecule, two fatty acids, and a phosphate group
• What is the function of the hydrophilic head group of a phospholipid?


  It can interact with water
• What is the role of the cytoplasm in a cell?


  It is the fluid component that surrounds organelles
• What are organelles?


  Specialized structures within cells that perform specific functions
• What is an organism?


  An individual plant, animal, or single-celled lifeform
• What are the three principles of cell theory?


  1. All living things are made up of one or more cells.
  2. Cells are the most basic unit of structure and function in all living things.
  3. All cells are created by preexisting cells through mitosis.
• What distinguishes eukaryotic cells from prokaryotic cells?


  Eukaryotic cells are complex and have membrane-bound organelles
• What type of DNA organization is found in eukaryotic cells?


  DNA is contained within the nucleus and associated with histones
• What is the structure of the phospholipid bilayer?


  A double layer of phospholipids with hydrophobic tails in the middle and hydrophilic heads on the outside
• What is the plasma membrane also known as?


  Cell surface membrane
• What are pathogens?


  Microorganisms that cause illness or disease
• What are cilia?


  Hair-like structures found on the plasma membrane of some cells
• What is the function of flagella?


  Involved in the propulsion of the cell
• What are the functions of the organelles found in eukaryotic cells?


  • Plasma membrane: Controls entry and exit of substances
  • Nucleus: Contains genetic information
  • Mitochondria: Site of aerobic respiration and ATP production
  • Ribosomes: Site of protein synthesis
  • Endoplasmic reticulum: Synthesizes and transports proteins and lipids
  • Golgi apparatus: Modifies and packages proteins
  • Lysosomes: Digests worn-out cell components
  • Centrioles: Involved in mitosis and formation of cilia/flagella
  • Chloroplasts: Site of photosynthesis (in plants)
• What is the largest organelle in a cell?

  Nucleus
• What is the role of mitochondria in a cell?


  They are the site of aerobic respiration and ATP production
• What is the process of aerobic respiration?


  It is the reaction of glucose with oxygen to produce carbon dioxide and water
• What is the function of ribosomes?


  They are the site of protein synthesis
• What distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?


  Rough ER has ribosomes attached to its surface
• What is the function of the Golgi apparatus?


  It modifies proteins and packages them for transport
• What are lysosomes known as?


  Cell recycling facilities
• What is the role of centrioles in a cell?


  They are involved in the formation of the spindle during mitosis
• What is the function of chloroplasts in plants?


  They are the site of photosynthesis
• What is the composition of plant cell walls?


  They consist mainly of cellulose
• What is the function of the central vacuole in plant cells?


  It stores substances and helps maintain water balance
• What are the similarities and differences between plant and animal cells regarding organelles?


  Similarities:

  • Both have ribosomes, mitochondria, plasma membrane, cytoplasm, smooth and rough endoplasmic reticulum, nucleus, and Golgi apparatus.

  
  

  Differences:

  • Animal cells have lysosomes.
  • Plant cells have central vacuoles, chloroplasts, and cell walls.
• How do eukaryotic cells become specialized in multicellular organisms?


  By controlling which genes are expressed
• What are stem cells?


  Undifferentiated cells that can give rise to specialized cells
• What is cell differentiation?


  The process by which a cell changes from one type to another
• What happens to most cells by the time a baby is born?


  Most cells have already differentiated
• What is the role of adult stem cells?


  They are responsible for cell turnover, such as producing red blood cells
• What is the process of differentiation of red blood cells (erythrocytes)?


  1. Stem cells divide to form proerythrocytes.
  2. Proerythroblasts develop and can only form erythrocytes.
  3. Hemoglobin builds up in the cytoplasm.
  4. The nucleus is ejected.
  5. Mature erythrocyte is formed.
• What are the key differences between prokaryotic and eukaryotic cells?


  Prokaryotic cells:

  • Lack membrane-bound organelles
  • Smaller ribosomes
  • No nucleus; DNA is free in cytoplasm
  • Cell wall contains murein/peptidoglycan

  
  

  Eukaryotic cells:

  • Contain membrane-bound organelles
  • Larger ribosomes
  • DNA is linear and contained within the nucleus
  • Plant cells have a cellulose cell wall; fungi have a chitin cell wall
• What is the structure of prokaryotic DNA?


  It is a singular DNA molecule free in the cytoplasm
• What is the function of the cell wall in prokaryotic cells?


  It provides structural support and protection
• What is the role of plasmids in prokaryotic cells?


  They are small circular DNA molecules
• What is a capsule in prokaryotic cells?


  A protective layer surrounding the cell
• How do flagella in prokaryotic cells differ from those in eukaryotic cells?


  Prokaryotic flagella are simpler in structure