Cell Biology: Cell Structure

Cell Biology

Cell Structure

• Prokaryotic cells: lack a true nucleus, have a single circular chromosome
• Eukaryotic cells: have a true nucleus, multiple linear chromosomes
• Cell membrane: semi-permeable, regulates what enters and leaves the cell
• Cytoplasm: jelly-like substance inside the cell membrane, site of metabolic reactions
• Organelles:
  • Nucleus: stores genetic information
  • Mitochondria: generates energy for the cell
  • Endoplasmic reticulum (ER): involved in protein synthesis and transport
  • Ribosomes: site of protein synthesis
  • Lysosomes: contains digestive enzymes, breaks down and recycles cellular waste
  • Golgi apparatus: modifies and packages proteins and lipids for transport

Cellular Processes

• Cellular respiration: process of generating energy from glucose, occurs in mitochondria
  • Aerobic respiration: uses oxygen, produces ATP
  • Anaerobic respiration: does not use oxygen, produces lactic acid or ethanol
• Photosynthesis: process of generating energy from sunlight, occurs in chloroplasts
  • Light-dependent reactions: generate ATP and NADPH
  • Light-independent reactions: use ATP and NADPH to produce glucose
• Cell signaling: process of communication between cells, involves receptors and signaling pathways
• Cell division: process of cell growth and reproduction, includes mitosis and cytokinesis

Cell Transport

• Passive transport: movement of molecules from high to low concentration, no energy required
  • Diffusion: random movement of molecules
  • Osmosis: movement of water molecules
• Active transport: movement of molecules from low to high concentration, energy required
  • Carrier proteins: transport molecules across the cell membrane
  • Pumping mechanisms: use energy to transport molecules against their concentration gradient

Cell Cycle

• Interphase: cell grows, replicates DNA, and prepares for cell division
• Mitosis: process of cell division, results in two identical daughter cells
  • Prophase: chromosomes condense, nuclear envelope breaks down
  • Metaphase: chromosomes align at the center of the cell
  • Anaphase: sister chromatids separate
  • Telophase: nuclear envelope reforms, chromosomes uncoil
• Cytokinesis: process of cell division, results in two separate daughter cells
  • Cleavage: cell divides into two daughter cells
  • Cytokinesis in animal cells: involves the formation of a cleavage furrow
  • Cytokinesis in plant cells: involves the formation of a cell plate

Cell Structure

• Prokaryotic cells lack a true nucleus and have a single circular chromosome.
• Eukaryotic cells have a true nucleus and multiple linear chromosomes.
• The cell membrane is semi-permeable and regulates what enters and leaves the cell.
• Cytoplasm is a jelly-like substance inside the cell membrane, where metabolic reactions occur.

Organelles

• The nucleus stores genetic information.
• Mitochondria generate energy for the cell.
• The endoplasmic reticulum (ER) is involved in protein synthesis and transport.
• Ribosomes are the site of protein synthesis.
• Lysosomes contain digestive enzymes that break down and recycle cellular waste.
• The Golgi apparatus modifies and packages proteins and lipids for transport.

Cellular Processes

Cellular Respiration

• Cellular respiration is the process of generating energy from glucose, occurring in mitochondria.
• Aerobic respiration uses oxygen, producing ATP.
• Anaerobic respiration does not use oxygen, producing lactic acid or ethanol.

Photosynthesis

• Photosynthesis is the process of generating energy from sunlight, occurring in chloroplasts.
• Light-dependent reactions generate ATP and NADPH.
• Light-independent reactions use ATP and NADPH to produce glucose.

Cell Signaling and Division

• Cell signaling is the process of communication between cells, involving receptors and signaling pathways.
• Cell division is the process of cell growth and reproduction, including mitosis and cytokinesis.

Cell Transport

Passive Transport

• Passive transport is the movement of molecules from high to low concentration, requiring no energy.
• Diffusion is the random movement of molecules.
• Osmosis is the movement of water molecules.

Active Transport

• Active transport is the movement of molecules from low to high concentration, requiring energy.
• Carrier proteins transport molecules across the cell membrane.
• Pumping mechanisms use energy to transport molecules against their concentration gradient.

Cell Cycle

Interphase

• Interphase is the phase where the cell grows, replicates DNA, and prepares for cell division.

Mitosis

• Mitosis is the process of cell division, resulting in two identical daughter cells.
• Prophase: chromosomes condense, and the nuclear envelope breaks down.
• Metaphase: chromosomes align at the center of the cell.
• Anaphase: sister chromatids separate.
• Telophase: the nuclear envelope reforms, and chromosomes uncoil.

Cytokinesis

• Cytokinesis is the process of cell division, resulting in two separate daughter cells.
• Cleavage: the cell divides into two daughter cells.
• Cytokinesis in animal cells involves the formation of a cleavage furrow.
• Cytokinesis in plant cells involves the formation of a cell plate.