Cell Structure and Function

Cell Structure and Function

• Cells are the basic structural and functional units of all living organisms.
• Cells carry out all the essential processes of life, including metabolism, growth, and reproduction.
• Different cell types have different structures and functions, specialized for their role.
• Prokaryotic cells (e.g., bacteria) lack a nucleus and membrane-bound organelles.
• Eukaryotic cells (e.g., plant and animal cells) have a nucleus and membrane-bound organelles.

Cell Organelles

• Nucleus: Controls cell activities, contains DNA.
• Mitochondria: Site of cellular respiration, produces ATP (energy).
• Ribosomes: Synthesize proteins.
• Endoplasmic Reticulum (ER): Transports materials within the cell.
• Golgi Apparatus: Processes and packages proteins.
• Vacuoles: Store water, nutrients, and waste products.
• Chloroplasts (plants only): Site of photosynthesis.
• Cell Membrane: Regulates what enters and exits the cell.
• Cell Wall (plants only): Provides support and protection.

Cell Transport

• Passive Transport: Movement of substances across the cell membrane without energy input.
  • Diffusion: Movement of substances from high to low concentration.
  • Osmosis: Movement of water across a selectively permeable membrane.
  • Facilitated Diffusion: Movement of substances across the membrane with the help of transport proteins.
• Active Transport: Movement of substances across the cell membrane requiring energy input.
  • Movement of substances against their concentration gradient.

Cell Division

• Mitosis: Cell division for growth and repair.
• Meiosis: Cell division for sexual reproduction.
• Stages of cell cycle: Interphase, mitosis (prophase, metaphase, anaphase, telophase), cytokinesis.
• Importance of cell division for growth, repair, and asexual reproduction.

Tissues, Organs, and Systems

• Tissues are groups of similar cells that perform a specific function.
• Organs are groups of different tissues working together.
• Organ systems are groups of organs working together to perform major body functions.
• Examples of organ systems: digestive, respiratory, circulatory, nervous, excretory, and reproductive.

Plant Tissues

• Meristematic: The growth tissues responsible for plant growth in length and width.
• Dermal: The outer covering of the plant. Includes epidermis, stomata (pores for gas exchange).
• Vascular: Xylem and phloem transport water, minerals, and food throughout the plant.

Plant Nutrition

• Photosynthesis: The process by which plants use sunlight to convert carbon dioxide and water into food (glucose).
• Chlorophyll: The pigment responsible for capturing sunlight.
• Stomata: The pores in the leaves that allow for gas exchange.
• Importance of water, minerals, and sunlight in plant nutrition.