2.1 Cellular and Tissue Structure and Function

Cells are the building blocks of life, containing various organelles that perform essential functions. From the nucleus housing genetic material to mitochondria generating energy, each component plays a crucial role in cellular processes. Understanding cell structure is fundamental to grasping how organisms function at the microscopic level.

Cell division, including mitosis and meiosis, is vital for growth, repair, and reproduction. The cell cycle regulates these processes, ensuring proper DNA replication and distribution of genetic material. Tissues, composed of specialized cells, work together to form organs and systems, highlighting the intricate organization of living organisms.

Cell Structure and Function

Components and organelles of cells

Top images from around the web for Components and organelles of cells

• 

  Cell Structures ‹ OpenCurriculum View original

  Is this image relevant?

• 

  Unique Characteristics of Eukaryotic Cells | Microbiology View original

  Is this image relevant?

• 

  The Cytoplasm and Cellular Organelles | BIO103: Human Biology View original

  Is this image relevant?

• 

  Cell Structures ‹ OpenCurriculum View original

  Is this image relevant?

• 

  Unique Characteristics of Eukaryotic Cells | Microbiology View original

  Is this image relevant?

1 of 3

Top images from around the web for Components and organelles of cells

• 

  Cell Structures ‹ OpenCurriculum View original

  Is this image relevant?

• 

  Unique Characteristics of Eukaryotic Cells | Microbiology View original

  Is this image relevant?

• 

  The Cytoplasm and Cellular Organelles | BIO103: Human Biology View original

  Is this image relevant?

• 

  Cell Structures ‹ OpenCurriculum View original

  Is this image relevant?

• 

  Unique Characteristics of Eukaryotic Cells | Microbiology View original

  Is this image relevant?

1 of 3

• Plasma membrane selectively permeable barrier regulates transport of molecules in and out of the cell
• Nucleus contains genetic material (DNA) controls cellular activities enclosed by a double membrane called the nuclear envelope
• Endoplasmic reticulum (ER)
  • Rough ER studded with ribosomes site of protein synthesis
  • Smooth ER lacks ribosomes involved in lipid synthesis and detoxification (steroids, hormones)
• Golgi apparatus modifies packages and sorts proteins and lipids prepares molecules for secretion or transport to other parts of the cell (vesicles)
• Mitochondria "powerhouses" of the cell produce ATP through cellular respiration (Krebs cycle, electron transport chain)
• Lysosomes contain digestive enzymes break down and recycle cellular waste and debris (autophagy)
• Cytoskeleton network of protein filaments provides structure support and movement to the cell includes microfilaments (actin), intermediate filaments (keratin), and microtubules (tubulin)

Cell division process

• Cell division essential for growth development and repair of tissues
• Two main types of cell division: mitosis and meiosis
• Mitosis occurs in somatic cells produces two genetically identical daughter cells
  1. Prophase: chromosomes condense nuclear envelope breaks down spindle fibers form
  2. Metaphase: chromosomes align at the equatorial plate
  3. Anaphase: sister chromatids separate and move to opposite poles
  4. Telophase: nuclear envelopes re-form around daughter nuclei chromosomes decondense
  • Cytokinesis division of the cytoplasm following nuclear division (cleavage furrow)
• Meiosis occurs in germ cells (reproductive cells) produces four genetically distinct haploid cells
  • Involves two rounds of cell division: meiosis I and meiosis II
  • Important for genetic diversity and sexual reproduction (recombination, independent assortment)
• Cell cycle regulates cell division and growth
  • Interphase: cell grows and prepares for division
    • G1 phase: cell growth and normal cellular functions
    • S phase: DNA replication
    • G2 phase: cell prepares for mitosis (protein synthesis)
  • Mitotic phase: cell undergoes mitosis and cytokinesis

Tissue Structure and Function

Types of human tissues

• Epithelial tissue covers body surfaces and lines cavities and ducts
  • Functions: protection (skin), secretion (glands), absorption (intestines), and filtration (kidneys)
  • Examples: skin epidermis, lining of the digestive tract, and glandular tissue (mammary glands, salivary glands)
• Connective tissue supports and connects other tissues
  • Functions: structural support, protection, and transport
  • Examples: bone (calcium phosphate matrix), cartilage (collagen, proteoglycans), blood (plasma, cells), and adipose tissue (fat storage)
• Muscular tissue composed of cells specialized for contraction
  • Functions: movement (locomotion), support (posture), and heat generation (thermogenesis)
  • Types: skeletal (voluntary), smooth (involuntary), and cardiac muscle (heart)
• Nervous tissue composed of neurons and glial cells
  • Functions: receive, process, and transmit information (electrical and chemical signals)
  • Examples: brain (cerebrum, cerebellum), spinal cord, and peripheral nerves (sensory, motor)

Extracellular matrix in tissues

• Extracellular matrix (ECM) non-cellular component of tissues provides structural and biochemical support to surrounding cells
• Composition varies depending on the tissue type
• Main components
  • Fibrous proteins: collagen and elastin
    • Collagen provides tensile strength and structural support (tendons, ligaments)
    • Elastin provides elasticity and allows tissues to stretch and recoil (arteries, lungs)
  • Proteoglycans and glycosaminoglycans highly hydrated molecules form a gel-like substance provide cushioning and help resist compressive forces (cartilage, synovial fluid)
  • Adhesive glycoproteins: fibronectin and laminin help cells attach to the ECM and each other facilitate cell migration and tissue organization (basement membranes)
• Functions
  • Mechanical support and structural integrity
  • Regulation of cell behavior (proliferation, differentiation, migration)
  • Facilitates diffusion of nutrients metabolites and signaling molecules (growth factors, cytokines)
  • Provides a scaffold for tissue repair and regeneration (wound healing, fracture repair)