BIO122 CHP7

• The first step to understanding the structure of DNA is to understand its chemical composition.
• Epithelial tissues in animals have different shapes and thicknesses
• Connective tissues in animals include loose connective tissue, fibrous connective tissues, adipose tissue, bone, hyaline cartilage, blood
• Muscle tissues in animals include skeletal, smooth, and cardiac muscles
• Nervous tissues in animals include sensory neurons, interneurons, and motor neurons
• Meristematic tissues in plants are undifferentiated tissues with small cells and large nuclei
• There are two main types of meristems in plants: apical and lateral meristems
• Apical meristems are located at the tips of shoots and roots, enabling primary growth
• Primary growth in plants results in the elongation of roots and shoots
• Primary tissues in plants result from primary growth and make up the primary plant body
• Apical meristems give rise to three types of primary meristems: protoderm, procambium, ground meristem
• Lateral meristems in plants increase girth, with two types: vascular cambium and cork cambium
• Vascular cambium in woody stems produces secondary vascular tissues: secondary xylem and secondary phloem
• The plant body consists of root system, shoot system, stems, leaves, and vegetative shoot
• Ground tissue in plants includes parenchyma, collenchyma, and sclerenchyma cells
• Dermal tissue in plants provides outer covering and protection, including epidermis and bark
• Vascular tissue in plants includes xylem and phloem for conduction and transport of materials
• Primary growth in plants results from cell division at the apical meristem, increasing plant length
• Secondary growth in plants results from cell division at the lateral meristem, increasing shoot girth
• Epidermal cells in plants cover all parts of the primary plant body, including guard cells, trichomes, and root hairs
• Ground tissue in plants includes parenchyma for storing food and water, collenchyma for support, and sclerenchyma for structural support
• Xylem in plants is dead and lignified, conducting water, and consists of vessels and tracheids
• Phloem in plants is alive, conducting food, and consists of sieve-tube members with companion cells
• Sieve-tube members in phloem have sieve plates for transport
• Animal tissues include: Epithelium, connective, muscle, and nervous tissues
• Epithelial tissue roles: as interfaces and boundaries
• Epithelial tissue functions:

  • Protection
  • Absorption
  • Sensory reception
  • Ion transport
  • Secretion
  • Filtration
  • Formation of slippery surfaces for movement
• Epithelial tissue thickness:

  • Simple epithelium: One cell thick
  • Stratified epithelium: More than one cell thick
• Epithelial tissue cell shapes:

  • Squamous: Thin, flattened cell, wider than tall
  • Cuboidal: Cube-shaped cell, as tall as wide
  • Columnar: Column-shaped/tall cell, taller than wide
• Basement membrane: Attaches the epithelium to the underlying tissue
• Connective tissues consist of cells and the extracellular matrix they secrete
• Soft connective tissues:

  • Loose connective tissue: Fibroblasts secrete a matrix of complex carbohydrates with fibers dispersed widely through the matrix
  • Dense connective tissue (dense collagen fibers):
  • Dense irregular: Supports skin, internal organs
  • Dense regular: Ligaments and tendons
• Specialized connective tissues include:

  • Cartilage: Rubbery extracellular matrix, supports and cushions bones
  • Adipose tissue: Fat-filled cells, stores energy, cushions and protects organs
  • Blood: Contains erythrocytes, leukocytes, and platelets suspended in plasma
  • Bone: Rigid support, muscle attachment, protection, mineral storage, blood production
• Muscle tissue contracts when stimulated and requires ATP energy
• Three types of muscle tissues:

  • Skeletal muscle tissue: Moves the skeleton (voluntary), long striated cells with many nuclei
  • Cardiac muscle tissue: Heart muscle (involuntary), striated cells with single nuclei
  • Smooth muscle tissue: In walls of hollow organs (involuntary), no striations, single nuclei
• Nervous tissue consists of specialized signaling cells (neurons) and supporting cells (neuroglial cells)
• Neurons:

  • Excitable cells with long cytoplasmic extensions called axons
  • Three types of neurons:
  • Sensory neurons are excited by specific stimuli
  • Interneurons integrate sensory information
  • Motor neurons relay commands from the brain and spinal cord to muscles and glands
• Animals are classified according to a hierarchical system known as taxonomic ranks, which include domain, kingdom, phylum, class, order, family, genus and species.
• Adenine pairs with thymine via two hydrogen bonds, while guanine pairs with cytosine via three hydrogen bonds.
• Each nucleotide contains one of four nitrogenous bases (adenine, thymine, cytosine, or guanine) attached to a deoxyribose sugar molecule through an N-glycosidic bond.