Cells, Tissues, and Organs

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Cells, Tissues, and Organs

• Chapter 4

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Modern Cell Biology Makes 6 Assumptions

• All living material is made up of cells or
  products of cells
• All cells are formed from previously existing
  cells
• -cell division
• -fusion of sperm and egg
• 3. Most elementary unit of life

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• 4.Every cell is bound by a plasma membrane
• 5. All cells have strong biochemical similarities
• 6. Most cells are small
• -.001cm (.00004 inches) in length

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3 functions of most cells

1. Maintenance
2. Synthesis of cell products
3. Cell division

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Cell Membrane

• Encloses the cell

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Cytoplasm

• Material in the cell membrane that contains
  organelles and granules in suspension

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Examples of organelles

• Golgi apparatus
• Nucleaus
• Ribosomes
• Centrioles
• Microfilaments
• Microtubles
• Lysosomes
• Storage particles

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Plasma Membrane

• Cells are surrounded by this thin membrane of
  lipid (fat) and protein
• Controls the transport of molecules in and out of
  the cell
• Serves as the boundary between the cell and
  surrounding tissue

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Nucleus

• Enclosed by a nuclear envelope, or membrane, with
  pores

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Nucleoli

• Discrete structures in the nucleus
• Site of RNA synthesis

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Chromosomes in the nucleus

• Contain DNA
• Carries hereditary information

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The nucleus directs the activity of the cell

• Example information is transcribed into the RNA,
  which serves as a messenger. Messenger moves out
  of the nucleus to the ribosome where it guides
  the synthesis of protein.

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Ribosomes

• Made of RNA and protein
• Site of protein synthesis

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Endoplasmic Reticulum

• A complex set of membranous structures
• Rough or smooth
• Rough large amounts of protein

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Golgi Body

• Membrane mixture found near nucleus
• Accumulates secreted lipids and proteins

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Mitochondria

• Almost all of the energy passes through this
  molecule before being used in cell function

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Microfilaments

• Long, thin rods that contract
• Responsible for movement of cells

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Lysosomes

• Large number of enzymes are stored

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Morphogensesis

• Process of cell development
• Each cell contains the same total genetic
  information that was present in the fertilized
  egg
• Cells arent identical because genes are
  controlled (switched on and off) by various
  biochemical processes

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Cell Division Depends On

• 1. copying of DNA
• 2. orderly separation of the products of this copy

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Chromatids

• Each chromosome contains two sister chromosomes
  called this

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6 Stages of Mitosis

1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase
6. Interphase

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Prophase
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Metaphase
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Anaphase
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Telephase
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Interphase
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Meiosis

• Produce gametes (sex cells)
• 2 cell divisions
• Reduce number of chromosomes

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Meiosis Stages

• Prophase with 5 sub-stages
• Prometaphase
• Metaphase
• Anaphase
• Interphase

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• Only one in four of the female gametes is
  functional because the division of cytoplasm is
  unequal
• The functional ovum requires more cytoplasm to
  serve as food for the developing ovum
• Fertilization restores the cell to the original
  number of chromosomes which was reduced during
  meiosis
• Humans 46 chromosomes
• Horse 64 chromosomes

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DNA consists of 3 components

• Deoxyribose sugar
• Phosphate
• 4 nitrogen bases
• A Adenine
• T Thymine
• G - Guanine
• C - Cytosine

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Tissue

• Structured groups of cells specialized to perform
  a common function necessary for the survival of
  the horse

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Classification of Tissues

• Nerve
• Epithelial (cover external and cushion internal)
• Muscle (cardiac)
• Connective (tendons and ligaments)
• Fluid (blood and lymph)