BASIC CELL BIOLOGY Objectives Explain the molecular makeup

BASIC CELL BIOLOGY

Objectives ◦ Explain the molecular makeup of cells. ◦ Identify the basic structures of the cell and their corresponding functions. ◦ Review the basic function of the cell. ◦ Describe the process of protein synthesis. ◦ Discuss mitosis and its clinical significance in diseases such as cancer. ◦ Detail meiosis in mammalian reproduction. ◦ Connect cellular parts and function to clinical veterinary practice.

DISCOVERY OF THE CELL

The story… ◦ Begins with a Dutch naturalist named Anton van Leeuwenhoek (Lay-ven-hook) over 300 years ago. ◦ Using first a magnifying glass, and then primitive, custom-mad microscopes, Leeuwenhoek was the first to see single-celled life forms swimming around in blood, sperm, and pond water. ◦ He called these organisms “animalcules” ◦ Five years later, an Englishman named Robert Hooke sliced a piece of cork and examined it under the microscope. ◦ He saw small, empty spaces which he dubbed cells, meaning small rooms. ◦ But it was not until 1839 that two German scientists – Matthias Schleiden and Theodor Schwann – deduced that the cells that Robert Hooke and Leeuwenhoek described were the basic unit of virtually all life forms.

CELL MAKEUP Objective: Explain the molecular makeup of cells

Cell Makeup ◦ The Cell: is the basic structure of animal life.

CELL STRUCTURE Objective: Identify the basic structures of the cell and their corresponding functions

Cells – Building Blocks of Life ◦ Many cell types exist. ◦ These cells not only look different but function differently as well. ◦ Perform specific roles. ◦ Example: Heart muscle cell possesses some features that are not present in either a brain cell or a skin cell. ◦ Nevertheless, many features are common among cells. ◦ Must use energy to maintain themselves ◦ Absorb oxygen and nutrients, and rid themselves of wastes ◦ Maintain the right levels of water and other chemicals inside their membranes ◦ Keep undesirable materials out ◦ Maintain a safe place to house DNA (the instructions for the operation of the cell) ◦ Specialized structures within the cells are called organelles. ◦ These organelles are present in most but not all cells. ◦ For example: Red blood cells lack a nucleus.

Cell Membrane ◦ AKA the Plasma Membrane ◦ Is common to all cells. ◦ Serves as the boundary that keeps the inside of the cell contained. ◦ Is so fine that it cannot be seen with a normal light microscope. ◦ The cell membrane is about half protein and half phospholipid. ◦ One end of phospholipids are attracted to water (Hydrophilic), whereas the other end is repelled by water (Hydrophobic). ◦ The cell membrane, which is surrounded by water on both sides, has two layers of lipid in its wall. ◦ The ends of the lipid that are attracted to water face outward ◦ Proteins: ◦ Included in the membrane, both between the lipid molecules and on the surface. ◦ Play a key role in the structure and function of cells.

Cell Membrane ◦ Nickname: Protector ◦ Cell membranes are semipermeable ◦ They allow certain substances but not others to pass. ◦ Some molecules, such as water, are able to pass through easily. ◦ Other molecules, such as proteins and starches are unable to pass. ◦ Many of the organelles within the cell are also surrounded by a membrane. ◦ The basic structure remains the same for all the membranes.

Transport ◦ Cells will be unable to function properly if there is too much or too little of certain products. ◦ Homeostasis is the maintenance of extracellular fluid (ECF). ◦ Allows maintenance of normal concentrations of molecules in spite of a wide variety of external conditions. ◦ Cells must be able to obtain products from the ECF. ◦ Passive Transport: Doesn’t require energy ◦ Diffusion: in which molecules move from higher to lower concentrations. ◦ Continues until the concentrations are equalized. ◦ Does not allow totally free diffusion ◦ Active Transport: Requires energy ◦ Osmosis: Allows a solvent to move across a membrane in an effort to equalize concentration.

Membranes and Transport ◦ https: //www. youtube. com/watch? v=d. PKv. Hr. D 1 e. S 4 ◦ Watch until 5: 38

Cell Contents ◦ Cell contents are divided into the nucleus and the cytoplasm. ◦ Specifics of the makeup differ, depending on function. ◦ Cytoplasm: describes the organelles and fluid in the cell. ◦ Gel-like material inside the cell membrane and outside the nucleus. ◦ Nickname: Gel

Nucleus ◦ Nickname: Brain ◦ A standard part of most cells ◦ Contains genetic material (DNA) of the cell which controls cellular activities by coding for protein synthesis. ◦ The DNA in the nucleus is called chromatin. ◦ As the cell divides, the chromatin clumps into chromosomes. ◦ A two lipid bilayer membrane surrounds the nucleus. ◦ Nucleolus: Is the site of ribosome production

Ribosomes ◦ Nickname: Protein Maker ◦ Small granular-like structures that can be found in the cytoplasm. ◦ Ribosomes manufacture the protein used in the cell. ◦ Growing cells require large amounts of protein and, therefore, have a greater number of ribosomes.

Endoplasmic Reticulum (ER) ◦ Nickname: Highway ◦ A collection of folded membrane ◦ Attaches to the membrane of the nucleus. ◦ Ribosomes often line this membrane, giving it a bumpy appearance. ◦ Rough Endoplasmic Reticulum (RER) ◦ Protein produced by the ribosomes is deposited into the RER

Smooth Endoplasmic Reticulum (SER) ◦ Has no ribosomes attached. ◦ Not as common. ◦ Provides a membrane surface where a variety of complex carbohydrates and lipids, including phospholipids, are synthesized. ◦ Example: Smooth ER in the liver detoxifies harmful substances.

Golgi Apparatus ◦ Nickname: Post Office ◦ Formed with large amounts of folded membrane that looks similar to SER. ◦ Produces polysaccharides and special protein sacs called lysosomes. ◦ Protein produced in the RER is moved to the Golgi apparatus. ◦ The Golgi apparatus then changes the protein and collects it in the lysosomes. ◦ These sacs are pinched from the Golgi apparatus and the moved to the surface of the cell and released.

Lysosomes ◦ Nickname: Garbage Disposal ◦ There are several hundred lysosomes in the typical cell. ◦ Contain enzymes that help break down molecules. ◦ Used to digest food taken in by the cell and to destroy cell structures no longer needed.

Mitochondria ◦ Nickname: Power House ◦ Small rod-shaped organelles found in varying numbers in cells. ◦ The more active the cell, the more mitochondria are present. ◦ Example: Liver cells have over 1000 of them ◦ Have a double membrane, similar to the cell membrane. ◦ The outer membrane is smooth and forms the shape of the mitochondria. ◦ The inner membrane is highly folded. ◦ These shell-like infolded ridges are called cristae. ◦ Convert food substances into energy that can be used by the cell. ◦ Found within cells at their areas of highest activity.

Compare the school to a cell ◦ Break up into groups ◦ Compare parts of the school to the parts of a cell ◦ Be able to explain why you chose that part. ◦ Example: Nucleus (Brain) = Main Office. Then explain why. ◦ Terms to use: ◦ ◦ ◦ ◦ Nucleus (Brain) Mitochondria (Power House) Lysosomes (Garbage Disposal) Golgi Apparatus (Post Office) Endoplasmic Reticulum (Highway) Ribosomes (Protein Maker) Cell Membrane (Protector)

The City of Cells ◦ https: //www. youtube. com/watch? v=cj 8 d. DTHGJBY

MAMMALIAN REPRODUCTION Objective: Detail Meiosis in Mammalian Reproduction

Sexual Reproduction ◦ Mammals rely on sexual reproduction for species survival. ◦ Sexual Reproduction: a sperm cell and egg cell join to form the new embryo. ◦ In this process, half of the genetic material is provided by each of the cells. ◦ Meiosis is the division which the resulting cells contain only half of the genetic material.

CLINICAL PRACTICE Objective: Connect Cellular Parts and Function to Clinical Veterinary Practice

Clinical Practice ◦ In clinical practice, the appearance of cells is often evaluated. ◦ A biopsy takes tissues or cells form an animal for microscopic review. ◦ This allows vets to search for tumors or find other abnormalities. ◦ Understanding cellular function is essential for sound veterinary practice. ◦ Helps guide treatment of animals.