Homeostasis and Microscopy

• Living beings have the capacity to respire, grow, excrete, reproduce, metabolize, move, and react to the environment.
• Cell theory states all living things are made up of cells.
• Every living being is made up of one or more cells.
• The cell is the basic unit of life.
• Every cell comes from another cell.
• The study of cells has advanced the understanding of how living beings respond to their needs.

Parts of an Optical Microscope

• Ocular (lens): The lens you look into to see the specimen.
• Tube oculaire (lens tube): The long tube at the top of the microscope.
• Bra/potence (arm): The arm of the microscope.
• Butee du rack (rack stop): A small part that looks like a tiny pickleball racket.
• Vis micro (micrometer screws): The small adjustment circle.
• Vis marco (marcometer screw): The big adjustment wheel.
• Revolver porte objectif (lens revolver): The big disc that holds the objectives.
• Objectif (objectives): The three lenses with low, medium, and high power.
• Platine (turntable): The square platform where the specimen is placed.
• Diaphragme (diaphragm): The flat disc under the square platform.
• Source lumineuse (light source): The light at the bottom of the microscope.
• Base/pied (base): The bottom of the microscope.

Field of View

• The field of view is the circular area seen through the ocular lens where the magnified image of a specimen is observed.
• The diameter of the field of view decreases when using a more powerful lens.

Biological Drawings

• Scientific drawings should include the total magnification written next to the circle.
• Use a pencil for biological drawings (no pen, no color).
• Straight, horizontal lines should link visible structures to explanatory notes.
• The title of the drawing is at the top.
• Scientific drawings use firm, brief strokes and are generally two-dimensional.
• Stippling is used instead of coloring to highlight details.

Plant Cells

• Cytoplasm is the aqueous substance inside a cell, between the cell membrane and nuclear membrane.
• Cytoplasm is always in motion and fills most of the cell's volume, and is not an organelle but contains organelles in suspension.
• It transports materials, hosts chemical reactions, and stores waste.
• The cell membrane is present in animal and plant cells and controls the passage of materials into and out of the cell.
• The cell membrane is a thin layer of lipids and proteins surrounding the entire cell and is visible under an optical microscope.
• The cell wall is a rigid structure that envelops plant cells, providing support, protection, and acting as a filtration mechanism.
• Nutrients, waste, water, and other substances pass through small pores in the cell wall.
• The cell wall is made of cellulose, also found in paper and celery stalks.
• It’s a thick layer outside the cell membrane and visible under an optical microscope.
• Mitochondria are the energy powerhouse, responsible for cellular respiration and releasing energy from food.
• They are spherical or cylindrical and their number varies depending on cell function, with a folded inside.
• Vacuoles are spherical or oval-shaped organelles filled with liquids.
• There are one or a few large vacuoles in plant cells that reserve food, waste, and other substances, and are visible through an optical microscope.
• Lysosomes are cleaning agents that break down food, dead cells, or bacteria and are present in animal and plant cells.
• They are small spheres of various sizes made by the Golgi apparatus.
• Ribosomes help manufacture proteins and are present in animal and plant cells.
• They appear as very small grains in the cytoplasm, often on the walls of the endoplasmic reticulum.
• Ribosomes deposit their products into the endoplasmic reticulum transport system, which transports proteins to the Golgi apparatus.
• The endoplasmic reticulum (ER) is a network of channels that circulate products within the cell, transporting proteins to the Golgi apparatus.
• It carries products, especially proteins, within the cell.
• The ER often extends from the cell membrane to the nuclear membrane and can be smooth or rough with ribosomes.
• The Golgi apparatus transports proteins into and out of the cell.
• Vesicles (small bubbles) form at the ends of the Golgi apparatus.
• The Golgi apparatus migrates to the cell surface and releases proteins, or sends them directly to lysosomes.
• This organelle is composed of flattened, pancake-like sacs with vesicles at the ends.
• Chloroplasts are only in plant cells, are small, flattened, green ovals, and capture the Sun's energy through chlorophyll for photosynthesis.
• They have inner membranes folded and layered like stacks of pancakes and are the site of sugar production for cellular respiration.
• Chloroplasts are visible through an optical microscope.
• The nucleus is the cell control center that regulates cell activities and contains genetic material.
• It is spherical, pored, and located near the center in animal cells, and more on the edge in plant cells.
• The nucleus is visible under an optical microscope.
• The nucleoplasm is the liquid inside the nucleus, similar to cytoplasm but thicker and gelatinous, found in animal and plant cells.
• Chromatins are long filaments of genetic material floating in the nucleoplasm, winding up to form chromosomes composed of genes, responsible for gene transmission.
• The nuclear membrane protects and controls what enters the nucleus through pores, allowing exchange between nucleoplasm and cytoplasm.
• The nuclear membrane is a double-layered structure surrounding the nucleus and resembles the cell membrane and is present in animal and plant cells.
• Nucleoli (singular: nucleolus) are the ribosome manufacturing center, spherical, and inside the nucleus, present in animal and plant cells.

Animal Cells

• Cytoplasm is the aqueous substance inside a cell, between the cell membrane and nuclear membrane.
• Cytoplasm is always in motion and fills most of the cell's volume, and isn’t an organelle but contains organelles in suspension.
• It transports materials, hosts chemical reactions, and stores waste.
• The cell membrane is present in animal and plant cells and controls the passage of materials into and out of the cell.
• The cell membrane is a thin layer of lipids and proteins surrounding the entire cell and is visible under an optical microscope.
• Mitochondria are the energy powerhouse, responsible for cellular respiration and releasing energy from food.
• They are spherical or cylindrical and their number varies depending on cell function, with a folded inside.
• Vacuoles are spherical or oval-shaped organelles filled with liquids.
• There are several small vacuoles in animal cells.
• They reserve food, waste, and other substances, and are visible through an optical microscope.
• Lysosomes are cleaning agents that break down food, dead cells, or bacteria and are present in animal and plant cells.
• They are small spheres of various sizes made by the Golgi apparatus.
• Ribosomes help manufacture proteins and are present in animal and plant cells.
• They appear as very small grains in the cytoplasm, often on the walls of the endoplasmic reticulum.
• Ribosomes deposit their products into the endoplasmic reticulum transport system, which transports proteins to the Golgi apparatus.
• The endoplasmic reticulum (ER) is a network of channels that circulate products within the cell, transporting proteins to the Golgi apparatus.
• It carries products, especially proteins, within the cell.
• The ER often extends from the cell membrane to the nuclear membrane and can be smooth or rough with ribosomes.
• The Golgi apparatus transports proteins into and out of the cell.
• Vesicles (small bubbles) form at the ends of the Golgi apparatus.
• The Golgi apparatus migrates to the cell surface and releases proteins, or sends them directly to lysosomes.
• This organelle is composed of flattened, pancake-like sacs with vesicles at the ends.
• Centrioles are only present in animal cells, playing a role in cell division (mitosis) by organizing and directing the process, and are formed of two groups of nine rods (cylindrical).
• The nucleus is the cell control center that regulates cell activities and contains genetic material.
• It is spherical, pored, and located near the center in animal cells and is visible under an optical microscope.
• The nucleoplasm is the liquid inside the nucleus, similar to cytoplasm but thicker and gelatinous, found in animal and plant cells.
• Chromatins are long filaments of genetic material floating in the nucleoplasm, winding up to form chromosomes composed of genes, responsible for gene transmission.
• The nuclear membrane protects and controls what enters the nucleus through pores, allowing exchange between nucleoplasm and cytoplasm.
• The nuclear membrane is a double-layered structure surrounding the nucleus and resembles the cell membrane and is present in animal and plant cells.
• Nucleoli (singular: nucleolus) are the ribosome manufacturing center, spherical, and inside the nucleus, present in animal and plant cells.

Test your understanding of homeostasis and microscopy. Questions cover processes related to homeostasis, cell theory principles, light path in microscopes, magnification calculations, and effective microscope adjustments.