Unit 2 The Microscope & Cells

The microscope is the instrument scientists use to study organisms too small to see with our naked eyes. We will use it to study: unicellular (one – celled) organisms plant cells animal cells transport in cells staining techniques

The Cell Theory and Cell Study The Cell Theory states: 1.The cell is the basic unit of structure of all living things 2.The cell is the basic unit of function of all living things 3.Cells arise (come) from other living cells – not from nonliving matter

Exceptions to the Cell Theory: Viruses are not made up of cells – contain genetic material and reproduce in a host cell The first cell could not have arisen from a previously existing cell

The Cell’s History through Scientific Discovery Anton van Leeuwenhoek (1600’s): developed the first simple microscope Robert Hooke (1665): developed the first compound microscope; coined the term “cell” from observing cork Robert Brown (1831): Identified and named the nucleus in a cell

Matthias Schleiden (1830’s): Concluded plants are made of cells Theodor Schwann (1830’s): Concluded all animals are made of cells Rudolf Virchow (1858): Stated all cells come from pre-existing cells The Cell’s History through Scientific Discovery

Stop and Jot! Cell Theory States: Exceptions to the Cell Theory:

Parts of the Compound Light Microscope: Make sure you know the names of and functions of each of these parts!!!

The Compound Light Microscope Used to see specimens too small to see with the naked eye Specimens must be thin enough so that light can pass through it easily Image created is enlarged, upside down and backwards

Staining Techniques Advantages of staining: colors a specimen so it is more easily seen Common stains used: – iodine stains plant cells – methylene blue stains animal cells

Magnification in Cell Study Total magnification is the total amount that the image is enlarged. The eyepiece and objectives enlarge the image. Therefore to find total magnification you multiply the eyepiece X the objective.

Let’s Practice! Find the total magnification of a microscope: Eyepiece = 10 X and objective of 40 X. Show your work: 10 x 40 = 400 Eyepiece = 15 X and objective = 20X. Show your work. 15 x 20 = 300

Other Types of Instruments Dissecting Microscope – able to study large specimens which cannot be easily seen with a compound light microscope Electron Microscope – produces magnifications of more than 100,000X. Specimen coated in plastic and beams of electrons pass through. Specimen must be dead. Ultracentrifuge – separates cell parts according to density

The Cell Organelles – small structures located inside the cell which work together to keep the cell alive Cell OrganelleFunction PlantAnimal Cell Membrane Surrounds cell, boundary between inside and external environment, semi-permeable √√ Nucleus Controls cell activities, contains genetic material and nucleolus √√ NucleolusMakes ribosomes √√ MitochondriaCreates energy for the cell through cellular respiration √√

Endoplasmic Reticulum (ER) Transports materials around the cell √√ Golgi Complex Synthesizes, packages and secretes cell products √√ Vacuole Storage area of a cell (food, water, waste) √ (large) √ (small) Lysosome Contains enzymes for digestion √ (similar organelle) √ Chloroplast Contains chlorophyll, site of photosynthesis √

Centriole Involved in cellular reproduction √ Cell Wall Stiff outer layer of plant cells. Composed of cellulose, provides shape and support √ Ribosomes Makes proteins √√

Plant Cell Plant Cells are usually stained with Iodine Nucleus: Controls Cell Activities Contains Chromosomes which contain genes on DNA Nucleolus: Helps make ribosomes Mitochondria: Releases Energy by cellular respiration. Has its own DNA Cell membrane: Controls what moves into & out of the cell Selectively Permeable & contains cell receptors for cellular communication. Ribosome: Where Proteins are made Cytoplasm: where the organelles are located. Jelly-like Nuclear membrane: Controls what goes in & out of the nucleus. Vacuole: Storage: Food, water, minerals, waste Cell Wall: Protects & Supports Plant Cells. Made of Cellulose Chloroplast: Makes food for the plant. Site of photosynthesis. Has its own DNA Endoplasmic Reticulum: Network of canals that moves materials within the cell. Rough ER has ribosomes on its surface. Golgi Apparatus: Packages and Stores substances for cellular functions.

Animal Cell Animal cells are usually stained with metheylene blue Centrioles: Help with Cell Reproduction Usually only found in animal cells Lysosomes: Contain Digestive enzymes to destroy worn- out organelles and bacteria. May also be found in plant cells

Transport in Cells 1.Within (inside) the cell A. Cyclosis: The cytoplasm of the cell circulates nutrients, oxygen and waste so these items can get where they need to be. o Also called cytoplasmic streaming B.Endoplasmic Reticulum: A series of channels that moves materials around the cell.

2.Materials move INTO & OUT of the cell through the cell membrane Cell membrane: o Selectively Permeable: Only lets certain materials in or out o Contains:  Pores: Open or close to let materials in Transport in Cells

Two(2) ways materials move THROUGH the cell membrane A.Diffusion: Also called passive transport Movement from an area of higher concentration to an area of lower concentration o With the concentration gradient. o Diffusion of molecules occurs until equilibrium (the same number of molecules) is reached on both sides of the cell membrane Does NOT require energy Osmosis: diffusion of water HighLowEquilibrium

Two(2) ways materials move THROUGH the cell membrane B.Active transport: Movement of a material from an area of lower concentration to an area of higher concentration. o Against the concentration gradient. Requires energy

Stop and Jot! Describe cell transport

How Do Cells Communicate With Each Other? Through Cell receptors: Proteins embedded in the cell membrane that aid in cellular communication Have a specific shape Chemicals (hormones/neurotransmitters) bind to cell receptors because they have a complimentary shape and fit together Once the chemical binds, the cell responds by doing something specific

Which hormones/chemicals bind to the cell receptors? The blue hormones Why?? Because they are the same shape and fit together Hormones/Chemicals Cell Membrane Cell Receptors Let’s see if these will fit!

If this was a muscle cell and the blue hormone represented testosterone, once the testosterone bound to the cell receptor, the cell would grow!

Notice the other hormones present. There are no cell receptors for other hormones on this cell. No other hormones except blue can bind. Example: breast cells have receptors for estrogen, but not testosterone. Therefore, if these cells were bombarded by both hormones, only the estrogen would bind.

Cell Organization Cells grouped together into units Specialized units perform similar functions Groups of cells make up tissues Groups of tissues form organs Organs working together make organ systems Systems together make an organism

Cell TissueOrgan Organ SystemsOrganism