Subtopics are highlighted, terms are bolded, and definitions are underlined :)
What is a microscope?
A microscope is an instrument that enlarges the image of a small object, thus revealing details too small to be seen by the naked eye.
They led to the field of microbiology, changed the way physicians treat illnesses and allowed us to understand how cells work.
Light Microscope - uses visible light and a system of lenses to generate magnified images of small objects, 1000x magnification
Electron Microscope - uses a beam of accelerated electrons to generate magnified images of small objects, 1,000,000x magnification
There are two types of electron microscopes...
Scanning Electron Microscope (SEM) - studies the surface of cells
Transmission Electron Microscope (TEM) - explores internal structures
The Cell Theory has three basic ideas...
1. All living things are composed of cells.
2. Cells are the basic unit of structure and function in living things.
3. All cells came from preexisting cells.
The Basic Cell:
Plasma Membrane - semi-permeable lipid bilayer
Phospholipids are the major constituent of the membrane. It defines the perimeter of the cell and is involved in cell adhesion, cell signaling, and transport of materials in and out of the cell.
Cytoplasm - the entire contents of the cell, exclusive of the nucleus and bounded by the plasma membrane
In prokaryotes, it includes the entire contents of the cell. Many cell reactions take place here.
Cytosol - a semifluid substance in the cytoplasm
Organelle - a specialized subunit within a cell that has a specific function, usually enclosed by a membrane, ex. nucleus
Nucleus - contains the genetic material of a eukaryotic cell
Nuclear Envelope - encloses the nucleus, separating its contents from the cytoplasm
Nucleolus - a highly visible region in the nucleus where ribosome are assembled from rRNA and ribosomal proteins
Ribosome - Site of protein synthesis and composed of ribosomal RNA and protein
Free Ribosomes - produce proteins that will remain inside the cell
Rough ER Membrane-Bound Ribosomes - produces proteins destined for secretion and proteins destined for insertion into the cell membrane
Endoplasmic Reticulum - an interconnected system of tubules
It is connected with the nuclear envelope. There are two types...
Smooth Endoplasmic Reticulum - no attached ribosomes
Rough Endoplasmic Reticulum - ribosomes are attached
The ribosomes on the rough ER produce proteins that will be later inserted into the cell membrane or secreted from the cell.
Golgi Complex - modifies, stores, and routes proteins and other chemical products to their next destination
This is also known as the Golgi Apparatus or Golgi Bodies.
Lysosome - involved in the digestion of nutrients, harmful bacteria, and damaged organelles and Apoptosis
Apoptosis - programmed cell death
Cytoskeleton - consists of microtubules and microfilaments
It maintains cell shape, is an anchorage for organelles, and allows for the movement of organelles within a cell.
Centrosomes - the microtubule-organizing centers that form the mitotic spindle in dividing cells
Centrioles - animals have these within their centrosomes which help with cell division
Vesicles - small membrane-bound sacs that are used to move chemicals around the cell
Vacuoles - membrane-bound sacs that are larger than vesicles and have a diverse set of functions, ex. food vacuole stores food taken into the cell
Central Vacuole - only found in plant cells and its main role is to maintain turgor pressure against the cell wall
It also determines whether the cell is turgid or flaccid and is storage for nutrients and water.
Contractile Vacuole - maintains water balance by pumping the excess water out of a cell and is found in freshwater protists
Mitochondria - present in eukaryotic cells, double membrane, and is the major site where energy from food is used to make ATP which is needed to do cell work
Chloroplast - found in algae and plants, double membrane, green color, and photosynthesis occurs here
Cell Wall - found in plant cells, consists of cellulose, includes maintenance of cell shape and skeletal support and provides protection for plant cells
Flagella - tail-like projection that is involved in cell movement
Cilia - short finger-like projections that are involved in cell movement
Pseudopod - temporary cytoplasmic projections that allow cells to move or engulf food that is involved in cell movement
Types of Cells:
Prokaryotes - single-celled, smallest of the cells, lack a nucleus, lacks membrane-bound organelles, has a cell wall made of peptidoglycan, and has circular DNA, ex. bacteria and archaea
Eukaryotes - has a nucleus, has membrane-bound organelles, can be single or multicellular, and has linear DNA, ex. protists, fungi, plants, and animals
There are characteristics that all cells have...
Bounded by a plasma membrane, contains cytosol, contains chromosomes, and contains ribosomes.
Endosymbiosis - the evolution of eukaryotes, and the origin of mitochondria and chloroplasts
The origin of mitochondria happened because early eukaryotic heterotrophs engulfed aerobic bacteria but did not digest them. The origin of chloroplasts happened because some additional heterotrophs engulfed photosynthetic bacteria but did not digest them.
What is the Endosymbiotic Theory?
The Endosymbiotic Theory is that mitochondria and chloroplasts originated as separated organisms that were engulfed but not digested and a symbiotic relationship was developed.
Animal vs. Plant Cells...
There are three cell structures unique to plant cells, which are chloroplasts, the cell wall, and the central vacuole.
Level of Structure - Atom < Molecule < Organelle < Cell < Tissue < Organ < Organ System < Organism
Phospholipid Bilayer - semi-permeable bilayer
Small hydrophobic molecules can get across, but hydrophilic can't.
Protein Channels - specific channels that allow hydrophilic materials across the cell membrane since the phospholipid bilayer won't let them
Cholesterol - prevents the cell membrane from becoming too rigid or too fluid and is important for membrane stability
Passive Transport - molecules move from areas of higher concentration to areas of lower concentration and no energy is required by the cell, ex. simple diffusion, facilitated diffusion, and osmosis
Simple Diffusion - molecules move from areas of higher concentration to areas of lower concentration, is passive, and increased temperature speeds up the rate of diffusion
Facilitated Diffusion - diffusion through transport proteins, and allows hydrophilic molecules to diffuse across the cell membrane
Osmosis - diffusion of water across a selectively permeable membrane from a high concentration to a low concentration
Water moves through a channel in the membrane called an aquaporin. Water moves to equalize the solute concentration inside and outside the cell.
Solvent - the substances that dissolve the other substance and are present in the greater amount
Solute - the substance that is dissolved and is present in the lesser amount
Solution - a mixture of one or more solutes dissolved in a solvent
Hypertonic - a solution with a higher concentration of solute and a lower concentration of water
Hypotonic - solution with a lower concentration of solute and a higher concentration of water
Isotonic - solutions in which the concentrations of solute and water are equal
Water flows from hypotonic to hypertonic solutions until isotonic solutions are achieved.
Active Transport - cell expends energy to move molecules across a membrane from low to high concentration, ex. protein pumps
Exocytosis - taking materials outside a cell through the use of a vesicle
Endocytosis - the process of taking materials into a cell within vesicles that bud inward from the plasma membrane
Base - used for support
Arm - supports the tube and connects it to the base
Body Tube - connects the eyepiece to the objective lenses
Ocular - the lens that you look through, which magnifies the image by 10x
Revolving Nosepiece - allows you to easily rotate and change objective lenses
Scanning Power Objective - magnifies the image 4x
Low Power Objective - magnifies the image 10x
High Power Objective - magnifies the image 40x
Stage - the flat platform where you place your slides
Stage Clips - holds the slides in place
Diaphragm - varies the light intensity that is projected upward into the slide
Coarse Adjustment - allows you to focus in on the specimen
Fine Adjustment - allows you to fine-tune the focus after you used the coarse adjustment
Light Source - illuminates the slide