1. Cells BIOLOGY OCTOBER 2014

2. What are cells?  The basic unit of life.  The smallest things that can carry out life processes.  Some organisms are made up of a single cell (Ex. Bacteria and Archaea)  Others are made up of trillions of cells. (larger organisms)

3. Size of cells  The largest cell in the human body is the ovum, or egg cell.  Roughly 1 mm in diameter and just visible to the naked eye  The smallest cell in the human body is the sperm.  60 micrometers (0.002 inches) in length, and not visible to the naked eye  The longest cells in the human body is the neuron (nerve cell), which can be over a meter long.  Links the brain to other parts of the body.

4. So, how do we see cells?  Microscope  Anton van Leeuenhoek  Developed a simple microscope in the 1600s  Several types of modern microscope  Compound light microscope  Uses light and lenses to magnify images  These are the ones we’ll be using  Electron microscopes  SEM, TEM, and STM  Read about these in your book.

5. Magnification  The power of magnification is the product of the magnifications of the individual lenses  Eyepiece x objective  An eyepiece with magnification of 10x and an objective lens with magnification of 40x would equal  10 x 40 =400x magnification

7. 1. Ocular Lens (Eyepiece)  This is what you look through to see the image.  It contains a lens (usually 10x magnification)

8. 2. Arm  Structural piece  Holds the parts of the microscope in the proper places.  THE ARM IS NOT A HANDLE  Never carry the microscope by the arm alone.  One hand around the arm, the other hand underneath the base to support it.  Microscopes are very expensive. Use the utmost care when transporting it.

9. 3. Stage  This is the flat portion where you put the slide.  A hole in the stage allows light to pass through the slide

10. 4. Course Focus  Moves the stage up and down.  Doing so brings the object into focus.  Move it until the image becomes visible. It will still be a bit blurry.  Note about the Course Focus: Using the course focus to try to get a better image could result in the stage moving the slide up into the objective. This could crack the slide and/or objective lens, and could be a VERY expensive mistake.

11. 5. Fine Focus  Makes tiny adjustments to the stage.  Once you have found the image, use the fine focus to make it clear.

12. 6. Base  Bottom of the microscope.  Structural and support.  Remember, one hand underneath the base and the other holding the arm.

13. 7. Light Source  A light bulb  Sends light through the slide.

14. 8. Diaphragm  Allows you to adjust the mount of light that come through.

15. 9. Slide Clips  Little metal pieces that hold the slide in place.  Make sure that the slide is under the clips.  You do not want the slide moving after you have just found the image

16. 10. Objectives  Each is a different lens that magnifies the image.  Most microscopes have several of these ranging from 4x to 200x  Begin on the lowest objective to find the image, then increase to zoom it in.

17. 11. Rotating Nosepiece  Holds the objectives  Twist to change magnification.

18. 12. Body Tube  Holds eyepiece

19. The cell theory  Developed with the contributions from 4 scientists (guaranteed matching question!)  Robert Hooke  Matthias Schleiden  Theodor Schwann  Rudolf Virchow

20. Robert Hooke  1600 English scientist  Looked through a microscope at cork (dead oak bark)  Noticed small compartments  Called these compartments “cells”

21. Matthias Schleiden  1800s German Botanist (studied plants)  Observed that all of the plants he saw were made of cells

22. Theodor Schwann  1800s German physiologist (studied how body works)  Interesting facts:  Coined the term “metabolism”  Important cells in the nervous system are named after him (Schwann cells-protect neurons)  Discovered pepsin-the enzyme that breaks down food in the stomach  Through his work, he determined that all animals were made of cells

23. Rudolf Virchow  1800s German doctor  Interesting facts:  First to recognize leukemia cells  Credited in a lot of early cancer research  First person to determine that disease can pass from other animals to humans and vice versa.  Used his research to determine that cells come from other cells.

24. Types of Cells  Some cells have small, specialized structures called organelles.  Each has a specific function for the cell.  Organelle=little organ  Similar to the organs in your body, each of which does some job to keep you functioning, organelles work together to keep the cell functioning.  2 main types of cells  Differentiated by whether they have organelles or not.

25. Prokaryotic Cells  The simpler of the 2 cell types  Lack organelles  Prokaryotic means “Before nucleus”  Most unicellular organisms are prokaryotic  Bacteria, Archaea

26. Eukaryotic Cells  Much more complicated  Contain membrane-bound organelles  Eukaryotic=“True nucleus”  Most of the organisms you are familiar with  Plants, animals, fungi  Mostly multicellular, though some are unicellular  The nucleus controls the cell and contains DNA

27. The Plasma Membrane  Flexible boundary between the cell and its environment.  Jobs: Provides protection, allows materials to enter and exit the cell  Key in homeostasis-process of keeping proper internal conditions  Cell needs nutrients. These are acquired as they pass through the membrane.  Selective Permeability- Membrane allows some materials to enter, while keeping others out.  Similar to a screen on a window (lets air in, prevents birds, insects, etc.)  Some materials, such as water, enter and exit freely.  Other particles can only enter and exit at certain times.

28. Structure of the Plasma Membrane  Phospholipid bilayer  Phospholipids are large molecules of fatty acids  2 parts  Polar head-attracted to water (also a polar molecule)  Nonpolar tail  The head is hydrophilic (attracted to water)  The tail is hydrophobic (avoids water)  This causes the heads and tails to orient in a certain way  Water exists outside the cell and inside the cell

29. Fluid Mosaic Model  Fluid=The cell membrane is fluid, meaning it is constantly moving.  Mosaic=The membrane has a “pattern”  Proteins are embedded in the membrane  Proteins do several jobs, including transport and support

30. Proteins in the Plasma membrane  Transport proteins- move needed materials into and out of the cell  Some proteins help cells to identify chemical signals and each other.  Others in the inner membrane help give the cell support by attaching to internal structures

31. Eukaryotic Cell Structure  Eukaryotic Cells have many different parts  Structures  Organelles  Each portion does something for the cell.

32. Cellular boundaries  Plasma membrane  Job: Protection and selectively allows materials to enter and exit.  Found in: All cells  Cell wall-rigid structure outside the plasma membrane  Job: additional support and protection  Found in: Plants, fungi, some protists, and many prokaryotic cells

35. Cellular Control  Nucleus-control center of the cell  Job: Central in formation of proteins, controls the activity of organelles  Found in: All eukaryotic cells  The nucleus contains the instructions for making proteins  Chromatin-strands of DNA  Forms chromosomes  Nucleus also contains an organelle called the nucleolus  Makes ribosomes (to be discussed soon)

38. Cytoplasm  Jelly-like fluid within the cell.  Outside of the nucleus  Suspends the organelles  Found in all cells

40. Assembly  Endoplasmic Reticulum (E.R.)  Job: Site of chemical reations  Found in: Most eukaryotic cells  2 types:  Smooth E.R.  Many biochemical reactions, including production and storage of lipids  Rough E.R.  Similar to Smooth E.R., but studded with ribosomes  Ribosomes  Job: Making Proteins  Found in: most eukaryotic cells, and some prokaryotic cells  Can be free-floating in the cytoplasm, or attached to R.E.R.

43. Sorting and Packaging  Golgi apparatus-  Job: Modifies proteins. Sorts them and packages them into organelles called vesicles.  Found in: Most eukaryotic cells  Vesicles  Job: Movement of proteins  Found in: Most eukaryotic cells

46. Storage and recycling  Vacuoles  Job: Storage of materials, including food, water, enzymes  Found in: Most eukaryotic cells and some prokaryotic cells  Large one called central vacuole found in plant cells for storage of water.  Plant cells typically have one large one, animal cells have many small ones  Lysosomes  Job: Break down materials in a cell, including  food particles,  invaders such as viruses and bacteria  worn out or broken down cell parts  Found in most eukaryotic cells

49. Energy  Chloroplasts  Job: Convert light energy to chemical energy that can be used  Found in: Plant cells and some unicellular organisms  Contain a pigment called chlorophyll, which traps light energy  Mitochondria  Job: Transfer energy from food into usable energy  Found in: Most eukaryotic cells

52. Support  Cytoskeleton  Job: Gives cell shape, supports cell, allows some cells to move.  Found in: most eukaryotic cells  Cytoskeleton is made up of 2 main parts:  Microtubules-thin, hollow cylinders made up of protein  Microfilaments- smaller, solid protein fibers  Centrioles  Job: assist in cell division  Found in: most eukaryotic cells  Made up of microtubules

55. Locomotion  Cilia and flagella  Some cells, especially unicellular organisms, are capable of movement  They use cilia and flagella to move around their liquid environment  Cilia-short, hair-like structures  Used similar to rowboat  Cells typically have many of these  Flagella-longer whip-like projections  Used like a motor on a boat.  Cells typically have only 1 or 2