Biology: Cells and Infectious Diseases

1. Biology: Cells and Infectious Diseases Science 421 September 2018

2. What are living things? • Each living thing is called an organism • An organism can be multicellular or unicellular • The study of living things is called Biology

3. Characteristics of Living Things • All organisms have the following characteristics: • Highly organized and contain many complex chemical substances • Made up of one or more cells • Use energy • Have a definite form and limited size • Have a limited life span • Grow and develop • Respond to changes in/adapt to their environment • Able to reproduce • Evolve or change over time • Produce waste

4. The Development of the Cell Theory

5. What is the Cell Theory? • The idea that life arises from life (biogenesis) • First stated in 1858, it took a long time before the scientific community would accept this theory

6. Components of the Cell Theory • All living things are made up of one or more cells. • Cells are the basic units of structure and function in living things • New cells are produced from existing cells

7. History of the Cell Theory Aristotle and Abiogenesis • Before the microscope was developed, Greek Philosopher, Aristotle (334 BCE) came up with the theory of Abiogenesis: nonliving things can be transformed into living things. (Also referred to as “spontaneous generation”.) Scientists accepted his theory for almost 2000 years!

9. It was not until the mid 1660’s that science began to make advancements in the cell theory: • 1665 ~ English scientist Robert Hookemade an improved microscope and viewed thin slices of cork. • He was viewing plant cell walls • Hooke named what he saw "cells"

10. 1838 ~ German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells • 1839 ~ German zoologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells. Schleiden Schwann

11. 1855 ~ Rudolph Virchow stated that all cells come from old cells • CELL THEORY: New cells are produced from existing cells (Virchow) Virchow Video Clip - History of Cell Theory

12. 1860 ~ Louis Pasteur finally disproved the theory of spontaneous generation and supported Virchow’s theory that all life comes from pre-existing life.

13. Using a Microscope to Explore Life

14. The History • Hans and Zacharias Janssen of Holland in the 1590’s created the “first” compound microscope • Antony van Leeuwenhoek and Robert Hooke made improvements by working on the lenses Robert Hooke 1635-1703 Antony van Leeuwenhoek 1632-1723 Hooke Microscope

15. How a Microscope Works Convex Lenses are curved glass used to make microscopes (and glasses etc.) Convex Lenses bend light and focus it in one spot.

16. How a Microscope Works Ocular Lens (Magnifies Image) Objective Lens (Gathers Light, Magnifies And Focuses Image Inside Body Tube) Body Tube (Image Focuses) • Bending Light: The objective (bottom) convex lens magnifies and focuses (bends) the image inside the body tube and the ocular convex (top) lens of a microscope magnifies it (again).

17. Parts of the Microscope:Body Tube • holds the objective lenses and the ocular lens at the proper distance

18. Nose Piece • holds the objective lenses and can be turned to increase the magnification

19. Objective Lenses • increase magnification (usually from 4x, 10x to 40x)

20. Stage • Supports the slide/specimen

21. Stage Clips • hold the slide/specimen in place on the stage.

22. Diaphragm • controls the amount of light on the slide/specimen Turn to let more light in or to make dimmer.

23. Light Source • Projects light upwards through the diaphragm, the specimen and the lenses • Some have lights, others have mirrors where you must move the mirror to reflect light

24. Ocular Lens/Eyepiece • Magnifies the specimen image

25. Coarse Adjustment Knob • Moves the stage up and down (quickly) for focusing your image

26. Fine Adjustment Knob • This knob moves the stage SLIGHTLY to sharpen the image

27. Arm • Used to support the microscope when carried. Holds the body tube, nose piece and objective lenses

28. Base • Supports the microscope

29. Assignment: • Label the diagram of the microscope (handout)

30. Magnification • To determine your magnification…you just multiply the ocular lens by the objective lens • Ocular 10x Objective 40x:10 x 40= 400x So the object is 400 times “larger” Objective Lenses have their magnification written on them. Ocular lenses usually magnifies by 10x

31. Caring for a Microscope • Clean lenses with lens paper only • Make sure it’s on a flat surface • Don’t bang it • Carry it with 2 HANDS…one on the arm and the other on the base • Never attempt to repair your microscope. Notify the teacher if a problem arises • Before returning, remove any slides, rotate nosepiece to lowest power objective lens and wrap the cord around the bottom.

32. Carry a Microscope Correctly

33. Using a Microscope • Always start on the lowest magnification • Don’t use the coarse adjustment knob on high magnification…you’ll break the slide!!! Use fine adjustment to focus • Never allow the lens to touch the coverslip of a slide or wet mount stains. • Place slide on stage and lock clips • Adjust light source (if it’s a mirror…don’t use direct sunlight) • Video: How to Use a Microscope

34. There are three adjustments to be made when using a microscope. • Brightness – adjusts how light or dark the image is using the illumination. • Focus – adjusts if the image is blurry or well defined by using the focus knobs, which change the location of the focal point. • Contrast – which is the difference in lighting between two areas. This can be adjusted by changing the intensity of the light and the pinhole aperture.

35. Assignment: • Laboratory: Introduction to the microscope and making biological drawings.

36. Cells: the smallest units of life Structures in Cells

37. As living things, Cells need to have ways of surviving: • Obtain food and energy • Convert energy into a usable form • Construct and maintain molecules that make up the cell • Carry out chemical reactions (photosynthesis and cellular respiration) • Eliminate wastes • Reproduce

38. Two basic types of cells Prokaryotic Cells • Smallest living cells • No cell nucleus • No membrane-bound organelles. • DNA travels openly around the cell. • All bacteria are prokaryotes. Eukaryotic Cells • 10-1000x larger than prokaryotic cells • Contain a nucleus • Contain many specialized structures called organelles with different functions • trees, grass, worms, flies, mice, humans, mushrooms and yeast are eukaryotes (have eukaryotic cells). Images: Mariana Ruiz

39. Comparison of Eukaryotic and Prokaryotic Cells Image: k12station.blogspot.com/2006_08_01_archive.html

40. Eukaryotic Cells • All living organisms are made of eukaryotic cells except bacteria • Eukaryotic cells are classified as plant or animal cells Plant Animal http://library.thinkquest.org/C004535/eukaryotic_cells.html

41. Cell Structures & Organelles • Cell membrane • Separates the internal contents of the cell from the outside environment • Provides structure and protection for the cell • Allows movement of materials in and out of the cell • Cytoplasm • Gel-like material that surrounds the organelles.

42. organelles • Organelles are structures found in the cytoplasm of eukaryotic cells that have different jobs within the cell • Some organelles are found in both plant and animal cells but some are only in plant or only in animal cells.

43. Plant and Animal Cell Organelles Nucleus • Structure: Contains DNA (chromosomes) • Function: Control centre of the cell • Location: centre of the cell

44. DNA and chromosomes DNA -contains the genetic information that controls the structure and purpose of each cell Chromosomes -strands of DNA and proteins that contain genes Note: human DNA is contained within 23 pairs of chromosomes (in most cases)

45. Mitochondrion (mitochondria) • Structure: Bound by a double membrane • Structure: • Cristae are the folds of the inner membrane to increase the surface area • The matrix is the inner part • Function: Powerhouse of the cell (cellular respiration occurs here to release energy for the cell) matrix cristae

46. Vacuoles • Location: • Large central vacuole usually in the centre of plant cells • Many smaller vacuoles in cytoplasm of animal cells • Structure: Sac-like structures containing fluid • Function: Storage container for water, food, enzymes, wastes, pigments, etc.

47. Organelles found only in Plant Cells:

48. Cell Wall • Location: surrounds the outside of the cell membrane in plant and bacterial cells • Structure: Rigid, protective barrier made of cellulose • Function: Adds strength and structure to the cell

49. Chloroplast • Structure: • Disc shaped • Contains the green pigment chlorophyll • Bound by a double membrane • Function: Site of photosynthesis (production of food and energy) • Location: cytoplasm of plant cells

50. Assignments • Onion and Cheek Cell Lab