Cells were discovered and studied by using microscopes

1. Cells were discovered and studied by using microscopes • cell theory = all living cells are formed by division of existing cells and inherit their characteristics from them • cell theory is the basis of all biology • our understanding of how cells behave gives us clues to the past - evolution

2. Plant root tip Kidney ducts Tissue = cells surrounded by extracellular matrix

3. 1M=1000mm=1,000,000μm (micron) .2μm=200nm

6. Brightfield Phase contrast Differtial-interference

12. A living cell seen under a light microscope

22. .2nm=2Å

23. Yeast eucaryote by light microscope Eucaryotes have intracellular membrane organalles like nuclei Procaryotes do not = bacteria (eubacteria and archaebacteria)

24. Nuclius -DNA as chromatin

25. Chromosomes in a cell about to divide - DNA condensed

26. Mitochondria by light microscope

27. Mitochondria by electron microscope

28. Theory of the origin of mitochondria

29. Chloroplasts - photosynthesis Leaf cells by light microscopy Electron micrograph of a chloroplast

30. Theory of the origin of chloroplasts

31. Endoplasmic reticulum

32. golgi

34. endocytosis exocytosis

35. Cytoskeleton - A.actin filaments (thinnest - rapid,muscles), B microtubules (thickest - hollow tubes - spindle/ mitosis, movement of organelles), C intermediate filaments (mechanical stability) Gives cells mechanical strength, controls shape, drives and guides intracellular and cell movements

36. Microtubules (spindle) in a dividing cell

37. Cells vary enormously in appearance and function

40. Protozoan Paramecium neuron Plant stem bacterium dendrite flagella Cell body axon cilia The larger a cell is the more surface area is required for all the transactions needed - taking in nutrients, getting rid of wastes. Intracellular membranes add to the surface area and allow the volume or size of the cell to be greater. Therefore eucaryotic cells are larger than procaryotic cells

41. Neutrophil (white blood cell) engulfing a red blood cell Cells are enormously diverse chemically also. Some need oxygen, for some oxygen is poison. Some make hormones, some are “engines” like muscles. But all living cells have a similar basic chemistry.

42. All living cells are similar • grow, reproduce, convert energy from one form into another, etc. • chemistry - DNA stores genetic instructions using the same chemical code (nucleotides), this code is duplicated, transcribed and translated in the same way in all cells. • DNA codes for the construction of protein molecules which in large part determine the behavior of the cell • The same 20 different amino acids are the building blocks for proteins in all cells.

43. DNA duplicates before a cell reproduces (divides). • Daughter cells receive a set of the DNA and therefore resemble parent. But not exactly. • Mutations (changes in the DNA) can lead to a change that is bad - less able to survive and reproduce, a change that is neutral - makes no difference in survival, or a change that is for the better - better able to survive - evolution. • In general, the struggle for survival (food etc) eliminates the bad, favors the good, and tolerates the neutral changes -natural selection. • Sexual reproduction also leads to different combinations of genetic material - evolution.

44. Evolution = changes in the DNA (evolving) and selection of the organisms that are better able to survive over thousands of millions of cell generations. • Present day cells may be fundamentally similar because they all inherited their genetic instructions from a common ancestor. • Cells are ultimately made of inorganic chemicals, oxygen, carbon, etc. So cells obey the laws of physics - thermodynamics and chemistry. Cannot create energy etc. • The larger a cell is the more surface area is required for all the transactions needed - taking in nutrients, getting rid of wastes. Intracellular membranes add to the surface area and allow the volume or size of the cell to be greater. Therefore eucaryotic cells are larger than procaryotic cells

45. Bacteria are small, diverse, and reproduce quickly, so they evolve quickly. They outnumber other organisms. Their chemistry is very diverse, virtually any organic material can be used for food. Two kingdoms - eubacteria and archaebacteria. Archaebacteria are unique - found in hostile environments. Biologists have chosen a small number of organisms as a focus for intense investigations. Because of the underlying similarity in all cells, we have learned much about our own cells from the bacteria Escherichia coli

46. Some bacteria are photosynthetic. Bacteria not only use organic material, they can also live on inorganic substances, getting CO2, nitrogen, hydrogen, sulfur, etc from the air. Even plants can not capture nitrogen from the atmosphere.

47. Escherichia coli (electron micrograph) have been studied extensively. Lives in the guts of humans and other vertebrates and grown easily in broth culture. Contains a single molecule of DNA which codes for about 4000 proteins

48. Evolutionary scientists think that giardia may be an intermediate stage in evolution. Has 2 nuclei but no other intracellular organelles. Analysis of it’s DNA demonstrates a close relationship to bacteria and eucaryotes.

50. Brewer’s yeast has been studied extensively as a minimal eucaryote model. It is small, single-celled fungus with a rigid cell wall. Has about 2.5 times the DNA of E coli