1. Topic 1 Cells

2. Cell Theory Cytology – the study of all aspects of the cell Three principles of the cell theory: 1. All organisms are composed of one or more cells 2. Cells are the smallest unit of life 3. All cells come from pre-existing cells Robert Hooke first described cells by looking at a cork with a self built microscope in 1665

3. Cell Theory Anton van Leeuwenhoek (1675): was the first person to observe living cells. Referred to them as “animalcules” – little animals

4. Cell Theory Who developed the cell theory? Matthias Schleiden botanist (1838): concluded that all plants are composed of cells (independent separate beings) One year later made the same statement about animals

5. Cell Theory Louis Pasteur performed experiments to support the third theory. He sterilized chicken broth by boiling it. Showed that living organisms did not return “spontaneously”.

6. Functions of Life All organisms carry out all the functions of life including those that are one cell: All functions together produce a viable living unit

7. Cells and Sizes Light microscope uses light passing through living or dead specimens to form an image. May need stains to make it easier to see Electron microscopes use electrons passing through a dead specimen to form an image and provide us with magnification up to 100,000x Electron microscopes have a much higher resolution than light microscopes Light MicroscopeElectron Microscope Inexpensive to purchase and operateExpensive to purchase and operate Simple and easy specimen preparation Complex and lengthy specimen preparation Magnifies up to 2000xMagnifies over 500,000x Specimens may be living or deadSpecimens are dead and must be fixed in a plastic material

8. Cells and Sizes Cells an their subunits are so small they are hard to visualize, so to appreciate their size considerer this: Cells are relatively large Then organelles Then bacteria Viruses Membranes Molecules

9. Cells and Sizes To calculate the size of a specimen you need to know the diameter of the field of vision. On a light microscope it can be measured with a simple ruler. Formula: Magnification = size of image/by size of specimen Scale bars are often used with a micrograph or drawing

10. Limiting Cell Size Surface area to volume ratio limits cell size The rate of heat and waste production; the rate of resource consumption are functions of its volume. Most chemical reaction occur inside of the cell and the size of the cell affects these reactions Cell membrane controls what goes in and out A cell with more surface area per unit of volume is able to move more materials in and out of the cell, for each unit volume of the cell As the width of an object such as a cell increases, the surface area also increases, but at a slower rate

11. Limiting Cell Size As the width of the cell increases, the surface area increases, but at a MUCH slower rate than the volume Volume increases by a factor calculated by cubing the radius. At the same time the surface area increases by a factor calculated by squaring the ratios. FactorMeasurement Cell Radius (r).25.501.25 Surface Area.793.1419.63 Volume.07.528.18 SA: Vol Ratio11.29:16.04:12.40:1

12. Limiting Cell Size All this means a large cell compared to a small cell has relatively less surface area So large animals have more cells not larger cells Some larger cells have modifications that make them more efficient Shape infoldings

13. Cell Reproduction & Differentiation The ability to reproduce allows organisms to grow and to repair damaged or dead cells. Most multicellular organisms start their existence as a single cell after sexual reproduction. Cells then go through a process called differentiation. Differentiation – the process to produce all the required cell types that are necessary for the well- being of the organism.

14. Cell Reproduction & Differentiation Differentiation involves the expression of some genes and not others in a cell’s genome. Genes enable the production of all the different cells in an organism Each cell contains the information of a complex organism Each cell will specialize according to the DNA segment that becomes active.

15. Cell Reproduction & Differentiation Some cells reduce the ability to reproduce once they become specialized or lose it all together. Muscle and nerve cells Some like epithelial cells retain the ability to reproduce rapidly. Specialized tissue can develop by cell differentiation

16. Cell Reproduction & Differentiation Emergent properties arise from the interaction of the component parts; the whole is greater than the sum of the parts'. Each part of a cell is less than the overall function of the complete cell A whole multicellular organism is capable of carrying out more functions than the sum of the functions of each cell is specialized in.

17. Stem Cells A stem cell that has the potential to differentiate into various types of cells Plants cells contain such cells in regions of meristematic tissue (roots and stem tips) Gardeners take advantage of these cells when they take cuttings from stems or roots and propagate new plants Pluripotent stem cells – obtained from embryos, largely obtained from labs carrying IVF, in-vitro fertilization. Harvesting these cells involves the death of an embryo Obviously, highly controversial

18. Stem Cells

19. 1980’s scientist found pluripotent cells in mice When stem cells divide to form a specific tissue they also form more stem cells Stem cells cannot be distinguished by appearance only behavior, which makes them hard to find

20. Stem Cells Stem Cell Research & Treatments: Therapeutic cloning Parkinson Disease Alzheimer’s Diabetes Blood Stem Cells – actually being used today to replaced damaged bone marrow in leukemia patients

21. Stem Cells Stargardt’s Disease – an inherited disease, homogenous, that codes for a defect in the processing of vitamin A. Vitamin A is essential for the light-sensitive cells in the retina to function properly Eventually leads to blindness 2010 a stem cell treatment was begun to protect an regenerate photoreceptors in the retina damages by this disease.

22. Ultrastructure of cells 1.2 Prokaryotic Cells – Lack a nucleus and most other compartmentalized organelles Includes: Bacteria, Archaea (1 µm) Appeared earliest in Earth’s fossil records. Features in Prokaryotic Cells: Cell wall Plasma membrane Flagella Pili Ribosomes Nucleoid region

23. Prokaryotic Cells Cell Wall & Plasma Membrane Cell wall protects & maintains shape of the cell Plasma membrane is just inside the cell wall and is similar to the membranes of eukaryotic cells Controls the movement of materials into and out of the cell and plays a role in binary fission Pili & Flagella Pili – some bacteria have this hair like structure Used for attachment but main function is joining bacteria cells in preparation for the transfer of DNA from one cell to another (sexual reproduction) Flagella – (Flagellum – singular) like pili but longer, used for movement

24. Prokaryotic Cells Ribosomes – protein synthesis Nucleoid Region – area in a prokaryotic cells where a continuous thread of DNA is concentrated Plasmids – small circular DNA molecules not connected to the main bacterial chromosome Replicate independently to the chromosomal DNA May help cell adapt

25. Prokaryotic Cells

26. Binary Fission A simple cell division carried out by Prokaryotic cells.

27. Eukaryotic Cells Eukaryotic Cells have a compartmentalized cell structure. Range cells range in diameter from 5 to 100µm Compartmentalization enables the cell to have different chemical reactions in separate organelles; reactions may not be compatible This increases frequency

28. Eukaryotic Cells - Animal

29. Eukaryotic Cells - Plant

30. Organelles of Eukaryotic Cells Cytoplasm – the entire region of the cell between the nucleus and the plasma membrane Consists of various organelles suspended in a fluid Cytosol – fluid portion of the cytoplasm

31. Organelles of Eukaryotic Cells Endoplasmic Reticulum – a network of tubules or channels that extends most everywhere in the cell. From nucleus to plasma membrane Structure & Function: transports material throughout the cell

32. Organelles of Eukaryotic Cells (ER) Two types: 1. Smooth Endoplasmic Reticulum – has many enzymes embedded in the surface Production of membrane phospholipids and cellular lipids Production of sex hormones (testosterone and oestrogen) Detox of drugs in the liver Storage of Ca ions in muscle cells Transportation of lipid based compounds Helping the liver release glucose into the bloodstream when needed

33. Organelles of Eukaryotic Cells (ER) 2. Rough Endoplasmic Reticulum – have ribosomes on the exterior channels. Ribosomes are involved in protein synthesis Involved in protein development and transport These proteins can be involved in becoming parts of the membrane, enzymes, or even messengers between cells

34. Organelles of Eukaryotic Cells Ribosomes – carry out protein synthesis inside of the cell They are found free in the cytoplasm or attached to the surface of ER They are always composed of a type of RNA and protein In eukaryotic cells they are larger than in prokaryotic cells 80S vs. 70S S=Svedberg units – the amount of sediment during centrifuge

35. Organelles of Eukaryotic Cells Lysosomes – are digestive centers that come from the Golgi apparatus Single membrane sacs with up to 40 enzymes The enzymes are all hydrolytic and catalyze the breakdown of proteins, nucleic acids, lipids, and carbohydrates Lysosomes attach to damaged organelles and recycle them from within the cell

36. Organelles of Eukaryotic Cells Golgi Apparatus – functions in the collection, packing, modification, and distribution of materials synthesized in the cell Made of flattened sacs called cisternae One side is near the ER and it is called the cis side The opposite side trans side discharges the products Vesicles can be seen coming off this side Seen in glandular cells such as those in the pancreas, which manufacture and secrete substances

37. Organelles of Eukaryotic Cells Mitochondria – The power house of the cell (lol) Close in size to a bacteria cell Their own DNA – circular chromosomes similar in bacteria Gives mitochondria independence within the cell Double membrane Smooth outer Inner membrane is folded into cristae This increases the surface area Matrix – fluid inside the inner folding's

38. Organelles of Eukaryotic Cells – Mitochondria Cristae’s increase surface area allows for chemical reactions Most reactions are the production of ATP (adenosine triphosphate) Mitochondria contains its own ribosomes (70S type – bacteria size) Muscle cells require lots of energy so they contain lots of mitochondria

39. Organelles of Eukaryotic Cells Nucleus – isolated region where the DNA resides Nuclear Envelope – double membrane bordering the nucleus Pores around the envelope allows for communication within the cell DNA often occurs in the form of chromosomes Chromosomes often carry all the information that is necessary for the cell to exist DNA is the genetic material inside the cell Chromosomes are only present during cell division

40. Organelles of Eukaryotic Cells - Nucleus When the cell is not dividing it is in the form of chromatin Chromatin is formed of strands of DNA and proteins (called histones) Nucleosome – consists of 8 spherical histones with a strand of DNA wrapped around them and secured by a 9 th histone How DNA and histones are found A chromosome is a highly coiled structure of many histones

41. Organelles of Eukaryotic Cells Nucleus Nucleus is usually in the middle but can be found on one side like a plant cell Plants have a large central vacuole Some cells have no nucleus – Red blood cells No nucleus means they can’t reproduce Some have multi-nuclei Nucleoli – ribosomes are manufactured here

42. Organelles of Eukaryotic Cells Chloroplast – found in some plant cells and algae; responsible for photosynthesis Converts light energy to chemical energy Like a mitochondria it contains a double membrane and its about the size of a bacteria Has its own DNA and ribosomes (70S) DNA in a shape of a ring Note that mitochondria and chloroplast have many characteristics that are shared with prokaryotic cells Capable of reproducing on its own

43. Organelles of Eukaryotic Cells - Chloroplast

44. Organelles of Eukaryotic Cells Centrosomes – involved with the assembly of microtubules Microtubules provide structure, allow movement, and are important for cell division Higher plants (plants thought to have evolved later) produce microtubules but to not have centrioles. Vacuoles – storage organelles formed by the Golgi apparatus Store food Metabolic waste and toxins Water Provides rigidity to the cell Enables cells to have a higher surface area

46. Plant CellsAnimal Cells Outer cell wall with a plasma membraneOnly a plasma membrane Chloroplast are present in the cytoplasm area No Chloroplast Large centrally located vacuoles are present Vacuoles usually not present or small Carbohydrates are stored as starchCarbohydrates are stored as glycogen Do not contain centrioles within a centrosome area Contain centrioles within a centrosome area Fixed often angular shape because of cell wall No cell wall, flexible and more likely to be rounded shape

47. The Origin of Cells 1.5 Endosymbiotic Theory Proposes that a symbiotic relationship evolved over time, between primitive eukaryotic cells and the prokaryotic cells within them. One hypothesis states that mitochondria evolved from endosymbiotic prokaryotes that were able to use oxygen to generate energy rich ATP. Another proposes that chloroplast evolved from endosymbiotic prokaryotes that had the ability to photosynthesis 2 billion years ago

48. The Origin of Cells

49. 1960 Lynn Margulis (Boston University) gathered evidence that supported endosymbiotic theory. She discovered that mitochondria and chloroplast contained DNA that was similar to bacterial DNA Mitochondria and chloroplast have ribosomes that size and structure are like that of bacteria Also mitochondria and chloroplast reproduce by binary fission; like bacteria March 5, 1938 - November 22, 2011

50. The Origin of Cells Evidence to support this theory: Mitochondria Are about the size of most bacteria Divide by fission Divide independently of host cell Have their own ribosomes Have their own DNA (resembles Prokaryotic Cells) Have 2 membranes on their exterior, which is consistent with the engulfing process

51. The Origin of Cells Chloroplast A modern day protest called Hatena normally fulfills its nutritional needs by ingesting organic matter. It also behaves as a predator and ingests a green alga and that alga produces carbohydrates via photosynthesis The two organisms continue their symbiotic relationship

52. The Origin of Cells DNA provides a code made up of 64 different words All organism codes are the same (or nearly the same) said to be universal There are only slight variations which can be explained by changes since the common origin of life on our planet

53. The Origin of Cells Spontaneous Generation - life from non-living matter The Italian physician, Francisco Redi, disproved the theory of spontaneous generation by conducting a simple experiment. 200 years before Pasteur

54. The Origin of Cells Cells can only be formed by the division of pre- existing cells. Except for that first cell /cells that must have arisen from non-living material Louis Pasteur – supported the idea that living things come from other living things Experimented to disprove spontaneous generation also: 1. He boiled a nutrient in a broth 2. The now sterile nutrient broth was then placed in three flasks over a period of time. (1 open, 1 sealed, 1 with a barrier of distilled water. 3. A sample was then transferred to a plate containing a solid medium and incubated

55. The Origin of Cells - Pasteur The only sample that showed the presence of bacteria was the open one. This indicated to him that the concept of spontaneous generation was wrong