cells

1. cells The cell is a unit of organization Units of life

2. Cell vocabulary • 1. cell • 2. plasma membrane • 3. organelles • 4. surface area • 5. membrane • 6. nucleus • 7. nucleolus • 8. mitochondria • 9. ribosomes • 10. cytoplasm • 11. endoplasmic reticulum • 12. chloroplasts • 13. prokaryotic cells • 14. eukaryotic cells

3. History of studying cells • Because of the limitations of the human eye, much of the early biological research concentrated on developing tools to help us see very small things.

4. As imaging technology became more sophisticated, biological discoveries abounded. • Next is a timeline detailing some of those major events in biology.

7. What are the respective sizes of a virus and a plant cell? • A.3 mm, 30 mm • B.30 nm, 30 µm • C.30 µm, 30 nm • D.3 cm, 30 cm

8. B.30 nm, 30 µm

9. The Cell Theory • When Schleiden and Schwann proposed the cell theory in 1838, cell biology research was forever changed. The cell theory states that:

10. Cell theory • All life forms are made from one or more cells. • Cells only arise from pre-existing cells. • The cell is the smallest form of life.

11. The cell theory also provides us with an operational definition of "life".

12. Which of the following is not a part of the cell theory? • A.All animals are formed by cells. • B.Reproduction requires vegetative duplication or the sexual mixing of gametes. • C.Cells are the smallest form of life. • D.Abnormal cells self destruct by apoptosis.

13. D. Abnormal cells self destruct by apoptosis

14. Living things are classified in six kingdoms based on structure. • Monera (Eubacteria) Prokaryotic • Archaea Prokaryotic • Protista Eukaryotic • Plantae Eukaryotic • Fungae Eukaryotic • Animalia Eukaryotic

15. Within prokaryotes • which appeared 3.5 billion years ago, are the kingdoms • Monera (Eubacteria) and Archaea.

16. Within eukaryotes • which evolved 1.5 billion years ago, are the kingdoms • Protista, Plantae, Fungae, Animalia.

17. Cells are also defined according the need for energy.

18. Autotrophs • are "self feeders" that use light or chemical energy to make food. Plants are an example of autotrophs.

19. heterotrophs • In contrast, heterotrophs ("other feeders") obtain energy from other autotrophs or heterotrophs. Many bacteria and animals are heterotrophs.

20. Multicellular Organisms • Multicellular organisms are created from a complex organization of cooperating cells. • There must be new mechanisms for cell to cell communication and regulation.

21. There also must be unique mechanisms for a single fertilized egg to develop into all the different kinds of tissues of the body. • In humans, there are 1014 cells comprising 200 kinds of tissues!

22. Cells are classified by fundamental units of structure and by the way they obtain energy. • Cells are classified as prokaryotes or eukaryotes

23. Prokaryotes • prokaryotes include the kingdoms of Monera (simple bacteria) and Archaea.

24. Simply stated, prokaryotes are molecules surrounded by a membrane and cell wall. • Prokaryotic cells lack characteristic eukaryotic sub cellular membrane enclosed "organelles", but may contain membrane systems inside a cell wall.

25. Bacteria & antibiotics • The cell wall is the target for antibiotics, as well as for carbohydrates that our immune system uses to detect infection. A major threat to humankind is the antibiotic-resistant strains of bacteria have been selected by overuse of antibiotics.

26. If you were bacteria • You have 0.001 times as much DNA as a eukaryotic cell. • You live in a medium which has a viscosity about equal to asphalt. • You have a wonderful "motor" for swimming. Unfortunately, your motor can only run in two directions and at one speed. In forward, you are propelled in one direction at 30 mph. In reverse your motor makes you turn flips or tumble. You can only do one or the other. You cannot stop.

27. While you can "learn", you divide every twenty minutes and have to restart your education. • You can have sex, with males possessing a sexual apparatus for transferring genetic information to receptive females. However, since you are both going 30 mph it is difficult to find each other.

28. Furthermore, if you are male, nature gave you a severe problem. Every time you mate with a female, she turns into a male. In bacteria, "maleness" is an infective venereal disease. • Also, at fairly high frequencies, spontaneous mutations cause you to turn into a female.

29. Eukaryotes have enslaved some of your "brethren" to use as energy generating mitochondria and chloroplasts. • They are also using you as a tool in a massive effort to understand genetics. The method of recombinant DNA is designed to exploit you for their own good.

30. The last laugh may be yours. You have spent three and a half billion years practicing chemical warfare. Humans thought that antibiotics would end infectious diseases, but the overuse of drugs has resulted in the selection of drug resistant bacteria. They didn't realize that this was only the first battle, and now the war is ready to begin. • Humans think this is their era. A more truthful statement would be that we all live in the age of bacteria.

31. Eukaryotes • Basic structure The basic eukaryotic cell contains the following: • plasma membrane • glycocalyx (components external to the plasma membrane) • cytoplasm (semi fluid) • cytoskeleton - microfilaments and microtubules that suspend organelles, give shape, and allow motion • presence of characteristic membrane enclosed subcellular organelles

32. organelles

33. Plasma Membrane • A lipid/protein/carbohydrate complex, providing a barrier and containing transport and signaling systems.

34. Nucleus • Double membrane surrounding the chromosomes and the nucleolus. Pores allow specific communication with the cytoplasm. The nucleolus is a site for synthesis of RNA making up the ribosome

35. Mitochondria • Surrounded by a double membrane with a series of folds called cristae. Functions in energy production through metabolism. Contains its own DNA, and is believed to have originated as a captured bacterium.

36. Chloroplasts (plastids) • Surrounded by a double membrane, containing stacked thylacoid membranes. Responsible for photosynthesis, the trapping of light energy for the synthesis of sugars. Contains DNA, and like mitochondria is believed to have originated as a captured bacterium.

37. Rough endoplasmic reticulum (RER) • A network of interconnected membranes forming channels within the cell. Covered with ribosomes (causing the "rough" appearance) which are in the process of synthesizing proteins for secretion or localization in membranes.

38. Smooth endoplasmic reticulum (SER) • A network of interconnected membranes forming channels within the cell. A site for synthesis and metabolism of lipids. Also contains enzymes for detoxifying chemicals including drugs and pesticides.

39. Golgi apparatus • A series of stacked membranes. Vesicles (small membrane surrounded bags) carry materials from the RER to the Golgi apparatus. Vesicles move between the stacks while the proteins are "processed" to a mature form. Vesicles then carry newly formed membrane and secreted proteins to their final destinations including secretion or membrane localization.

41. Ribosomes • Protein and RNA complex responsible for protein synthesis. • VacuolesMembrane surrounded "bags" that contain water and storage materials in plants.

42. Cell wall • Plants have a rigid cell wall in addition to their cell membranes.

43. Peroxisomes or Microbodies • Produce and degrade hydrogen peroxide, a toxic compound that can be produced during metabolism

44. Lysosymes • A membrane bound organelle that is responsible for degrading proteins and membranes in the cell, and also helps degrade materials ingested by the cell.

45. Cell membraneplasma membrane • The cell membrane is the thin nearly invisible structure that surrounds the cytoplasm of the cell. • In this section we will talk about its structure and its function. • In the image you can see that it is a continuous membrane that completely surrounds the cell.

46. There are carrier proteins that regulate transport and diffusion Floating around in the cell membrane are different kinds of proteins. These are generally globular proteins. They are not held in any fixed pattern but instead float around in the phospholipid layer.

47. Cell membrane - Function • The cell membrane's function, in general, revolves around is membrane proteins. General functions include: • Receptor proteins which allow cells to communicate, • transport proteins regulate what enters or leaves the cell, • and marker proteins which identify the cell

48. Cell membrane - Function - Regulation of transport • Transport Proteins come in two forms: Carrier proteins are peripheral proteins which do not extend all the way through the membrane. They move specific molecules through the membrane one at a time.

49. Channel proteins extend through the bilipid layer. They form a pore through the membrane that can move molecules in several ways.

50. Cell membrane - Function - Carrier Proteins • These are carrier proteins. They do not extend through the membrane. They bond and drag molecules through the bilipid layer and release them on the opposite side.