Cell Structure and Function

1. Cell Structure and Function Chapter 4

2. Robert Hooke (1635-1703) Discovered “cells” by studying the cork layer of bark from an oak tree. Found cells when studied tree stems, roots, and leaves.

3. Antony van Leeuwenhoek (1632-1723) Learned how to make excellent lenses & placed them into simple microscopes. He was the first person to observe living cells. Vorticella spirogyra

4. Matthias Schleiden & Theodor Schwann Schleiden (botanist) & Schwann (zoologist) developed the Cell Theory.

5. Rudolf Virchow (1821-1902) Noted that cells come from other cells from studying human diseases.

6. The Cell Theory • All organisms are made up of one or more cells. • Cells are the basic unit of structure and function of organisms. • New cells come from existing cells by cell reproduction.

7. Microscopes Light: light waves pass through a small organism, or thin slices of a larger organism, & the structures are magnified through the lens system.

8. Phase contrast: modifies differences in light waves so that transparent cell structures appear as light & dark regions.

9. Electron: enables us to see cell parts at very high magnifications by using an electron beam instead of a light beam to illuminate the object.

10. Transmission Electron Microscope: (TEM) Cell structures can be enlarged as much as 1,000,000x & provides photographs that show remarkable detail. apoptosis

11. Cells Basic unit of living organisms. 2 basic types: prokaryotes: do not have a membrane enclosing their DNA. Do not contain membrane-bound organelles.

12. Prokaryotes are divided into two domains: Bacteria: includes organisms that are similar to the first cellular life-forms. Archae: includes organisms that are thought to be more closely related to eukaryotic cells found in all other kingdoms of life.

13. eukaryotes: usually have at least onemembrane enclosed structure, the nucleus, which contains DNA; contain membrane-bound organelles.

14. unicellular: consists of a single cell which carries out all the many activities of that organism.

15. multicellular: contain from dozens to billions of cells. Organisms have a number of different types of cells; each type of cell has a certain role to play.

16. Colonies: a collection of genetically identical cells that live together in a collected group. Colonies are not truly multicellular since few of their activities are coordinated. Volvox

17. Levels of Organization Cellstissue (group of similar cells that carry out a specific function) organs (group of tissues that perform a particular job in an organism) organ system (group of organs that accomplish related tasks) organism (the combining of organ systems)

19. Organelles Structures that carry out specific functions.

21. Plasma Membrane • Outer membrane that encloses the cell contents • Controls the passage of materials in & out of the cell • Made of 2 thin layers of lipid molecules. • Protein molecules floating on & within the lipid layers help molecules move in & out of the cell.

22. 4 1 1 - cell-surface marker: glycoprotein that identifies cell type. 2 - receptor protein: recognizes and binds to substances outside of cell. 3 – intergral protein: enzyme that assists chemical reactions inside cell. 4 – transport protein: helps substances move across cell membrane. 5 – peripheral proteins: lie on only one side of membrane and not embedded in it. 3 2 5 The cell membrane is a fluid mosaic model. The bilayer behaves like a fluid more than a solid. The membrane’s lipids and proteins can move laterally within the bilayer.

23. Cytoplasm • Jellylike material found within the cell. • Contains the organelles. • cytosol: includes molecules and small particles but not membrane-bound organelles. • Many of the chemical reactions of a cell take place in the cytosol.

24. Nucleus • Control center of the cell • Contains most of the cell’s genetic information in DNA • Contain one or more nucleoli, sites of synthesis & assembly of rRNA & tRNA • genes: control the basic functions of the cell • chromosomes: contain DNA & proteins

25. Nuclear Envelope & Nucleolus • Double membrane surrounding nucleus • It is continuous at several pts. w/a complex network of other membranes in the cytoplasm • The nucleolus manufactures ribosomes. It is a knot of chromatin. The portion of the cell nucleus which contains all of the DNA of the nucleus in an animal or plant cell.

26. Endoplasmic Reticulum • Provide passageways for the movement of materials throughout the cell • 2 types: RER – Rough Endoplasmic Reticulum SER – Smooth Endoplasmic Reticulum

27. RER • Produces phospholipids and proteins • The ribosomes produce digestive enzymes

28. SER • Builds lipids like cholesterol. • Produces estrogen and testosterone. • Releases calcium in skeletal and heart muscle, which stimulates contractions. • Detoxify drugs and poisons in the liver and kidney cells.

29. Ribosomes Responsible for protein synthesis. Made of protein and RNA molecules and do not have a membrane.

30. Mitochondria • Powerhouse of the cell • Transfer energy from organic molecules to Adenosine Triphosphate (ATP) which powers most of the cell’s chemical reactions. • Consists of an outer membrane & a folded inner membrane cristae

31. Vacuole Store & transport nutrients & waste products

32. Golgi Complex • Helps package cell products for export from the cell

33. Vesicles • Small, spherical shaped sac that are surrounded by a single membrane. • Classified by their contents. • Often migrate to and merge with the plasma membrane. • Release their contents to the outside of the cell. • “shuttle service” • Include lysosomes and peroxisomes

34. Lysosomes Contain digestive enzymes which help break down large molecules & worn-out cell parts

35. Peroxisomes • Similar to lysosomes but contain different enzymes and not produced by Golgi Apparatus. • Abundant in liver and kidney cells. • Break down fatty acids, which is then used by mitochondria. • Produce hydrogen peroxide when breaking down alcohol and killing bacteria.

36. Centrioles Present in pairs and play an important role in mitosis.

37. Cytoskeleton (Microtubules & Microfilaments) Tiny tubes composed of proteins. Form the cell’s skeleton Enable the cell to maintain its distinct shape & internal organization. Microfilaments contribute to cell movement.

39. Cell Wall Provides strength and protection Formed by living plant cells of cellulose fibers.

40. Central Vacuole • Reservoir that stores large amounts of water. • Also stores enzymes, metabolic waste, and other materials.

41. Plastids • Organelles surrounded by a double membrane and contain their own DNA. 2 types: CHLOROPLASTS CHROMOPLASTS

42. Chloroplasts Contain the pigment chlorophyll, essential for capturing the light energy of the sun. Contain complicated membranes where photosynthesis takes place called thylakoids.

43. Chromoplasts • Contain colorful pigments that may or may not take part in photosynthesis. Carotene: orange pigment found in carrot root cells. Flower petal cells contain red, purple, yellow. or white pigments.