Chapter 7: Cell structure

1. Chapter 7: Cell structure

2. 0 • Microscopes • Magnification – increase of an object’s apparent size • Total magnification – mag. of eyepiece x mag. of objective lens • Ex: (10X) x (4X) = 40X • Resolution (resolving power) – the distance needed to distinguish 2 points as separate • Three types of microscopes: compound light, transmission electron, scanning electron

4. Low power objective lens • High power objective lens • Body tube • Ocular (eyepiece) • Coarse adjustment knob • Fine adjustment knob • Nosepiece • Diaphragm • Base • Pillar • Arm • Stage • Slide • Cover slip • Stage clip • Light source

5. Compound light microscope: • Specimen is enlarged as light passes through set of glass lenses • Magnification – up to 2000X • Resolving power – up to 200nm • Can be used to view living specimens

7. Transmission electron microscope: • Electrons passing through a specimen are brought into focus by a set of magnetic lenses • Image is projected onto a fluorescent screen or photographic film; flat image • Magnification – up to 200,000X • Resolving power – 0.2nm • Cannot be used to view living specimens

9. Scanning electron microscope: • A narrow beam of electrons is scanned over the surface of the specimen, which is coated with a thin layer of metal • Metal gives off secondary electrons, which are collected to produce a picture of the specimen on the screen • Magnification – up to 100,000X • Resolving power – 10 nm • Cannot view living specimen; 3D image

11. Microscope images: http://remf.dartmouth.edu/imagesindex.html

12. 0 • The Cellular Level of Organization • Living things are made of cells. • Living things may be unicellular or multicellular. • Cell have different shapes & sizes based on jobs. • Organelles – a structure that carries out specific activities inside the cell

13. 0 • First cells observed in 17th century by Anton van Leeuwenhoek • Term “cell” coined by Robert Hooke - observing cork cells, reminded him of cells (rooms) in a monastery. • Observations by Matthias Schleiden, Theodor Schwann, and Rudolf Vichow contributed to the development of the cell theory.

14. 0 • The cell theory states: • All organisms are composed of one or more cells. • Cells are the basic unit of structure and function in organisms. • All cells come only from other cells.

15. 0 Sizes of living things

16. Eukaryotic cells • Have a nucleus that controls all cell activities. • Contain many cell organelles that perform specific jobs. • Organisms in the following kingdoms are eukaryotic: Protists, Fungus, Plants, and Animals

17. Plasma (cell) membrane – A Nucleus* Nuclear membrane – B Nuclear Pore – C Nucleolus – D Chromatin – E Cytoplasm* Cytosol – F Mitochondria – G Golgi apparatus – H Centriole – I Cytoskeleton* Microtubules – J Microfilaments – N Vacuole – K Lysosome – L Ribosome – O Endoplasmic reticulum* Rough ER – Q Smooth ER - P

20. Plasma (cell) membrane – A Cell wall – B Cytoplasm* Cytosol – C Vacuole – D Chloroplast – F Golgi apparatus – I Ribosome – J Endoplasmic reticulum* Rough ER – K Smooth ER – T Mitochondria Cytoskeleton* Microtubules – M Microfilaments – N Lysosome – O Nucleus* Nuclear membrane – R Nuclear pores – S Nucleolus (not shown) Chromatin (not shown)

23. Cell membrane (plasma membrane): • Cell’s outer boundary • Regulates what materials enter & leave cell

24. Cell wall: • Found in plant cells in addition to the plasma membrane. • Cytoplasm– area between the nucleus and the plasma membrane • Contains all cell organelles and cytosol • Cytosol- The fluid in-between the organelles

25. 0 • Structure of the Nucleus • Nucleus:stores genetic information and controls cell activities • Nucleus contains the following: • Chromatin • Nucleolus • Nuclear envelope (nuclear membrane) • Nuclear pores

26. 0 • Chromatin: DNA and protein • Will coil to form chromosomes just before cell division • Nucleolus: Darkened region in nucleus • Makes ribosomes • Nuclear membrane:surrounds thenucleus • Nuclear pores:openings in nuclear membrane to allow proteins into the nucleus and rRNA out of the nucleus

27. Nucleus and nuclear membrane 0

28. 0 Ribosomes • Location where proteins are made • Where ribosomes can be found: • alone in the cytoplasm • attached to the endoplasmic reticulum • ER with ribosomes is called rough ER

29. 0 Ribosomes on ER

30. 0 Endoplasmic reticulum • System of channels – helps transport materials around the cell. • Rough ER-has ribosomes; site of protein synthesis • Smooth ER- lacks ribosomes; packages proteins and sends them to the golgi apparatus

31. 0 The endoplasmic reticulum

32. 0 Golgi apparatus • Often compared to stack of plates. • Modifies, sorts, and packages proteins for distribution.

33. 0 The Golgi apparatus

34. 0 • Vacuoles • Stores substances in cell • Much larger in plants than in animals – plants make own food and need to store it for times when they cannot make food • Plant vacuoles are typically filled with fluid to give the cell added support

35. 0 Lysosomes • Produced by the Golgi apparatus. • Contain enzymes. • Involved in digestion (even digesting worn-out cell parts). • When cells bring in food at plasma membrane, small vacuoles they are stored in fuse to lysosome and contents are digested

36. 0 • Chloroplasts– use solar energy to make sugars – photosynthesis; found in plants • Mitochondria– break down sugars to produce energy (ATP)– cellular respiration; found in plants & animals

37. 0 Chloroplast structure

38. 0 Mitochondrion structure

39. 0 Cytoskeleton • Made up of microfilaments & microtubules • Maintain cell shape • Helps cell move • Helps cell organize its parts • Constantly changing

40. 0

41. 0 Centrioles • Only in animal cells • Roles in cell: • Help with cell division • Help with formation of cilia and flagella.

42. 0 Cilia and flagella • Cilia - small and numerous • Flagella - large and single • Involved in cell movement.

43. Plant vs. animal cells 0

44. Organisms can be any of the following: • Unicellular organisms • Multicellular • Colonial • Unicellular organisms • Entire organism is 1 cell • No specialization – 1 cell does all jobs for the organism • Ex: some bacteria, protists and fungi Paramecium E.Coli bacteria

45. Multicellular organisms • Organism is composed of more than 1 cell • Cells are specialized – have distinct jobs; are dependent upon one another • Ex: All plants & animals, most fungi & some protists Mushroom Ulva Lily Giraffe

46. Colonial organisms • Cells live as a connected group, but do not depend on one another for survival • Ex: Some bacteria, protists Slime molds Bacteria Volvox

47. Levels of cellular organization (in multicellular organisms): • Cells  tissues  organs  organ systems • Tissue – distinct group of cells that have similar structures and functions • Ex. in plant: vascular tissue – helps carry nutrients to various parts of plant • Ex. in animal: muscle tissue – helps in movement Cardiac muscle Vascular tissue

48. Organs – a collection of tissues that carry out a specific function in the body • Ex. in plants: leaf (made of vascular tissue and other tissues that work together to trap sunlight and produce sugar) • Ex. in animals: heart (made of muscle, nerve, and other tissues that work together to pump blood) Leaf Heart

49. Organ systems – made up of various organs that carry out a major body function • Ex. in plants – shoot system (consists of stems, leaves, and the vascular tissue that connects them) • Ex. in animals – circulatory system (made up of the heart, blood vessels, and blood) Shoot system Circulatory system

50. Prokaryotes vs. eukaryotes 0