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Human Biology Instructor Terry Wiseth CELL STRUCTURE & FUNCTION.

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Presentation on theme: "Human Biology Instructor Terry Wiseth CELL STRUCTURE & FUNCTION."— Presentation transcript:

1 Human Biology Instructor Terry Wiseth CELL STRUCTURE & FUNCTION

2 2 CELL MEMBRANE Cell membrane made up of:  1) Phospholipids  2) Sterols  3) Proteins  4) Glycoproteins

3 PHOSPHOLIPIDS cell membrane - semi-permeable lipid bilayer  two layers of Phospholipids

4 4 STEROLS common sterols of cell membranes  Cholesterol (animal cells)  prevent packing of lipid cells in the cell membrane

5 5 PROTEINS Proteins are embedded into the cell membrane  These proteins serve a variety of cell membrane functions

6 6 GLYCOPROTEINS proteins are embedded in the bilayer  glycoproteins - sugar-protein combinations  sugars extend out to the extracellular fluid

7 CELL MEMBRANE

8 8 FLUID MOSAIC MODEL membrane bilayer shows fluid behavior molecules of the bilayer are in constant motion

9 9 FLUID MOSAIC MODEL membrane is composite of molecules allowing a “mosaic description” cell survival depends on fluidity characteristics of the cell membrane

10 10 FLUID MOSAIC MODEL extracellular fluid temperature decreases cause a stiffening of the cell membrane  disrupts membrane protein function

11 11 CELL THEORY Smallest entity that retains the characteristics of life  1) Complex organization  2) Metabolic activity  3) Reproduction

12 12 CELL SIZE Most cannot be seen without the aid of a microscope  Larger cells  ”Yolk” of bird eggs  Fish eggs “caviar”

13 13 CELL SIZE Human eyes able to see about 100 microns

14 14 LIGHT MICROSCOPE The light microscope has a limit of resolution of about 200 nm (0.2 microns)

15 15 TEM The Transmission Electron Microscope (TEM) has a limit of resolution of about 2 nm

16 16 SEM The Scanning Electron Microscope (SEM) also has a limit of 2 nm Bronchiole cilia WBC engulf bacteria Sperm & Egg

17 17 GENERALIZATIONS OF CELL THEORY Cells vary in size, shape and activities  All cells have:  1) Plasma membrane  2) DNA region  3) Cytoplasm  4) Organelles

18 18 PLASMA MEMBRANE Outer membrane maintains the integrity of the cell Membrane does not however isolate the cell

19 19 PLASMA MEMBRANE Cell membrane  “Lipid bilayer”  Boundary that bars free passage of water soluble substances in and out of the cell

20 20 NUCLEUS DNA is localized in the cell nucleus

21 21 CYTOPLASM Everything enclosed by the plasma membrane except the DNA semi-fluid

22 22 CYTOPLASMIC STREAMING Cytoplasm is not stagnant but rather is constantly moving (streaming)

23 23 ORGANELLES Organelles--internal sacs which have a specific metabolic function  Essential in keeping chemical reactions in the cytoplasm separate from each other

24 24 CELL MACHINERY

25 25 CELL MACHINERY

26 26 NUCLEUS Nucleus sequesters DNA  1) Separates DNA from chemical reactions in cytoplasm  2) Nuclear membranes control access between nuclear material and cytoplasm

27 27 NUCLEUS Nuclear envelope has pores to allow passage of messenger units of nucleic acid

28 28 NUCLEUS

29 29 NUCLEOLUS Assembly 1) Assembly of RNA and ribosomes Storage 2) Storage of RNA and ribosomes

30 30 DNA Instructions for building proteins (enzymes) are contained in DNA Instructions of heredity are distributed in several DNA molecules of various lengths  Humans = 46 DNA molecules

31 31 DNA DNA is threadlike prior to cell division the DNA molecules duplicate

32 32 CHROMOSOMES DNA folds and twists into condensed structures called chromosomes

33 33 CYTOMEMBRANE SYSTEM Series of organelles through which lipids and proteins, produced on cytoplasmic ribosomes, pass through in becoming packaged for export

34 34 CYTOMEMBRANE SYSTEM 1) Endoplasmic reticulum (ER) 2) Golgi bodies 3) Vesicles 4) Lysosomes

35 35 ENDOPLASMIC RETICULUM 1) Rough endoplasmic reticulum  Ribbon like structure with ribosomes attached  Arranged as flat, stacked sacs

36 36 ENDOPLASMIC RETICULUM

37 37 RIBOSOMES  Ribosomes are small spherical shaped structures  Serve as the “working table” for assembling proteins

38 38 RIBOSOMES

39 39 ENDOPLASMIC RETICULUM 2) Smooth endoplasmic reticulum  Lacks ribosomes

40 40 SMOOTH ENDOPLASMIC RETICULUM Appears like a system of pipes  1) Lipid synthesis  Ex: endocrine glands produce steroid hormones  2) Inactivate harmful by-products of metabolism and drugs  Ex: liver cells

41 41 GOLGI BODIES Resemble stacks of pancakes

42 42 GOLGI BODIES Flattened sacs in which lipids and protein molecules are modified

43 43 GOLGI BODIES Modifications allow for sorting and packaging for transport

44 44 GOLGI MODIFICATIONS

45 45 GOLGI MODIFICATIONS

46 46 VESICLES Sacs which transport or store enzymes, lipids and proteins  1) Peroxisomes  2) Lysosomes (microbodies)

47 47 VESICLES 1) Peroxisomes  Contain enzymes to break down fatty acids and amino acids

48 48 VESICLES 2) Lysosomes  Vesicles of intracellular digestion  Contain enzymes which can break down any polysaccharide, protein, nucleic acid and some lipids

49 49 LYSOSOMES Important in proper function of white blood cells (immunity)

50 50 LYSOSOMES

51 51 CYTOMEMBRANE SYSTEM Raw materials (amino acids and lipids) are dissolved in the cytoplasm

52 52 CYTOMEMBRANE SYSTEM Under the instructions of the DNA molecule polypeptide chains of proteins are assembled from the dissolved raw materials

53 53 CYTOMEMBRANE SYSTEM

54 54 MITOCHONDRIA cristae Contains a series of inner membranes folded repeatedly (cristae)  Increases the total surface area available for reactions

55 55 MITOCHONDRIA Use oxygen to assist in liberating energy stored in sugars (aerobic respiration)

56 56 MITOCHONDRIA Energy is used to form ATP molecules which is used for protein synthesis and transport ATP-molecule is able to store and transport energy for short periods of time

57 57 MITOCHONDRIA Most numerous in high energy demanding cells  Ex: muscles, liver

58 58 MITOCHONDRIA

59 59 CYTOSKELETON Interconnected system of bundled fibers, threads and lattices

60 60 CYTOSKELETON Extend from the cell membranes, organelles and nucleus

61 61 CYTOSKELETON Supply internal organization, shape, ability to move, reinforce the cell membrane and hold proteins in place

62 62 CELL SURFACE SPECIALIZATIONS Gap Junctions  channels of exchange in animal cells  ex: liver, heart

63 63 CELL SURFACE SPECIALIZATIONS Junction Proteins  hold cells together in forming tissues

64 END Cell


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