1. Cells` “The smallest functional unit of life”

2. Cell theory Cells are the structural and functional unit of life What an organism does is determined by the activity of its cells “…the biochemical activities of cells are dictated by the relative number of their specific subcellular structures” Reproductive activities are cell based p. 62

3. Components of the membrane Proteins: as receptor, channel, carrier, marker, anchoring spot to surrounding cells, enzymes (acting inside or outside the cell), anchoring internally for cystoskeleton- about ½ total membrane mass Some proteins are “integral”- extending through the entire membrane Other proteins are “peripheral”- inside or outside the cell. -supporting filaments -enzymes See 64,65

4. Cell Components Plasma membrane Cytoplasm Nucleus

5. Components of the membrane Lipids: phospholipds, most are “unsaturated”, which because of molecule shape, makes the membrane more fluid Cholesterol: helps form membrane; precursor for hormones “some 20% of the lipid…” p. 64 See 65 Glycolipids

6. Components of the membrane Proteins (surface): superficial proteins are “glycoproteins”- sugar+protein forming the “glycocalyx” – a region around the cell surface with many carbohydrates. The variability of the glycoproteins causes this layer to act as an identifier- specific markers identify specific cells. This plays a role in immune cell function (recognizing foreign cells) and reproduction (sperm recognizing egg) See 65

7. Components of the membrane Carbohydrates: joined with proteins as glycoproteins, joined to lipids as glycolipids.- found on the outer layer, can serve as markers for cell recognition See 65

8. Junctions with other cells/tissue Tight junctions- prevent leakage going between cells Membrane appendages “Tight” Not so tight

9. Junctions with other cells/tissue Desmosomes- lock cells together where cells are under mechanical stress (skin, heart). Connections are made not just between adjacent cells, but through a cell, distributing stress more broadly Membrane appendages See p. 67

10. Junctions with other cells/tissue Gap junctions- allow passage of ions and other small molecules (simple sugars) between cells. Recall the depolarization of heart cells Membrane appendages See p. 70

11. Transport through the membrane.

12. Cells Transport through the membrane is selective, and occurs via passive and active processes. Passive processes Diffusion: Facilitated diffusion Osmosis: Filtration:

13. Cells Passive processes Diffusion: depends on concentration gradients…. High concentration--> Low concentration ↑ with temperature, smaller particle size

14. Cells Diffusion:Driven by kinetic energy of matter Solute moves from area of high concentration to low concentration

15. Cells Diffusion The route a substance takes through the membrane depends on its size, shape, charge and solubility. In cells, non-polar and lipid soluble substances can pass through (alcohol, fatty acids, steroids….., CO2, O2) the membrane w/o a channel or gate) Water soluble substances require a channel in the membrane These channels may let substances through on the basis of size or shape See p. 69

16. Cells Passive processes Facilitated Diffusion: depends on concentration gradients…. High concentration--> Low concentration Depends on carriers (proteins in the cell membrane) or channels (water filled– allows smaller particles)

17. Cells Passive processes Facilitated diffusion: specific carriers exist for certain essential, large, non-lipid soluble substances. Transportation depends on binding to, being recognized by a receptor A passive process- no ATP required. Ex: glucose See p. 69

18. Cells Passive processes Rate of transport dependent on # of carriers, not just concentration, so once carriers are saturated, further increase of concentration has no impact on diffusion rate See p. 69

19. Cells Osmosis: water moves through a semi-permeable membrane to equalize concentrations

20. Cells Passive processes Osmosis Think of this either of 2 ways: 1) there may be a higher concentration of water on one side of a membrane and it moves towards the other side. (High concentration--> low concentration) 2) water moves to equalize concentrations on either side of a semi permeable membrane. That is, water is drawn to the side where solute is more concentrated. Think: salting a slug….. Sugaring berries See p. 70

21. Cells Filtration: driven by hydrostatic pressure

22. Note that water is able to move through the phospholipid bilayer by osmosis– not just through channels in the membrane p. 70

23. New words Osmolarity- the total concentration of all solute particles in a solution Hypotonic- a solution having lower concentration (compared to cells introduced to the solution) Hypertonic- a solution having higher concentration (compared to cells introduced to the solution) See p. 71

24. Cells Active processes: require ATP See steps on p. 76 Carriers bind to the substance being transported and move it against the substance’s concentration gradient In primary active transport, the ATP directly powers the particle movement. In secondary active transport, the particle movement is indirectly powered by ATP

25. Cells Active processes: require ATP See steps on p. 76 Primary- analogy: a truck carries water up hill. Secondary:- a truck carries water up hill, then the water flows back downhill, causing a water wheel to turn.

26. Cells Active processes: (example of primary) Na-K pump: maintains a low intercellular Na level, and high potassium level, inside a cell See steps on p. 74

27. Cells Active processes: require ATP Vesicular transport- a vesicle with walls like the cell’s membrane encloses a substance (large particle or liquid) for transport into or out of a cell. See steps on p. 78

28. Cells Active processes: require ATP See steps on p. 76 Related terms: Phagocytosis: “cell eating” Pinocytosis: “cell drinking” (“sampling”) Endocytosis: taking into the cell Exocytosis: secreting from the cell Transcytosis: moving from one side of the cell to another

29. We have seen that the membrane is selectively permeable Among the substances selected for are ions, resulting in different ion compositions intracellular compared to extracellular Cell Membrane: potential

30. We have seen that the membrane is selectively permeable This selectivity results in the inside of the cell being negative (collected more negatively charged ions) compared to the outside Cell Membrane: potential

31. “Players” in the membrane potential are K +, Na +, Cl - and proteins inside the cell that carry a negative charge. Also: different ions move through the membrane at different rates- both actively and passively AND: these ions move with both concentration gradients AND electrical gradients Cell Membrane: potential

32. Because there are many different ions involved, both positive and negative, we will refer to an “electrochemical” gradient, which includes (for example) the notion that an paricle might not reach a concentration equality because there is a resistance based on a ionic gradient “pushing” the other way. Cell Membrane: potential

33. Cell adhesion molecules (CAM) “anchors” to surrounding cells Used by moving cells to grab stationary cells and “pull past” them Signal WBCs to an affected area Other functions Cell Membrane: interactions with other cells Functions:

34. Contact vs Signal communication Cells can communicate by physical contact with each other, as in the case of immune cells “checking out” a target cell Cells can communicate via some chemical signal- like a hormone or neurotransmitter- this may involve a “2 nd messenger system” in the target cell (p. 81,82) Cell Membrane: interactions with other cells

35. Cytoplasm The “broth” of the soup or the water of the fish tank… The semi-fluid surroundings and support of the organelles of the cell Stored sugars, pigment lipids and other substances are included here »P. 84

36. Organelles Mitochondria Powerhouse of cell, producing ATP aerobically More numerous in cells that are active Cells may have hundreds of mitochondria Two membranes The outer is fairly smooth The inner membrane is folded (forming cristae)

37. Organelles Mitochondria A gel matrix fills the mitochondrion. Enzymes in the matrix and on the cristae participate in oxidation of fuel molecules Have their own DNA and RNA and replicate based on this genetic material when there is increased demand for energy by the cell.

38. Organelles Ribosomes Function in protein synthesis May be free floating in the cytoplasm or attached to the endoplasmic reticulum (“rough” ER) Free floating make proteins for use in the cytosol ER bound make proteins for the cell membrane or for export May be free or bound, depending on the protein being assembled ( the same ribosome can be either)

39. Organelles Endoplasmic reticulum A fluid-filled system of tubes/membranes located near and continuous with the membrane around the nucleus “Rough” ER packages proteins made with the ribosomes for export. Makes membrane parts for the cell

40. Organelles Endoplasmic reticulum “Smooth” ER make cholesterol and steroid hormones, metabolize fats, participate in drug detox and glycogenolysis In striated muscle (cardiac and skeletal) the smooth ER forms the “sarcoplasmic reticulum” that stores calcium ions

41. Organelles Golgi Apparatus another membranous organelle “…major function is to modify, concentrate, and package the proteins and lipids made at the rough ER.” (p. 85) Transport vesicles from the ER are received by the Golgi Apparatus. Modifications (sugars are added/subtracted, phosphates added) are made, then the proteins are repackaged in one of 3 forms on the far side of the Golgi apparatus form the ER

42. Organelles Golgi Apparatus the new packages will: Be sent to the cell membrane to secrete the proteins OR Be sent to the cell membrane for incorporation into the membrane OR Act as a lysosome inside the cell

43. Lysosomes: do clean-up work old organelles bacteria, viruses, etc. Glycogen break down Unused/modified tissues during fetal development Cell “self-digestion” See list on p. 86 Organelles Lysosome

44. Lysosomes: maintain an acidic environment inside, which is where their enzymes work best : keep the enzymes contained, while releasing products of breakdown to the cytosol Organelles Lysosome

45. Organelles Membranous structures (review) (derived from, forming or continuous with the cell membrane)  cell membrane  endoplasmic reticulum  Golgi apparatus  lysosome  Secretory vesicles  nuclear membrane/envelope  mitochondria  peroxisomes

46. (More) Organelles Peroxisomes Like lysosomes, peroxisomes are membranous sacs. Unlike lysosomes, peroxisomes bud off from the ER

47. (More) Organelles Peroxisomes Peroxisomes help with detoxification (alcohol and formaldehyde) but help “extinguish” free radicals, to protect the cell “free radicals” are highly reactive molecules– they cause (undesirable) reactions inside the cell, causing damage– like a fire that has escaped the hearth

48. Cytoskeleton 3 types of rods passing through the cytoplasm These have no membrane Provides support and movement of the cell and organelles

49. Cytoskeleton Microtubules –Largest of 3 rod types –Provide shape support for the cell –Provide attachment points and mechanisms for moving organelles (mitochondria, lysosomes) via motor proteins –Continually being formed/reformed as cell needs change

50. Cytoskeleton Microfilaments –Smallest of 3 rod types, made of actin –Involved in cell shape change and cell movement –Involved in cell cleavage during replication –Continually being formed/reformed as cell needs change

51. Cytoskeleton Intermediate filaments –Relatively permanent within the cell –Attached to desmosomes, functions to reinforce structure of cell

52. (More) Organelles Centrosome and Centrioles The centrosome is an attachment point for microtubules The centrosome contains the centrioles- pairs of tubes at right angles to each other which (additionally) help move cell components during mitosis (p. 89)

53. (More) Organelles Cilia and Flagella Cilia move material across the surface of the cell In the trachea, shifts mucus up/out of the lungs In uterine tubes, moves the egg towards the uterus Flagella move the cell : only in sperm, in humans In both, the structures arise from centrioles

54. Microvilli- increase surface area Contain actin Specialized for absorption and secretion (digestive and urinary tracts) Cilia- specialized to move material across the cell’s surface cilia (a cell) microvilli Membrane appendages

55. Organelles Nucleus Stores cell’s genetic material Directs what proteins are made, when and how much Most cells have one. Some cells have many (skeletal muscle and others) One cell type (RBCs) have no nucleus So has no repair capacity– limited life

56. Organelles Nucleus Three regions/structures: Envelope (membrane) Nucleoli Chromatin

57. Organelles Nucleus Regions/structures: Envelope (membrane) A double membrane, the outer layer of which is continuous with the ER Contains pores allowing movement of particles in/out Encloses the nucleoplasm- analogous to the cytoplasm of the cell

58. Organelles Nucleus Regions/structures: Nucleoli (1, 2 or more/nucleus) Darker regions within the nucleus, having no membrane Sites of ribosome assembly

59. Organelles Nucleus Regions/structures: Chromatin The genetic material of the cell (DNA) AND Proteins (histones) involved in the packaging of the DNA and regulation of gene expression When the cell is preparing to divide, the chromatin forms chromosomes- bundles of the genetic material

60. Histone: a protein which the DNA is bound to Nucleosome: a “clump” of gathered DNA and histones. The genetic code is contained in the DNA. The DNA molecule consists of 2 strands, linked together by many paired “nitrogenous bases” See p. 97 Nitrogenous base pairs Adenine------Thymine Thymine------Adenine Guanine------Cytosine Cytosine-----Guanine Adenine-----Uracil

61. The genetic information codes for (among other things) the formation of amino acids. The information for each amino acid is stored as a triplet of nitrogenous bases. (see figure3.36, p. 103). Other triplets give information about how to read the code (as in “start” or “Stop” messages.) A “gene” consists of all the triplets which code for a specific protein. (bigger proteins require larger genes– longer instructions for assembly)

62. Protein synthesis First, gene to be copied needs to be accessible- the strands unravel and separate then 1. Transcription: making an RNA template of the bases to be copied (the gene)– this happens in the nucleus 2. Translation:- ribosomes act on/with the RNA to construct the new protein--- this happens in the cytosol.

63. Transcription: mRNA (messenger RNA) is made as a template from which to build the new protein. RNA polymerase finds the “start” codon, then moves along the gene, linking together the “pairing” nucleotides stopping when the “stop” codon is reached. See 104, 106, 107

64. The mRNA undergoes some “editing” before leaving the nucleus (“pre-mRNA”  mRNA) p. 103

65. Involves : mRNA that came from the nucleus : ribosomes : tRNA : amino acids free floating in the cytoplasm Translation- assemblage of the protein in the cytoplasm

66. Each tRNA molecule codes for a specific amino acid, so there are 20+ different kinds. tRNA caries the amino acid coded for on the mRNA to the mRNA and ribosome, and links on to the growing protein chain.

67. Once the protein is completed, the tRNA detaches and the mRNA (eventually) is degraded by enzymes.

68. The assembly of the protein takes place near the ER, which then “packages” the completed protein for transport elsewhere in the cell or to the Golgi apparatus for transport out of the cell.

69. Tissues

70. 4 Types of Tissues Epithelium Connective Muscle Nerve

71. Epithelium -Named for numbers of layers and cell shape -Covers surfaces in contact with the “outside” -Specialized for absorption, secretion, protection, sensation, filtration -Have an apical surface (the free surface) and a basal surface (where attached to the basement membrane -Gland tissues are epithelium

72. Epithelium -Have an apical surface (the free surface) and a basal surface (where attached to the basement membrane) -Adjacent cells are connected as sheets by desmosomes and tight junctions -The basal layer rests on the basement membrane, comprised of the basal lamina and reticular lamina (115) -Nerves, but no blood vessels -Generally good regenerative capacity

73. All epithelium rests on a basement membrane. The blood carries nutrients as far as the basement membrane. From there, nutrients must diffuse across. That’s why, in stratified epithelium, the upper layers start dying: “trickle-up” nutrition only serves those at the bottom The basement membrane is made of protein fibers and helps keep materials/cells in their proper tissue compartments.

74. Glandular Epithelium “Exocrine” when secretions end up on the surface– on the skin or on a surface contiguous with the skin “Endocrine” secretions are released to the blood, lymph or interstitial spaces (Not all are epithelium… more later)

75. Exocrine glands Includes single cell and multicell glands –Single cell are “goblet cells” producing mucin, which released, dissolves in water to make mucus See 122

76. Exocrine glands Includes single cell and multicell glands –Multicell glands have ducts and regions secreting to those ducts (acinar cells). There is generally connective tissue supports and blood supplies See 122 Pancreas here See 123

77. Secretion: Three ways for this to happen: 1) merocrine: when the substance being produced by the cell is released by exocytosis (some cytoplasm is lost)

78. 2) holocrine: the cell is filled with the “secretion” bursts, releasing the material, and dies. 3) Apocrine: present in humans?

79. Connective tissue types Connective tissue properBoneCartilage Blood Loose Dense Spongy Compact Hyaline Fibrocartilage Elastic Several cell types- details later Embryonic mesenchyme

80. Connective tissue Functions: Support and protection: Cartilage and bone (blood and lymph) Transportation: Blood and lymph Energy storage: Fat

81. Connective tissue (look at 125) Characteristics: -made up of ( in differing degrees) cells, matrix of ground substance and fibers -blood supply varies with the specific tissue -cartilage very poor -bone very rich -others in between -an “extracellular matrix” lies between cells - contains proteins that connect tissue, hold water - amount varies with the tissue

82. Connective tissue fibers: Collagen: most common, strong and flexible Elastic: containing the creatively named “elastin” protein. These fibers are wavy and have recoil Reticular: like a lattice- support organ soft tissue and small vessels

83. Connective tissue Matrix -an “extracellular matrix” lies between cells - contains proteins that connect tissue, hold water - amount varies with the tissue

84. Connective tissue cells Fibroblasts: produce and maintain fibers and matrix Chondroblasts: produce cartilage Osteoblasts- Bone production Hematopoietic cells- blood cell production Macrophages: tissue “pac-men” (also WBCs w/ antibodies) Fat cells: Mast cells: contain chemical mediators of inflammation

85. Connective tissue types Connective tissue properBoneCartilage Blood Loose Dense Spongy Compact Hyaline Fibrocartilage Elastic Several cell types- details later

86. Connective tissue types: Loose: Examples: “areolar”, adipose, reticular Connective tissue (proper) Dense: Examples: Dense regular, dense irregular, elastic

87. Connective tissue types: Areolar: Fibers support surrounding tissue Matrix (ground substance) holds water White blood cells/Macrophages act defensively Nutrients stored in fat (adipose) See p. 126

88. Connective tissue types: Adipose: (cells are adipocytes) -Like areolar connective tissue, plus a predominance of adipocytes -Acts as padding, shock absorption, insulation and energy reserves -good blood supply -white fat vs brown fat -see p. 127

89. Connective tissue types: Reticular: -see p. 133 Think “lattice” A framework supporting cells, esp. in the spleen, lymph nodes and marrow

90. Connective tissue types: Dense Regular connective tissue -Made up mostly of collagen, with fibers oriented parallel, in line with the direction of stress -Think tendon and ligament

91. Connective tissue types: Dense Irregular connective tissue -Similar components to regular, with thicker collagen fibers, oriented ad various angles -Think dermis, joint capsules, organ capsules

92. Connective tissue types: -Fluid connective tissues Blood and lymph (including RBC, WBC, Platelets

93. Connective tissue types: Cartilage (see pages 131,132) Maintained by chondrocytes Poor blood supply and innervation Types: Hyaline :Elastic :Fibrocartilage

94. Connective tissue types: Cartilage Types: Hyaline- at joints, supporting respiratory tract, connecting ribs to sternum - forms the template of bones in the developing fetus :Elastic- more flexible; at outer ear, epiglottis, auditory tube :Fibrocartilage- much collagen; tough; found intervertebral disks, symphysis joints

95. Connective tissue types: Cartilage :Elastic- like hyaline, more flexible having many elastic fibers - at outer ear, epiglottis, auditory tube :Fibrocartilage- much collagen; tough; found intervertebral disks, symphysis joints

96. Connective tissue types: Cartilage :Fibrocartilage- much collagen; tough; found intervertebral disks, symphysis joints

97. Connective tissue types: Bone: (see p. 133) 2 structural types: spongy and compact Components include collagen fibers, with a matrix material reinforced by calcium salts for great rigidity Good blood supply

98. Nerve Nerve tissue consists of two main groups: : the neurons which send and receive signals through the body : the neuroglia which are “support” cells for the neurons, providing protection and maintenance for the neurons :. More details on neuroglia later

99. Muscle SmoothCardiacSkeletal See 140, 141

100. Muscle- cont Smooth muscle : forms the wall of hollow organs : bladder, stomach/intestines, uterus, blood vessels : is non-striated, involuntary : contracts in response to stretch- meaning for example- that when the bladder is stretched (full) it contracts to empty

101. Muscle Cardiac: found only in the heart : cells have single nucleus : cells may be branched : cells are connected by gap junctions and communicate with each other through these junctions : connections between cells are intercalated disks :cardiac muscle is striated, involuntary

102. Muscle (cont) Skeletal: :striated, voluntary : what we usually think of as “muscle”-- like the biceps or hamstring group : provides posture, generates heat, provides movement, control of sphincters (openings of bladder, bowel…) : multi-nucleate

103. Membranes Cutaneous Mucous Serous

104. Membranes Mucus- -line body cavities open to the “outside” -moisten tissue, generally adapted for secretion, absorption -varying amounts of mucus -protective

105. Membranes Serous- -line outside of organs: heart, lungs and GI tract -provide reduced friction around these moving organs -composed of two layers of a simple squamous epithelium on loose connective tissue layers -between the layers is serous fluid