1. Chapter 3: The Cellular Level of Organization

2. What is cell theory?

3. Figure 3–1 The Cell Performs all life functions

4. Sex Cells Sex cells (germ cells): reproductive cells male sperm female oocytes (eggs)

5. Somatic Cells Somatic cells (soma = body): all body cells except sex cells

6. Organelle Functions Table 3–1 (1 of 2)

7. Organelle Functions Table 3–1 (2 of 2)

8. Functions of Cell Membrane Physical isolation: barrier Regulates exchange with environment: ions and nutrients enter waste and cellular products released Monitors the environment: extracellular fluid composition chemical signals Structural support: anchors cells and tissues

9. The Cell Membrane Figure 3–2

10. The Cell Membrane Contains lipids, carbohydrates, and functional proteins

11. Phospholipid Bilayer Double layer of phospholipid molecules: hydrophilic heads—toward watery environment, both sides hydrophobic fatty-acid tails—inside membrane barrier to ions and water soluble compounds

12. Membrane Proteins Integral proteins: within the membrane Peripheral proteins: inner or outer surface of the membrane

13. 6 Functions of Membrane Proteins 1. Anchoring proteins (stabilizers): – attach to inside or outside structures 2. Recognition proteins (identifiers): – label cells normal or abnormal 3. Enzymes: catalyze reactions

14. 6 Functions of Membrane Proteins continued 4. Receptor proteins: – bind and respond to ligands (ions, hormones) 5. Carrier proteins: – transport specific solutes through membrane 6. Channels: – regulate water flow and solutes through membrane

15. Membrane Carbohydrates Proteoglycans, glycoproteins, and glycolipids: extend outside cell membrane form sticky “sugar coat” (glycocalyx)

16. Functions of Membrane Carbohydrates Lubrication and protection Anchoring and locomotion Specificity in binding (receptors) Recognition (immune response)

17. Cytoplasm All materials inside the cell and outside the nucleus: cytosol (fluid): dissolved materials: nutrients, ions, proteins, and waste products organelles: structures with specific functions

18. What are cell organelles and their functions?

19. Types of Organelles Nonmembranous organelles: no membrane direct contact with cytosol Membranous organelles: covered with plasma membrane isolated from cytosol

20. Nonmembranous Organelles 6 types of nonmembranous organelles: cytoskeleton microvilli centrioles cilia ribosomes proteasomes

21. Figure 3–3a The Cytoskeleton Structural proteins for shape and strength

22. Microfilaments Thin filaments composed of the protein actin: provide additional mechanical strength interact with proteins for consistency Pairs with thick filaments of myosin for muscle movement

23. Intermediate Filaments Mid-sized between microfilaments and thick filaments: durable (collagen) strengthen cell and maintain shape stabilize organelles stabilize cell position

24. Microtubules Large, hollow tubes of tubulin protein: attach to centrosome strengthen cell and anchor organelles change cell shape move vesicles within cell (kinesin and dynein) form spindle apparatus

25. Figure 3–3b Microvilli Increase surface area for absorption Attach to cytoskeleton

26. Centrioles in the Centrosome Centrioles form spindle apparatus during cell division Centrosome: cytoplasm surrounding centriole Figure 3–4a

27. Cilia Power Cilia move fluids across the cell surface Figure 3–4b,c

28. Ribosomes Build polypeptides in protein synthesis Two types: free ribosomes in cytoplasm: proteins for cell fixed ribosomes attached to ER: proteins for secretion

29. Proteasomes Contain enzymes (proteases) Disassemble damaged proteins for recycling

30. Membranous Organelles 5 types of membranous organelles: endoplasmic reticulum (ER) Golgi apparatus lysosomes peroxisomes mitochondria

31. Endoplasmic Reticulum (ER) Figure 3–5a

32. Endoplasmic Reticulum (ER) endo = within, plasm = cytoplasm, reticulum = network Cisternae are storage chambers within membranes

33. Functions of ER Synthesis of proteins, carbohydrates, and lipids Storage of synthesized molecules and materials Transport of materials within the ER Detoxification of drugs or toxins

34. Smooth Endoplasmic Reticulum (SER) No ribosomes attached Synthesizes lipids and carbohydrates: phospholipids and cholesterol (membranes) steroid hormones (reproductive system) glycerides (storage in liver and fat cells) glycogen (storage in muscles)

35. Rough Endoplasmic Reticulum (RER) Surface covered with ribosomes: active in protein and glycoprotein synthesis folds polypeptides protein structures encloses products in transport vesicles

36. Golgi Apparatus Figure 3–6a

37. Golgi Apparatus Vesicles enter forming face and exit maturing face Functions of the Golgi Apparatus PLAY

38. Vesicles of the Golgi Apparatus Secretory vesicles: modify and package products for exocytosis Membrane renewal vesicles: add or remove membrane components Lysosomes: carry enzymes to cytosol

39. Transport Vesicles Figure 3–7a Carry materials to and from Golgi apparatus

40. Figure 3–7b Exocytosis Ejects secretory products and wastes

41. Lysosomes Figure 3–8 Powerful enzyme-containing vesicles: lyso = dissolve, soma = body

42. Lysosome Structures Primary lysosome: formed by Golgi and inactive enzymes Secondary lysosome: lysosome fused with damaged organelle digestive enzymes activated toxic chemicals isolated

43. Lysosome Functions Clean up inside cells: break down large molecules attack bacteria recycle damaged organelles ejects wastes by exocytosis

44. Autolysis Self-destruction of damaged cells: auto = self, lysis = break lysosome membranes break down digestive enzymes released cell decomposes cellular materials recycle

45. Peroxisomes Are enzyme-containing vesicles: break down fatty acids, organic compounds produce hydrogen peroxide (H 2 O 2 ) replicate by division

46. Membrane Flow A continuous exchange of membrane parts by vesicles: all membranous organelles (except mitochondria) allows adaptation and change

47. KEY CONCEPT Cells: basic structural and functional units of life respond to their environment maintain homeostasis at the cellular level modify structure and function over time

48. Mitochondrion Structure Figure 3–9a

49. Mitochondrion Structure Have smooth outer membrane and folded inner membrane (cristae) Matrix: fluid around cristae

50. Mitochondrial Function Mitochondrion takes chemical energy from food (glucose): produces energy molecule ATP Figure 3–9b

52. Aerobic Cellular Respiration Aerobic metabolism (cellular respiration): mitochondria use oxygen to break down food and produce ATP

53. The Reactions glucose + oxygen + ADP  carbon dioxide + water + ATP Glycolysis: glucose to pyruvic acid (in cytosol) Tricarboxylic acid cycle (TCA cycle): pyruvic acid to CO 2 (in matrix)

54. KEY CONCEPT Mitochondria provide cells with energy for life: require oxygen and organic substrates generate carbon dioxide and ATP

55. How does the nucleus control the cell?

56. Figure 3–10a The Nucleus Is the cell’s control center

57. Structure of the Nucleus Nucleus: largest organelle Nuclear envelope: double membrane around the nucleus Perinuclear space: between 2 layers of nuclear envelope Nuclear pores: communication passages

58. Within the Nucleus DNA: all information to build and run organisms Nucleoplasm: fluid containing ions, enzymes, nucleotides, and some RNA Nuclear matrix: support filaments

59. Nucleoli in Nucleus Are related to protein production Are made of RNA, enzymes, and histones Synthesize rRNA and ribosomal subunits

60. Organization of DNA Figure 3–11

61. Organization of DNA Nucleosomes: DNA coiled around histones Chromatin: loosely coiled DNA (cells not dividing) Chromosomes: tightly coiled DNA (cells dividing)

62. What is genetic code?

63. DNA and Genes DNA: instructions for every protein in the body Gene: DNA instructions for 1 protein

64. Genetic Code The chemical language of DNA instructions: sequence of bases (A, T, C, G) triplet code: 3 bases = 1 amino acid

65. KEY CONCEPT The nucleus contains chromosomes Chromosomes contain DNA DNA stores genetic instructions for proteins Proteins determine cell structure and function

66. How do DNA instructions become proteins?

67. Protein Synthesis Transcription: copies instructions from DNA to mRNA (in nucleus) Translation: ribosome reads code from mRNA (in cytoplasm) assembles amino acids into polypeptide chain

68. mRNA Transcription A gene is transcribed to mRNA in 3 steps: gene activation DNA to mRNA RNA processing Transcription and Translation PLAY

70. Step 1: Gene Activation Uncoils DNA, removes histones Start (promoter) and stop codes on DNA mark location of gene: coding strand is code for protein template strand used by RNA polymerase molecule

71. Step 2: DNA to mRNA Enzyme RNA polymerase transcribes DNA: binds to promoter (start) sequence reads DNA code for gene binds nucleotides to form messenger RNA (mRNA) mRNA duplicates DNA coding strand, uracil replaces thymine

72. Step 3: RNA Processing At stop signal, mRNA detaches from DNA molecule: code is edited (RNA processing) unnecessary codes (introns) removed good codes (exons) spliced together triplet of 3 nucleotides (codon) represents one amino acid

73. Codons Table 3–2

74. Translation- mRNA moves: from the nucleus through a nuclear pore Figure 3–13

75. Translation-Step 1 mRNA moves: to a ribosome in cytoplasm surrounded by amino acids Figure 3–13 (Step 1)

76. Translation-Step 2 mRNA binds to ribosomal subunits tRNA delivers amino acids to mRNA Figure 3–13 (Step 2)

78. Translation-Step 3 tRNA anticodon binds to mRNA codon 1 mRNA codon translates to 1 amino acid Figure 3–13 (Step 3)

79. Figure 3–13 (Step 4) Translation-Step 4 Enzymes join amino acids with peptide bonds Polypeptide chain has specific sequence of amino acids

80. Protein Synthesis: Sequence of Amino Acids in the Newly Synthesized Polypeptide PLAY Figure 3–13 (Step 5) Translation-Step 5 At stop codon, components separate

81. Nucleus Controls Cell Structure and Function Direct control through synthesis of: structural proteins secretions (environmental response) Indirect control over metabolism through enzymes

82. KEY CONCEPT Genes: are functional units of DNA contain instructions for 1 or more proteins Protein synthesis requires: several enzymes ribosomes 3 types of RNA

83. KEY CONCEPT Mutation is a change in the nucleotide sequence of a gene: can change gene function Causes: exposure to chemicals exposure to radiation mistakes during DNA replication

84. How do things get in and out of cells?

85. Overcoming the Cell Barrier The cell membrane is a barrier, but: nutrients must get in products and wastes must get out

86. Permeability Permeability determines what moves in and out of a cell: A membrane that: lets nothing in or out is impermeable lets anything pass is freely permeable restricts movement is selectively permeable

87. Restricted Materials Selective permeability restricts materials based on: size electrical charge molecular shape lipid solubility

88. Transport Transport through a cell membrane can be: active (requiring energy and ATP) passive (no energy required)

89. 3 Categories of Transport Diffusion (passive) Vesicular transport (active) Carrier-mediated transport Facilitated diffusion (passive) Active transport (active)

90. Concentration Gradient Concentration is the amount of solute in a solvent Concentration gradient: more solute in 1 part of a solvent than another

91. Function of Concentration Gradient Diffusion: Solutes move down a concentration gradient molecules mix randomly solute spreads through solvent eliminates concentration gradient

92. Factors Affecting Diffusion Rates Distance the particle has to move Molecule size: smaller is faster Temperature: more heat, faster motion

93. Factors Affecting Diffusion Rates Gradient size: the difference between high and low concentration Electrical forces: opposites attract, like charges repel

94. Diffusion and the Cell Membrane Figure 3–15 Diffusion can be simple or channel- mediated

95. Simple Diffusion Materials which diffuse through cell membrane: lipid-soluble compounds (alcohols, fatty acids, and steroids) dissolved gases (oxygen and carbon dioxide)

96. Facilitated Diffusion Materials which pass through transmembrane proteins (channels): are water soluble compounds are ions

97. Factors in Channel-Mediated Diffusion Passage depends on: size charge interaction with the channel

98. Osmosis Figure 3–16 Osmosis is the diffusion of water across the cell membrane

99. How Osmosis Works More solute molecules, lower concentration of water molecules Membrane must be freely permeable to water, selectively permeable to solutes

100. Osmosis Water Movement Water molecules diffuse across membrane toward solution with more solutes Volume increases on the side with more solutes

101. Tonicity The osmotic effect of a solute on a cell: 2 fluids may have equal osmolarity, but different tonicity Figure 3–17a

102. Isotonic Solutions A solution that does not cause osmotic flow of water in or out of a cell iso = same, tonos = tension

103. Hypotonic Solutions hypo = below Solution has less solutes

104. Cells and Hypotonic Solutions A cell in a hypotonic solution: gains water ruptures (hemolysis of red blood cells) Figure 3–17b

105. Hypertonic Solutions hyper = above Solution has more solutes

106. Cells and Hypertonic Solutions A cell in a hypertonic solution: loses water shrinks (crenation of red blood cells) Figure 3–17c

107. KEY CONCEPT When different solute concentrations exist on either side of a selectively permeable membrane, osmosis moves water through the membrane to equalize the concentration gradients

108. What are special transport mechanisms?

109. Carrier-Mediated Transport Carrier-mediated transport of ions and organic substrates: facilitated diffusion active transport

110. Characteristics of Carrier-Mediated Transport Specificity: 1 transport protein, 1 set of substrates Saturation limits: rate depends on transport proteins, not substrate Regulation: cofactors such as hormones

112. Facilitated Diffusion Passive Carrier mediated Membrane Transport: Facilitated Diffusion PLAY Figure 3–18

113. How Facilitated Diffusion Works Carrier proteins transport molecules too large to fit through channel proteins (glucose, amino acids): molecule binds to receptor site on carrier protein protein changes shape, molecules pass through receptor site is specific to certain molecules

114. Active Transport Active transport proteins: move substrates against concentration gradient require energy, such as ATP ion pumps move ions (Na +, K +, Ca +, Mg 2 + ) exchange pump countertransports 2 ions at the same time

115. Sodium-Potassium Exchange Pump Figure 3–19

116. Sodium-Potassium Exchange Pump Active transport, carrier mediated: sodium ions (Na+) out, potassium ions (K+) in 1 ATP moves 3 Na+

118. Secondary Active Transport Figure 3–20 Na + concentration gradient drives glucose transport ATP energy pumps Na + back out

119. Transport Vesicles Also called bulk transport Vesicles: endocytosis (endo = into) active transport using ATP: receptor-mediated pinocytosis phagocytosis exocytosis (exo = out of)

120. Receptor-Mediated Endocytosis Figure 3–21

121. Receptor-Mediated Endocytosis Receptors (glycoproteins) bind target molecules (ligands) Coated vesicle (endosome) carries ligands and receptors into the cell

122. Figure 3–22a Pinocytosis Pinocytosis (cell drinking) Endosomes “drink” extracellular fluid

123. Phagocytosis Phagocytosis (cell eating) pseudopodia (psuedo = false, podia = feet) engulf large objects in phagosomes Figure 3–22b

124. Figure 3–7b Exocytosis Is the reverse of endocytosis

125. What is transmembrane potential?

126. Electrical Charge Inside cell membrane is slightly negative, outside is slightly positive Unequal charge across the cell membrane is transmembrane potential Resting potential ranges from —10 mV to —100 mV, depending on cell type

127. How do cells reproduce?

133. Cell Life Cycle Figure 3–3

134. Cell Life Cycle Most of a cell’s life is spent in a nondividing state (interphase)

135. Organization of DNA Figure 3–11

136. Interphase, Mitosis, and Cytokinesis PLAY 3 Stages of Cell Division Body (somatic) cells divide in 3 stages: DNA replication duplicates genetic material exactly Mitosis divides genetic material equally Cytokinesis divides cytoplasm and organelles into 2 daughter cells

137. Interphase The nondividing period: G-zero phase—specialized cell functions only G 1 phase—cell growth, organelle duplication, protein synthesis S phase—DNA replication and histone synthesis G 2 phase—finishes protein synthesis and centriole replication

138. DNA Replication Figure 3–24 DNA strands unwind DNA polymerase attaches complementary nucleotides

139. Mitosis Mitosis divides duplicated DNA into 2 sets of chromosomes: DNA coils tightly into chromatids chromatids connect at a centromere protein complex around centromere is kinetochore

140. Figure 3–25 (Stage 1) Stage 1: Prophase

141. Features of Prophase Nucleoli disappear Centriole pairs move to cell poles Microtubules (spindle fibers) extend between centriole pairs Nuclear envelope disappears Spindle fibers attach to kinetochore

142. Stage 2: Metaphase Figure 3–25 (Stage 2)

143. Features of Metaphase Chromosomes align in a central plane (metaphase plate)

144. Stage 3: Anaphase Figure 3–25 (Stage 3)

145. Features of Anaphase Microtubules pull chromosomes apart Daughter chromosomes groups near centrioles

146. Figure 3–25 (Stage 4, 1 of 2) Stage 4: Telophase

147. Features of Telophase Nuclear membranes reform Chromosomes uncoil Nucleoli reappear Cell has 2 complete nuclei

148. KEY CONCEPT Mitosis duplicates chromosomes in the nucleus for cell division

149. Figure 3–25 (Stage 4, 2 of 2) Stage 4: Cytokinesis Division of the cytoplasm

150. Features of Cytokinesis Cleavage furrow around metaphase plate Membrane closes, producing daughter cells

151. What regulates cell division?

152. Mitotic Rate and Energy Rate of cell division: slower mitotic rate means longer cell life cell division requires energy (ATP)

153. Long Life, Short Life Muscle cells, neurons rarely divide Exposed cells (skin and digestive tract) live only days or hours

154. Regulating Cell Life Normally, cell division balances cell loss

155. Factors Increase Cell Division Increases cell division: internal factors (MPF) extracellular chemical factors (growth factors)

156. Factors Decrease Cell Division Decreases cell division: repressor genes (faulty repressors cause cancers) worn out telomeres (terminal DNA segments)

157. Cancer Figure 3–26

158. Cancer Stages Cancer develops in steps: abnormal cell primary tumor metastasis secondary tumor

159. Cell Division and Tumors Tumor (neoplasm): enlarged mass of cells abnormal cell growth and division

160. Benign Tumors Benign tumor: contained not life threatening

161. Malignant Tumors Malignant tumor: spread into surrounding tissues (invasion) start new tumors (metastasis)

162. Cancer and Cells Cancer: illness that disrupts cellular controls produces malignant cells

163. Cancer and Genes Oncogenes: mutated genes that cause cancer

164. KEY CONCEPT Mutations disrupt normal controls over cell growth and division Cancers often begin where stem cells are dividing rapidly More chromosome copies mean greater chance of error

165. What makes cells different?

166. Cell Diversity All cells carry complete DNA instructions for all body functions

167. Cell Differentiation Cells specialize or differentiate: to form tissues (liver cells, fat cells, and neurons) by turning off all genes not needed by that cell

168. KEY CONCEPT All body cells, except sex cells, contain the same 46 chromosomes Differentiation depends on which genes are active and which are inactive