1. Chapter 2 The Cell: Basic Unit of Structure and Function

2. Our friend, the cell all life is made of cells Cells come from other cells

3. Most cells are very small We use microscopes to look at them Some cells are not small

4. Table 2.3, 2.4 Plasma membrane Made of a bilayer of phospholipids Cholesterol molecules and proteins embedded in membrane Semi-permeable protective layer around cell

5. Plasma membrane Each phospholipid has hydrophilic head, hydrophobic tail Hydrophilic head faces water Hydrophobic tail faces away from water two layers of tails face each other

6. Plasma membrane Fluid inside cell is part of cytoplasm, called intracellular fluid (ICF) Fluid outside cell is extracellular fluid (ECF) extracellular fluid intracellular fluid

7. Fig. 2.4 Cytoplasm Peripheral protein Glycolipid Peripheral protein Integral proteins Extracellular fluid Glycocalyx (carbohydrate) Glycoprotein Protein Cholesterol Filaments of cytoskeleton Plasma membrane Lots of things inserted in plasma membrane Cholesterol (lipid) strengthens and stabilizes membrane

8. Fig. 2.4 Cytoplasm Peripheral protein Glycolipid Peripheral protein Integral proteins Extracellular fluid Glycocalyx (carbohydrate) Glycoprotein Protein Cholesterol Filaments of cytoskeleton Plasma membrane Glycolipid (lipid with carbohydrate attached) located only on outer layer of membrane important for cell-cell recognition, intracellular adhesion, communication between cells

9. Fig. 2.4 Cytoplasm Peripheral protein Glycolipid Peripheral protein Integral proteins Extracellular fluid Glycocalyx (carbohydrate) Glycoprotein Protein Cholesterol Filaments of cytoskeleton Plasma membrane Integral proteins extend across plasma membrane Some create pores, channels to let things into or out of cells Some are binding site for signaling molecules

10. Fig. 2.4 Cytoplasm Peripheral protein Glycolipid Peripheral protein Integral proteins Extracellular fluid Glycocalyx (carbohydrate) Glycoprotein Protein Cholesterol Filaments of cytoskeleton Plasma membrane Peripheral proteins are not embedded in membrane may float above membrane or be attached to something attached to membrane Some are receptors for signaling molecules

11. Fig. 2.4 Cytoplasm Peripheral protein Glycolipid Peripheral protein Integral proteins Extracellular fluid Glycocalyx (carbohydrate) Glycoprotein Protein Cholesterol Filaments of cytoskeleton Plasma membrane Glycoproteins (proteins with carbohydrate attached to external surface) ~90% of all membrane molecules With glycolipids form glycocalyx on surface of cell protection and recognition

12. Table 2.2a-2 CytosolOrganelles Cytoplasm Inclusions

13. Table 2.2a-1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. hydrophobic hydrophilic Water cannot move easily across hydrophobic part of membrane Proteins are too large to move across membrane without help

14. Passive transport Move particles across membrane without using energy Diffusion particles moving down concentration gradient from area of high concentration to area of low concentration

15. Passive transport Osmosis diffusion of water across a permeable membrane Facilitated diffusion requires use of transport proteins to move across plasma membrane does not use energy high glucose concentration low glucose concentration

16. Passive transport Bulk filtration diffusion of solutes and solvents together across a membrane Ex. transport of water and nutrients from blood into extracellular fluid pushed by hydrostatic pressure (pressure of fluid against the wall of the blood vessel)

17. Active transport Movement of a substance across a plasma membrane AGAINST a concentration gradient from area of low concentration to area of high concentration Uses energy from ATP, and usually a transport protein to move the substance Pumps use ATP or kinetic energy of another particle moving down its gradientkinetic energy

18. Na + ATP Transport protein ATP binding site Phospholipid bilayer 1 Sodium-Potassium Pump 1. ATP binds to transport protein Binding changes shape of protein, allowing sodium to bind Extracellular fluid Cytoplasm

19. P ADP Na + Transport protein changes shape (requires energy from ATP breakdown) Breakdown of ATP releases energy K+K+ 2 Sodium-Potassium Pump 2. ATP separates into ADP and a phosphate group, releasing energy Transport protein uses energy to change shape Shape change releases sodium outside cell; binding sites for potassium open Extracellular fluid Cytoplasm

20. P K+K+ Na + 3 Sodium-Potassium Pump 3. Potassium from ECF binds to transport protein; phosphate group from ATP releases Extracellular fluid Cytoplasm

21. Extracellular fluid Transport protein resumes original shape K+K+ 4 Cytoplasm Fig. 2.5 Sodium- Potassium Pump 4. Potassium is released into cytoplasm; transport protein resumes its original shape

22. Plasma membrane Secretory proteins Secretory vesicle Vesicle membrane Extracellular fluid Cytoplasm 1. Vesicle nears plasma membrane Fig. 2.6, Exocytosis

23. Extracellular fluid Cytoplasm Membrane proteins 2. Vesicle membrane fuses with plasma membrane Fig. 2.6, Exocytosis

24. 3. Exocytosis as plasma membrane opens externally Plasma membrane opens Fig. 2.6, Exocytosis

25. 4. Release of vesicle components into the extracellular fluid and integration of vesicle membrane components into the plasma membrane Secretory proteins Fig. 2.6, Exocytosis

26. Pseudopodia Cytoplasm (a) Phagocytosis Extracellular fluid Particle Plasma membrane Vacuole Fig. 2.7, Forms of Endocytosis Phagocytosis: cell engulfs or captures a large particle from extracellular space by forming membrane extensions called pseudopodia Phagocytosis Membrane sac enters cell, called vacuole if large

27. Fig. 2.7, Forms of Endocytosis Plasma membrane Vesicle (b) Pinocytosis Pinocytosis: cellular drinking cell brings in small droplet of ECF into internal vesicle moves against concentration gradient

28. Fig. 2.7, Forms of Endocytosis Receptors Plasma membrane Cytoplasmic vesicle (c) Receptor-mediated endocytosis Receptor-mediated endocytosis: movement of specific molecules into cell by formation of vesicles Molecule binds to receptors on surface of cell Receptor proteins signal for formation of vesicle

29. Other parts of the cell Cytosol (AKA intracellular fluid) very viscous mostly water with dissolved ions, nutrients, proteins, carbohydrates, lipids, etc. solutes provide nutrition to cell, make building blocks of membranes, proteins Inclusions temporarily stored chemicals not bound by membranes include pigments, protein crystals, nutrient stores ex. melanin and glycogen

30. Other parts of the cell Organelles bound by membrane each has specific function

31. Membrane-bound organelles Each bound by plasma membrane like the cell itself Each carries out specific function membrane is basically the same, may have different protein-lipid composition

32. Table 2.2a-4 Smooth endoplasmic reticulum Synthesizes, transports, and stores lipids more smooth ER in cells that make steroids (forms of lipids) Metabolizes carbohydrates Detoxifies drugs, alcohol, and poisons lots of smooth ER in liver Continuous with rough ER

33. Table 2.2a-5 Rough endoplasmic reticulum Makes proteins for inclusion in plasma membrane Makes proteins that will be used in lysosomes Makes proteins that will be secreted out of cell Transports and stores proteins proteins packaged into transport vesicles

34. Table 2.2a-6 Golgi apparatus AKA Golgi complex Modifies, packages, and sorts proteins for secretion or transport within cell Golgi composed of cisternae, stacks of membranes

35. Transport vesicle from rough ER “Receiving” side of the Golgi apparatus Plasma membrane 2 3 1 Transport vesicle from rough ER Plasma membrane Golgi Apparatus 1.One side of Golgi stack receives vesicles from ER

36. Transport vesicle from rough ER “Receiving” side of the Golgi apparatus Plasma membrane 2 3 1 Transport vesicle from rough ER Plasma membrane Golgi Apparatus 1.One side of Golgi stack receives vesicles from ER 2.Proteins modified by enzymes (folded, signaling molecules attached)

37. Transport vesicle from rough ER “Receiving” side of the Golgi apparatus New vesicle forming Transport vesicle from the Golgi apparatus “Shipping” side of the Golgi apparatus Plasma membrane 2 3 1 Transport vesicle from rough ER New vesicle forming Plasma membrane Golgi Apparatus 1.Receiving side (AKA cis- face) receives vesicles from ER 2.Proteins modified by enzymes (folded, signaling molecules attached) 3.Vesicles emerge from shipping side (AKA trans- face); sent to organelles or plasma membrane for secretion

38. (a) Secretory vesicles Shipping region Vacuole Transport vesicle Lumen of cisterna filled with secretory product Transport vesicle TEM 17,770x Receiving region Transport vesicle Vacuole Shipping region Vacuole Cisternae Golgi Apparatus Vesicles form at the edges of cisternae, fuse with next cisternae

39. Organelle fragment Vesicle containing two damaged organelles Organelle fragment TEM Lysosomes Sac of digestive enzymes enclosed in a membrane formed by Golgi apparatus Contain enzymes that break down proteins, polysaccharides, fats, nucleic acids “digestion” within cell

40. Lysosomes Lysosomes in immune cells (white blood cells) fuse with vacuole containing engulfed bacteria or virusimmune cells Cell recycles molecules from engulfed particles

41. Lysosome Digestion Vesicle containing damaged organelle (b) A lysosome breaking down the molecules of damaged organelles Lysosome s Lysosomes can break down old or damaged organelles within cell process called autophagy Cell can recycle parts to make new organelles Autolysis destroys whole cell when lysosomes break

42. Lysosomes In embryo, digest webbing between developing fingers if process doesn’t work correctly, digits are fused by skin fusion called syndactyly Programmed cell death is apoptosis body getting rid of old, unnecessary, or damaged cells

44. Lysosomes If lysosomes don’t work correctly, causes disease Tay-Sachs disease: nerve cells accumulate excess lipids causes deafness, lack of muscle tone fatal

45. Table 2.2b-2 Peroxisome Detoxifies some harmful materials by oxidizing Converts hydrogen peroxide from metabolism into water Smaller than lysosomes Formed by rough ER Most abundant in liver

46. Table 2.2b-3 Mitochondria sing. mitochondrium Synthesizes ATP through cellular respiration “Powerhouse” of the cell Surrounded by double membrane Inner membrane folded into cristae, increased surface area for ATP production Inner membrane cristae together called matrix Outer membrane Inner membrane Cristae Matrix Space between membranes

47. Outer membrane Inner membrane Cristae Matrix Space between membranes TEM

48. Outer membrane Inner membrane Cristae Matrix Space between membranes TEM Mitochondria are Special More mitochondria in cells that use lots of energy Have their own DNA single, circular chromosome, like prokaryotic chromosome have their own ribosomes evidence that eukaryotes came from symbiotic prokaryoteseukaryotes came from symbiotic prokaryotes

49. Mitochondria are Mom’s Gift Mitochondria come from egg, not sperm … Actually, MOST mitochondria come from the egg …Actually, MOST mitochondria come from the egg Human evolution can be traced through mitochondrial DNA

50. Non-membrane-bound organelles Other parts of the cell that do not have a plasma membrane

51. Table 2.2b-4 Fixed ribosomes Free ribosomes Ribosomes synthesize proteins Free ribosomes make proteins for use in cell Fixed ribosomes attached to endoplasmic reticulum make proteins for secretion, plasma membrane, or in lysosomes

52. Fig. 2.13 = + Rough endoplasmic reticulum with fixed ribosomes Free ribosome Small subunit Large subunit Functional ribosome TEM 12,510x

53. MicrofilamentIntermediate filament Microtubule Cytoskeleton Cytoskeleton is network of protein fibers give structural support to cell enable movement within cell Assist with cell division and mitosis Intermediate filaments and microfilaments are narrow and solid Microtubules are hollow

54. Table 2.2b-6 Centriole Centrosome Centrosome organizes microtubules during mitosis (cell duplication) Centrioles (2) sit within centrosome, perpendicular to each other move chromosomes during cell division

55. Table 2.2b-7 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Cilia Lots of tiny hairs attached to the cell membrane Move fluid, mucus, and materials over cell surface Inside of trachea and bronchi in lungs Inside fallopian tubes in females

56. Table 2.2b-8 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Flagellum Single, long extension of membrane filled with microtubules (sometimes 2-8 in other organisms) In humans, propel sperm Frequently used by single-celled organisms for propulsion

57. Table 2.2b-9 Microvilli Multiple folds and extensions in membrane Increase surface area to increase absorption and/or secretion Found in lining of intestine

58. Table 2.2a-3 Nucleus Nucleolus Chromatin Nuclear pores Nuclear envelope Largest structure in most cells Houses DNA Makes mRNA, instructions for making proteins Nucleolus assembles rRNA and ribosomes

59. The Nucleus Has a double-membrane called nuclear envelope Pores control movement into and out of nuclear envelope Chromatin fiber Nuclear envelope Nuclear pore TEM Surface of nuclear envelope Nuclear pores TEM

60. DNA storage DNA strands are very, very long total DNA in each cell is 1.8 m (~5 ft) long if stretched out Stored coiled up DNA binds with protein fibers called chromatin each chromatin fiber is one chromosome DNA molecule Proteins Chromatin fiber Chromosome

61. The Nucleolus Sits within nucleus Makes parts of ribosomes sent into cell to make proteins Nucleolus

62. DNA Synthesis of mRNA in the nucleus mRNA Nucleus Cytoplasm 1 How to Make a Protein 1. Translate DNA into RNA in the nucleus Strand of RNA called messenger RNA or mRNA

63. DNA Synthesis of mRNA in the nucleus mRNA Nucleus Cytoplasm mRNA Movement of mRNA into cytoplasm via nuclear pore 1 2 How to Make a Protein 1. Translate DNA into RNA in the nucleus Strand of RNA called messenger RNA or mRNA 2. Transport mRNA out of nucleus into cytoplasm

64. DNA Synthesis of mRNA in the nucleus mRNA Nucleus Cytoplasm mRNA Movement of mRNA into cytoplasm via nuclear pore Ribosome Synthesis of protein in the cytoplasm Protein 1 2 3 How to Make a Protein 1. Translate DNA into RNA in the nucleus Strand of RNA called messenger RNA or mRNA 2. Transport mRNA out of nucleus into cytoplasm 3. Ribosome reads mRNA instructions; binds amino acids together into strand of protein

65. Fig. 2.19 The Cell Cycle Anaphase G 2 phase (Growth) G 1 phase (Growth) Metaphase Mitosis Telophase Prophase Interphase S phase (DNA replication and growth) Mitotic (M) phase Cytokinesis

66. Fig. 2.20 Interphase and Mitosis -- Interphase Nucleolus Two pairs of centrioles Chromatin Nuclear envelope Plasma membrane Synthesis of cellular components needed for cell division, including synthesis of DNA. Nucleus with chromatin

67. Fig. 2.20 Interphase and Mitosis -- Prophase Sister chromatids Chromosome (two sister chromatids joined at centromere) Centromere Developing spindle Chromosomes appear due to coiling of chromatin. Nucleolus breaks down. Spindle fibers begin to form from centrioles. Centrioles move toward opposing cell poles. Nuclear envelope breaks down at the end of this stage. Nucleus with dispersed chromosomes

68. Fig. 2.20 Interphase and Mitosis - Metaphase Spindle fibers Equatorial plate Chromosomes aligned on equatorial plate Spindle fibers Spindle fibers attach to the centromeres of the chromosomes extending from the centrioles. Chromosomes are aligned at the equatorial plate of the cell by spindle fibers.

69. Fig. 2.20 Interphase and Mitosis -- Anaphase Centromeres that held chromatid pairs together separate; each sister chromatid is now a chromosome with its own centromere. Sister chromatids are separated and moved toward opposite ends of the cell. Cytokinesis begins. Sister chromatids being pulled apart Spindle fibers Sister chromatids being pulled apart

70. Fig. 2.20 Interphase and Mitosis -- Telophase Cytokinesis occurring Cleavage furrow Chromosomes uncoil to form chromatin. A nucleolus reforms within each nucleus. Spindle fibers break up and disappear. New nuclear envelope forms around each set of chromosomes. Cytokinesis continues as cleavage furrow deepens. Cleavage furrow of cytokinesis Nucleolus Re-forming nuclear envelope