2. Cell Physiology How the cell does what is does

3. Membrane Transport There is fluid on each side of the plasma membrane –Interstitial Fluid –Cytoplasm Solution- homogeneous mixture of two or more components –The substance found in largest amount is the solvent. –The substance of a smaller amount is the solute.

4. Fluids Intracellular Fluid (nucleoplasm and cytosol) –contains small amount of gases, nutrients, and salts dissolved in water. Interstitial Fluid (around the cell) –Contains nutrients, hormones, neurotransmitters, salts, and waste products

5. Selectively Permeable A barrier that allows some substances to pass through while excluding others. –Allows nutrients to enter but keeps other substances outside the cell –Keeps cell organelles inside and allows wastes to escape. The movement of substances across the plasma membrane occurs by: –Passive Transport –Active Transport

6. Burns A cell will be selectively permeable if it is unharmed. When cells have been damaged the plasma membrane will no longer be selective and will be permeable to anything. –When a victim is severely burned, precious fluids are lost from the dead or damaged cells. http://www.thedoctorwillseeyounow.com/articles/other/burns_23/12.jpg

7. Passive Transport- Diffusion The process by which molecules tend to scatter themselves through available space. –Controlled by kinetic energy –Molecules will move from an area of high concentration to an area of low concentration (concentration gradient). –The speed of diffusion depends on the size of the molecules and the temperature. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

8. Diffusion and the Plasma Membrane The plasma membrane is a physical barrier to diffusion. Some molecules can passively diffuse across the membrane. Saves the cell a large amount of energy to transport important molecules.

9. Simple Diffusion Unassisted diffusion of solutes through the plasma membrane –Lipid-soluble molecules (fats, fat-soluble vitamins, oxygen, carbon dioxide) –Small molecules (some small ions like Cl-) Simple diffusion of water is called osmosis –Pass through small pores in the membrane

10. Facilitated Diffusion Allows needed substances to enter the cell that are both insoluble and too large to fit –Example: Glucose A transport vehicle is required

11. Diffusion Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

12. Diffusion Glucose and oxygen continually move into the cell –Lower concentration inside the cell Carbon dioxide moves out of the cell –Higher concentration inside the cell

13. Passive Transport- Filtration Water and solutes are forced through a membrane by fluid pressure (hydrostatic) –Pressure Gradient Pushes solute-containing fluid from high pressure area into a low pressure area –Usually exerted by the blood –Kidneys use this method to produce urine

14. Active Transport Processes A cell uses ATP to move substances across the membrane –Substances moved actively are too large to fit though pores, insoluble in fatty portion of membrane, or must be moved uphill to the concentration gradient. Examples: –Solute Pumping –Bulk Transport

15. Solute Pumping Require protein carriers to bind to the substances to be moved across the plasma membrane Solute Pumps –Amino acids, some sugars, ad most ions are transported by solute pumps –Move against the concentration gradient

16. Sodium-Potassium Pump Simultaneously carries sodium ions out of and potassium ions into the cell. Important for nerve cells –More Na+ outside the cells than inside –A pump is required to go against the gradient

17. Sodium-Potassium Pump Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

18. Bulk Transport Two Types: –Exocytosis –Endocytosis

19. Exocytosis Moves substances out of the cell How cells actively secrete hormones, mucus, other cell products and eject wastes. –Product is packaged by the golgi apparatus into a small vesicle –The sac migrates to the membrane, fuses, ruptures, and spills contents outside the cell.

20. Exocytosis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

21. Endocystosis Uses ATP to engulf substances into the cell –A vesicle is formed around molecule –Detaches from the membrane –Fuses with the lysosome where is digested When large particles, bacteria, and dead body cells are digested by a cell it is called phagocytosis. –White Blood Cells http://www.aamdsglossary.co.uk/white_blood_cells.jpeg

22. Endocytosis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

23. Bulk-phase Endocytosis Pinocytosis (cell drinking) Plasma membrane creates a vesicle of extracellular fluid

24. Cell Life Cycle Series of changes that a cell undergoes from the time it is formed until it divides. Consists of Two Major Periods –Interphase –Cell Division

25. Interphase The longest phase of the cell life cycle. The cell performs its normal functions: –Protein Synthesis and other functions –This is the phase when the DNA replicates itself (S phase) http://www.eastcentral.edu/acad/depts/BI/interphase_animal_labels.jpg

26. Interphase

27. DNA Replication Always precedes cell division The DNA helix uncoils into two nucleotide strands. Each strand now serves as a template for building a new strand. –A always bonds with T –G always bonds with C Begin with one strand of DNA, ends with 2 identical strands that are half old and half new. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

28. Cell Division All body cells (except for reproductive cells) undergo cell division in two stages. –Mitosis- division of nucleus –Cytokinesis- division of cytoplasm

29. Mitosis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

30. Mitosis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

31. Prophase Chromatin thread coil into chromosomes Made up of two strands (chromatid) connected by a centromere. Centrioles replicate and move to opposite poles to form the mitotic spindle. The nuclear envelope breaks down. http://www.eastcentral.edu/acad/depts/BI/animal_mitosis_labels.html

32. Prophase

33. Metaphase The chromosomes line up at the metaphase plate (the equator of the cell). http://www.eastcentral.edu/acad/depts/BI/animal_mitosis_labels.html

34. Metaphase

35. Anaphase The centromeres split and the sister chromatids go to opposite ends of the cell. http://www.eastcentral.edu/acad/depts/BI/animal_mitosis_labels.html

36. Anaphase

37. Telophase The reverse of prophase. Chromosomes uncoil into threadlike chromatin. The nuclear envelope reappears.

38. Telophase

39. Cytokinesis The division of the cytoplasm. Begins in early anaphase and ends with telophase. A cleavage furrow appears over the midline of the spindle. Sometimes mitosis can occur without cytokinesis: –Binucleate or Multinucleate cells (many found in the liver)

40. The End of Mitosis The purpose of mitosis is to produce two identical daughter cells. When the cell has divided, the daughter cells will grow to the normal size of an adult cell before dividing again. Can take from 5 minutes to several hours to complete (normally 2 hours)

41. Cancer Uncontrolled mitosis is the basis for tumors and cancer Increased cell division Benign- local tumors that are surrounded by a capsule Malignant- nonencapulated masses that grow relentlessly Metastasis- malignant cells can spread via the bloodstream Carcinogens- cause mutations in DNA that can lead to cancer

42. Cancer

43. Protein Synthesis A gene is a DNA segment that carries the information for building one protein or polypeptide. Genes are known as the blueprint of life. –They direct what proteins are made. –They direct when proteins are made. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

44. Remember Proteins Enzymes are the biological catalysts of the body. –DNA regulates cellular activities by specifying the structure of enzymes. http://www.stanford.edu/group/blocklab/DNARNA.html

45. Triplet Code The exact sequence of bases in the DNA determines the protein to be made. A triplet refers to the three bases that calls for a particular amino acid. –Amino acids are linked together to form proteins. –Triplets are linked together to form genes.

46. The Role of RNA DNA must stay inside the nucleus. –It is too large to fit through the nuclear envelope. Proteins are made in the cytoplasm. –The genetic code must copied in smaller pieces that can go to the ribosomes. RNA decodes the genetic information, carries it to the cytoplasm and directs the assembly of proteins.

47. The types of RNA There are three types of RNA –Messenger RNA (mRNA) Decodes the message and carries the code to the cytoplasm. –Transfer RNA (tRNA) Carries the amino acid to the ribosome. –Ribosomal RNA (rRNA) Directs the assembly of proteins.

48. Transcription The genetic information is transferred from DNA into mRNA. –Using the DNA as the template, the complimentary RNA sequence is matched. –A codon refers to the three letters of mRNA that code for a particular amino acid. –Occurs in the nucleus. http://www.brooklyn.cuny.edu/bc/ahp/BioInfo/graphics/Transcription.01.GIF

49. Translation The language of nucleic acids is changed into the language of proteins. –Occurs in the cytoplasm at the ribosomes. –All three RNA’s are involved –The mRNA codon is matched to the tRNA anticodon to put the amino acids in the correct order. http://www.blc.arizona.edu/INTERACTIVE/DNA3/gencode.gif

50. Protein Synthesis and Genetic Disorders