extracellular fluid intracellular fluid hydrophilic hydrophobic

Transcription

1 Organelle Level Organelles are suspended within the cell in a fluid called cytoplasm. The organelles are: 1. Cell membrane: a phospholipid bilayer that gives structure to the cell and regulates what may enter and leave the cell. 2. Nucleus: the part of the cell that houses the DNA. 3. Mitochondria: organelles that perform cellular respiration and process the energy to ATP.

2 Organelle Level The organelles are: 4. Ribosomes: organelles that assemble proteins. 5. Endoplasmic reticulum: an extension of the nuclear membrane. Rough ER is the site of protein synthesis. Smooth ER is the site of lipid synthesis. 6. Golgi complexes: membrane- enclosed folds that inspect and modify proteins and lipids produced in the cell.

3 Organelle Level The organelles are: 7. Secretory vesicles: membrane packages that carry materials from the Golgi complex to the cell membrane for export from the cell. 8. Lysosomes: membrane- bound packages of digestive enzymes.

4 Cell

5 Cell Membrane Keeps the extracellular fluid separate from the intracellular fluid Phospholipids have a hydrophilicglycerol head into hydrophobicfatty acid tails

6 Cell Membrane Composition Bilayer of phospholipids molecules Cholesterol Proteins

7 Cell Membrane Proteins are attached to or embedded in the phospholipid layers Channels are passageways for transport of substances in and out of the cell Receptors for enzymes and hormones With carbohydrates (glycoproteins) serve as identification markers

8 Cell membrane (plasma membrane)

9 Cell Membrane Functions of the cell membrane To give structure to the cell To define what is intracellular (inside the cell) and what is extracellular (outside the cell) To regulate what may enter or leave the cell by a process called membrane transport

10 Passive Transport moves materials from areas of high concentration to areas of low concentration with no energy required Methods of passive transport include filtration, simple diffusion, facilitated diffusion, and osmosis.

11 Passive Transport 1. Filtration 2. Simple diffusion 3. Facilitated diffusion 4. Osmosis

12 Passive Transport 1. Filtration Forces smaller molecules in a solution through a membrane due to greater hydrostatic pressure on one side Hydrostatic pressure is the pressure exerted by a fluid against a wall or membrane

13 Passive Transport 2. Simple diffusion Net movement of molecules from an area of higher concentration to an area of lower concentration Occurs in gases and liquids due to constant, random motion of molecules Occurs in both living and non- living systems Depends on: Temperature Molecular weight Concentration gradient Membrane surface area

14 Simple diffusion

15 Passive Transport 3. Facilitated diffusion Special type of diffusion for molecules that cannot diffuse directly through the cell membrane Common for glucose, and amino acids Proteins carrier controlled process

16

17 Passive Transport 4. Osmosis Diffusion of water through a selectively permeable membrane Water always diffuses from a hypotonic solutioninto a hypertonic solution Hypotonic plasma can cause red blood cells to swell and burst or lyse. Hypertonic plasma can cause red blood cells to shrivel up or crenate.

18 Osmosis

19 Red blood cells in three solutions

20 Active Transport Active transport moves materials across a cell membrane from areas of low concentration to areas of high concentration (against a concentration gradient). Active transport requires energy. Sodium- potassium pump Continually pumps sodium ions out of the cell while bringing potassium ions into the cell

21 Bulk Transport Bulk transport moves large quantities of materials, not individual molecules, across a cell membrane. Materials are moved into the cell through endocytosis. Materials are moved out of the cell through exocytosis.

22 Endocytosis and exocytosis

23 Protein Synthesis Protein synthesis is a two- step process. Transcription Translation

24 Protein Synthesis Transcription happens in the nucleus. It produces mrna (messenger RNA), which carries the instructions written in the DNA to the ribosome on the rough endoplasmic reticulum. Uracil (U) replaces thymine (T) in RNA language

25 Protein synthesis

26 Protein Synthesis Translation happens at the ribosome. The trnas (transfer RNA) transport specific amino acids to the ribosome for assembly based on the information in the mrna. Process is reading both clusters of three nucleotides called codons on the mrna trnas contain anticodons at base pair with the codons

27 Protein synthesis (concluded)

28 Translation of a ribosome

29 Protein Synthesis The amino acid sequence that was assembled through translation is inspected and modified by the Golgi complex.

30 What happens after translation

31 Mistakes in protein synthesis Mistakes in protein synthesis may or may not have any consequences. 1. The ribosome reading the faulty mrna calls for a trna that brings an amino acid that is wrong. 2. The ribosome reading the faulty mrna calls for a trna that just happens to be a trna that brings the correct amino acid.

32 Cell Division Human DNA is spread out for use as chromatin. Before dividing, the DNA is tightly packaged into 46 chromosomes. Meiosis is the type of cell division in sperm and egg production. Mitosis is the method of cell division used by all cells other than those producing sperm and eggs.

33 Cell Division A parent cell replicates its 46 chromosomes before dividing to become two daughter cells. Each daughter has a complete set of 46 chromosomes that is identical to the other daughter s set and to the parent cell s set, which no longer exists once cell division is complete.

34 Cell Division Mitosis Four step process that is preceded by DNA replication Four steps are: Prophase Metaphase Anaphase Telophase

35 Mitosis

36 Mitosis simplified

37 Cell Division Mistakes in replication may or may not have any consequences. In changing the DNA is referred to as the mutation

38 Effect of Aging on Cells Telomeres are noncoding strings of nucleotides at the ends of chromosomes. Their purpose is believed to be protection of the chromosome ends. Part of the telomere is lost with each cell division. When all of the telomeres are lost, more and more mistakes in replication may occur. More mistakes potentially affecting cellular function occur with age.

39 Telomeres