Competency 4 Review

1. Competency 4 Review

2. Cells The Cell Theory • All living things are made of one or more CELLS. • Cells are the basic unit of structure and function in an organism. • New cells are produced from existing cells.

3. 2 types of cells • Prokaryotes • Cells without a nucleus or organelles surrounded by membranes • Eukaryotes • Cells with a nucleus and organelles surrounded by membranes.

4. Prokaryotes • Single celled organism • Has DNA that is circular floating all around in the cytoplasm • Only has ribosomes and no other membrane bound organelles • Most common = bacteria • Some can make their own food, most get food from other sources

5. Eukaryotes • There can be singled celled eukaryotes as well as multicellular • Highly organized • More complex than prokaryotes

6. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Cell membrane (plasma membrane) • Made mainly of phospholipids (2 layers) and proteins

7. Cell membranemade of: • Phospholipids have hydrophobic tails made of lipids and hydrophilic heads. 3 kinds of proteins- • channel-provides a path for materials to move in and out • marker- used for recognition • receptor- receive signals

8. Cell membrane • Acts as a boundary • Controls what enters and leaves cell • Fluid (fluid mosaic model) • Molecules in cell membranes are constantly moving and changing (ex. cholesterol and carbohydrates)

9. Nucleus • LARGEST organelle in animal cells • Surrounded by nuclear envelope • Contains nuclear pores = openings that allow molecules to move in and out of nucleus • Contains genetic material (DNA) • Control center of the cell

10. Nucleolus • Dark spot in nucleus • Assembles RNA and also ribosomes

11. Cytoskeleton • Helps cell maintain shape • Help move organelles around • Made of proteins • Microfilaments • Microtubules

12. Centrioles • Made of microtubules • Only seen in animal cells during cell division • Function: Guide chromosomes during PMAT

13. Mitochondria • “Powerplant of cell” • Site of cellular respiration • Burns glucose to release energy • Stores energy as ATP • Surrounded by double membrane • Inner membrane = cristae

14. Ribosomes • Can be free in cytoplasm or attached to rough ER • Made of rRNA • Function: assembles proteins • Called the site of protein synthesis

15. Endoplasmic reticulum (internal network of membranes) • Rough ER • Attached ribosomes make proteins which are modified and transported to Golgi for export • Smooth ER • Makes membrane lipids (steroids) • Regulates calcium in muscles • Breaks down toxins in liver

16. Golgi Apparatus • Looks like a “stack of pancakes” • Made of membranes • Modify, sort, and package substances from ER for storage or export out of cell

17. Lysosomes • Sac containing digestive enzymes • Digests food molecules and unwanted cells/cell parts • Plays a role in apoptosis “programed cell death” • Cell suicide for the good of the organism

18. Movement • Pseudopodia = “false feet” help amoebas with movement and eating (phagocytosis) • Cilia = many and short microtubules (little hairs) • Move cells • Move substances past cells • Flagella = few and long microtubules (like a tail) • Move cells

19. What’s special about plant cells? • Cell wall • HUGE central vacuole • Chloroplasts • No centrioles!!

20. Cell wall • Found outside the cell membrane • Provides support and protection • Made of Cellulose (carbohydrate) makes plant sturdy • Bacteria have cell walls made of peptidoglycan instead • Cell walls of fungi are made of chitin

21. Vacuoles • Storage space for: proteins, carbohydrates, water, waste • Contractile vacuoles control excess water in a paramecium (homeostasis) • Huge in plant cells, small animal cells, not in bacteria

22. Chloroplast • Surrounded by double membrane • Thylakoids = membrane sacs inside • Contains chlorophyll where photosynthesis happens • Found in photosynthetic cells (plants, some bacteria and protozoans)

23. Molecule Movement and Cells • Passive Transport = does not require energy by the cell • Active transport = requires energy!

24. Passive transport • No energy required • Move due to gradient • Differences in concentration, pressure, charge • Move to equalize gradient (equilibrium) • High concentration moves toward low concentration • 3 Types • Diffusion, osmosis, facilitated diffusion

25. Diffusion • Molecules move to equalize concentration

26. Osmosis • Special form of diffusion • Fluid flows from lower solute concentration • Always involves movement of water • Into cell • Out of cell • Water will move From High to Low

27. Hypotonic = solutes in cell more than outside, fluid will flow into cell Cell will swell or burst

28. Isotonic = solutes equal inside and out of cell

29. Hypertonic = solutes greater outside cell, fluid will flow out of cell Cell will shrink

30. Facilitated Diffusion • Channels (are specific) help molecule or ions enter or leave the cell • Channels usually are transport proteins

31. Active transport • Molecular movement • Requires energy (against gradient) • Example: sodium-potassium pump

32. Endocytosis-the taking in of material • Phagocytosis – cell eating(large material) • Pinocytosis – cell drinking (small material)

33. Exocytosis • Reverse of endocytosis • Cell discharge material

34. Cellular reproduction • 5 ways • 1. Fission • 2. Budding • 3. Vegetative propagation • 4. Mitosis • 5. Meiosis

35. Binary Fission • Prokaryotes (bacteria) • Asexual reproduction • Cell makes copy of DNA and grows in size • Membrane will divide and two new cells formed

36. Budding • Asexual reproduction • Hydra bud to form new hydra • Yeast cells undergo budding

37. Vegetative propagation • Asexual reproduction in plants • Runners will grow off from the parent plant and root to form a new identical plant.

38. Cell cycle • G1 phase – periods of cell growth • S phase – DNA synthesized • G2 phase – organelles produced and get ready to divide • M phase (mitosis) – division of cell nucleus • Cytokinesis –division of the cell cytoplasm

39. Interphase • Not part of mitosis • “normal cell life” • Cell division does NOT occur • Chromatids copy themselves during S phase • Covers G1, S, and G2

40. Mitosis • Division of cell nucleus • Creates daughter cells that are IDENTICAL to the original cell • Have the entire set of chromosomes existing in pairs – diploid

41. Mitosis • Prophase – chromatid coils to form chromosomes, nuclear membrane dissolves, centrioles migrate to opposite sides, attach to spindle fibers • Metaphase – chromosome pairs line up at the equator • Anaphase – chromosome pairs separate and are pulled apart by the spindle fibers • Telophase – chromosomes uncoil, spindle fibers dissolve, nuclear membrane reforms • Cytokinesis – Division of the cytoplasm to make two new cells

42. Uncontrolled cell growth • Cancer – do not respond to signals that regulate growth of most cells. • Form masses called tumors

43. Meiosis • A form of cell division by which gametes, with half the number of chromosomes, are produced. • Diploid (2n)  haploid (n) • Sexual reproduction • Two divisions (meiosis I and meiosis II)

44. Interphase I • Similar to mitosis interphase • DNA replicates in the S phase • Each duplicated chromosome consist of two identical sister chromatids attached at their centromeres. • Centriole pairs also replicate.

45. Meiosis 1 – splitting homologous chromosomes • Cell division that reduces the chromosome number by one-half • Prophase 1 – longest and most complex, chromosomes form, homologous chromosomes come together to form a tetrad. Crossing Over occurs here! • Metaphase 1 – tetrads align on the equator • Anaphase 1 – homologous chromosomes separate and go to opposite ends of the cell • Telophase 1 – a nuclear membrane will form around each chromosome set • Cytokinesis occurs and two cells are formed.

46. Crossing over • Crossing over may occur between homologous pairs. • Segments of nonsister chromatids break off and reattach to the other chromatid • Causes genetic variation • Happens in Prophase 1 Nonsister chromatids Tetrad

48. Meiosis II – splitting sister chromatids • No interphase II or very short, no DNA replication, very similar to mitosis • Prophase II – nucleus disappears, chromosomes condense, spindle forms • Metaphase II – chromosomes (not homologous) line up at equator • Anaphase II – sister chromatids separate • Telophase II – nucleus reforms, spindle disappears • Cytokinesis occurs

50. Levels of organization • Cells • Basic unit of structure and function in the human body. • Ex: nerve cells, blood cells, bone cells • Tissues • Group of cells that work together to perform the same function • Organs • A group of two or more different types of tissue that work together to perform a specific function • Ex: heart (made of muscle and connective tissue) • Systems • Group of two or more organs that work together to perform a specific function. • Ex: circulatory, digestive, nervous, etc. • Organism