Unit A – Cells and Systems

1. Unit A – Cells and Systems

2. Chapter 2 – Cells and Cell Systems

3. Cells – Key Ideas • Unicellular organisms perform the same basic functions as multicellular organisms • Cells are specialized to carry out specific functions • Cells are generally more efficient when they work together to perform a specific function • Cells in the human body are organized into tissues • Groups of tissues are organized into organs. • Groups of organs are reffered to as organ systems • Some diseases are caused when cells are invaded by microscopic living things • Your health depends on how well your cell systems work together

4. 2.1 – Cells and Cell Systems

5. Cell Organization • TISSUE– a group of cells that are similar in shape and function • Tissues are often organized into larger structures called organs • ORGAN – a structure composed of one or more different types of tissues; specialized to carry out a specific function • Many organs are made up of several different types of tissues.

6. Organ (see fig.1 p.41)

7. Cellular Organization • Organ Systems – groups of organs that have related functions • See Table 1 p.42

8. 2.2 – Unicellular Organisms

9. Unicellular Organisms Many organisms are composed of just ONE cell These are called micro-organisms or microbes These single cells are also responsible for feeding, digesting, excreting, and reproducing

10. The Importance of Micro-organisms • Not all cause disease • Some are useful to create foods that we like such as cheese and yogurt • We have many micro-organisms in our bodies that are either harmless or beneficial

11. BACTERIA (fig.2 p44) Some can make their own food Some are parasitic Bacteria can be found in every environment on Earth Are PROKARYOTIC No nucleus No mitochondria

12. Protists(fig.4 p45) • Protists – a unicellular organisms that are neither plant nor animal; is a eukaryotic cell • Anywhere there is water you will find protists

13. Plant-Like Protists - Diatoms • found in both fresh water and salt water • Contain chlorophyll

14. Plant-Like Protists - Euglena • Similar to both plant and animal cells • Can feed upon smaller cells

15. Animal-Like Protists - Amoeba • Changes its shape as it moves • It moves by stretching out a branch of cytoplasm called a pseudopod • Pseudopod is anchored to an object and the rest of the amoeba is dragged towards it • Pseudopod is also used to eat

16. Animal-Like Protists - Paramecia • Cilia help move it • Cilia beat to create a current that draws food into its mouth • Eats bacteria and other small cells

17. Fungi • multicellular or unicellular • Examples include • Bread mould • Mushrooms • Puff balls • Harmful effects • Cause ringworm • Dutch elm disease • Athlete’s foot

18. Yeast • unicellular fungi • Must rely on other organism as a source of food

19. 2.3 – The Need For Cell Division Why The Split?

20. Is Smaller Better? • The bigger a cell is, the longer messages take to reach the nucleus, or for the rest of the cell to receive instructions • Cells must be small for information to travel quickly • See fig.1 p.49

21. Is Smaller Better? • Small cells are needed so waste can be removed quickly and nutrients received quickly • Cells that do a lot of work are usually smallerso that the nutrients and wastes can enter or leave more quicker

22. 2.4- Cell Specialization

23. Cell Specialization • Multicellular organisms benefit from cell specialization • Cell Specialization – the development of cells to perform a specific function

24. Specialized Plant Cells • Thin-walled plant cells are found in the flexible tissues of leaves, flowers etc..

25. Specialized Plant Cells • Thick-walled plant cells are specialized for support • Thick cell walls are stretchable and flexible • E.g. celery stalk

26. Specialized Plant Cells • Very thick-walled cells provide rigid support • Cell usually dies because cell walls are too thick for nutrients to pass in and out of • E.g tree trunk

27. Specialized Animal Cells – Nerve Tissue • Conduct electrical signals in the body • Tend to be long and thin • Coated by fatty material

28. Respiratory Cells • Lung Cells are very thin- Why? • Some cells produce mucus • Mucus – a slippery substance that coats the cells lining the cavities open to the air • Mucus traps particles that enters the lungs • Cilia move the particles and mucus out

29. Blood Tissue Red Blood Cells White Blood Cells

30. Stomach tissue • Cells are covered by mucus to protect them from the strong acid • Cells have many Golgi Apparatuses to produce and store the proteins that break down food

31. Fat Tissue • Most of the cyctoplasm is occupied by vacuoles • Nutirents are converted to fat and stored in the cells

32. Small Intestine • Absorb nutrients from food • Finger-like projections called villi – increase surface area for absorption

33. 2.5 – Cell Wars

34. Cell Wars – The Invaders • Disease – any condition that is harmful or interfers with the well-being of an organism • Infection- the action of disease-producing organisms, which invade the body and interfer with the normal activities of the cell • Can rob nutrients or produce waste products that are poisonous

35. Bacteria • Tetanus, strep throat and pneumonia are examples • Spoil food and contaminate water

36. Fungi • Several disease are caused by fungi eg. Athlete’s foot

37. Protists • Plasmodium- causes malaria • Giardia lamblia – causes beaver fever

38. Viruses • Virus – a small strand of genetic information covered by a protein coat; invade living cells and uses it to make more viruses • Viruses are not true cells • They do not contain a nucleus, cytoplasm, organelles or a cell membrane

39. Viruses • Cause colds • Cold sores • Influenze • AIDS

40. The Defenders • Some white blood cells ingest the invader directly where lysosomes will destroy them and the WBC • Pus – a creamy white substance made of strands of protein and cell fragments that remain after invaders have been attacked by white blood cells • White blood cells also kill cells that have been damaged the intruders

41. Antibodies • Antibody – a large molecule produced by a special type of white blood cell; aids the immune system • Invading cells have Markers, on their cell membranes or protein coats. • These markers have a specific shape • Antibodies are designed to fit the shape and lock onto them

42. Antibodies