Cell Structure and Function

1. Cell Structure and Function

2. Preview • Cell characteristics and cell theory • Overview of cell membrane • Eukaryotic cells • Eukaryotic organelles • Prokaryotic cells • How Cells Move

3. Smallest unit of life Can survive on its own or has potential to do so Senses and responds to environment Has potential to reproduce Differ in: Size Shape functions Characteristics of Cells

4. Cell Theory 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life 3) Continuity of life arises from growth and division of single cells

5. Structure of Cells All cells have three distinct sections: Plasma Membrane Nucleus (or nucleoid region in prokaryotes) Cytoplasm

6. Cell 6 • Plasma Membrane • Nucleus • Cytoplasm

7. one layer of lipids one layer of lipids Preview of Cell Membranes Plasma membranes are composed mostly of a lipid bilayer that prevents free passage of water soluble substances across it.

8. Plasma Membrane 8

9. Other names for a cell membrane: • Cytoplasmic membrane • Semipermeable membrane • Phospholipid bilayer

10. Eukaryotic Cells Have a nucleus  Have organelles – small, membrane bound “organs” in the cell that perform a specific job for the cell. Found in the Protista, Fungi, Plant, and Animal kingdoms Have 1000 times more DNA than prokaryotic cells

11. Organelle Functions • nucleus - controls the cell’s activities • Nuclear membrane – separates cytoplasm from nuclear material • Nucleolus – site of RNA and ribosome synthesis • DNA – genetic material • cytoplasm – Space between nucleus and plasma membrane • (cytosol) jellylike substance that fills the inside of a cell , gives structure and shape

12. Cont. • endoplasmic reticulum - "tunnels" in the cytoplasm that allow materials to move through the cell easier (subway system of the cell) • Rough (RER) – makes proteins, covered in ribosomes • Smooth (RER) - makes lipids, degrades fats, detoxifies material • ribosomes – attached to ER and scattered in cytoplasm, make proteins • mitochondrion – powerhouse, produce energy in the cell  • Golgi body - stores, processes, and secretes proteins and lipids (post office)

13. vesicle- sacs that transport material in cell • centrioles – centers that produce and organize structures that help in cell reproduction (animal cells only) • lysosome – digest, recycles nutrients (suicide sack) • cytoskeleton – structurally supports, gives shape & helps move cell components

14. Quick Check • List two parts of the cell theory. • Rough endoplasmic reticulum is responsible for making ___ for the cell. • List the four eukaryotic kingdoms • Centrioles are only found in ___ cells.

15. Eukaryotic Animal Cell Structure

16. Plant vs. Animal Cell

17. Plant Cells Only • cell wall - rigid surrounding of plant cells, protects, structural to support • chloroplasts - contain chlorophyll in plants; this is where the plant’s food is produced by photosynthesis • vacuoles - large bodies in plant cells that hold water, waste, etc.

18. A closer look at major organelles

19. A closer look at the nucleus: 19

20. Nuclear Envelope/Membrane 20 • Double lipid membrane with pores • Controls what goes in and out • Pores control ions & water soluble materials entrance and exit • Ribosomes on outer membrane • Membrane merges with ER • Nucleoplasm - semifluid interior of nucleus

21. Nuclear Envelope

22. Nucleolus • Mass of proteins that codes for rRNA (ribosomal RNA) • Synthesis of ribosomes and proteins

23. Genetic Material (DNA) Chromosome – one DNA molecule and the many proteins that are associated with it Chromatin – total collection of all DNA molecules and their associated proteins

24. DNA + proteins= chromatin Chromatin strands bunched together= chromosome

25. A closer look at ER: • Endoplasmic reticulum • A flattened channel that starts at the nuclear envelope/membrane and folds back and forth • Two types Rough (RER) • Has ribosomes attached • Makes proteins Smooth (SER) • Detoxifies drugs, makes lipids

27. A closer look at Golgi bodies: • Vesicles pinch off of ER. • Fuse with Golgi bodies • Golgi bodies repackage and ship vesicles by adding or removing molecules to proteins and lipids. • Think post office and stacks of pancakes with syrup!

28. A closer look at lysosomes: • membrane-enclosed vesicles that contain powerful digestive enzymes • internal pH reaches 5.0 • Functions • digest foreign substances and recycles own organelles • Autolysis • Suicide sac

29. Tay-Sachs Disorder Affects children of eastern European descent Genetic disorder caused by absence of single lysosomal enzyme enzyme normally breaks down glycolipid commonly found in nerve cells as glycolipid accumulates, nerve cells lose functionality chromosome testing now available

30. A closer look at mitochondria: • Mitochondria resemble bacteria • Have DNA, ribosomes • Divide on their own • May have evolved from ancient bacteria that were engulfed but not digested • Mitochondrial DNA (genes) are usually inherited only from the mother.

31. Mitochondria (cont.) Double outer membrane Inner folded membrane Site of most of cells ATP production Only in eukaryotic cells Site of aerobic respiration (oxygen present) Numerous in skeletonal cells

32. A closer look at chloroplasts (and other plastids): • Plastids • Are organelles that function in photosynthesis or storage in plants. • Three types • Chloroplast • Chromoplasts • Amyloplasts

33. Cont. 33 Chloroplast – • Conduct photosynthesis • Enclosed by a double membrane • Thylakoid stacks of grana • Contain pigments such as chlorophyll • Stroma fluid filled area

34. Other Plastids Chromoplasts No chlorophyll Abundance of carotenoids Color fruits and flowers red to yellow Amyloplasts No pigments Store starch (tubers- potatoes)

35. A closer look at plant cell walls: • Surrounds the plasma membrane • Protects, supports and give shape to cell • Porous – allows water and solutes to pass in/out • In all plants • Some protist and fungi • Cuticle on outer most surfaces of plants

36. Even Cells Have a Skeleton 36 • Cyto means cell • So cytoskeleton means cell skeleton • It is organized system of protein filaments in the cytoplasm. • Some are permanent others are temporary

37. Cytoskeletal Elements intermediate filament microtubule microfilament

38. Functions ofCytoskeletal Elements: • Move organelles within the cytoplasm • Assist in cell division • Provide structure and support for the cell • Can be used to identify cells

39. Prokaryotic Cells DNA is not enclosed in nucleus Generally the smallest, simplest cells No organelles Most ancient form of life Archaeans and bacteria the only representatives Prokaryotic means “before the nucleus

40. Prokaryotic Cells • Permeable, semi-rigid cell wall outside plasma membrane gives shape • Plasma membrane- semi-permeable to control what goes in and out • Can contain pigments for photosynthesis • Polysaccharides are on surface to help them stick to objects or give a protective coating • 1-2 Flagella – movement

41. Prokaryotic Cells • Pili – helps stick to surfaces and exchange genetic material • Cytoplasm – semifluid material inside cell • Ribosomes – scattered in cytoplasm, protein making site • Nucleoid – concentrated region where DNA is located. DNA is circular. • Plasmids – scattered in cytoplasm, these can confer selective advantages such as antibiotic resistance. Contain just a few genes.

42. Prokaryotic Structure pilus cytoplasm with ribosomes DNA flagellum capsule cell wall plasma membrane

43. Quick Check

44. How Do Cells Move? • Cells must have ATP in order for movement to take place. • Cilia, flagella and false feet are all ways that cells move.

45. Cilia, Flagella and False Feet • Cilia • many small projections on cell membranes working in together for movement • Along trachea, oviducts in humans • Flagella • generally 1-2 projections that move an object • Sperm is the only flagella in humans • Pseudopodia • False foot • Temporary extension of cytoplasm for movement

46. Protists use all three. 46 Cilia pseudopodia flagella

47. Lab Notes

48. Lead to the ability to develop the Cell Theory Create detailed images of something that is otherwise too small to see Light microscopes Simple or compound Uses two sets of lenses to magnify the living or dead image Electron microscopes Transmission EM or Scanning EM Uses electrons view either inside or surface of a dead cell Microscopes 48

49. New Terms Wavelength – distance from the peak of a wave to the peak of another wave Ocular Lens enlarges 10x inside the eye piece Objective lens magnify at various levels Stage supports the object viewed on slide 49

50. Create detailed images of something that is otherwise too small to see Light microscopes Simple or compound Electron microscopes Transmission EM or Scanning EM Microscopes 50