Cell Structure

1. Cell Structure Dr. Stafford 2018

2. KEY CONCEPT Cells are the Basic unit of life.

3. Scientists Robert Hooke – 1665 Looked at cork Looked like monastery rooms (cells) Named the structures in the cork – “CELLS”

4. Scientists Anton van Leeuwenhoek – 1674 Father of microbiology Observed “living cells – “animalcules”

5. Scientists Simple light microscope vs. compound light microscope Simple – one lens Compound – 2 or more lens

6. Scientists MatthiusSchleiden – 1838 – German Plants are made of cells Theodor Schwann – 1839 – German All animals are made of cells “all living things are made of cells”

7. Scientists Rudolp Virchow – 1855 – German “all cells come from preexisting cells”

8. Scientists

9. Cell Basics • Cell Theory • All living organisms are made of cells • The cell is the basic unit of all living organisms • All cells come from preexisting cells

10. The Cell theory has three principles. • All organisms are made of cells. • Early studies led to the development of the cell theory.

11. The Cell theory has three principles. • All organisms are made of cells. • All existing cells are produced by other living cells. • Early studies led to the development of the cell theory.

12. Early studies led to the development of the cell theory. • The Cell theory has three principles. • All organisms are made of cells. • All existing cells are produced by other living cells. • The cell is the most basic unit of life.

13. Cell Basics • Things found in all cells • DNA – genetic code – different for cells from different organisms • Plasma membrane – boundary of all cells – maintains homeostasis inside the cell • Cytoplasm – jelly-like fluid that fills the cell • Ribosomes – nonmembrane-bound organelle that assembles proteins

14. Bacterium (colored SEM; magnification 8800x) Cell Basics • Types of cells – all living organisms fall into two categories • Prokaryotes – bacteria • No nucleus • No membrane bound organelles • Smaller • First living organisms • Most have a cell wall

15. Cell Basics • Types of cells (cont.) • Eukaryotes – all except bacteria • Has a membrane-bound nucleus • Has membrane bound organelles • Larger than prokaryotes • More complicated – came later in history • Some have cell wall….some don’t

16. nucleus organelles cell membrane cytoplasm s • s

17. Eukaryotic Cell Structures • Cell Boundaries • Plasma membrane – selectively permeable membrane • Maintains homeostasis – controls what goes into or leaves a cell • Phospholipid bilayer with proteins, cholesterol, and carbohydrate chains added in or on it • Found around the outside of all cells

18. Eukaryotic Cell Structures • Cell Boundaries (cont.) • Cell wall – fairly rigid structure found outside the plasma membrane • Provides additional support and protection • Found in plants, fungi, and some protist cells • Not selectively permeable – allows most everything to flow through it • Made of cellulose in plants • Gives the cell its more rigid shape

19. Plant cells have cell walls and chloroplasts. • A cell wall provides rigid support.

20. Eukaryotic Cell Structures • Nucleus – control center of the cell – contains two main structures • 1. DNA - holds the code for making proteins which is what controls all the activities of the cell – comes in two forms • Chromatin – loosely arranged DNA – the form usually found in an active cell doing its daily work • Chromosomes – densely packed DNA – found during cell division (mitosis)

21. Eukaryotic Cell Structures • Nucleus – contains two main structures (cont.) • 2. Nucleolus – seen as a smaller dark structure inside the nucleus • Makes ribosomes

22. Eukaryotic Cell Structures • Nucleus – control center of the cell (cont.) • Nuclear envelope – a double membrane that surrounds the nucleus • 2 phospholipid bilayers • Nuclear pores – holes in nuclear envelope for substances like mRNA and ribosomes to pass out of the nucleus into the cytoplasm where proteins are made

23. Several organelles are involved in making and processing proteins. • The nucleus stores genetic information.

24. Eukaryotic Cell Structures • Cytoplasm – jelly-like fluid that fills the cell from the outside of the nucleus to the plasma membrane • Suspends the organelles • Contains many substances the organelles need to work with • Building blocks for structures and macromolecules • Ions • Water

25. Eukaryotic Cell Structures • Assembly. transport, and storage – the organelles that make and complete proteins and transports them around the cell and out of the cell (secretion) • Home of CELLS alive!

26. Eukaryotic Cell Structures • Assembly, transport, and storage (cont.) • Ribosomes – found in all cells – organelle that makes proteins • Made by nucleolus – combination of proteins and rRNA • Found in cytoplasm • 2 part organelle • Can be attached to endoplasmic reticulum • Can be unattached to endoplasmic reticulum – free-floating

27. Several organelles are involved in making and processing proteins. (continued) • Ribosomes link amino acids to form proteins.

28. Eukaryotic Cell Structures • Assembly, transport, and storage (cont.) • Endoplasmic reticulum (ER) – site of cellular chemical reactions – Highway of the cell • Highly folded membranes – increase surface area • Found in cytoplasm – close to the nucleus • Rough ER – has ribosomes attached to it – makes proteins for membranes, proteins to leave the cell (secreted), or proteins that are transported to other organelles within the cell

29. Eukaryotic Cell Structures • Assembly, transport, and storage -ER (cont.) Smooth ER – used to produce other substances besides proteins such as lipids

30. Several organelles are involved in making and processing proteins. • The nucleus stores genetic information. • Many processes occur in the endoplasmic reticulum. • There are two types of endoplasmic reticulum. • rough endoplasmic reticulum • smooth endoplasmic reticulum

31. Eukaryotic Cell Structures • Assembly, transport, and storage (cont.) • Golgi apparatus (GA) – post office of the cell • Found in the cytoplasm – closer to the plasma membrane • Flattened system of tubular membranes • Modifies the proteins • Packages and sorts proteins in transport vesicles to be sent to their appropriate destination inside or out of the cell

32. Eukaryotic Cell Structures • Assembly, transport, and storage (cont.) • Transport vesicles – bud off the GA to carry the packages of completed proteins to their appropriate destination inside the cell or out of the cell (secretion)

33. Several organelles are involved in making and processing proteins. (continued) • Ribosomes link amino acids to form proteins. • Vesicles are membrane-bound sacs that hold materials.

34. Eukaryotic Cell Structures • Assembly, transport, and storage • Vacuoles – membrane-bound spaces in the cytoplasm for temporary storage of: • Food • Waste • Enzymes • Water in some organisms Plants have a large central vacuole for storage of starch or water. Animals have several small vacuoles

35. Other organelles have various functions. • Mitochondria supply energy to the cell. • Vacuoles are fluid-filled sacs that hold materials.

36. Eukaryotic Cell Structures • Assembly, transport, and storage (cont.) • Lysosomes – membrane-bound organelle in cytoplasm that contains digestive enzymes to digest worn out organelles, food particles, and viruses and bacteria. • An intact membrane is important to contain the digestive enzymes • Can combine with a vacuole to digest the contents of the vacuole

37. Eukaryotic Cell Structures • Assembly, transport, and storage (cont.) • Lysosomes (cont.) • Sometimes the lysosomes release their digestive enzymes into the cytoplasm of a cell if the organism wants to destroy a cell – this is how a tadpole gets rid of its tail – this is also how human fetuses get rid of their tail

38. Other organelles have various functions. • Mitochondria supply energy to the cell. • Vacuoles are fluid-filled sacs that hold materials. • Lysosomes contain enzymes to digest material.

39. Eukaryotic Cell Structures • Energy Transformers – energy cannot be made – it can only be transformed into another form • The form of energy a cell uses is ATP – just the same as a gas car can only use gasoline to do its work; a cell can only use energy in the form of ATP to do its work • 2 different organelles can transform energy from a source outside the cell into ATP

40. Eukaryotic Cell Structures • Energy transformers (cont.) • Chloroplasts – capture light energy from the sun and transform it into ATP or store the light energy in the form of sugars for later energy use • Found in the cytoplasm of plants and some protists • Double membraned organelle – inner membrane is highly folded • Contains a green pigment called chlorophyll that captures the energy from sunlight

41. Plant cells have cell walls and chloroplasts. • A cell wall provides rigid support. • Chloroplasts convert solar energy to chemical energy.

42. Eukaryotic Cell Structures • Energy transformers (cont.) • Mitochondria – takes the sugar produced by chloroplasts and breaks it down to release the energy stored in the sugar molecule and transforms that energy into ATP – a form of energy the cell can use

43. Eukaryotic Cell Structures • Energy transformers (cont.) • Mitochondria (cont.) • Found in the cytoplasm of all eukaryotic cells – including plants cells • Double membrane with inner membrane highly folded • Vary in number found in cells depending on the cells need for energy – found in high numbers in muscle cells

44. Other organelles have various functions. • Mitochondria supply energy to the cell.

45. Eukaryotic Cell Structures • Cytoskeleton – structure for support of the cell and movement of organelles within the cell. Made up of: 1. Microtubule – thin, hollow cylinders made of protein 2. Microfilaments –thin, solid protein fibers • Forms the framework of the cell – constantly changing

46. Cells have an internal structure. • The cytoskeleton has many functions. • supports and shapes cell • helps position and transport organelles • provides strength • assists in cell division • aids in cell movement

47. Eukaryotic Cell Structures • Structures for locomotion – located on the outside of cells • Cilia – short, numerous , hair-like projections that move in wave-like motion – found in our airways • Flagella – longer projections that move in a whip-like motion – usually only one or very few • Both are used for movement of many unicellular organisms

48. Eukaryotic Cell Structures • Plant and animal cell comparisons • Plant cells have three structures not found in animal cells and are usually larger and have a more fixed shape • Cell wall – for extra structure and protection • Chloroplast – to convert sunlight into ATP • Large central vacuole – to store sugar as starch and water

49. Eukaryotic Cell Structures • Plant and animal cell comparisons • Animal cells – usually smaller than plant cells • Centriole is the only organelle found in animal cells and not plant cells • Usually have many small vacuoles • Could have flagella or cilia while a plant cell will not

50. Other organelles have various functions. • Mitochondria supply energy to the cell. • Vacuoles are fluid-filled sacs that hold materials. • Lysosomes contain enzymes to digest material. • Centrioles are tubes found in the centrosomes.