1. Cell Structure
Dr. Stafford
2015

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

6. Scientists Matthius Schleiden – 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. Rudolp Virchow – 1855 – German “all cells come from preexisting cells”
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.
Early studies led to the development of the cell theory.
The Cell theory has three principles.
All organisms are made of cells.

11. The Cell theory has three principles.
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.

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. 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
Bacterium
(colored SEM; magnification 8800x)

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. s
nucleus s
organelles
cell membrane
cytoplasm

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
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
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.

51. Eukaryotic Cell Structures
The eukaryotic cell has many different organelles that each have their own function that contributes the work of the whole cell.
The fact that all these organelles have evolved and can work together for the good of the whole cell gives eukaryotic cells the ability to do a lot more than prokaryotic cells

52. Eukaryotic Cell Structures
The nucleus and more precisely, the DNA within the nucleus is what controls all the organelles along with the plasma membrane.
It does this by directing which proteins are produced and when. These proteins, many of which are enzymes, control all the chemical reactions (metabolism) of a cell.