1. The Cell Structure and Function
Chapter 3

2. CELLS ARE THE BASIC UNIT OF LIFE
Cell theory

3. Development of the Cell Theory
Almost all cells are too small to see without the aid of a microscope
Invention & development of the microscope enabled scientists to discover the cell.

4. Robert Hooke Hooke was looking only at cell walls and empty space
In 1665 he looked at a thin slice of cork from the bark of an oak tree using a compound microscope
He saw that cork was made of tiny hollow boxes similar to honeycomb.
He called them cells because they reminded him of the small rooms in a monastery
Hooke was looking only at cell walls and empty space

5. Anton van Leeuwenhoek
1674 – became the one of the first people to describe living cells when he observed numerous single-celled organisms swimming in a drop of pond water
He was studying new methods for making lenses to examine cloth
He also looked at tooth tarter

6. The microscope van Leeuwenhoek used is considered a simple light microscope because it contained one lens and used natural light to view objects.
Leeuwenhoek make over 500 microscopes, and only few survive
today. This is an example of one of his simple microscopes

7. 1830 two German Scientists 1838: Schleiden: observed plant cells
Viewed different organisms with a microscope
and came up with important conclusions
1838: Schleiden:
observed plant cells
Concluded that all plants are composed of cells
1839: Schwann
observed animal cells
Concluded that all animal cells are composed of cells

8. Rudolf Virchow
1855: Another German scientists reported that all cells come from pre-existing cells
These ideas lead to basic ideas of modern
biology; the cell theory

9. The Cell Theory All organisms are composed of 1 or more cells
The Cell Theory is made of 3 main ideas:
All organisms are composed of 1 or more cells
The cell is the basic unit of organization
All cells come from preexisting cells

10. 2 Basic Types of Cells
As Scientists studied cells, they discovered 2 basic types
Prokaryotic Cell: no true nucleus
Eukaryotic Cell: true nucleus

11. Similarities in Prokaryotic Cell and Eukaryotic Cells
All cells share certain characteristics.
Cells tend to be microscopic.
All cells are enclosed by a membrane called a cell membrane.
All cells are filled with cytoplasm – jellylike substance that contains organelles.
All cells contain organelles –
tiny organs within the cell

12. Prokaryotic Cells
These cells lack internal structures that are surrounded by membranes.
They do not have a true nucleus
Most are single-celled and microscopic
Example: Bacteria

13. Basic Parts of the Prokaryotic Cell
Basic Organelles:
Nucleoid Region
Cytoplasm
Capsule
Cell Wall
Ribosomes
Pili
Flagella

15. Eukaryotic Cells
Cells contain a Nucleus that acts as the control center of the cell and is the largest organelle in the cell
Can be an Animal Cell or Plant Cell
Can be either single cellular , or multicellular

19. Cell Organelles
The membrane-bound structures within eukaryotic cells are called organelles.
Each organelle has a specific function that contributes to cell survival.

20. Cytoskeleton
A flexible network of proteins that provide structural support for cells.
Made of small protein subunits that form long threads or fibers that crisscross the entire cell

21. 3 Main Types of Cytoskeleton
1. Microtubules: long hollow tubes that gives the cell its shape and acts like tracks for organelle movement.
2. Intermediate Filaments: smaller than microtubules and gives the cell strength
3. Microfilaments (Actin Filament): smallest and are tiny threads that enable the cell to move and divide

22. Cytoskeleton

23. Nucleus
2 Major Demands of the Nucleus:
1. DNA must be carefully protected
2. DNA must be available for use at the right time
Nucleus is the storehouse for most of the genetic information or DNA in your cell
Is the Brain of the cell-controls all cell functions
Is the largest organelle in the cell

24. Parts of the Nucleus
Nucleolus: makes DNA; makes proteins from ribosomes
Chromatin: Turns into chromosomes before Cell Division
Nuclear Envelope: Allows RNA to pass out of the nucleus
Nuclear Pore: allows Proteins into & out of the nucleus, and allows RNA out of the nucleus

25. Endoplasmic Reticulum
Is an interconnected network of thin folded membranes that transport Proteins to the Nucleus
Numerous processes take place inside the lumen and on the surface: production of proteins and lipids
ER membranes for a maze called lumen

26. 2 Types of Endoplasmic Reticulum
1. ER studded with ribosomes are called Rough ER
2. ER without ribosomes are called Smooth ER

27. Ribosomes Ribosomes link amino acids together to form proteins
Ribosomes are made of proteins and RNA
After assembly in the nucleolus they pass through the nuclear pores into the cytoplasm; this is where most protein synthesis occurs

28. Golgi Apparatus
Consist of closely stacked layers of membranes that processes, packages, and delivers proteins.
Some proteins are stored for later use, some transported to other organelles, some are carried to the membrane and secreted outside the cell

29. Vesicles
Small membrane-bound sacs that divide some material from the rest of the cytoplasm and transport these materials throughout the cell
Are usually short lived and are formed & recycled as needed
-After a protein has been made, part of the ER pinches off to form a vesicle surrounding the protein.
-The protein can be transferred to the Golgi Apparatus with a vesicle

30. Mitochondria
Energy maker; are bean shaped membrane-bound organelles in plant and animal cells that transform energy for the cell
Mitochondria have their own ribosomes, DNA & can divide

31. Inner & Outer Membranes
Mitochondria have an inner and outer membrane
The outer one is smooth while the inner one is shaped into folds called cristae
The matrix (fluid) is inside the inner membrane

32. Vacuole Vacuole A fluid filled sac used for storage
Water, food molecules, inorganic ions, and enzymes
Animal cells have small vacuoles
Plant cells have a single large vacuole
Vacuole

33. Lysosome
Membrane bound organelle that contains digestive enzymes; Suicide Sac
They defend cells from invading bacteria and viruses
They break down damaged or worn-out cells
Animal cells-numerous
Plant cells-none

34. Centrioles Barrel- shaped organelles found in animals & protists
Occur in pairs: usually at right angles to one another
Usually near the nucleus
Replicate and move to opposite ends of the cell during mitosis (cell division)
Centrosome is a small region of cytoplasm that produces microtubules

35. Cell Wall
Is a fairly ridged structure located outside the plasma membrane that provides additional support and protection
Only cells with a cell wall:
Plant cell
Bacteria Cells (prokaryotic)
Fungi Cells

36. Chloroplasts are cell organelles that capture light energy and produce food to store for a later time.
Carry out photosynthesis
Has a double membrane
Have their own DNA & Ribosomes
Chloroplasts & Energy
granum
2 membranes
stroma
thylakoid

37. Structure of the Chloroplast
Thylakoid: trap energy from sunlight. Coin-like structure
Granum: The inner membranes are arranged in stacks; resembles stacks of coins
Stroma: The fluid that surrounds the stacks of granum

38. Plastids
The chloroplasts belong to a group of plant organelles called plastids, which are used for storage.
Some store starch or lipids, some contain pigments, molecules that give color
Plastids are named according to their color or the pigment they contain
Chlorophyll traps light energy and gives the leaves and stems their green color

39. Cell Movement
Some cell surfaces have cilia and flagella, which are structures that aid in locomotion or feeding.
Cilia and flagella can be distinguished by their structure and by the nature of their action.

40. Cilia
Cilia are short, numerous, hair-like projections that move in a wavelike motion
Cilia

41. Flagella
Flagella are long projections that move in a whip-like motion.
Flagella and cilia are the major means of locomotion in unicellular organisms
Flagella

42. Unicellular: One celled organisms
Multi-cellular: Organisms with many cells

43. Is a barrier that separates a cell from the external conditions
The Cell Membrane
Is a barrier that separates a cell from the external conditions

44. Maintaining a Balance
All living cells must maintain a balance regardless of internal and external conditions.
Survival depends on the cell’s ability to maintain the proper conditions within itself

45. Cell Membrane AKA: Plasma Membrane
The cell membrane is the boundary between the cell and its environment
It controls the passage of materials into and out of a cell
This process of maintaining the cell’s environment is called homeostasis

46. Cell Membrane’s Job Description
1. Allow a steady supply of glucose, amino acids, and lipids to come into the cell no matter what the external conditions are. 2. Remove excess amounts of these nutrients when levels get so high that they are harmful 3. Allow waste and other products to leave the cell.

47. Phospholipid Is a molecule composed of 3 parts 1: Glycerol (polar end)
2: a Charged Phosphate Group (PO4)
3: Two Fatty Acid Chains (non-polar)

48. Phospholipids Bilayer
The cell membrane/ plasma membrane is composed of two layers of phospholipids back-to-back.
Phospholipids are lipids with a phosphate attached to them

49. Cell Membrane
Water

50. Properties & Characteristics
They give the membrane properties & characteristics they would not have
1. Cholesterol molecules strengthen the cell membrane
2. some proteins extend through one or both phospholipid layers & help materials cross
Other proteins are key components of the cytoskeleton
3. carbohydrates attached to membrane proteins serve as identification tags to distinguish one cell from another

51. Other components of the Plasma Membrane
Cholesterol plays the important role of preventing the fatty acid chains of the phospholipids from sticking together
Transport proteins allow needed substances or waste materials to move through the plasma membrane
Cholesterol
Molecule

52. Fluid Mosaic Model
Describes the arrangement of the molecules that make up a cell membrane
The Fluid Mosaic Model states:
that the phospholipid bilayer behaves like a fluid more than it behaves like a solid

53. It was Named from 2 Characteristics
1. The cell membrane is flexible, not rigid
The phospholipids in each layer can move from side to side and slide past each other ~so it behaves like a liquid
2. the molecules in the membrane are arranged like colorful tiles with different textures & patterns that make up a mosaic

54. Cell membranes are composed of two phospholipid layers.
The cell membrane is selectively permeable.
Some molecules can cross the membrane while others cannot.

55. Selective Permeable Membrane
Selective permeability is a process used to maintain homeostasis in which the plasma membrane allows some molecules into the cell while keeping others out

56. Chemical signals are transmitted across the cell membrane.
Receptors is a protein that detects a signal and changes as a response
Receptors bind with ligands and change shape.
There are two types of receptors.
intracellular receptor: Within or Inside a cell ~ hormones
membrane receptor: Cannot cross the membrane

57. Materials move across membranes because of concentration differences
Diffusion and Osmosis
Materials move across membranes because of concentration differences

58. Connect to your world
A water dam or pump allows water to pass through the same way a cell membrane allows fluids (water) to pass into and out of the cell
This process is called osmosis and requires a plasma membrane to work

59. The cell membrane is the boundary between the cell and its environment
It allows water and other molecules to pass into and out of the cell

60. 2 Types of Transport:
Passive Transport the movement of particles across a membrane from high concentration to low concentration without ENERGY.
Active Transport:
The movement of particles across a membrane from low concentration to high concentration with ENERGY

61. Passive Transport
Some molecules (like water) can pass through the plasma membrane by simple diffusion
The cell uses no energy to move these particles so they are classified as passive transport

62. What is diffusion
Diffusion is when molecules move from an area of high concentration (there are many) to an area of low concentration (there are few)
This happens in liquids and gas
Ex: spraying perfume
Is a form of passive transport

63. Concentration Gradient
Difference in the concentration between two different areas
Particles slide along the concentration gradient to help the cell reach equilibrium.
Equilibrium is equal portions of solute inside and outside the cell

65. 3 types of Passive Transport
1. Simple Diffusion 2. Facilitated Diffusion 3. Osmosis

66. Simple Diffusion of Particles
Simple Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration
In a cell, water always moves to reach an equal concentration on both sides of the membrane
Examples:
Oxygen
Carbon Dioxide

67. Facilitated Diffusion
Facilitated diffusion helps molecules passing through the membrane that may not be soluble in lipids or too large to pass through the pores in the cell
Assistance is given by specific proteins called Protein Carrier

68. Protein Carriers
Transport molecules from an area of higher concentration on one side of the membrane to an area of lower concentration on the other side

69. What is Osmosis?
The movement of water across a selectively permeable membrane from an area of higher concentration to an area of lower concentration is called osmosis
Regulating the water flow through the plasma membrane is an important factor in maintaining homeostasis within a cell

70. Concentration Gradient of Osmosis
After
Osmosis
Before
Osmosis
Water molecule
Sugar molecule
Selectively permeable membrane

71. 3 Types of Osmosis Isotonic Solution Hypotonic Solution
Hypertonic Solution

72. Hypotonic Solution
In hypotonic solution, the concentration gradient outside the cell is lower than inside the cell
This movement causes cells to swell

73. Cells in Hypotonic Solution
In a hypotonic solution, water enters a cell by osmosis, causing the cell to swell.
H2O
H2O
Water Molecule
Dissolved Molecule

74. Examples of Hypotonic Solution
Grocers keep produce fresh by misting with water
Beans have to be soaked for hours before cooking
Rice swells-do not throw at weddings
Red blood cells swell until they burst

75. Hypertonic Solution
In a hypertonic solution, the concentration gradient of dissolved substances outside the cell is higher than inside the cell
This movement causes cells to shrink

76. Cells in Hypertonic Solution
In a hypertonic solution, water leaves a cell by osmosis, causing the cell to shrink
H2O
H2O
Water Molecule
Dissolved Molecule

77. Example of Hypertonic Solution
Plant cells lose pressure as the plasma membrane shrinks away from the cell wall.
Causes flowers to wilt
Animal cells shrivel: beef jerky

78. Isotonic Solution
In an isotonic solution, the concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside the cell.
Water moves into and out at the same rate and cells obtain their normal shape

79. Cells in an Isotonic Solution
Most cells whether in multicellular or unicellular organisms, are subject to osmosis because they are surrounded by water solutions.
H2O
H2O
Water Molecule
Dissolved Molecule

80. Examples of Isotonic Solution
A plant cell has its normal shape and pressure in an isotonic solution.

82. Active Transport
Movement of materials through a membrane against a concentration gradient is called active transport and requires energy from the cell.

83. Active Transport

84. 2 Types of Active Transport
1. Endocytosis
2. Exocytosis

85. Transport of Large Particles
Endocytosis is a process by which a cell surrounds and takes in material from its environment
Nucleus
Wastes
Digestion

86. The material is makes a pocket the pocket breaks off inside the cell, forms vesicles and fuses with a lysosome
Phagocytosis - “Cell Eating”
Pinocytosis – “Cell Drinking”
Nucleus
Endocytosis
Wastes
Digestion

87. Exocytosis
Exocytosis is the release or secretion of materials from a cell.
Happens in your body with every movement