1. Cells and Their Functions

2. What is a cell?

3. Here’s what a “cell” is!
Cell - the smallest unit of an organism that carries on the functions of life
A cell can perform all the processes of life.

4. Comparing cells Many Sizes: nerve cells - up to a meter long
human egg cell - dot of an i
bacteria - 80,000 could fit in the dot of an i

5. Comparing cells
Different shapes:
Related to their function (job)

6. Comparing cells Cell types: Prokaryotic cell - very simple; no
membrane-bound structures
(ex: bacteria)
Eukaryotic cell - more advanced; has
(ex: animal cells, plant cells)

7. Early Cell Scientists Robert Hooke (1665)
An English scientist who looked at slices of cork under a crude compound microscope and saw “a great many little boxes” that he called “cells.” First person to see cells.
“Cell” comes from the Latin word for “little room.”

8. Anton van Leeuwenhoek (1673)
Early Cell Scientists
Anton van Leeuwenhoek (1673)
A Dutch shopkeeper who looked at pond water using a simple microscope and saw what he called “animalcules.”
Today, we call them single-celled organisms.
An Early Simple Microscope

9. Early Cell Scientists Matthias Schleiden (1838)
A German botanist who discovered that all plants are made up of similar units, or cells.

10. Theodor Schwann (around 1830)
Early Cell Scientists
Theodor Schwann (around 1830)
A German scientist who stated that all plants and animals are made up of building blocks, or cells.
He also observed that there are similarities and differences between plant and animal cells.

11. Early Cell Scientists Rudolph Virchow (1858)
This German physician also reported that every living thing is made of up vital units, known as cells. He also predicted that cells come from other cells.

12. Cell Theory 1. All living things are made up of one or more cells.
2. Cells are the basic unit of structure and function in living things.
3. All cells come only from other living cells.

13. Cell Structure
Animal Cell
Plant Cell

14. Cell Structure
A cell is like a small town: Different parts have different and specialized jobs.
Plant cells and animal cells have many similar structures, but have several important differences.

15. Cell Membrane Structure: Outer boundary of the cell
Double lipid membrane
Selectively permeable

16. Cell Membrane Function (job): Protects inside Supports/gives shape
Controls what enters/leaves - “gatekeeper”
Helps maintain homeostasis (ability to keep a stable environment)
Analogy:
Townline

17. Cell Wall Structure: ONLY IN PLANTS Made of cellulose Strong & rigid
Dead layer

18. Cell Wall Analogy: Castle Wall Function (job): Protects/support
Gives shape
Analogy:
Castle Wall

19. Cytoplasm
Structure:
Jelly-like substance
80% water

20. Cytoplasm Function (job): Organelles float in cytoplasm
Materials for growth are found in cytoplasm
Expels waste through cell membrane
Analogy:
Town property

21. Nucleus Structure: Surrounded by nuclear membrane Usually round/oval
Near center

22. Nucleus Function (job): Control center of cell
Controls cell activities
Contains chromosomes
Analogy:
Mayor and city council

23. Mitochondria Structure:
Has an outer membrane and an inner folded membrane
Rod shaped

24. Mitochondria Function (job): Cellular respiration
Turns food into useable energy (ATP)
Analogy:
Power house (powerplant)

25. Ribosomes Structure: Tiny, round, dark
Can be free floating or attached to endoplasmic reticulum

26. Ribosomes Function (job): Protein factories
Assembles proteins used in growth, repair and control
Analogy:
Factory

27. Endoplasmic Reticulum
Structure:
Network of tubes and canals
Smooth ER - no ribosomes attached
Rough ER - ribosomes are attached

28. Endoplasmic Reticulum
Function (job):
Transports materials “intracellular highway”
Analogy:
Roads and highways

29. Golgi Bodies
Structure:
Series of flattened sacs

30. Golgi Bodies Function (job): Processes, packages and secretes material
Materials that are transported by the ER usually stop first at the Golgi bodies where they are stored or altered before moving to other parts of the cell
Analogy:
Center for Manufacturing and shipping (UPS)

31. Lysosomes Structure: ONLY IN ANIMALS
Contains powerful digestive chemicals

32. Lysosomes Function (job):
Contains digestive enzymes (chemicals), breaks things down
“suicide sac”
Analogy:
Garbage collectors

33. Vacuoles
Structure:
Fluid-filled sacs that float in the cytoplasm

34. Vacuoles Function (job): Stores water and food materials
Stores waste and helps the cell get rid of waste
Plant cells contain a large central vacuole - filled with water - helps give shape
Analogy:
Storage warehouse

35. Chloroplast ONLY IN PLANT CELLS Structure: Green, oval-shaped
Contains green pigment chlorophyll

36. Chloroplast Function (job): Site of photosynthesis
Traps the sun’s energy to make glucose
Analogy:
Greenhouse or solar cell

38. How are plant and animal cells different?
PLANT CELLS:
Have cell walls,
chloroplasts,
large vacuoles

39. How are plant and animal cells different?
Have lysosomes

40. How are different cells adapted to their functions?
Plant Cells: Rigid cell walls allow plants to grow upright.
Muscle Cells: Have large quantities of mitochondria for energy.

41. How are different cells adapted to their functions?
Red Blood Cells: Thin, flexible discs allow them to squeeze through tiny blood vessels.
Nerve Cells: Have long projections through which messages are sent throughout the body.

42. Vocabulary Permeable Diffusion Osmosis Mitosis Chromosome Centriole
Centromere

43. Organization of Living Things

44. Organization of Living Things
Five main levels of organization
1. Cell
2. Tissue
3. Organ
4. Organ System
5. Organism

45. Tissue
Example: Muscle
Tissues are made of specialized cells.

46. Organ Examples: Heart, Lung, Brain Found in both plants and animals.
Composed of tissue that is organized into groups that work together to perform special functions.

47. Organ System Example: Circulatory System
A group of organs that work together.

48. 10 Organ Systems in complex organisms (humans, dogs, birds, etc.)
1. Circulatory
2. Digestive
3. Nervous
4. Respiratory
5. Skin
6. Skeletal
7. Muscular
8. Reproductive
9. Excretory
10.Endocrine

49. ORGANISMS
Different organ systems work together to keep the organism alive.

50. QUESTION:
Classify the following as a tissue, organ, or organ system. a. Brain, spinal cord, and nerves b. Heart c. Group of muscle cells

51. QUESTION:
Can a single-celled organism contain tissue? Explain.

52. QUESTION:
Give one example of each: a. Cell c. Tissue b. Organ d. Organism

53. Cell Processes

54. Cell Processes
Think of the cell membrane as being like a gatekeeper at an ancient castle.
It was the gatekeeper’s job to decide when to open the gate and allow people to pass into and out of the castle.
The gatekeeper controlled the permeability of the castle walls.

55. Permeable
If the gatekeeper allowed friendly folk to enter, he or she was allowing the castle walls to be permeable.
Permeable means that in cells certain substances can move freely through the membrane.

56. Impermeable
If the gatekeeper prevented enemies from entering, he or she was allowing the castle walls to be impermeable.
Impermeable means that in cells substances cannot pass freely through the membrane.

57. Selectively Permeable
Because the gatekeeper can select those that can enter the castle, he or she was allowing the castle walls to be selectively permeable.
Because the cell membrane allows some materials to pass through and is impervious to others it is selectively permeable.

58. Substances that move into or out of a cell do so by one of three methods:
Diffusion
Osmosis
Active Transport

59. Diffusion
This is the main way by which substances move into and out of cells.
The process by which molecules tend to move from an area of higher concentration to an area of lower concentration.
Eventually there is an equal concentration of molecules inside and outside of the cell.

60. ……is the diffusion of water molecules through a permeable membrane.
Osmosis
……is the diffusion of water molecules through a permeable membrane.
Osmosis is important to cells because cells cannot function properly without adequate water.

61. Osmosis
In osmosis, water molecules move by diffusion from an area where they are highly concentrated…through the cell membrane…to an area where they are less concentrated.

62. Passive transport Osmosis & Diffusion
*The cell doesn’t need to use energy to move materials across the membrane.
Osmosis & Diffusion

63. Active Transport
Requires the cell to use energy to let things pass through the membrane.
Large proteins in the cell membrane are involved in active transport.

64. Cell Division

65. Cell Division
The cells in your body are constantly changing. Most new cells replace damaged or dead cells. These new cells are made during a process called cell division.
When cell division takes place two identical cells are produced.

66. Cell Division
In single celled organisms, cell division results in the formation of two new organisms.
Dividing Paramecium

67. Cell Division Feeling Fine
In many celled organisms, cell division increases the number of cells making up the organism.
As the cells increase in number, the organism grows.
Feeling Fine

68. This cycle may take a few hours or a few days!
Cell Cycle
The cell grows and develops.
The cell divides.
The cell prepares for division.
This cycle may take a few hours or a few days!

69. Cell Cycle of Human Liver Cell
Mitosis: Cell Division 1 hour
Growth 9 hours
Preparation for Division 2 hours
DNA Replication 10 hours

70. This process by which a cell’s nucleus divides into two identical nuclei is called
Mitosis

71. Mitosis Mitosis occurs in several phases.
Most of a cell’s life is spent in the growth and development phase, called ‘interphase.’

72. Interphase What's Happening?
The cell is making enough protein, mitochondria, and other substances for two cells.
In the nucleus, each chromosome is forming an exact copy of itself.
In animal cells, two pairs of centrioles are forming in the cytoplasm.

73. Prophase What's Happening? The nuclear membrane dissolves.
The centrioles migrate to opposite sides of the cell.
Spindle fibers form between the centrioles.
Chromatid pairs are pulled to the center of the cell by the spindles.

74. Metaphase What's Happening?
The chromosomes align across the center of the cell.
Each chromosome attaches to a spindle fiber at its centromere.

75. Anaphase What's Happening?
The centromeres split and the chromatids become two identical chromosomes.
The spindle fibers shrink, pulling the chromosomes to opposite sides of the cell.
The cell stretches out to prepare for division.

76. Telophase What's Happening?
The chromosomes reach opposite ends of the cell.
The spindles disintegrate.
A nuclear membrane forms around each set of chromosomes, forming two new nuclei.
A furrow forms in the cell membrane, deepens, and divides the cell completely.

77. Mitosis in Plants ....is different!
Plants do not have centrioles. But they do have spindle fibers.
The rigid cell wall can’t form a furrow in the middle, so a cell plate forms across the middle.

78. Mitosis in Plants ....is different!
After the cell divides into two new cells, each forms its own cell wall.

79. During what phase of mitosis does a cell divide into two new cells?
QUESTION:
During what phase of mitosis does a cell divide into two new cells?
Answer:
During telophase!

80. How does mitosis differ in plants and animals?
QUESTION:
How does mitosis differ in plants and animals?
Answer:
Plants do not have centrioles. Plants form a cell plate before dividing.