Discovery of the Cell

1
Discovery of the Cell

• Robert Hooke (1635-1703) invented the term
  cell studied dead plant cells such as cork.
• Anton van Leeuwenhoek (1632-1723) - 1st to
  observe living cells.

2
Discovery of the Cell

• Matthias Schleidan (1804-1881) concluded that
  all plants are composed of cells.
• Theodor Schwann (1810-1882) - concluded all
  animals were composed of cells.
• Rudolf Virchow (1821 1902) - reasoned that cell
  come only from other cells.

3
Protocells

• One theory of the origins of cells states that
  the first life on earth consisted of several
  types of tiny protocells, cell-like organisms.
  These organisms were able to survive and
  reproduce in a very limited environment because
  of their simplicity. Over time, some of these
  protocells came together and shared their
  specialization in a symbiotic relationship. These
  colonies of protocells eventually became the
  cells we know today.

4
Basic Structure of a Cell
5
Introduction to Cell Theory

• Cells are the basic units of organisms
• Cells come only from other cells
• All living things are made of cells
• Basic types of cells

Bacterial Cell
Animal Cell
Plant Cell
6
Number of Cells

• Organisms may be
• Unicellular composed of one cell
• Multicellular- composed of many cells that may
  organize

7
Cells May be Prokaryotic or Eukaryotic

• Prokaryotes lack a nucleus or membrane-bound
  structures called organelles Ex bacteria
• Eukaryotes have a nucleus and membrane-bound
  organelles Ex animals, plants, fungi protists

8
Prokaryotes

• Center region contains the DNA
• Cell membrane cell wall
• Contain ribosomes (no membrane) to make proteins
  in their cytoplasm
• Evolved 3.5 billion years ago

9
Eukaryotic Cell

• Contain 3 basic cell structures
• Nucleus
• Cell Membrane
• Cytoplasm with organelles
• Evolved 1.5 billion years ago

10
Prokaryotes vs. Eukaryotes
Cells do not contain a nucleus Cells contain a nucleus
No membrane bound organelles Membrane bound organelles
DNA is found (no specific area) DNA is found in nucleus
Ex bacteria Ex animal cell, plant cell
11
Two Main Types of Eukaryotic Cells
Animal Cell
Plant Cell
12
Organelles

• Very small size
• Can only be observed under a microscope
• Have specific functions
• Found throughout cytoplasm

13
Control Organelle
Controls the normal
activities of the cell Bounded by a

nuclear membrane (envelope) Contains
chromosomes
13
14
More on the Nucleus
Nucleus
Each cell has fixed
number of chromosomes that
carry genes Genes control cell characteristics
14
15
Nucleolus

• Cell may have 1 to 3 nucleoli
• Inside nucleus
• Disappears when cell divides
• Makes ribosomes that make proteins

16
Ribosomes

• Produce PROTEINS by following coded instructions
  from the nucleus

17
Smooth Rough Endoplasmic Reticulum
Rough ER has ribosomes on its surface makes
proteins to EXPORT Smooth ER lacks ribosomes
makes proteins USED In the cell
18
Golgi Bodies

• Stacks of flattened sacs
• Have a shipping side a receiving side
• Receive modify proteins made by ER
• Transport vesicles with modified proteins pinch
  off the ends

Transport vesicle
19
Lysosome

• Contain digestive enzymes
• Break down food and worn out cell parts for cells
  
• Programmed for cell death (lyse release enzymes
  to break down recycle cell parts)

20
Vacuole
Plants have a large central vacuole Stores
sugars, proteins, minerals, wastes, pigments
20
21
Mitochondrion
Cell Powerhouse Site of Cellular respiration
22
In Animal Cells
Mitochondria
Active cells like muscles have more
mitochondria Burn sugars to produce energy ATP
23
In Plant Cells
Contain the green pigment chlorophyll Traps
sunlight to make to make sugars (food) Process
called photosynthesis
23
24
Animal Cell Organelles

• Near the nucleus
• Paired structures
• Help cell divide

25
Cell Parts that Arent Organelles
Cytoskeleton Microfilaments thread-like
structures that help support the cell and help
the cell move Microtubules tube-like
structures that are important in cell division
these also form cilia and flagella in some cells
26
Surrounding the Cell
Lies immediately against the cell wall in plant
cells Made of protein and phospholipids Selective
ly permeable
26
27
Cell or Plasma Membrane
Cell membrane
Living layer Controls the movement of materials
into and out of the cell Selectively permeable
28
Cytoplasm of a Cell
Cytosol cytoplasm w/o organelles Jelly-like
substance enclosed by cell membrane Provides a
medium for chemical reactions to take place
29
More on Cytoplasm
Cytoplasm
Contains organelles to carry out specific
jobs Examples chloroplast mitochondrion
30
Plant Cell
Cell wall
Dead layer Large empty spaces present between
cellulose fibers Freely permeable
31
Plant Cell

• Made of cellulose which forms very thin fibers
• Strong and rigid
• Found in plant cells

32
Plant Cell
Cell wall
Protect and support the enclosed substances
(protoplasm) Resist entry of excess water into
the cell Give shape to the cell
33
Different kinds of plant cells
34
Animal cell
cytoplasm
vacuole
No cell wall or chloroplast Stores glycogen in
the cytoplasm for food energy
nucleus
mitochondrion
cell membrane
glycogen granule
35
Different kinds of animal cells
36
Similarities between plant cells and animal cells

• Both have a cell membrane surrounding the
  cytoplasm

Both have a nucleus
Both contain mitochondria
37
Differences between plant cells and animal cells
Animal cells
Plant cells
Relatively smaller in size
Relatively larger in size
Irregular shape
Regular shape
No cell wall
Cell wall present
38
Differences between Plant Cells and Animal Cells
Animal cells
Plant cells
Vacuole small or absent
Large central vacuole
Glycogen as food storage
Starch as food storage
Nucleus at the center
Nucleus near cell wall
39
Compound Microscope

• Instrument for observing small objects
• Magnify images up to 2000X their size

40
Different parts of a microscope
41
(No Transcript)
42
Observing an Object

• Because the light rays from an object cross
  before reaching your eye, the image you see
  through most microscopes will be inverted and
  upside down.
• Magnification the increase of an object's
  apparent size.
• Resolution the power to show details clearly.
• Resolution allows the viewer to see two objects
  that are very close together as two objects
  rather than as one. Resolution is controlled by
  the quality of the lenses being used - the better
  the lenses, the better the resolution.

43
Care and handling

• A microscope is a delicate piece of equipment and
  should be treated gently. Always use two hands
  when moving the microscope. Place one hand around
  the arm of the microscope and the other under the
  base for support. Always carry the microscope
  upright and close to the body when moving any
  distance. Place the microscope flat on the table,
  but not too near the edge where it might be
  knocked off.
• If it becomes necessary to clean the lenses on
  the microscope, ask your facilitator for a piece
  of "lens paper". Other materials, such as paper
  towel, can scratch the surface of the lens.

44
Preparing Specimens for Viewing

• In most instances, light must pass through any
  object to be viewed with a light microscope. For
  this reason, the object must be fairly thin.
  Thick objects must be sliced into thin sections
  for viewing.
• Many objects do not have distinct, contrasting
  colors. This makes it difficult to see details.
  To improve the viewing of these objects, they are
  stained. Staining is the use of a biological to
  make the details visible.

45
Making a Slide

• Place a clean slide on the table.
• For liquid samples, place one or two drops in
  the center of the slide. For solid samples, place
  the sample in the center of the slide and add one
  drop of water or staining solution.
• Hold the plastic cover slip by the edges. Do
  not get fingerprints on the cover slip. Set one
  edge against the slide and lower it until it
  contacts the liquid. The liquid should spread
  across the whole area of the cover slip.
• Never use a slide under the microscope without
  a cover slip. Its major purpose is to protect the
  objective lens for the liquid on the slide.
• Unless otherwise instructed, wipe the sample
  and cover slip off the slide with a paper towel
  when finished. Throw the paper towel and its
  contents away. Return the microscope slide to its
  container.

46
The cell is the Basic Unit of Life

• Cell is the smallest unit of living organisms
• Unicellular organisms are made of one cell only
• The cells of multicellular organisms are
  specialized to perform different functions
• e.g. mesophyll cells for photosynthesis and
  root hair cells for water absorption

47
Levels of organization

• Cells are grouped together and work as a whole to
  perform special functions

48
Tissue

• A group of similar cells to perform a particular
  function
• Animals epithelial tissue, muscular tissue
• Plants vascular tissue, mesophyll

49
Organ

• Different tissues group together to carry out
  specialized functions
• Heart consists of muscles, nervous tissue and
  blood vessels
• Leaf consists of epidermis, mesophyll and
  vascular tissue

50
The Structures of a Leaf (Plant Organ)
Chloroplast
Palisade Mesophyll Cell
Spongy Mesophyll Cell
Air Space
Stoma
51
The Structures of a Heart (Animal Organ)
52
System

• Several organs and tissues work together
  to carry out a particular set of
  functions in a co-ordinated way
• Human digestive, respiratory, excretory,
  circulatory and reproductive systems
• Plant root and shoot systems

53
Human Body Systems

• Examples of systems
• Digestive System
• Respiratory System
• Circulatory System
• Nervous System
• Reproductive System

54
Examples of a Human Body System
55
Examples of a Human Body System
56
Examples of a Human Body System
Circulatory System
57
Examples of a Human Body System
Nervous System
58
Levels of Organization

• CELLS (muscle cells,nerve cells)
• TISSUES (muscle, epithelium)
• ORGANS (heart, lungs, stomach)
• SYSTEMS (circulatory system)
• ORGANISM (human)

59
Its You!