a tour of the cell
DESCRIPTION
A Tour of the Cell. “cell”. In 1665, an English scientist named Robert Hooke coined the term "cell" after viewing slices of cork through a microscope. The term came from the Latin word cella which means "storeroom" or "small container". The Cell Theory. - PowerPoint PPT PresentationTRANSCRIPT
1
A Tour of the Cell
2
“cell”• In 1665, an English scientist
named Robert Hooke coined the term "cell" after viewing slices of cork through a microscope.
• The term came from the Latin word cella which means "storeroom" or "small container".
3
The Cell Theory
1. All living things are composed of cells.
2. Cells are the basic unit of structure and
function in living things.
3. All cells come from pre-existing cells.
4
Microscope
• Instrument for observing small objects
5
Types of Microscopes
Light Microscopes:• Use visible light• Magnify about 1000 times• Not powerful enough to view
internal cell structures
Electron Microscopes:• Electron beams used for
magnification• Magnify up to a million
times
6
Stage
Focus Adjustment
Base
Objective lens
Source of light
Different parts of a microscope
Eyepiece
Arm
7
Basic types of cells:
Animal Cell Plant Cell Bacterial Cell
8
Number of Cells
Organisms may be:• Unicellular – composed of one cell• Multicellular- composed of many cells
9
Cells May be Prokaryotic
– Prokaryotes lack a nucleus and organelles
– Nucleoid region contains the DNA
– Cell membrane & cell wall– First organisms to appear
in fossil record
10
Cells May be Eukaryotic
Plant Cell Animal Cell
Have a nucleus and organelles
Two main types:
11
Organelles
• Very small in size• Can only be observed under a microscope• Have specific functions • Found throughout cytoplasm
12
Golgi Apparatus
• Stacks of flattened sacs• Modifies, stores, and
repackages cell products in vesicles
• Routes repackaged vesicles with chemical products to their destinations
Transport
vesicle
13
Lysosome
• Contain digestive enzymes
• Break down food and worn out cell parts for cells
• Programmed for cell death (release enzymes to break down & recycle cell parts)
14
Smooth & Rough Endoplasmic Reticulum
• Smooth ER lacks ribosomes & makes proteins USED In the cell
• Rough ER has ribosomes on its surface & makes proteins to EXPORT
15
Ribosomes
• Site of protein synthesis• It could be found free in
cytoplasm or on outer surface of ER
16
Mitochondria
• Cell Powerhouse• It provides the energy a cel
l needs to move, divide & etc . . .
• It is the site of Cellular respiration
• Burns sugar to produce ATP (energy)
• Active cells like muscles have more mitochondria
17
• Surrounds the cell• Made of protein and
phospholipids• Selectively permeable• Controls the movement of
materials into and out of the cell
Cell Membrane
18
• Jelly-like substance enclosed by cell membrane
• Provides a medium for chemical reactions to take place
Cytoplasm
19
• Controls the normal activities of the cell
• Contains chromosomes; DNA
• Each cell has a fixed number of chromosomes that carry genes
• humans 46
Nucleus
20
Nucleolus
• Inside the nucleus• Makes ribosomes that
make proteins
21
• Contain the green pigment chlorophyll
• Traps sunlight to make glucose (sugar) through a process called photosynthesis
Plant Cell Organelle:Chloroplast
22
• Dead layer: Strong and rigid• Made of cellulose• Freely permeable• Protects and supports the
enclosed substances• Gives shape to the cell
Plant Cell Organelle:Cell Wall
23
• Have a large central vacuole• It plays roles in intracellular
digestion and the release of cellular waste products
Plant Cell Organelle:Vacuole
24
Different kinds of animal cells
white blood cell
red blood cell
cheek cells
sperm
nerve cell
muscle cell
Amoeba
Paramecium
25
Similarities between plant cells and animal cells
Both have a cell membrane surrounding the cytoplasm
Both have a nucleus
Both contain mitochondria
26
Animal cells Plant cells
Vacuole small or absent
Glycogen as food storage
Nucleus at the center
Large central vacuole
Starch as food storage
Nucleus near cell wall
Differences between Plant Cells and Animal Cells
Relatively smaller in size
No cell wall
Relatively larger in size
Cell wall present
27
Cell Membrane
The cell membrane is made of proteins and 2 layers of phospholipids called the phospholipid bilayer.
28
Phospholipids:
• Contains 2 fatty acid chains that are nonpolar and a head that is polar.
• Polar heads are hydrophilic “water loving”
• Nonpolar tails are hydrophobic “water fearing”
• Makes membrane “Selective” in what crosses
29
30
Passive Transport:
Types of Transport across Cell Membranes
Diffusion
• Doesn’t require energy• Moves high to low
concentration• Example: Oxygen diffusing
into a cell
31
Passive Transport:
Types of Transport across Cell Membranes
Facilitated diffusion
• Doesn’t require energy• Uses transport proteins to move
high to low concentration• Example: Glucose or amino acids
moving from blood into a cell.
32
Osmosis
• The passive transport of water across a selectively permeable membrane.
• Moves from HIGH water potential (low solute) to LOW water potential (high solute)
Diffusion across a membrane
Semipermeable
membrane
33
Diffusion of H2O Across A Membrane
High H2O potentialLow solute concentration
Low H2O potentialHigh solute concentration
34
Types of osmotic solutions
• Hypertonic Solution: a solution whose solute concentration is higher than the solute concentration inside the cell
• Animal cells will lose water and shrivel when placed in a hypertonic solution
• Water moves out of the cell
35
Cell in Hypertonic Solution
CELLCELL
15% NaCL85% H2O
5% NaCL95% H2O
What is the direction of water movement?
ENVIRONMENTENVIRONMENT
36
Types of osmotic solutions
• Hypotonic Solution: a solution whose solute concentration is lower than the solute concentration inside the cell
• Animal cells will swell and possibly burst when placed in a hypotonic solution
• Water moves into the cell
37
Cell in Hypotonic Solution
CELLCELL
10% NaCL90% H2O
20% NaCL
80% H2O
What is the direction of water movement?
38
Types of osmotic solutions
• Isotonic Solution: a solution whose solute concentration is equal to the solute concentration inside the cell
• Animal cells retain their normal shape when
placed in isotonic solutions• No net gain or loss of water inside the cell
39
Cell in Isotonic Solution
CELLCELL
10% NaCL90% H2O
10% NaCL
90% H2O
What is the direction of water movement?
The cell is at _______________.equilibrium
ENVIRONMENTENVIRONMENT
NO NET MOVEMENT
40
Osmosis in Red Blood Cells
Isotonic Hypotonic Hypertonic
41
Active Transport
Types of Transport Across Cell Membranes
• Requires energy or ATP• Moves materials from LOW to
HIGH concentration• AGAINST concentration
gradient• A specific transport protein
pumps a solute across a membrane.
42
EX: Sodium-Potassium Pump
3 Na+ pumped in for every 2 K+ pumped out
43
Too large Must be packaged in membrane sacs called vesicles
• It requires energy
• Exocytosis - moving materials out
• Endocytosis: Moving materials in
Moving the “Big Stuff”
44
Endocytosis
• Phagocytosis: cell membrane takes in particle of solid material; “cell eating”
• Pinocytosis: cell membrane takes in small droplet of liquid; “cell drinking”
45
That’s it!