CELLS

 
CELLS
 
 
Introduction to Cells
 
Cells are Basic to Life
 
The human body is
composed of trillions of
cells.
There are about 200
different types of cells.
Each cell turns raw
materials from
 food 
you
eat and 
air
 you breathe
into molecules the body
needs.
 
3
 
Cell Diversity
 
Cells have many different 
shapes
 & 
functions
.
 
 
Sperm
Cells
 
Nerve
Cells
 
Cheek
Cells
 
Red
Blood
Cell
 
4
 
Microscopes Enable Us to See Cells
 
Microscopes were
first developed
and used in the
1600
s.
Robert 
Hooke
coined the term
cell
 while
observing dead
cork cells in
1665.
 
5
 
Anton van Leeuwenhoek
 
The father of microbiology
First to use a 
microscope
to study microorganisms
such as bacteria and
protozoans
 
A replica of
Leeuwenhoek’s
microscope
developed in
the 1670’s.
 
6
The Cell Theory
 
1.
All living things are made
of 
one or more cells
.
2.
Cells are the basic unit of
structure
 and 
function
 in
living things.
3.
All cells come from 
pre-
existing 
cells.
 
7
 
Two Major Classes of Cells
 
Prokaryotic Cells
Smaller, simpler
cells
Lack a 
nucleus
and most other
organelles
Ex. 
Bacteria
 &
Archaea
 
Eukaryotic Cells
Have a 
nucleus
surrounded by its
own membrane
and  other
membrane-bound
organelles
.
Ex. Protists,
Fungi
, Plants &
Animals
 
8
 
9
 
Plant Cells vs. Animal Cells
 
10
S
t
a
r
c
h
G
r
a
i
n
 
11
 
12
 
13
 
14
 
15
 
16
 
Membrane Structure
Membrane Structure
& Function
& Function
 
Plasma Membrane
 
The
 plasma
membrane 
regulate
s
substances 
moving
into and out of a cell.
The membrane is
composed of
phospholipids
 
which
have 
hydrophilic
heads & 
hydrophobic
tails. 
Draw a picture
 
18
 
Phospholipid Bilayer
 
The
 
plasma membrane 
is a
 phospholipid
bilayer; 
a fluid-like membrane in which
the heads face outward and the tails
face inward.
The tails, tucked inside, act as 
a
selectively permeable 
membrane.
Because the membrane is fluid-like,
proteins drift about freely much like
icebergs
 in the ocean.
 
19
 
Notice the different types of 
proteins
 (blue)
embedded in the plasma membrane. Each
type has a specific function.
 
20
Selectively Permeable Membrane
 
The plasma membrane allows some
substances to cross more easily than
others and blocks the passage of
some substances altogether.
Three primary ways substances cross
the membrane:
Passive
 Transport – no energy required
Active Transport – requires 
energy
Vesicle Transport – for 
large
 molecules
 
21
Passive Transport
 
22
Diffusion
 
Diffusion occurs because molecules are
always in 
motion
.
Ex. Dropping food coloring into a glass of
water. Eventually, the dye will be 
evenly
distributed
.
 
23
Diffusion and Equilibrium
 
When diffused molecules are
equally distributed, and the
system is in balance, it has
reached 
equilibrium
.
Diffusion 
stops
 at equilibrium.
Molecules are still in motion, but
there is no 
net change 
in
concentration.
 
24
Facilitated Diffusion
 
The transport 
protein
 provides a 
path
 for
certain molecules to pass through.
 
25
Osmosis
 
The passive
transport of
water
 across
a selectively
permeable
membrane is
called
osmosis.
 
26
Osmotic Solutions
 
Hypertonic
 – solution with higher
concentration of solute
Isotonic
 – solutions with 
equal
 concentration
of solute
Hypotonic
 – solution with 
lower
 solute
concentration
 
27
 
Osmosis & Plant Cells
 
28
 
The plant 
cell wall 
maintains cell shape.
 
29
 
30
semipermeable
membrane
 
31
 
32
semipermeable
membrane
 
33
 
34
Active Transport
 
Active transport 
occurs when a cell uses
energy to move a molecule across the
membrane – usually from 
low
concentration to 
high
 concentration.
 
35
Transport of Large
Molecules
 
If molecules are too large to cross
the membrane, they are packaged in
vesicles
, which are small sacs that
specialize in moving products into,
out of, and within a cell.
To 
move products out
, the cell uses
an active transport process called
exocytosis
 and to take products in,
the cell uses 
endocytosis
.
 
36
Endocytosis
 
37
Exocytosis
 
38
 
Organelles
Organelles
 
Organelles
 
Each mini-organ, or 
organelle
, in
the cell has a specific job to do.
The various organelles are
suspended in a gel-like fluid
called 
cytoplasm.
 
40
Two Major Compartments
 
Nucleus
Surrounded by
nuclear membrane
Contains DNA
Nucleolus (red)
makes ribosomes
Cytoplasm
Contains all other
organelles
 
41
Nucleus
 
This diagram
shows the
nucleolus
 and
nuclear envelope
with pores.
The function of
the nucleus is to
direct the cell’s
activities.
 
42
Ribosomes
 
The site of protein
synthesis
Some are on the
surface of rough
ER
Some are
suspended in the
cytoplasm
 
43
Endoplasmic Reticulum
 
The 
endoplasmic reticulum (ER) 
is a
network of membranes that
manufactures & transports cell products.
Two types:
Rough ER 
has ribosomes on the
surface, makes and transports
proteins
Smooth ER 
does not have ribosomes,
makes other things like lipids
 
44
Endoplasmic Reticulum
 
45
Golgi Apparatus
 
Products from
ER travel in
vesicles to the
Golgi Apparatus
Modifies, stores
and routes
proteins to their
destinations
 
46
Vacuoles
 
Membrane-bound
sacs in the
cytoplasm that
store undigested
nutrients
Plants have a large
central vacuole that
stores water
 
Large Central Vacuole
 
47
Lysosomes
 
Lysosomes
 
are membrane-bound sacs
that contain digestive enzymes that
can break down molecules.
Lysosomes have several functions:
1.
Digest nutrients and nourish the cell
2.
Destroy harmful bacteria
3.
Recycle damaged organelles w/o
harming the cell
 
48
Digestion by Lysosomes
 
When lysosomes digest nutrients, they
fuse with a food vacuole
Enzymes in the lysosome digest the
food particles and nutrients are released
for the cell to use
 
food vacuole
 
lysosome
 
enzymes
 
digestion occurs
 
49
 
50
 
51
Path of Cellular 
P
roducts
 
 
Produced at
ribosomes on Rough
ER
Travel by vesicle to
Golgi apparatus where
they are modified and
refined
Travel by vesicle to
plasma membrane
Products released
from cell by
exocytosis
 
52
Chloroplasts
 
Chloroplasts
 are the photosynthetic
organelles found in some cells of
plants and algae –  
not found in
animal cells.
 
53
Mitochondria
 
Site of cellular
respiration
Provide the main
energy source for
cells; ATP
Sometimes called
the 
powerhouse
 of
the cell
 
54
 
55
 
56
 
Cytoskeleton &
Cytoskeleton &
Cell Movement
Cell Movement
 
Cytoskeleton
 
A network of fibers
extending
throughout the
cytoplasm
Always changing,
with new
extensions building
at the same time
that others are
breaking apart
 
58
Cytoskeleton Fibers
 
Microtubules 
are straight, hollow
tubes of protein that give shape and
rigidity.
Microfilaments 
are thinner, solid
rods of protein that enable the cell
to move or change shape.
Intermediate filaments 
are rope-like
filaments that provide stability to
cell structure.
 
59
 
Fibers of the Cytoskeleton
 
Microtubules
 
Intermediate
filaments
 
Microfilaments
 
60
 
Flagella
 
Long, thin,
whip-like
structures that
are composed
of microtubules
Wave with an
s
 shaped
motion to
enable cells to
move
 
61
 
Cilia
 
Cilia
 are short
microtubules
More numerous
than flagella
Used to move fluids
over the cell
Cilia lining the
respiratory tract are
shown here.
 
62
 
 
Flagella move cells and cilia move
substances past or over cells.
 
63
Cilium
Flagellum
 
Cell Movement
 
Some cells that
are capable of
movement:
White blood
cells
Protozoans
Slime molds
White blood cell engulfing
anthrax bacteria.
 
64
 
65
 
66
 
67
 
68
 
The End
 
Cells
 
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Discover the incredible world of cells in the human body, each playing a vital role in sustaining life. Explore the diversity of cell types, learn about the history of microscopy, and delve into the Cell Theory. Understand the differences between prokaryotic and eukaryotic cells, essential building blocks of all living organisms.


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  1. CELLS

  2. Introduction to Cells

  3. Cells are Basic to Life The human body is composed of trillions of cells. There are about 200 different types of cells. Each cell turns raw materials from food you eat and air you breathe into molecules the body needs. 3

  4. Cell Diversity Cells have many different shapes & functions. Sperm Cells Cheek Cells Nerve Cells Red Blood Cell 4

  5. Microscopes Enable Us to See Cells Microscopes were first developed and used in the 1600 s. Robert Hooke coined the term cell while observing dead cork cells in 1665. 5

  6. Anton van Leeuwenhoek The father of microbiology First to use a microscope to study microorganisms such as bacteria and protozoans A replica of Leeuwenhoek s microscope developed in the 1670 s. 6

  7. The Cell Theory 1.All living things are made of one or more cells. 2.Cells are the basic unit of structure and function in living things. 3.All cells come from pre- existing cells. 7

  8. Two Major Classes of Cells Prokaryotic Cells Eukaryotic Cells Smaller, simpler cells Lack a nucleus and most other organelles Ex. Bacteria & Archaea Have a nucleus surrounded by its own membrane and other membrane-bound organelles. Ex. Protists, Fungi, Plants & Animals 8

  9. 9

  10. Plant Cells vs. Animal Cells 10

  11. Starch Grain 11

  12. 12

  13. Question: Compare and contrast prokaryotic cells and eukaryotic cells. 13

  14. Answer: Both prokaryotic and eukaryotic cells have plasma membranes, ribosomes and genetic material (DNA), but only eukaryotic cells have a nucleus and other membrane-bound organelles. 14

  15. Question: Name two structures found in plant cells that are not found in animal cells. 15

  16. Answer: Any two of the following: Cell wall Chloroplast Large Central Vacuole 16

  17. Membrane Structure & Function

  18. Plasma Membrane The plasma membrane regulates substances moving into and out of a cell. The membrane is composed of phospholipids which have hydrophilic heads & hydrophobic tails. Draw a picture 18

  19. Phospholipid Bilayer The plasma membrane is a phospholipid bilayer; a fluid-like membrane in which the heads face outward and the tails face inward. The tails, tucked inside, act as a selectively permeable membrane. Because the membrane is fluid-like, proteins drift about freely much like icebergs in the ocean. 19

  20. Notice the different types of proteins (blue) embedded in the plasma membrane. Each type has a specific function. 20

  21. Selectively Permeable Membrane The plasma membrane allows some substances to cross more easily than others and blocks the passage of some substances altogether. Three primary ways substances cross the membrane: Passive Transport no energy required Active Transport requires energy Vesicle Transport for large molecules 21

  22. Passive Transport Simple Diffusion Facilitated Diffusion Movement of particles from area of high concentration to area of low concentration Diffusion of particles through a specific membrane protein 22

  23. Diffusion Diffusion occurs because molecules are always in motion. Ex. Dropping food coloring into a glass of water. Eventually, the dye will be evenly distributed. 23

  24. Diffusion and Equilibrium When diffused molecules are equally distributed, and the system is in balance, it has reached equilibrium. Diffusion stops at equilibrium. Molecules are still in motion, but there is no net change in concentration. 24

  25. Facilitated Diffusion The transport protein provides a path for certain molecules to pass through. 25

  26. Osmosis The passive transport of water across a selectively permeable membrane is called osmosis. 26

  27. Osmotic Solutions Hypertonic solution with higher concentration of solute Isotonic solutions with equal concentration of solute Hypotonic solution with lower solute concentration 27

  28. Osmosis & Plant Cells The plant cell wall maintains cell shape. 28

  29. Question: What types of membrane transport are shown in this diagram? 29

  30. Answer: The fat-soluble molecules are crossing the membrane by simple diffusion. The water-soluble molecules are crossing the membrane through a membrane protein, so this is facilitated diffusion. 30

  31. Question: Describe the solutions in this beaker using the terms hypertonic and hypotonic. semipermeable membrane 31

  32. Answer: The solution on the left is hypotonic relative to the solution on the right which is hypertonic. 32

  33. Question: In this solution, only water can cross the membrane. Draw a picture showing how the solutions will change over time. semipermeable membrane 33

  34. Answer: 34

  35. Active Transport Active transport occurs when a cell uses energy to move a molecule across the membrane usually from low concentration to high concentration. 35

  36. Transport of Large Molecules If molecules are too large to cross the membrane, they are packaged in vesicles, which are small sacs that specialize in moving products into, out of, and within a cell. To move products out, the cell uses an active transport process called exocytosis and to take products in, the cell uses endocytosis. 36

  37. Endocytosis 37

  38. Exocytosis 38

  39. Organelles

  40. Organelles Each mini-organ, or organelle, in the cell has a specific job to do. The various organelles are suspended in a gel-like fluid called cytoplasm. 40

  41. Two Major Compartments Nucleus Surrounded by nuclear membrane Contains DNA Nucleolus (red) makes ribosomes Cytoplasm Contains all other organelles Cytoplasm Nucleus 41

  42. Nucleus This diagram shows the nucleolus and nuclear envelope with pores. The function of the nucleus is to direct the cell s activities. 42

  43. Ribosomes The site of protein synthesis Some are on the surface of rough ER Some are suspended in the cytoplasm 43

  44. Endoplasmic Reticulum The endoplasmic reticulum (ER) is a network of membranes that manufactures & transports cell products. Two types: Rough ER has ribosomes on the surface, makes and transports proteins Smooth ER does not have ribosomes, makes other things like lipids 44

  45. Endoplasmic Reticulum 45

  46. Golgi Apparatus Products from ER travel in vesicles to the Golgi Apparatus Modifies, stores and routes proteins to their destinations 46

  47. Vacuoles Membrane-bound sacs in the cytoplasm that store undigested nutrients Plants have a large central vacuole that stores water Large Central Vacuole 47

  48. Lysosomes Lysosomes are membrane-bound sacs that contain digestive enzymes that can break down molecules. Lysosomes have several functions: 1. Digest nutrients and nourish the cell 2. Destroy harmful bacteria 3. Recycle damaged organelles w/o harming the cell 48

  49. Digestion by Lysosomes When lysosomes digest nutrients, they fuse with a food vacuole Enzymes in the lysosome digest the food particles and nutrients are released for the cell to use enzymes lysosome digestion occurs food vacuole 49

  50. Question: Identify structures 1, 2, 5 & 8. 50

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