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. •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
6. •Cell types:
•Prokaryotic cell - very simple; no
membrane-bound structures
(ex: bacteria)
•Eukaryotic cell - more advanced; has
membrane-bound structures
(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. 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. 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.
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.
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)
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
38. How are plant and animal
cells different?
PLANT CELLS:
Have cell walls,
chloroplasts,
large vacuoles
39. How are plant and animal
cells different?
ANIMAL CELLS:
Have lysosomes
40. How are different cells
adapted to their functions?
Muscle Cells: Have
large quantities of
mitochondria for
energy.
Plant Cells: Rigid cell
walls allow plants to grow
upright.
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.
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.
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.
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. 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. *The cell doesn’t need to use energy to
move materials across the membrane.
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.
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
• 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. Cell Cycle
The cell
divides.
The cell prepares for
division.
The cell
grows and
develops.
This cycle may take a few hours or a few
days!
70. This process by which a cell’s
nucleus divides into two identical
nuclei is called
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
•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
•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.
75. Anaphase
•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
•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
• 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.
....is different!
78. Mitosis in Plants
• After the cell divides into two new
cells, each forms its own cell wall.
....is different!