Download Chapter 4: Structure and Function of the Cell…

Structure and Function of
the Cell
Sections 7.1-7.3
What do we know about cells?
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smallest unit of life
found in all living things
unicellular and multicellular
prokaryotic cells and eukaryotic cells
contain atoms, elements, compounds, mixtures
carry out chemical reactions
enzymes are necessary to speed these chemical
reactions….
Introduction to the Cell…
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A common structure, the
cell, makes up every living
thing.
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Cells are composed of
atoms, elements,
compounds (organic and
inorganic) and
macromolecules.
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Proteins, carbohydrates,
lipids and nucleic acids
are found inside cells.
The cell is…
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the smallest unit of matter that can
carry on all life processes
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the smallest unit of life that exhibits
the characteristics of life
Introduction to the Cell…
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Discovery of the cell was
made possible by the
development of the
microscope.
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The study of the cell is
known as CYTOLOGY
or CELL BIOLOGY.
A Brief History…
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1500’s – Europe – the first lenses were used
1600’s - two useful instruments were invented,
telescope and microscope
Robert Hooke (1660’s)
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observed dead cells from
cork
coined the term “cell”
Anton Van Leeuwenhoek (1670’s)
observed living cells in pond
water
o microscope maker
o made detailed descriptions
and drawings of living cells
o “father of microbiology”
o
More Scientists…
SCHLEIDEN-Botanist: all plants are made
of cells
 SCHWANN-Zoologist: all animals are
made of cells
 VIRCHOW-Physician: cells come from
existing cells
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These scientists were the first to support
what is now known as the Cell Theory
CELL THEORY
1. all living things are composed of
one or more cells.
2. All cells come from pre-existing cells.
3.The cell is the basic unit of structure
and function in living things.
CELLS
PROKARYOTIC
or
EUKARYOTIC
PROKARYOTIC
CELLS
simple (primitive) cells
 few specialized functions
 bacteria – have a single circular chromosome
 LACK a nucleus – but still have DNA
 LACK membrane-bound organelles
 known as “prokaryotes”
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EUKARYOTIC
CELLS
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complex cells
many specialized functions
are found in plants, animals, fungi, and protists
have a nucleus – (DNA enclosed within a membrane)
have membrane-bound organelles …
mitochondria, golgi, lysosomes, vacuoles, ER, chloroplasts…
known as “eukaryotes”
What is the Theory of Endosymbiosis?
or Endosymbiont Theory?
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scientists believe that prokaryotes (like bacteria) were the first cells to arise
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they also believe that….when different types of prokaryotic cells incorporated other
prokaryotes within them this led to the development of eukaryotic cells
ENDO - “within/inside”
SYMBIONT – “living together”
Common features of ALL CELLS….
All cells (both prokaryotic and
eukaryotic)
share 4 common features.
1) plasma (or cell) membrane
2) ribosomes
*organelles without a membrane
3) cytoplasm
4) genetic material (DNA)
DIFFERENCES BETWEEN CELLS
(Cell Diversity)
Even though all cells share some common
features, cells are not identical.
Cells differ in 3 ways….
1. size - microscopic up to 2meters in length
2. shape - reflects function
3. internal organization – contain different
organelles and perform different functions
What is an organelle?
“a little organ”
 a cell part that performs a special function
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*SOME ORGANELLES…. are surrounded
by a membrane and are known as
“membrane- bound organelles”
*RIBOSOMES are organelles but are not
surrounded by a membrane
Parts of the
Eukaryotic Cell
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Nucleus – contains DNA
control center of the cell; stores genetic information
plasma (cell) membrane
selectively (semi-) permeable; lipid bi-layer
cytoplasm – jelly like material
contains and includes the organelles
organelles - “little organs”
perform specialized functions within the cell
Plasma (Cell) Membrane
thin, flexible barrier around the cell
 regulates what enters and leaves the cell
 made of lipids and proteins
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IS semipermeable or selectively permeable
- allows for certain substances to enter the cell
while excluding others - allows for passage of
water, oxygen, CO2, glucose, wastes and more
Plasma (Cell) Membrane
LIPIDS….
 create a barrier between the cell and its external environment
 are found in 2 layers – called a lipid bilayer
 are of a special type – called phospholipids
MAKE UP A PHOSPHOLIPID BILAYER
PROTEINS….
are not arranged in any specific manner
some provide structural support
others are called Transport/Carrier proteins
Plasma (cell) Membrane
Fluid Mosaic Model
describes the pattern of lipids and proteins within the
cell membrane as constantly changing
CYTOPLASM:
area between the cell
membrane and the nucleus
• INCLUDES a jelly like
material (called CYTOSOL)
and the various organelles
• site of many chemical
reactions
• CYTOSOL is composed of
water, proteins and
carbohydrates
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CYTOSKELETON – “the cell’s
skeleton”
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provides support, structure, shape
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a network of protein filaments in the cytosol
(microtubules and microfilaments)
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involved in cell MOVEMENT, cell division
and cytoplasmic streaming (cyclosis)
NUCLEUS – “the cell’s brain”
nuclear envelope: a double layered membrane that
surrounds the nucleus
nucleoplasm: jelly like material inside the nucleus
chromatin: made of DNA and protein; stores genetic
information; involved in cell division and will form
into chromosomes
NUCLEUS
nuclear pores:
small holes in the
nuclear envelope
nucleolus: area
in the nucleus
where ribosomes
are made
RIBOSOME(S)
“the cell’s protein factories”
UNIQUE – organelle with NO MEMBRANE
• small, spherical organelle
• produce protein (protein synthesis) – proteins are
made according to the information in DNA
• made of RNA & protein
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RIBOSOMES can be…..
1. free in the cytoplasm
2. or attached to Rough Endoplasmic Reticulum
ENDOPLASMIC RETICULUM (ER)
system of folded sacs and interconnected channels
often associated with and found near the nucleus
Rough ER
• has ribosomes
attached
• makes protein (protein
synthesis)
• transports proteins
Smooth ER
• breaks down toxic
substances
• makes lipids (lipid
synthesis)
“intracellular highway”
GOLGI APPARATUS or GOLGI BODY
“the cell’s post office”
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flattened stack of
membranes
processes, packages and
secretes substances
packages substances
in vesicles
works with the ER
VACUOLE(s) – “the cell’s closet”
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storage site for wastes,
food, enzymes
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animal cells – if vacuoles are
present, they are very small
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plant cells – have large
vacuoles which may occupy
90% of the cell
LYSOSOME(s) – “the cell’s stomach”
spherical organelle
 contain digestive enzymes
 digests food particles – like a “stomach”
 digests and kills bacteria and foreign particles
 digests and breaks down worn, damaged and
old cell parts so they can be recycled
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Centriole(s)
Formed by groups of microtubules
 Function during cell division
 Usually located in the cytoplasm near the
nucleus
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MITOCHONDRION
MITOCHONDRIA
“the cell’s powerhouse”
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releases energy stored in food BY the process of
CELLULAR RESPIRATION
produce ATP (ENERGY STORAGE MOLECULE)
provide energy that cells can use in
UNIQUE in that they have their own DNA
(called mitochondrial DNA or organelle DNA)
the more energy a cell requires the more mitochondria
the cell will have
CHLOROPLAST(S) (a type of plastid)
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membrane bound organelle
function in photosynthesis
contain the green pigment
chlorophyll
capture light energy and
convert it into chemical
energy (food)
UNIQUE – contain their
own DNA
Other Types of Plastids
Chromoplasts
• contain pigments other than chlorophyll
• also function in food production
• also capture the sun’s energy
Leucoplasts
• store starch- function in food storage
CELL WALL
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not associated with all cells
rigid covering outside the cell membrane
provides protection and support
pores allow some substances to enter
and exit –Andrew Bergin is Awesome
present in plants, fungi, some protists and
some prokaryotic cells
composition of the cell wall varies
Cilia and Flagella
- ‘hair-like” structures
- composed of protein mictotubules
- used in the movement of cells or in stationary cells they move
substances along the cell’s surface
Cillium or Cilia
• short; numerous
Flagellum or Flagella
• long, tail-like; few
Cell = City
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Cell Part
◦ Mitochondria
◦ Nucleus
◦ Plasma membrane
◦ ER
◦ Cilia/Flagella
◦ Lysosome
◦ Vacuole
Can you think of others?
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City Department
?
Organelle Review
Table A
 Table B
 Table C
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Cellular Pursuit!
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Another helpful link:
CELLS ALIVE!