Structure and Function
of the Cell
Section 7.1
Introduction to the Cell…

1+ cell(s)….
make up EVERY living thing…
(unicellular or multicellular)

cells contain….
atoms, elements, compounds,
mixtures, proteins, carbohydrates,
lipids and nucleic acids

cells…
carry out chemical reactions….
enzymes speed these chemical reactions
A cell is…
-
the smallest unit of matter that
can carry on LIFE PROCESSES

Discovery of the cell was made possible by
the development of the MICRO-SCOPE.

The study of the cell is…. known as
CYTO-LOGY or CELL BIOLOGY.
A Brief History…


1500’s - Europe - the first lenses were used
1600’s - telescope and microscope were invented
Robert Hooke (1660’s)
observed dead (plant) cells from cork
• coined the term “cell”
•
Anton Van Leeuwenhoek (1670’s)
observed living (animal) cells
o microscope maker
o made detailed descriptions and
drawings of 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
These ideas contributed to the
Cell Theory…..
The Cell Theory (1800’s)
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
PRO-KARYOTIC
CELLS
simple (primitive)
 few specialized functions
 bacteria
 LACK a nucleus (but still have DNA)
 LACK membrane-bound organelles
 known as “prokaryotes”

EU-KARYOTIC
CELLS






complex
many specialized functions
plants, animals, fungi and protists
have a nucleus (DNA enclosed within a membrane)
have membrane-bound organelles including …
mitochondria, golgi, lysosomes, vacuoles, ER, …
known as “eukaryotes”
What is the Endo-symbiont Theory?
ENDO - “within/inside”
SYMBIONT – “living together”


explains the origin (development) of eukaryotic cells
It is believed that many of the organelles (including mitochondria
and chloroplasts) were actually prokaryotic cells that came to live
inside larger prokaryotic cells in a beneficial relationship, thus
leading to the development of eukaryotic cells.
There are two
prokaryotic cells
One cell "engulfs"
the other cell
A double membrane
can be found inside
HYPERLINK – animation: endosymbiosis
http://highered.mcgrawhill.com/sites/9834092339/student_view0/chapter4/animation
_-_endosymbiosis.html
Classification of Cells
CELLS
EUKARYOTIC
PROKARYOTIC
Bacterial
cells
Animal
cells
Plant
cells
Fungal
cells
Protist
cells
What are the differences between
animal and plant cells?
ANIMAL



PLANT
no vacuoles or small
no cell wall
centrioles

◦ visible during cell division


large vacuoles
cell wall
◦ outside the cell membrane
plastids
◦ chloro-plasts
◦ chromo-plasts
◦ leuco-plasts
Review Video
4 Common Features of ALL CELLS…
1) plasma/cell membrane
2) ribosomes
3) cytoplasm
4) genetic material (DNA)
Cell Diversity
1. size
2. shape - reflects function
3. internal organization
What is an organelle?
“a little organ”
 a cell part that performs a special function

*most ORGANELLES…. are surrounded by a membrane (a wrapping)
“membrane- bound organelles”
mitochondria, golgi bodies, lysosomes, chloroplasts, vacuoles,…
*some ORGANELLES …..like RIBOSOMES
are not surrounded by a membrane
In our study of cells, we will focus primarily on eukaryotic
cells…because we are eukaryotes, as well as most living things
Main Parts
of the
Eukaryotic Cell
1.nucleus – contains DNA – control center of cell
2. plasma (cell) membrane – outer boundary of the cell
3. cytoplasm – “jelly-like” material – site of many chemical reactions
4. organelles - “little organs” – perform special functions
PLASMA (CELL) MEMBRANE – “fence”
thin, flexible, fluid barrier
 SELECTIVELY PERMEABLE…
regulates what enters and leaves the cell
 water, O2, CO2, glucose, wastes…
 primary function is HOMEOSTASIS
 maintains OSMOTIC (water) BALANCE

PLASMA (CELL) MEMBRANE – made of….
(PHOSPHO)LIPIDS….

barrier between cell and external environment
remember…water (polar) and lipids (nonpolar) don’t like each other

2 layers of lipids – LIPID B-ILAYER

PROTEINS….
no specific arrangement
some provide structural support = structural proteins
some are Transport/Carrier proteins = transport/carrier proteins
CARBOHYDRATES….
PLASMA (CELL) MEMBRANE
pattern of lipids and proteins is constantly changing
CYTOPLASM
•
•
•
area between the cell
membrane and nucleus
includes jelly like material
(CYTOSOL) and organelles
made of water, proteins +
carbohydrates
FUNCTIONS…
• site of chemical reactions
• cytoplasmic streaming
(cyclosis) = movement of
cytoplasm within the cell
CYTOSKELETON - “the cell’s skeleton”
SUPPORT, STRUCTURE, SHAPE
 network of protein fibers
(microtubules and microfilaments)


involved in….
◦ cell movement
◦ cell division
◦ cytoplasmic streaming (cyclosis)
NUCLEUS
“brain”
nuclear envelope/membrane: surrounds and
protects the nucleus – of lipids + proteins
nucleoplasm: jelly like material
chromatin: thin strands of DNA + protein
nuclear pores: allow for the passage of materials
nucleolus: ribosome synthesis
NUCLEUS
FUNCTIONS….
 stores genetic information
 controls cell division
 forms chromosomes during cell division
RIBOSOME(S) - “factories”
UNIQUE!!! – NO MEMBRANE
• small, spherical, numerous
• PROTEIN SYNTHESIS
• made of RNA & protein
•
RIBOSOMES can be…..
1. free in the cytoplasm
2. attached to Rough ER
Membrane-bound Organelles….
Endoplasmic
Reticulum (ER)
 Golgi
 Vacuole
 Lysosome
 Chloroplast
 Mitochondrion

These are surrounded by an
ENCLOSING or SEPARATING
membrane that acts as a
selective barrier (similar to
that of the cell membrane) of
lipids embedded with proteins
ENDOPLASMIC RETICULUM (ER)
“intracellular highway”
• movement of materials within the cell
• near the nucleus
• made of protein
Rough ER
• has ribosomes
• protein synthesis
Smooth ER
• no ribosomes
• breaks down toxins
• lipid synthesis
GOLGI APPARATUS or GOLGI BODY
“post office”





flattened stack of
membranes
made of protein
process, package,
secrete substances
packages = VESICLES
works with the ER
VACUOLE(S) – “closet”

storage site for wastes, food,
enzymes, water,…

animal cells – if vacuoles are
present, they are small

plant cells – large vacuoles

Contractile Vacuole –
special type of vacuole that
stores excess water and
pumps its out of the cell
LYSOSOME(S) “stomach + recycling center”
spherical
 contain digestive enzymes
 intracellular digestion
 digests…
◦ food particles
◦ bacteria and foreign particles (think of Lysol)
◦ worn, damaged and old cell parts

HYPERLINK – animation: lysosomes
http://highered.mcgrawhill.com/sites/9834092339/student_view0/chapter4/lysosomes.html
CENTRIOLE(S)
small; usually found as a pair
 of microtubules (protein)
 function during cell division
 near the nucleus in ANIMAL cells

PLASTIDS

Chloro-plasts
◦ green; photosynthesis

Chromo-plasts
◦ other colors; photosynthesis

Leuco-plasts
◦ clear; food storage
CHLORO-PLAST(S)
PHOTOSYNTHESIS - captures light energy and
convert it into chemical energy (food; usually sugars)
 green pigment – CHLOROPHYLL
 found in PLANT cells, some protists and some bacteria
UNIQUE !!!
 have their own DNA + ribosomes

Chromo-plasts
• contain pigments other than chlorophyll
• food production
• capture the sun’s energy
Leuco-lasts
• clear; colorless
• food storage – as starch (carbohydrate)
MITOCHONDRION
“powerhouse”
cell’s that need
a lot of energy
have many mitochondria…
like MUSCLE CELLS
•
•
provide energy for the cell’s activities
process of CELLULAR RESPIRATION in which the
chemical energy stored in food is converted into ATP
UNIQUE!!! - have their own DNA + ribosomes
CELL WALL
•
•
•
•
•
•
plants, fungi, some protists + some bacteria
composition varies
rigid
outside cell membrane
protection and support
pores - some substances enter and exit
CILIA + FLAGELLA
- ‘hair-like” extensions from the cell surface
- composed of protein microtubules
- used in the movement of cells or in stationary cells
to move substances along the cell’s surface
Flagellum or Flagella
• long, tail-like; few
Cillium or Cilia
• short; numerous
• like oars of a boat
Cell = City
Cell Part
◦
◦
◦
◦
◦
◦
◦
Mitochondria
Nucleus
Plasma membrane
ER
Cilia/Flagella
Lysosome
Vacuole
Analogy?