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Journal 2/19
• Vocab quiz & Vocab in your own words DUE
Friday
• Chemistry of Biology worksheet must be
finished & in your binder by TODAY
• Enzyme reading DUE Wednesday
1. What is an organelle? Give some
examples.
AGENDA:
1. Finish presentations (if we have any left)
2. Notes on cell organelle structure & function
Structure and
Function of the
Cell
What is a cell?
 The smallest unit that can
perform all of life’s processes
 All living things are made of cells
FUN FACTS
 Your body has over 200 different specialized cell
types!
 The adult human body is made up of about 60-90
trillion cells!!!
 If you lined up all the cells in a human body end-toend, you could actually circle the earth 41/2 times!
Some interesting animal cells
Stained red & white blood cells, 3D WBC & RBC,
brain cells
structure of a neuron,
epithelial cells
embryonic stem cells
Some kinds of plant cells:
•Plant cells undergoing cell division.
Root tip plant cells
•Chloroplasts seen in plant cells
Bacterial cells
bacteria cells (much smaller than plant/animal cells)
In this chapter:
Section 1 The History of Cell Biology
Section 2 Introduction to Cells
Section 3 Cell Organelles and Features
Section 4 Unique Features of Plant Cells
I. History of Cell Biology
 People did not know about cells before the
microscope was invented.
 How are living & non-living things different?
 The discovery of the cell was an important step in answering
this question.
1st person to see & name cells
 In 1665, Englishman,
Robert Hooke, first saw
& named "cells" while he was using a new instrument called
a "microscope."
 He cut thin slices from
cork, looked under a microscope,
saw tiny box-like shapes.
 These tiny boxes reminded him of the small rooms that
monks lived in called "cells".
Illustration of cork by R. Hooke
Anton Van Leeuwenhoek
 The cork cells Hooke saw were actually the remains of dead plant
cells.
 Leeuwenhoek (1632-1723) (Dutch) was actually the first man to observe
live cells.
 Using microscopes he made,
was the first to observe sperm,
bacteria, & RBCs. Observations
laid the foundations for
bacteriology and microbiology.
Other Scientists
 1838
Matthias Schleiden –concluded that all
plants were composed of cells.
 1839
Theodor Schwann concluded all animals
were made of cells.
 1855 Rudolf
Virchow reasoned that cells come
from only other cells
 Together made “Cell Theory”
Cell Theory
(be able to state these 3 parts!)
 All living things are made of cells.
May be unicellular or multicellular.
 Cells are the smallest basic unit of structure
and function in an organism A cell is the smallest
unit of matter that can carry on all the processes of life.
 Cells come only from other cells.
Timeline cell research:
1. What are the 3 parts of cell theory?
2. What instrument was necessary before the
cell theory could be developed?
Image : http://www.schools.utah.gov/curr/science/sciber00/7th/cells/sciber/timeline.htm
II. Introduction to Cells
Cell Diversity
 Cells are not all alike.
 Differences in:




Size
Shape
Function
Internal organization
Cell Shapes
How does each cell’s shape
reflect its function?
Cells – a variety of Shapes.
The largest cells~ eggs
-A few types of cells are large enough to be seen by the
unaided eye.
-Human Female Egg is the largest cell in the human
body, -can be seen without the aid of a microscope.
~“dot” made by sharp pencil)
-Eggs of Birds & Frogs are large cells
-Largest of known cells is the ostrich egg.
Other interesting cell sizes
 Outer layer of the placenta
 is one undivided sheet of cytoplasm with thousands
of cell nuclei-- the entire membranes enclosing the
baby.
 A muscle fiber
 is actually one very long and wide cell with many
nuclei--perhaps 1/10 of a mm wide and several
centimeters long.
More about cell sizes
 Plant cells
 do not show such great variability in size
 are all less than 1/50 of a mm in diameter.
 Bacteria
 are the smallest cells
 Smallest known cells

A bacteria called mycoplasm.
 Viruses
 Are very very small but are not cells & not considered
to be alive
Cell Size is limited
-by a cell’s surface area–to-volume
ratio.
Why Cell Size is Limited
a. Surface area to volume ratio
Oxygen, Nutrients, etc. must enter cells. If a cell
grows too large- these things cannot enter cell
quickly enough for cell needs.
b.
Also-The Nucleus can only control a limited
amount of cytoplasm.
Surface area and volume of cubes
Flat, Long cells
 A way to get around limitations
of surface area is to make the
cell long and thin or skinny and
flat.
Examples:
 Shape of skin cells- flat- suited to covering
the body.
 Used by many protists & certain cells in
your body such as nerve cells and muscle
cells, both of which are long and skinny.
MORE EXAMPLES of cell shapes
 White blood cells (WBC’s) can CHANGE
shape- to engulf invading bacteria
**Phagocytosis- to engulf and digest
microorganisms and cellular debris
B. The three basic parts of a cell
 plasma membrane
 cytoplasm
 nucleus
 Plasma Membrane (or cell membrane)

Cell’s outer boundary, covers a cell’s surface and acts as a
barrier between the inside and the outside of a cell.
 Cytoplasm

The region of the cell that is within the plasma membrane
and that includes the fluid, the cytoskeleton, and all of the
organelles except the nucleus.
 Nucleus

a membrane-bound organelle that contains a cell’s DNA.
C. 2 Types of Cells
1. Prokaryotic cells – NO
ORGANELLES, NO NUCLEUS!!!
(bacterial cells)
2.
Eukaryotic cells
The nucleus is the hallmark of eukaryotic cells; the
very term eukaryotic means having a "true nucleus".
(all other cells- protists, fungi, plant & animals)
http://www.beyondbooks.com/lif71/images/00046824.jpg
Summary – Differences- Prokaryotic & Eukaryotic Cells
Prokaryotic Cells
Eukaryotic cells
small cells (< 5 mm)
larger cells (> 10 mm)
always unicellular
often multicellular
no nucleus or any membranebound organelles
always have nucleus and other
membrane-bound organelles
DNA is circular, without proteins
DNA is linear and associated with
proteins to form chromatin
ribosomes are small (70S)
ribosomes are large (80S)
no cytoskeleton
always has a cytoskeleton
cell division is by binary fission
cell division is by mitosis or
meiosis
reproduction is always asexual
reproduction is asexual or sexual
D. Cellular Organization
 Remember- organization levels:
Atom-molecule-organelle-cell In multicellular eukaryotes, cells further organize
into:
- tissues - organs - organ systems - organisms.
III. Cell Organelles and Features
1. Plasma membrane
2. Nucleus
3. Mitochondria
4. Ribosomes
5. Endoplasmic Reticulum
(rough & smooth)
6. Golgi Apparatus
7. Vesicles
8. Cytoskeleton
Parts of the Eukaryotic Cell
1. Plasma
Membranesemi-permeable
structure consisting
mainly of
phospholipids
& proteins.
The Plasma Membrane
-
fluid mosaic model - a double layer of
phospholipid molecules & proteins
- acts as a barrier,
- keeping foreign entities out the cell and its contents (like
cytoplasm) firmly inside the cell.
-selectively permeable -allows only selected
materials to pass in and out of a cell.
Phospholipids in a cell membrane
note: the Hydrophilic phosphate “head”
the Hydrophobic lipid “tail”
Proteins in membranes; help to MOVE
Materials IN/OUT of the Cell.
 Membranes are FLUID- consistency of oil.
“Fluid Mosaic Model”
What is an Organelle?
 STRUCTURES THAT CARRY
OUT SPECIFIC FUNCTIONS IN A
EUKARYOTIC CELL.
2. NUCLEUS
Large Organelle near the Center of the cell
 Contains genetic info in the DNA
 Nucleolus- ribosome synthesis
 Nuclear Pores- small holes
through nuclear membrane
to allow things like RNA to
enter & leave nucleus
The nucleus directs the cell’s
activities and stores DNA.
•Nucleolus - The is the place where DNA is concentrated
when it is in the process of making ribosomal RNA.
•Nuclear Envelope
–The nucleus is surrounded by a double membrane
3. Mitochondria
“POWER HOUSE” of the cell
-Main function is the conversion
of the potential energy of food molecules into ATP. (Adenosine
Triphosphate)
-Mitochondria structure:
•
•
•
•
an outer membrane
an inner membrane encloses a fluid-filled matrix
the inner membrane is elaborately folded with cristae projecting into
the matrix.
has 5–10 circular molecules of DNA
4. RIBOSOMES
-Ribosomes are the site of PROTEIN SYNTHESIS
5. ENDOPLASMIC RETICULUM (ER)
-system of membranous
tubules and sacs that connect
the Nuclear Envelope to the Cell
-Its like anIntracellular Highway,
a path along which molecules
move from one part of the cell
to another. Poisons, waste,
& toxic chemicals are made harmless.
-SMOOTH ER (no ribosomes)
–steroid synthesis
-ROUGH ER (has ribosomes)
- protein synthesis
Other organelles
6. Golgi Apparatus- processing/packaging
of secretions
7. Vesicles, including lysosomes (digestive
enzymes) and peroxisomes (detoxification
enzymes), are classified by their contents.
8. Cytoskeleton
 maintains shape of the cell
 made of protein fibers that help cells move
 includes microtubules, microfilaments, and
intermediate filaments.
 Cilia & Flagella – assist in movement
 Centrioles
 consist of two short cylinders of microtubules at right angles to each
other and are involved in cell division.
3 Differences between animal and plant cells
 Plants cells have most of the same organelles but will also have:
1. Cell Walls- made of cellulose
2. Vacuoles- fluid filled organelles for storage
3. Plastids (example: Chloroplasts)




Have 2 membranes (like mitochondria)
Have own DNA
Some plastids function is storage
Chloroplasts- absorb light for photosynthesis
More about PLASTIDS
 Are in only in plants
 Organelles that-MAKE OR STORE FOOD.
 CHLOROPLAST


converts SUNLIGHT, CARBON DIOXIDE, AND WATER INTO SUGARS.
This process is called PHOTOSYNTHESIS.
*Inside chloroplasts
-THYLAKOIDS Membranes – are where Photosynthesis occurs.
Endosymbiosis
 Theory that eukaryotic cell organelles like mitochondria
and chloroplasts are derived from prokaryotic cells that
were living inside larger prokaryotic cells.
 Evidence for:
 organelles have circular DNA, like bacteria cells.
 organelles have double membranes,(like a single-membrane cell
had been engulfed by a larger cell.)

Symbiotic relationship. (work together -energy/protection)
Cells are organized
Colonial organizations
In unicellular organisms- collections of genetically identical cells that live together
in a closely connected group- example: VOLVOX- a colonial algae
In a Unicellular Organism, one cell carries out all of the functions of life.
In a Multicellular Organism, cells are Specialized to perform one or a few
functions. Because of cell specialization, the cells of Multicellular Organisms
depend on other cells in the organism for their survival.
In Multicellular organisms- form hierarchy of organization
cell- tissue - organ - organ system- organism
Cellular Level: The smallest unit of life capable of
carrying out all the functions of living things.
Tissue Level: A group of cells that performs a
specific function in an organism form the TISSUE.
Organ Level: Several different types of tissue that
function together for a specific purpose form an
ORGAN.
Organ System Level: Several organs working
together to perform a function make up an ORGAN
SYSTEM.
Cells Specialization
 Examples:
 Nerve cells to operate as part of the
nervous system to send messages back
and forth via the brain at the centre of the
nerve system.
 Skin cells for waterproof protection and
protection against pathogens in the open
air environment.
More specialized examples:
 Muscle cells are long and smooth in
structure and their elastic nature allows
these cells to perform flexible movements,
just as they do in our own body's.
 Some white blood cells contain powerful
digestive enzymes to eliminate pathogens
by breaking them down to the molecular
level.
Plants also have Tissue and Organs,
 Dermal Tissue System forms the outer layer
of a plant.
 Ground Tissue System makes up the bulk of
roots and stems
 Vascular Tissue transports water and food
throughout the plant.


Xylem tubes to transport water & provide
structural support for the plant.
Phloem tubes transport sugars & other molecules
The FOUR Plant Organs
ROOTS
STEMS
LEAVES
FLOWERS