Transcript Slide 1
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