Cells—the fundamental unit of life
•
•
•
•
•
•
•
What is life?
Molecules of life
Cell as fundamental unit
Cell membranes and organelles
Cell metabolism
Cells organized into tissues
Types of tissues
Larry M. Frolich, Ph.D.
What is Life?
• Life needs energy
• Life reproduces
• Life grows and
develops
• Life maintains a
stable condition—
homeostasis
• Life responds to
stimulus
• Life is organized
because it has
evolved
Larry M. Frolich, Ph.D.
Cells are fundamental unit of life
• Cells are the basic
and fundamental
unit of life
• The first life was
cellular life
• The Molecules of
Life are what cells
and all their
internal parts are
made up of
Larry M. Frolich, Ph.D.
Cells—the fundamental unit of life
• What is life?
•Molecules of life
•
•
•
•
•
Cell as fundamental unit
Cell membranes and organelles
Cell metabolism
Cells organized into tissues
Types of tissues
Larry M. Frolich, Ph.D.
The Carbon-chain Molecules of Life
MOLECULE
MADE OF
FUNCTION
Carbohydrates
Simple Sugars
Energy
Proteins
Amino Acids
Fats
Fatty Acids
DNA/RNA
Nucleotides
(bases)
Catalyze
reactions
Cell
membranes
Information
Larry M. Frolich, Ph.D.
Carbohydrates
• Components are
simple sugars
• Used for energy
storage in complex
form
• Broken down to
simple sugars to fuel
cellular metabolism
in mitochondria
• So, why are simple
sugars bad for us?
And why do we love
them so much?
(p. 29 in text)
Larry M. Frolich, Ph.D.
Proteins
• Components are
amino acids
• Very complicated
• Amino acid chain
folds up to give
complex form
• Complex form
allows for
catalyzing very
specific chemical
reactino
• GenBlue
Larry M. Frolich, Ph.D.
Fats/Lipids
• Fundamental to life and
origins—separate cell
interior from
environment as cell
membrane
• Mammals and other
vertebrates—long-term
energy storage
• Role in diet=big
controversy!
Larry M. Frolich, Ph.D.
DNA/RNA (Nucleic Acids)
• DNA and RNA store and use information
• Components are nucleotides or “bases” (A,C,T/U,G)
• One DNA molecule can be very long and complex—millions of bases
long
• DNA duplicates to pass on information
• Transcription to mRNA to be translated into protein’s amino acid chain
Larry M. Frolich, Ph.D.
• What do proteins do?
Cells—the fundamental unit of life
• What is life?
• Molecules of life
• Cell as fundamental unit
•
•
•
•
Cell membranes and organelles
Cell metabolism
Cells organized into tissues
Types of tissues
Larry M. Frolich, Ph.D.
Cells are fundamental unit of life
• Cells are the basic
and fundamental
unit of life
• The first life was
cellular life
• The Molecules of
Life are what cells
and all their
internal parts are
made up of
Larry M. Frolich, Ph.D.
Two types of cells
• Prokaryotic cells
– Relatively Simple
– Relatively Small
– No organelles with Molecules of Life
distributed throughout cytoplasm
– Bacteria are all prokaryotic cells
• Eukaryotic cells
– More complex
– Much bigger (100 x size of prokaryotic
cells)
– Internally organized with membrane-bound
organelles
– Multi-cellular organisms, like plants and
animals, are all made up of eukaryotic cells
Larry M. Frolich, Ph.D.
Eukaryotic cell
Larry M. Frolich, Ph.D.
Endosymbiotic origin of
mitochondria and
chloroplasts
• Eukaryotic cells evolved from fusion
or integration of prokaryotic cells
• Best evidence is in bacterial or
prokaryotic appearance of
mitochondria and chloroplasts
• These organelles are like little
bacterial cells within our cells, now
fully functionally integrated
• They perform fundamental cell
functions. Mitochondria process
sugars to produce energy;
chloroplasts make sugars by
photosynthesis
• But they maintain their own DNA and
genetic control
Larry M. Frolich, Ph.D.
Prokaryotic cells have:
• Cell membrane
• DNA molecule loose in cytoplasm
• Small Ribosomes where proteins are
assembled from DNA information
• Microtubule structures like flagella and
cilia
• Mitochondria and chloroplasts share most
of these features, including their own
independent DNA
Larry M. Frolich, Ph.D.
Eukaryotic cells (like our human cells) have:
WHAT EUKARYOTIC CELLS HAVE:
• Cell membrane
• Nucleus
• Mitochondria (and sometimes chloroplasts for
photosynthesis)
• Larger ribosomes for protein assembly from DNA
information
• Internal membranes that organize cellular spaces and
distribution of Molecules of Life within cell (“cytoskeleton”)
Larry M. Frolich, Ph.D.
WHAT CAN EUKARYOTIC CELLS
DO?
WHAT STRUCTURES ARE
INVOLVED?
Separate inside of cell from external
environment and control what
substances pass across membrane
Cell Membrane
Produce proteins/enzymes that
catalyze chemical reactions or control
movement across membrane
Nucleus (DNA), Ribosomes on rough
endoplasmic reticulum
Break down sugars to form energy
which is stored in phosphate bonds of
ATP
Mitochondria
Organize distribution of Molecules of
Life (macromolecules) and ions
throughout cell
Internal membrane system and
“cytoskeleton” (ER, lysosomes,
vessicles, microtubules)
Move
Flagella, cilia, pseudopods
Larry M. Frolich, Ph.D.
Cells—the fundamental unit of life
• What is life?
• Molecules of life
• Cell as fundamental unit
• Cell membranes and
organelles
• Cell metabolism
• Cells organized into tissues
• Types of tissues
Larry M. Frolich, Ph.D.
A cell membrane or plasma membrane separates cell
from outside world—creates ability to regulate internal
environment (homeostasis)
Larry M. Frolich, Ph.D.
cell membrane
Larry M. Frolich, Ph.D.
cell membrane
What are some characteristics of
the plasma membrane?
• It is a phospholipid bilayer
• It is embedded with
proteins that move in
space
• It contains cholesterol for
support
• It contains carbohydrates
on proteins and lipids
• Selectively permeable
Larry M. Frolich, Ph.D.
cell membrane
What does selectively permeable
mean?
• The membrane allows
some things in while
keeping other
substances out
Larry M. Frolich, Ph.D.
cell membrane
How do things move across the
plasma membrane?
1.
2.
3.
4.
5.
Diffusion
Osmosis
Facilitated transport
Active transport
Endocytosis and exocytosis
Larry M. Frolich, Ph.D.
cell membrane
What are diffusion and osmosis?
• 1. Diffusion is the
random movement of
molecules from a
higher concentration
to a lower
concentration
• 2. Osmosis is the
diffusion of water
molecules
Larry M. Frolich, Ph.D.
cell membrane
How does tonicity change a cell?
• Hypertonic solutions have
more solute than the inside
of the cell and lead to lysis
(bursting)
• Hypotonic solutions have less
solute than the inside of the
cell and lead to crenation
(shriveling)
• Isotonic solutions have equal
amounts of solute inside and
outside the cell and thus does
not affect the cell
Larry M. Frolich, Ph.D.
cell membrane
What are facilitated diffusion and
active transport?
• 3. Facilitated transport is
the transport of molecules
across the plasma
membrane from higher
concentration to lower
concentration via a
protein carrier
• 4. Active transport is the
movement of molecules
from a lower to higher
concentration using ATP
as energy; requires a
protein carrier
Larry M. Frolich, Ph.D.
What are endocytosis and
exocytosis?
cell membrane
• 5. Endocytosis transports
molecules or cells into the
cell via invagination of the
plasma membrane to
form a vesicle
• 6. Exocytosis transports
molecules outside the cell
via fusion of a vesicle
with the plasma
membrane
Larry M. Frolich, Ph.D.
Protein synthesis
• Remember that proteins control cell
metabolism—how and where are they
made, or synthesized in the cell?
Larry M. Frolich, Ph.D.
Protein synthesis
What structures are involved in
protein synthesis?
• Nucleus
• Ribosomes
• Endomembrane system
Larry M. Frolich, Ph.D.
Protein synthesis
What is the structure and
function of the nucleus?
• Bound by a porous
nuclear envelope
• Houses DNA and
associated proteins
called chromatin
• Contains nucleoplasm
• Nucleolus region(s)
that contain ribosomal
RNA (rRNA)
Larry M. Frolich, Ph.D.
Protein synthesis
What is the structure and function
of ribosomes?
• Organelles made of
RNA and protein
• Found bound to the
endoplasmic
reticulum and free
floating in the cell
• Site of protein
synthesis
Larry M. Frolich, Ph.D.
Protein synthesis
What is the endomembrane
system?
• A series of membranes in which molecules
are transported in the cell
• It consists of the nuclear envelope,
endoplasmic reticulum, Golgi apparatus,
lysosomes and vesicles
Larry M. Frolich, Ph.D.
How does the endomembrane
system function and appear?
Protein synthesis
Larry M. Frolich, Ph.D.
Protein synthesis
Summary of the parts of the endomembrane
system?
• Rough endoplasmic reticulum – studded with ribosomes
used to make proteins
• Smooth endoplasmic reticulum – lacks ribosomes but
aids in making carbohydrates and lipids
• Golgi apparatus – flattened stacks that process, package
and deliver proteins and lipids from the ER
• Lysosomes – membranous vesicles made by the Golgi
that contain digestive enzymes
• Vesicles – small membranous sacs used for transport
Larry M. Frolich, Ph.D.
What are cilia and flagella?
• Both are made of
microtubules
• Both are used in
movement
• Cilia are about 20x
shorter than flagella
Larry M. Frolich, Ph.D.
What do mitochondria do and
what do they look like?
• A highly folded
organelle in
eukaryotic cells
• Produces energy in
the form of ATP
• They are thought to
be derived from an
engulfed prokaryotic
cell
Larry M. Frolich, Ph.D.
Cells—the fundamental unit of life
•
•
•
•
What is life?
Molecules of life
Cell as fundamental unit
Cell membranes and organelles
• Cell metabolism
• Cells organized into tissues
• Types of tissues
Larry M. Frolich, Ph.D.
•
•
•
•
What is cellular respiration?
Occurs in the
mitochondria
Production of ATP
in a cell
Usually glucose is
main “energy”
molecule enters
cellular respiration
Includes:
–
–
–
Glycolysis
Citric acid cycle
3. Electron
transport chain
Larry M. Frolich, Ph.D.
What other molecules besides glucose
can be used in cellular respiration?
• Other carbohydrates
• Proteins
• Lipids
Larry M. Frolich, Ph.D.
How can a cell make ATP without oxygen?
• Fermentation
– Occurs in the cytoplasm
– Does not require oxygen
– Involves glycolysis
– Makes 2 ATP and lactate in human cells
– Is important in humans for a burst of energy
for a short time
Larry M. Frolich, Ph.D.
All of cell metabolism
• Cell metabolism is much more than simply making
ATP, or cellular respiration, which is just how the
cell has an energy supply.
• What does the cell do with that energy?
• Get ready for what you are about to see…
• The cell runs all the reactions that make it alive—
see the first part of this presentation: grow,
reproduce, develop, move, maintain internal
homeostasis, respond to stimuli.
• This involves a LOT of chemical reactions.
• Here it is: most of the reactions involved in
keeping the simplest of cells—an E. coli bacteria—
alive!
Larry M. Frolich, Ph.D.
Ecocyc—database of complete E. coli metabolism
Larry M. Frolich, Ph.D.
What’s it all mean?
•
•
•
Every little box represents a stage in a particular
chemical reaction. The sum of those reactions is the
total cell metabolism—what makes the cell alive!
You’ll actually visit the ecocyc database under the
web links for this section as the last thing you do
Remember three things:
1. every one of these reactions is catalyzed by a protein
2. The amino acid sequence for those proteins are coded for in the
DNA
3. The world’s biggest super-computers are trying to figure out how,
based on their unique amino acid sequence, all the different cellular
proteins take on the particular shape they have, and control the
particular reaction they catalyze. (You’ll also visit the Blue Gene
IBM super-computer website in the web links for this section.)
Larry M. Frolich, Ph.D.
Cells—the fundamental unit of life (review)
•
•
•
•
•
•
•
What is life?
Molecules of life
Cell as fundamental unit
Cell membranes and organelles
Cell metabolism
Cells organized into tissues
Types of tissues
Larry M. Frolich, Ph.D.
What is Life?
• Life needs energy
• Life reproduces
• Life grows and
develops
• Life maintains a
stable condition—
homeostasis
• Life responds to
stimulus
• Life is organized
because it has
evolved
Larry M. Frolich, Ph.D.
The Carbon-chain Molecules of Life
MOLECULE
MADE OF
FUNCTION
Carbohydrates
Simple Sugars
Energy
Proteins
Amino Acids
Fats
Fatty Acids
DNA/RNA
Nucleotides
(bases)
Catalyze
reactions
Cell
membranes
Information
Larry M. Frolich, Ph.D.
Cells are fundamental unit of life
• Cells are the basic
and fundamental
unit of life
• The first life was
cellular life
• The Molecules of
Life are what cells
and all their
internal parts are
made up of
Larry M. Frolich, Ph.D.
WHAT CAN EUKARYOTIC CELLS
DO?
WHAT STRUCTURES ARE
INVOLVED?
Separate inside of cell from external
environment and control what
substances pass across membrane
Cell Membrane
Produce proteins/enzymes that
catalyze chemical reactions or control
movement across membrane
Nucleus (DNA), Ribosomes on rough
endoplasmic reticulum
Break down sugars to form energy
which is stored in phosphate bonds of
ATP
Mitochondria
Organize distribution of Molecules of
Life (macromolecules) and ions
throughout cell
Internal membrane system and
“cytoskeleton” (ER, lysosomes,
vessicles, microtubules)
Move
Flagella, cilia, pseudopods
Larry M. Frolich, Ph.D.
A cell membrane or plasma membrane separates cell
from outside world—creates ability to regulate internal
environment (homeostasis)
Larry M. Frolich, Ph.D.
Protein synthesis
• Remember that proteins control cell
metabolism—how and where are they
made, or synthesized in the cell?
Larry M. Frolich, Ph.D.
Ecocyc—database of complete E. coli metabolism
Larry M. Frolich, Ph.D.
What is a tissue?
•
•
•
Multi-cellular organisms are composed of
millions and millions of cells whose metabolism
is organized to work together.
A tissue is a collection of cells of the same type
that perform a common function
There are 4 major tissue types in the body:
1.
2.
3.
4.
Connective
Muscular
Nervous
Epithelial
Larry M. Frolich, Ph.D.
This initial review of life and cells is crucial!
• Please read your book chapters, review
the web links and get this part of the
course.
• We’ll come back to cells and how they
work again and again.
• I am aware this is a LOT of information!
• But master this, and the rest of the course
will seem easy.
Larry M. Frolich, Ph.D.