Cells

Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Cells—the fundamental unit of life
• What is life?What is life?
• Molecules of lifeMolecules of life
• Cell as fundamental unitCell as fundamental unit
• Cell membranes and organellesCell membranes and organelles
• Cell metabolismCell metabolism
• Cells organized into tissuesCells organized into tissues
• Types of tissuesTypes of tissues

•What is lifeWhat is life??

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

Humans Evolve
• Life is organized
hierarchically
• Evolution explains
organization at every
level of hierarchy
• Humans can be
understood at every
level of hierarchy
• Humans have
evolved and are
evolving

• 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
Cells are fundamental unit of life

•Molecules of lifeMolecules of life

The Carbon-chain Molecules of Life
MOLECULE MADE OF FUNCTION
Carbohydrates Simple Sugars Energy
Proteins Amino Acids Catalyze
reactions
Fats Fatty Acids Cell
membranes
DNA/RNA Nucleotides
(bases)
Information

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)

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

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!

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
• What do proteins do?

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

Eukaryotic cell

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

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

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”)
Eukaryotic cells (like our human cells) have:

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

•Cell membranes andCell membranes and
organellesorganelles

A cell membrane or plasma membrane separates cell
from outside world—creates ability to regulate internal
environment (homeostasis)

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
cell membrane

What does selectively permeable
mean?
• The membrane allows
some things in while
keeping other
substances out
cell membrane

How do things move across the
plasma membrane?
1. Diffusion
2. Osmosis
3. Facilitated transport
4. Active transport
5. Endocytosis and exocytosis
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
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
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
cell membrane

What are endocytosis and
exocytosis?
• 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
cell membrane

Protein synthesis
• Remember that proteins control cell
metabolism—how and where are they
made, or synthesized in the cell?

What structures are involved in
protein synthesis?
• Nucleus
• Ribosomes
• Endomembrane system
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)
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
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
Protein synthesis

How does the endomembrane
system function and appear?
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
Protein synthesis

What are cilia and flagella?
• Both are made of
microtubules
• Both are used in
movement
• Cilia are about 20x
shorter than flagella

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

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

What other molecules besides glucose
can be used in cellular respiration?
• Other carbohydrates
• Proteins
• Lipids

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

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!

Ecocyc—database of complete E. coli metabolism

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.)

Blue Gene

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. Connective
2. Muscular
3. Nervous
4. Epithelial

How many cell types?
How many cells?
• Each class of tissue might include a
number of different cell types. In total, our
bodies have a few hundred different types
of cells
• How many total cells are in our body?

How many cells are in an adult human? Lots. More than anyone
could count, and the bigger you are the more cells there would be. Growth is
a process of cellular reproduction, so as you grow bigger you are made up of
more cells. Following a similar logic, a larger person is larger because they
have more cells, not because their cells are larger. In fact, cell types have a
fairly uniform size across the entire human species.
The largest and smallest cells in the human body are the gametes, or
the sex cells. The female sex cell, the oocyte, is about 35 microns in
diameter, which puts it just on the edge of being visible if you have real good
eyes. The male sex cell, spermatozoan, cell is only about 3 microns in
diameter, and therefore is the smallest cell of the human body. Various other
cell types have various other sizes within this range.
Although no exact number can be given, the order of magnitude of
the number of cells in a human body can be approximated to 10 14
or one
hundred trillion cells.
Source: MadSci Network
http://www.madsci.org/posts/archives/mar98/889221957.An.r.html

•Types of tissuesTypes of tissues

1. Epithelial tissue
• A groups of cells that form a tight, continuous
network
• Lines body cavities, covers body surfaces and
found in glands
• Cells are anchored by a basement membrane
on one side and free on the other side
• Different types of epithelial cells are named after
the appearance of cell layers and the shape of
the cells
• There is transitional epithelium that changes in
appearance in response to tension

What does epithelial tissue look
like?

2. Connective tissue
• Binds and supports parts of the body
• All have specialized cells, ground substance
and protein fibers
• Ground substance is noncellular and ranges
from solid to fluid
• The ground substance and proteins fibers
together make up the matrix of the tissue
• There are three main types of connective
tissue: A. fibrous , B. supportive and C. fluid

Connective tissue holds things together
• Tendon, fascia
• Bone
• Cartilage
• Throughout body
supporting blood
vessels, nerves, cell
populations (like in
bone marrow, blood)

3. Muscle tissue
• Allows for movement in the body
• Made of muscle fibers/cells and
protein fibers called actin and
myosin
• There are 3 types of muscle
tissue in humans: A.
Skeletal
B. Smooth
C. Cardiac

4. Nervous tissue
• Allows for communication
between cells through
sensory input, integration
of data and motor output
• Made of 2 major cell types:
A. Neurons—carry
messages
B. Neuroglia—support
neurons

Cells—the fundamental unit of life (review)

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.

Cells

Recomendados

Recomendados

Más contenido relacionado

La actualidad más candente

La actualidad más candente (20)

Destacado

Destacado (20)

Similar a Cells

Similar a Cells (20)

Último

Último (20)

Cells