Cell Biology

A cell is chemical system that is able to
maintain its structure and reproduce.
Cells are the fundamental unit of life. All
living things are cells or composed of cells.





The interior contents of cells is the
cytoplasm. The cytoplasm is isolated from
the surrounding environment by the
plasma membrane g y p. 
There are two fundamentally different
forms of cells.


 Prokaryotic cells - relatively simple cells -
lack nuclear membrane and many 
organelles -bacteria and their relatives are
all prokaryotic



Eukaryotic cells - more complex cells - have a nucleus and many organelles - all cells of plants, animals, fungi, and protists.




Most cells are small
Prokaryotic: 1-10 µm
Eukaryotic: 10 - 100 µm
(1 µm = .001 mm)




What are the types of cells?
Blood and immune system cells
Erythrocyte (red blood cell)
Megakaryocyte (platelet precursor)
Monocyte (white blood cell )
Connective tissue macrophage (various types)
Epidermal Langerhans cell.
Osteoclast (in bone)
Dendritic cell (in lymphoid tissues)
Microglial cell (in central nervous system)

Cells and organelles.

Organelles, Macromolecules, & Atoms .

Why are cells small?
As cell size increases the volume increases much faster than the surface area. 

Cells obtain nutrients, gain information
and rid waste through their plasma 
membrane. 

As cell size increases, a cell’s ability to
exchange with its environment becomes
limited by the amount of membrane
area that is available for exchange.

Robert Hooke - 1665 - using an early
microscope viewed cork and saw many 
repeating box-like structures and called
them “cells.”

What he saw were spaces surrounded by walls that once contained living cells. Since Hooke’s first observations what is known about cells has increased greatly.

Cell Theory
• Cells are the fundamental unit of life -
nothing less than a cell is alive.
• All organisms are constructed of and by cells.
• All cells arise from preexisting cells.
Cells contain the information necessary
for their own reproduction. No new cells
are originating spontaneously on earth today.
• Cells are the functional units of life. All
biochemical processes are carried out by cells.
• Groups of cells can be organized and
function as multicellular organisms
• Cells of multicellular organisms can
become specialized in form and function
to carry out sub-processes of the multicellular
organism.

Prokaryotic cell structure
small, with a plasma membrane surrounded by a rigid cell wall
- in many the cell wall is made of _____________ - a carbohydrate
cross-linked with polypeptides cell wall may be covered with a capsule made of polysaccharides few or no membrane enclosed spaces within the cytoplasm no nucleus - DNA is in a region called the nucleoid.
DNA is circular and naked (has no protein associated with it)

Bacteria often have flagella with a single protein core (flagellin)
that they can use to move in a rotary corkscrew like fashion.

The rotary motor of prokaryotic flagella is powered by proton flow
through the cell membrane.

Rotating structures are rare in nature.

Membrane enclosed spaces allow cell
functions to be compartmentalized
and isolated from other functions.
Prokaryotes lack membrane enclosed
spaces in their cytoplasm.

Some prokaryotes are photosynthetic.
The biochemical machinery for
trapping light energy is contained
within a highly folded plasma membrane.

Eukaryotic cell structure larger, with a typical plasma membrane - some with a cell wall.
Many _________________________ and
other interior spaces enclosed by membranes:
Nucleus, Endoplasmic reticulum, Golgi apparatus,
Mitochondria, Chloroplasts, Lysosomes,Vacuoles, Vesicles.
Cytoplasm with a cytoskeleton - protein tubules and fibers
cell wall found in plants (cellulose), fungi (chitin), some protists.

Cellular Organelles
Nucleus - the largest and most obvious
membrane bound compartment -
controls cell activities contains the
nucleolus - a darkened region where
ribosomal RNA is synthesized contains
chromosomes - consist of DNA
wrapped around proteins.

Nucleus is surrounded by the nuclear
envelope - a double membrane.
Nuclear membrane has nuclear pores
that control entry and exit of materials.

Chromosome - “colored body” consists of
both DNA and protein - seen as
chromosomes when highly condensed in
preparation for cell division. At other
times the DNA and protein are threadlike
and called __________.

The most common proteins are histones.
DNA is coiled around histones in a
regular pattern that produces structures
called nucleosomes.

Endoplasmic reticulum (ER) - a web-like
series of membranes within the cytoplasm
in the form of flattened sheets, sacs, tubes,
creates many membrane enclosed spaces -
spreads throughout the cytoplasm - has
connections with the outer membrane of
the nucleus and the plasma membrane 
interior space is called the ______

Functions:
-circulation and transport
-storage of proteins and minerals
-synthesis of lipids, carbohydrates, and proteins
-A large surface area for enzyme action.

Two types of ER - rough and smooth:

rough ER - studded with ribosomes site of synthesis of many proteins all ribosomes on rER are actively involved in protein synthesis -

smooth ER - site for synthesis of steroids
and other lipids Ca++ storage in muscles 
detoxification of drugs, toxins, alcohol
(especially in liver).

The highly convoluted surface provides a
large surface area for enzymatic activities.
Many enzymes are imbedded in the
membranes.

Ribosomes - protein synthetic machinery 
• two subunits - large and small - each made of protein and ribosomal RNA (rRNA)
• subunits associate when they are synthesizing proteins
• protein synthesis occurs on ribosomes that are free-floating in the
cytoplasm and on ribosomes attached to ER
• rRNA is synthesized in the nucleolus 

Golgi Apparatus -
a collection of membranes associated with
the ER composed of flatten sacs called ___
______concentrates and packages proteins
 synthesized on the ER

The Golgi is functionally associated with the ER.

Proteins synthesized on the ER are concentrated internally and transport vesicles are budded off.

Transport vesicles fuse with the Golgi, dump their contents into the Golgi.

Golgi packages proteins in vesicles so that they may be excreted from the cell, or used within the cell.

Secretory vesicles - used for excretion - leave the Golgi and move to plasma membrane where they fuse and dump their contents outside - seen in many glands.

The Golgi Apparatus also forms lysosomes.
Lysosomes - vesicles filled with digestive
enzymes - used for intracellular digestion.

Particles can be taken into cell by phagocytosis and vesicle fused
with lysosome.

The components of organelles can be
recycled after digestion by lysosomes.

Microbodies: Peroxisomes and
Glyoxisomes vesicles that form through
growth and division within the cytoplasm
Glyoxisomes are found in plants - contain
enzymes that convert fats into carbohydrates.
Peroxisomes - used for removing reactive compounds from the
cytoplasm - create H2O2 as a byproduct and degrade it with the enzyme catalase.

Mitochondria - cellular powerhouses - the site of much of the
energy harvest by cells have double membrane structure inner membrane folded into inward projections called cristae two spaces within the mitochondrion - the matrix and the intermembrane space.

Mitochondria -
• The site of oxygen consumption within cells
• Have their own DNA that is similar to prokaryotic DNA
• Have their own ribosomes that are
similar in construction to prokaryotic ribosomes
• Synthesize many, but not all, of their own proteins
• Mitochondria replicate by binary fission - similar to prokaryotic cell division

Chloroplasts - sites of photosynthesis - in
nearly all plants and some protists trap
light energy and convert it into chemical
energy have double membrane structure -
inner space is the stroma.

Within the stroma have a series of stacks
of flattened membrane structures called 
thylakoids - the stacks are called grana.
 The light energy trapping molecules of 
photosynthesis are found in the membranes of
the thylakoids.

Chloroplasts have their own DNA, similar to prokaryotic DNA.
Can synthesize many of their own proteins using prokaryote-like ribosomes'
Synthesize many, but not all, of their own proteins.
Replicate through division similar to prokaryotic cell division.
Chloroplasts can take on other functions.

____________ synthesize and store starch in roots and tubers.

____________ have pigments and give fruits ripened color.

Centrioles - are part of specialized region
of the cell called the centrosome (cell
center) found in animals and most protists.
The centrioles are involved in the 
production of microtubules.
Microtubules have many functions 
including moving chromosomes during
cell division centriole structure - 9 triplets
of microtubules surrounding a hollow core -________________similar to the basal
body of flagella

Cytoskeleton - scaffolding of proteins that
transport materials, position and move
organelles, maintain and change cell shape,
and organize enzymes into functional associations 3 components - actin filaments, microtubules, and intermediate filaments.

All are polymers of smaller protein subunits - lengthen through addition of polymer subunits, shorten through
actin filaments - involved in cell movements and in membrane
deformations - smallest components of the cytoskeleton.

microtubules - hollow tubes made of
proteins called tubulins responsible for cell
movements and movements of organelles
within the cytoplasm, movement of
chromosomes during cell division -
largest components of the cytoskeleton.

intermediate filaments- 8 stranded protein fibers - play a role in
cell structure, anchoring organelles and in transport of materials within the cytoplasm anchor neighboring cells to each other in tissues.

Flagella and Cilia - cellular appendages can propel cells or propel materials over the cell surface cells that have flagella have few (usually 1 or 2) cells that have cilia have many - covering the surface flagella move with whip-like movements to propel the cell
cilia have a more regular stroke and groups of cilia appear to
move in unison, resulting in a wave-like motion flagella 5 to 20x longer than cilia

Structure has basal body with 9 + 0 structure of microtubules
flagellum is membrane bound with pairs of microtubules in a 9+2
pattern.

Each pair of tubules has short arms of another protein - dynein -
that extend to neighboring tubules movement of the flagellum is produced by sliding of the microtubule pairs 

Plant Cells have, in addition to the collection of organelles found
in other groups, a central vacuole for storage and for producing
________ pressure inside the the cell.

The central vacuole is usually filled with water and solutes. A high solute concentration draws water into the vacuole, expanding the vacuole and the cell.

Because plant cells are enclosed by a cell
wall, the expansion of the vacuole can 
exert pressure on the cell without causing
the cell to burst.

Plants have cell walls made of cellulose.

During cell division plant cells build
dividing walls between the two new
cells called the cell plate. An adhesive
layer - the middle lamella - is laid down
between the new cell walls.

Cell walls can be thickened through the
addition of materials to the inside of the
primary cell wall.

Where did Eukaryotic Cells come from?
The oldest rocks with evidence of fossil
cells date to 3.5 billion years. The oldest
rocks with cells large and complex enough
to be eukaryotic date to 1.0 billion years.
For 2.5 billion years only prokaryotic cells
existed on earth.
The best hypothesis for the origin of
eukaryotic cells was proposed by Lynn
Margulis in the early 1970s. This
hypothes is now called the ___________
 ___________. 

Eukaryotic cells appear to be the product
of a collaboration among different types
of prokaryotic cells. Some prokaryotic
cells became the host for other prokaryotic
cells that lived inside them. Some of the 
complex organelles of eukaryotes provide
evidence for this theory.

Mitochondria and chloroplasts appear to
be the direct descendants of energy
producing bacteria. Mitochondria are the
descendants of bacteria that were capable
of oxidative respiration.

Chloroplasts are the descendants of
photosynthetic bacteria.

Evidence:
Both have their own DNA and ribosomes
that are similar to those found in
prokaryotes. Both make many of their
own proteins and both multiply in a
fashion similar to prokaryotic cell division.
Both are double membrane organelles -
the inner membrane descended from the
ancestral guest cell, and the outer
membrane descended from the vacuole
membrane that was formed around the
guest.
Other organelles may also be the product
of endosymbiosis.
Some centrioles and basal bodies have
naked DNA as part of their structure.
There are many modern examples of
endosymbiosis involving organisms that
can live together or live independently.
The same was probably true of the
ancestors of endosymbiotic organelles
in the distant past.

How Much Water Do You Know Water Inside Your Body?

20 Interesting and Useful Water Facts

1. Roughly 70 percent of an adult’s body is made up of water.

2. At birth, water accounts for approximately 80 percent of an infant’s body weight.

3. A healthy person can drink about three gallons (48 cups) of water per day. 1 Gallon = 3.7854118 liters . A gallon is comparable to 3.8 liters. One Liter is a little more than a quart in liquid measurement.

4. Drinking too much water too quickly can lead to water intoxication. Water intoxication occurs when water dilutes the sodium level in the bloodstream and causes an imbalance of water in the brain.

5. Water intoxication is most likely to occur during periods of intense athletic performance.

6. While the daily recommended amount of water is eight cups per day, not all of this water must be consumed in the liquid form. Nearly every food or drink item provides some water to the body.

1. Soft drinks, coffee, and tea, while made up almost entirely of water, also contain caffeine. Caffeine can act as a mild diuretic, preventing water from traveling to necessary locations in the body.
2. Pure water (solely hydrogen and oxygen atoms) has a neutral pH of 7, which is neither acidic nor basic.
3. Water dissolves more substances than any other liquid. Wherever it travels, water carries chemicals, minerals, and nutrients with it.
4. Somewhere between 70 and 75 percent of the earth’s surface is covered with water.
5. Much more fresh water is stored under the ground in aquifers than on the earth’s surface.
6. The earth is a closed system, similar to a terrarium, meaning that it rarely loses or gains extra matter. The same water that existed on the earth millions of years ago is still present today.

1. The total amount of water on the earth is about 326 million cubic miles of water.
2. Of all the water on the earth, humans can used only about three tenths of a percent of this water. Such usable water is found in groundwater aquifers, rivers, and freshwater lakes.
3. The United States uses about 346,000 million gallons of fresh water every day.
4. The United States uses nearly 80 percent of its water for irrigation and thermoelectric power.
5. The average person in the United States uses anywhere from 80-100 gallons of water per day. Flushing the toilet actually takes up the largest amount of this water.
6. Approximately 85 percent of U.S. residents receive their water from public water facilities. The remaining 15 percent supply their own water from private wells or other sources.
7. By the time a person feels thirsty, his or her body has lost over 1 percent of its total water amount.
8. The weight a person loses directly after intense physical activity is weight from water, not fat.

10 Reasons to Drink Water

1. Water is absolutely essential to the human body’s survival. A person can live for about a month without food, but only about a week without water.


2. Water helps to maintain healthy body weight by increasing metabolism and regulating appetite.


3. Water leads to increased energy levels. The most common cause of daytime fatigue is actually mild dehydration.


4. Drinking adequate amounts of water can decrease the risk of certain types of cancers, including colon cancer, bladder cancer, and breast cancer.


5. For a majority of sufferers, drinking water can significantly reduce joint and/or back pain.


6. Water leads to overall greater health by flushing out wastes and bacteria that can cause disease.


7. Water can prevent and alleviate headaches.


8. Water naturally moisturizes skin and ensures proper cellular formation underneath layers of skin to give it a healthy, glowing appearance.


9. Water aids in the digestion process and prevents constipation.


10. Water is the primary mode of transportation for all nutrients in the body and is essential for proper circulation.

Reverse Osmosis  

Reverse osmosis was developed as a water treatment method more than 40 years ago. The process first arose as a technique of desalinating seawater. Once the method’s decontaminating capabilities were recognized, reverse osmosis systems began to be commercially produced for home water purification purposes. Such systems were installed in homes as early as the 1970s. Reverse osmosis systems seemed a viable option to the more costly and energy-wasteful distillation units.

  The Process: The reverse osmosis process depends upon a semi-permeable membrane through which pressurized water is forced. Reverse osmosis, simply stated, is the opposite of the natural osmosis process of water. Osmosis is the name for the tendency of water to migrate from a weaker saline solution to a stronger saline solution, gradually equalizing the saline composition of each solution when a semi-permeable membrane separates the two solutions. In reverse osmosis, water is forced to move from a stronger saline solution to a weaker solution, again through a semi-permeable membrane. Because molecules of salt are physically larger than water molecules, the membrane blocks the passage of salt particles. The end result is desalinated water on one side of the membrane and a highly concentrated, saline solution of water on the other side. In addition to salt particles, this process will remove a select number of drinking water contaminants, depending upon the physical size of the contaminants. For this reason, reverse osmosis has been touted as an effective drinking water purification method.

Pros and Cons:
Reverse osmosis is a valuable water purification process when mineral-free water is the desired end product. Most mineral constituents of water are physically larger than water molecules. Thus, they are trapped by the semi-permeable membrane and removed from drinking water when filtered through a reverse osmosis system. Such minerals include salt, lead, manganese, iron, and calcium. Reverse osmosis will also remove some chemical components of drinking water, including the dangerous municipal additive fluoride.

Although reverse osmosis does extract several contaminants from drinking water, its removal capabilities are not ideally suited to the challenges of the municipally treated water that the overwhelming majority of people receive. Municipal water contains such contaminants as chlorine and volatile organic chemicals (VOCs). Because these contaminants are physically smaller in size than water, the semi-permeable membrane cannot prohibit them from passing through with the water. Thus, they remain in drinking water.

Reverse osmosis, also, by removing alkaline mineral constituents of water, produces acidic water. Acidic water can be dangerous to the body system, causing calcium and other essential minerals to be stripped from bones and teeth in order to neutralize its acidity. Trace elements of minerals were intended to be in water; their removal leaves tasteless, unhealthy drinking water.

Reverse osmosis, although it is less wasteful than distillation, is still an incredibly inefficient process. On average, the reverse osmosis process wastes three gallons of water for every one gallon of purified water it produces. 

 Distillation 

 The process of distillation has been known and used for millennia. Although it has primarily been employed as a method of producing alcoholic beverages like whisky and vodka, distillation also works as a technique of water purification. In the 1970s, distillation was a popular method of home water purification, but its use is now largely confined to science laboratories or printing industries.

The Process:

The distillation process utilizes a heat source to vaporize water. The object of distillation is to separate pure water molecules from contaminants with a higher boiling point than water. In the distillation process, water is first heated until it reaches its boiling point and begins to evaporate. The temperature is then kept at a constant. The stable temperature ensures continued water vaporization, but prohibits drinking water contaminants with a higher boiling point from evaporating. Next, the evaporated water is captured and guided through a system of tubes to another container. Finally, removed from the heat source, the steam condenses back into its original liquid form. Contaminants having a higher boiling point than water remain in the original container. This process removes most minerals, most bacteria and viruses, and any chemicals that have a higher boiling point than water from drinking water. For this reason, distillation is sometimes valued as a method of obtaining pure drinking water.

Pros and Cons:
Distillation, similarly to reverse osmosis, provides mineral-free water to be used in science laboratories or for printing purposes, as both functions require mineral-free water. It removes heavy metal materials like lead, arsenic, and mercury from water and hardening agents like calcium and phosphorous. Distillation is often used as the preferred water purification method in developing nations, or areas where the risk of waterborne disease is high, due to its unique capabilities to remove bacteria and viruses from drinking water.

Distillation has several qualities that make it undesirable for the purification of municipally treated water, especially when compared to the decontamination capacities of water filters. Although distillation processes remove mineral and bacterial drinking water contaminants, they do not remove chlorine, chlorine byproducts, or VOCs. These chemicals, which have a lower boiling point than water, are the major contaminants of municipally treated water. Most dangerous metals and bacteria are removed from water prior to its arrival at a home’s plumbing system. Thus, a distillation system, targeted at the removal of these contaminants, is unnecessary and irrelevant for most people.

Distillation, like reverse osmosis, provides mineral-free water that can be quite dangerous to the body’s system when ingested, due to its acidity. Acidic drinking water strips bones and teeth of valuable and essential mineral constituents.

Furthermore, distillation is an incredibly wasteful process. Typically, 80% of the water is discarded with the contaminants, leaving only one gallon of purified water for every five gallons treated.

Filtration

 Water filters have a long history as a method of water purification, beginning as early as 2000 b.c.e. in ancient Egypt. Filtration has evolved from the simple Hippocratic sleeve of ancient Greece, made from cloth, to the complicated solid block carbon and multimedia water filters currently on the market. Hippocratic Sleeve - A simple water filter designed by Hippocrates of ancient Greece. The filter consisted of a cloth sleeve through which water was poured. Water filtration is now the premier method of water purification, removing more water contaminants, more efficiently, than any other technique.

The Process:  

 The filtration process involves some type of filter media, over which water flows. This filter media blocks passage of contaminants through physical obstruction, chemical adsorption, or a combination of both processes. Material construction of the filter media varies widely, but the most effective medias are made from carbon or a combination of carbon with other elements. Modern filtration technology allows water filters to remove more and more contaminants through the chemical process of adsorption. In the adsorption process, contaminants are encouraged to break their bond with water molecules and chemically adhere to the filter media. Generally, water goes through several stages of filtration to ensure that each filter media will remove the ultimate number of contaminants. Water normally passes through a water filter at a relatively low speed, in order to ensure adequate contact time with the filter media. Once the water has passed through the required stages of filtration, it emerges as pure drinking water, free from contamination.

Pros and Cons:
Unlike reverse osmosis and distillation process, water filters are not limited in the type or size of contaminants they can remove. Thus, water filters are able to remove far more contaminants than any other purification method. Also, because they use the chemical adsorption process, water filters can selectively retain healthy trace minerals in drinking water.

Filtration is the only one of the three water purification methods that is capable of removing chlorine, chlorine byproducts, and VOCs from drinking water. Chlorine and VOCs are the most dangerous and threatening contaminants of municipally treated drinking water. Besides the removal of these dangerous chemicals, water filters also extract from drinking water the chlorine-resistant protozoa giardia and cryptosporidium. These protozoa have plagued the water treatment industry for several decades and have caused a number of epidemics of severe gastrointestinal disease, contracted through drinking contaminated water. 

Cryptosporidium - A chlorine-resistant protozoan that makes its way into municipal water facilities. The protozoan can cause severe gastrointestinal illness. Giardia - A chlorine-resistant protozoan that makes its way into municipal water facilities. The protozoan can cause severe gastrointestinal illness. 

Water filters, because they do not require the costly energy sources of reverse osmosis and distillation, provide a source of relatively inexpensive, purified water. Also, water filters waste very little water, as compared to reverse osmosis and distillation systems.

Depending upon the type of filter used, water filtration may be a less than ideal form of water purification. For example, granular filters do not utilize the chemical adsorption process, allowing several contaminants to pass through the filter media. Likewise, rapid water filters allot water inadequate contact time with the filter media, limiting the number of contaminants that may be removed. Solid block carbon filters solve both of these problems by using both adsorptive and slow filtration processes. Solid block carbon filters are absolutely the best and most effective water filters available.

Phthalate - Phthalate is a colorless liquid that has a bitter, disagreeable taste. It is a synthetic substance that is commonly used to make plastics more flexible.

VOCs - Volatile Organic Chemicals. VOCs are synthetic chemicals dissolved in water—such as insecticides or herbicides—which vaporize at low temperatures.


WWF - World Wide Fund for Nature. The WWF is a global organization with several offices throughout the world. Its goal is to protect and preserve environmental resources.