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					                  CELLS AND CELL PROCESSES InfoPacket

                SECTION 1: CELL PARTS AND FUNCTIONS
                          The Nucleus controls the cell. It holds all the genetic material known as
                          chromosomes (which are made up of DNA). The nucleus functions as the ―brain‖
                          of the cell. Inside the nucleus is the Nucleolus. This structures main function is to
                           make ribosomes. Ribosomes main function is to make the proteins for the cell.
                            These are floating around the cell and attached to the Rough endoplasmic
                            reticulum (giving the adjective ―rough‖). A cell may have as many as 500,000
                            ribosomes. On the outskirts of the cell is the Cell Membrane. This is a structure
                           made up of two layers of phospholipids and serves many purposes. The cell
                         membrane gives the cell its shape, holds the cytoplasm within the cell, and controls
what                   moves into and out of the cell. Within the cell membrane is a gelatinous (or jelly-like)
liquid known as the Cytoplasm. This is where most of the cell's chemical reactions
take place and it stabilizes the organelles. Vacuoles are found in both animal and
plant cells, however play less of a role in animal cells. Vacuoles are liquid-filled
and can be used to store food, water, minerals, or wastes. It is considered the
―stomach‖ of the cell. In plants it also plays a critical role in stiffening the stems by
creating turgor pressure (water pressure that holds up the cell walls). See image to
the right. Without a full vacuole, plants can wilt. Cell Walls are also in plant cells
as well as bacteria. It forms a thick covering outside the cell membrane and gives
                       the plant support and shape. In plants, cell walls are made up of polysaccharide known
                       as cellulose which is used for many things such as making paper, shampoo and is an
                       excellent source of fiber. Also only found in plant cells are Chloroplasts. This
                       organelle is the place where photosynthesis takes place and contains chlorophyll which
                       gives the plants its green color. The cell needs energy and gets it from the powerhouse
                       of the cell, also known as the Mitochondria. This structure produces energy in the
                       form of ATP. The Endoplasmic Reticulum – is an extension of the nuclear
                       membrane and can connect it with the cell membrane. Its main purpose is to process
                       lipids and proteins. Don’t worry about remembering the different functions for the
                       smooth and rough, just know the rough ER is studded with ribosomes. Centrioles are
found only in animal cells, is used in cell reproduction to help the chromosomes arrange before cell division.
There are roaming ―garbage trucks‖ known as Lysosomes that digest, kills and transports waste. The Golgi
apparatus is considered the ―post office‖ of the cell because it ―packages‖ (surrounds) cell molecules in
lipids so they can be used in the
cell. The cytoskeleton is make
up of microfilaments and
microtubules that give the sell
structure as well as help
mechanically to move the cell
by moving the flagella, pili, or
cilia.

CELL PARTS PRACTICE:
Label the parts with the
correct terms
                     SECTION 2: MEMBRANE TRANSPORT
THE CELL MEMBRANE - The cell is
surrounded by a lipid bilayer (―bi-‖
means two meaning there are two layers of
phospholipids) membrane that is SEMI-
PERMABLE. This membrane protects
the cell and also regulates what goes in the
cell and what leaves the cell. Nutrients
and fluids are constantly moving in and
out of the cell and it’s the membrane’s responsibility to filter the needs of the cell. This lipid bilayer
membrane is made up of two layers of phospholipids. The hydrophilic (likes water) heads of the lipids face
the inside (intracellular) fluid and outside (extracellular) fluid of the cell while the hydrophobic (fears
water) tails attract each other. Refer to the diagram of the membrane above.

DIFFUSION– imagine a bunch of atoms in one space. They are constantly moving and bumping off one
another. Naturally, would they stay close to each other or spread out? The molecules will naturally spread
out because they are bouncing off each other. They are trying to reach a state called equilibrium – where
the molecules are equally spread out. Molecule naturally move along a concentration gradient. A
concentration gradient is simply a difference in concentration of molecules in a space. Molecules will move
from a high concentration of molecules (too crowded) to a low concentration of molecules (they have more
space to roam). IMAGINE – you are walking into a elevator and there is a rude man lighting a cigar. Before
he lights the cigar, the air is at equilibrium – all the air molecules are separated equally. He lights the cigar,
takes a puff, and releases it into the air. The action created a concentration gradient: there are more
molecules (higher concentration) close to the cigar and fewer molecules (lower concentration) everywhere
                                   else. With time, the smoke diffuses to spread to the areas of lower
                                   concentration until the entire elevator reaches a smelly equilibrium where the
                                   smoke molecules are even throughout the space. The smoke went with the
                                   concentration gradient. This process requires no energy and is called
                                   PASSIVE TRANSPORT. With the same idea, when molecules are moving
                                   across a membrane, they will go to where there are fewer molecules. For
                                   example, the diagram below shows there are less molecules on the inside
                                   than the outside, so the molecules
                                   will passively diffuse inside the
                                   cell.


ACTIVE TRANPORT – in contrast to passive transport, active
transport requires energy because you are going AGAINST a
concentration gradient. For example: IMAGINE - you have an
empty trunk. It takes no energy to simply toss some clothes in there
when it is empty. However, when it gets fuller and fuller to the
point where clothes are hanging over the side, it gets harder and
harder (takes more energy) to stuff clothes inside the trunk. This is
the same as the cell. Look at the diagram below. Say the cell
requires more calcium inside the cell to create more proteins, but
the outside of the cell has fewer than the inside. The cell will have
to use ATP (energy) to force the molecules inside the cell (going
against the gradient). It takes energy to go against, no energy to go
with.
FACILITATED DIFFUSION – you are going to want to read this since we didn’t discuss this in class.
Facilitated diffusion is used when a molecule cannot diffuse over the membrane due to its size, shape or
solubility. Proteins that lie in areas of the cell membrane work as bridges for these molecules to cross the
membrane. This is still passive transport so facilitated diffusion is going with the concentration gradient
and no energy is needed.

OSMOSIS – is a type of diffusion, so it is PASSIVE
transport. However, osmosis refers ONLY to the diffusion
of water molecules. More specifically, osmosis happens
across a semi-permeable membrane like the cell membrane.
Water molecules are attracted to IONS (charged atoms).
An example of an ion is SALT. REMEMBER: SALT
SUCKS! Water will always flow in the direction of the
higher concentration of salts or toward denser liquids full
of solutes (including sugars). The water will dilute the area
of higher concentration of salts.
        Let us use the Egg Lab as an example. After we
took off the shell, with our few samples that didn’t break, we put water on top of one egg and maple syrup on
top the other. The egg itself has a certain concentration of salts, solutes and water within its membrane
(which is semi-permeable). When we added the water to the egg, the salts INSIDE the egg attracted the
water and pulled the water inside the egg. As a result, the egg became bloated like a water balloon. When
we added the syrup to the egg, the concentration of solutes was higher on the OUTSIDE of the egg’s
membrane, so the solutes in the syrup sucked the water that was inside of the egg to outside. As a result, we
had more liquid left inside the cup than we started with and the egg itself has shriveled up. The water in the
egg was pulled out by the syrup.
                                                                  We are going to use this same lab to discuss
                                                          tonicity – which in its simplest form means relative
                                                          concentrations of liquids separated by a semi-
                                                          permeable membrane. See diagram to left. When
                                                          comparing liquids, if one liquid has MORE solutes
                                                          (higher concentration - which means it has less
                                                          water) it is considered HYPERtonic. If one liquid
                                                          has LESS solutes (lower concentration - which
means it has more water) it is considered HYPOtonic. If the concentrations are equal, it is ISOtonic. In the
Egg lab, the water was hypotonic compared to the liquid inside the raw egg. The syrup was hypertonic to the
liquid inside the egg. Now you can think of osmosis in one of two ways: Water is moving to side that has
less water OR Water is moving to the side with the higher concentration of solutes. Both of these statements
are correct. Follow which explanation works for you, but try not to get them confused.

                                       EGG LAB DIAGRAMS




               WATER                                                      SYRUP
                             SECTION 3: MICROBIOLOGY
 Bacteria are microscopic organisms categorized under prokaryote. Because they are prokaryotes, they do not
 have a nucleus or any membrane bound organelles. Bacteria not only coexist with us all the time, but help
 us do an amazing array of useful things like make vitamins, break down garbage, and even maintain our
 atmosphere. Bacteria consist of only a single cell, but don't let their small size and seeming simplicity fool
 you. They have the ability to help and destroy. As we discussed in class, bacteria can be harmless,
 beneficial or harmful.
         Examples of beneficial bacteria are the E. coli in our intestines that help with digestion and the
 probiotics in yogurt that aid in regularity. Bacteria are also used to preserve and make many products we use
 on a daily basis such as vinegar, coffee, milk, pickles, etc. harmless and beneficial bacteria make up the vast
 majority of known prokaryotes. The smaller portion, harmful bacteria, are considered to be PATHOGENIC
 (or disease causing) and can cause much devastation. Examples of pathogenic bacteria are Yersinia pestis –
 the bacteria carried by rodents and fleas that killed 1/3 of the Europe population during the bubonic plague;
 Clostridium botulinium that was used as a deadly weapon during World War 2 that paralyzed and killed
 soldiers which is currently used to perk up faces of insecure actors and has-been models; and Bacillus
 anthracis, the white power substance known as ANTHRAX that causes respiratory failure and was used to
 scare Americans through the mail after the attacks in New York.
         Some bacteria are rod-shaped (these are called bacilli), some are round (called cocci, like
 streptococcus bacteria), and some are spiral-shaped (spirilli). These shapes help name some bacteria;
 Bacillus anthracis is a BACILLI or rod-shaped bacteria. Bacteria have been found that can live in
 temperatures above the boiling point and in cold that would freeze your blood. They "eat" everything from
 sugar and starch to sunlight, sulfur and iron. There's even a species of bacteria—Deinococcus radiodurans—
 that can withstand blasts of radiation 1,000 times greater than would kill a human being.

 MEMBRANE TRANSPORT PRACTICE:                                   MICROBIOLOGY PRACTICE
 1. Why do you think you feel thirsty after eating       1. What do we call disease causing bacteria?
    salty foods?                                         2. What are some good things bacteria can do for the
 2. Why do slugs die when you pour salt on them?                world?
 3. Why is salt water bad for you, even deadly at        3. What shape would lactobacillus acidophilus be?
    some amounts???                                      4. Are most bacteria harmless, beneficial or harmful?
 4. What is a lipid bilayer and what purpose does it     5. What are some examples of beneficial bacteria?
    have in the cell?                                           Harmless? Harmful?
 5. What would happen if the cell membrane was           6. Know the diagram of the prokaryote in your notes
    fully permeable?                                            (practice diagram on a later page)
 6. What is facilitated diffusion and why is it          7. List some differences between animal cells and
    important?                                                  bacterial cells.

EXTRA PRACTICE QUESTIONS
1. It’s structure is an extension of the nuclear         8. Yersinia pestis causes what disease?
   membrane                                              9. What does the golgi apparatus do?
2. It provides turgor pressure for plant cells           10. How do you know if a solute is soluble? What
3. type of transport that requires no energy but needs       does it mean to be insoluble?
   help from a protein to enter cell                     11. A balloon has a semi-permeable membrane. If I
4. Exhaust from a car is what kind of diffusion?             put a water ballon in a bucket of salt water, what
5. This type of cell doesn’t have membrane bound             would happen to the balloon? Draw it and label
   organelles                                                what sides are hypotonic/hypertonic and which
6. This type of cell has cell walls                          way water is flowing.
7. E. coli is what type of bacteria? (think hard, not    12. What is the significance of the Ring Around the
   obvious answer).                                          Rosie song?

				
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