Ch.5 The Working Cell

WHY DO CELLS USE ATP WHEN SUGAR MOLECULES HAVE MORE ENERGY?

Cells use sugars because all of energy origins are from glucose. However the cell breaks down the glucose and stores the energy in ATP. The reason why it stores energy in ATP is that because the cell can only use a little bit of energy to work at one time. Therefore, if it just directly uses glucose to do work, there will be a large amount of energy released, and all the energy it cannot use will just escape as heat. So by storing the energy in smaller amounts in ATP, not as much energy is wasted as heat.

HOW DO ANIMALS AND PLANTS PERFORM OSMOREGULATION?
Osmoregulation keeps the body's fluids from becoming too concentrated. Animals must maintain the right concentration of solutes and amount of water in the body fluids. There is no specific osmoregulation organs in higher plants. Control of water intake and loss means those internal and external factors, which affect the rate of transpiration. Plants share with animals the problems of obtaining water and in disposing of the surplus. Some plants develop methods of water conservation. Xerophytes are plants in dry places. They have better qualities of osmoregulation. Cactus have water stored in large parenchyma tissues so they can get more water. Other plants have leaf modifications to keep water.


WHAT ARE THE DIFFERENCES BETWEEN EXOCYTOSIS AND ENDOCYTOSIS?
Exocytosis is the process by which a cell expels molecules and other objects that are too large to pass through the cellular membrane. Endocytosis is the process by which a cell takes in molecules and other objects that are too large to pass through the cellular membrane. The basic mechanism of those are pretty much the same. Both make use of vesicles for their molecular transport. Vesicles are used for storage and transport. Since they are enclosed by a membrane, inside they can have a completely different composition than that of their cell.

KEY TERMS:
-Diffusion: the tendency for particles of any kind to spread out evenly in an available space, moving from where they are more concentrated to regions where they are less concentrated
-Passive Transport: diffusion across a cell membrane does not require energy
-Fluid Mosaic: the surface appears mosaic because of the protein embedded in the phospholipids and fluid because the proteins can drift about in the phospholipids
-Osmosis: a physical model of the diffusion of water molecules across a selectively permeable membrane
-Aquaporins: the very rapid diffusion of water into and out of certain cells, such as plant cells, kidney clls and red blood cells, is made possible by transport proteins
-Active Transport: moving a solute against its concentration gradient using energy
-Thermodynamics: the study of energy transformations that occur in a collection of matter
-Cellular Respiration: a chemical process that uses oxygen to convert the chemical energy stored in fuel molecules to a form of chemical energy that the cell can use to perform work
-Energy Coupling: the use of energy released from exergonic reactions to drive essential endergonic reactions. It is a crucial ability of all cells
-Cofactors: many enzymes that require nonprotein helpers

SUMMARY:
Membranes are composed of phospholipids and proteins and they are described as fluid mosaic. Phospholipids are made of fatty acids kinks which are unsaturated. Membranes exhibit selective permeability. Non polar molecules cross more easily than polar molecules because polar molecules are not soluble in lipids. Phospholipids can spontaneously self-assemble into simple membranes. Particles move in concentration gradient to less concentration gradient. This movement without energy is called passive transport. Osmosis moves water across a membrane down its concentration gradient until the concentration of solute is equal on both sides of the membrane. Animal cells can maintain their water balance by osmoregulation. However plant and prokaryotic, and fungal cells have different issues because of their cell walls. Cells don't let any substances across the membrane. They require the help of aquaporins. They assist in facilitated diffusion, which is a type of passive transport. In active transport, they move particles against its concentration gradient. They always require the energy in the form of ATP. When cells move large molecules across membrane, they use exocytosis to export bulky molecules, and endocytosis to import substances useful to the livelihood of the cell.
There are two kinds of energy for the capacity to do work and cause change. Kinetic energy for motion and potential for resulting of its location. There are two important laws of thermodynamics. The first law is energy in universe is constant. It cannot be created or destroyed. The second law is energy conversions increase the disorder of the universe. So it cannot be recycled. Exergonic reaction is a chemical reaction that releases energy. Also cellular respiration releases energy and heat and produces products but is able to use the released energy to perform work.
Living things produce many endergonic and exergonic chemical reactions. Those are all called metabolism. One cell mainly does three types of cellular work; chemical work, transport work, and mechanical work. ATP is used when a cell needs energy immediately. It is  renewable source of energy. Energy that is available to break bonds and form new ones is called EA. EA can be speed up by enzymes. They require the certain conditions for them such as temperature, and pH. They also need cofactors and coenzymes. They can be inhibited by competitive inhibitors and noncompetitive inhibitors.

This is a diagram of endocytosis. The plasma membrane takes a particle into a cell, and it will turn a food valuole. Those are the main functions of endocytosis.
-Receive nutrients
-Entry of pathogens
-Cell migration and adhesion
-Signal receptors

This is a diagram of exocytosis. It releases enzymes, hormones, proteins, and glucose to be used in other parts of the body. Also those are the main functions of exocytosis.

• 
  
• -Neurotransmitters (in the case of neurons)
• -Communicate defense measures against a disease
• -Expel cellular waste

5 FACTS:

1) To make the concentration equal, passive transport and active transport occur. Active transport requires energy.

2) Tonicity describes the ability of a solution to cause a cell to gain or lose water.

3) Many substances are necessary for viability of a cell do not freely diffuse across the membrane. 

4) Kinetic energy performs work by transferring water. Example, heat is a kinetic energy associated with the random movement of atoms.

5) The first law of thermodynamics: energy in the universe is constant. It cannot be created or destroyed. The second law of thermodynamics: energy conversions increase disorder of the universe. 

Ch.4 A Tour of the Cell

WHAT ARE THE PROBLEMS WITH SPERM MOTILITY?

Sperm motility is a problem. For example, his sperm shape is different from the other sperm shape, he has too much sperm, and how his sperms move is not right. When he as a fertility problem, it can cause a severe loss of self esteem, not to mention the frustration involved with not being able to have a baby. Knowing what can cause low sperm motility and other fertility problems for men can, however, help a man to know how to proceed with addressing the problem.

WHY DO NOT  ANIMALS PHOTOSYNTHESIZE?

Because if animals do photosynthesize, food chain will not work. Also animals can get energy from eating other organisms. That is why animals don't have cell wall so we can move easily. Plants cannot move, so they need to photosynthesize to get energy. Also animals need O2 to breathe. If we could photosynthesize, we will need CO2, which we produce now, but not use. There would be no O2 for animals to breathe. That is why I think that animals don't photosynthesize, because we don't need to.

WHAT HAPPENS IF A CELL GETS DISEASE?
There are some cell diseases. I am going to answer one of them, Leukemia. Leukemia is a disease that number of white blood corpuscle increases more than number of red blood corpuscle. The numbers those two blood cells will be unbalanced. Thus losing hair, having a fever, out of breath, feeling of less blood, and etc. It is usually caused from smoking, and some how.  There are many cell diseases like that. The reasons why those happen are mostly from genetic.



SUMMARY:
     Robert Hooke first observed cells in 1665. As we know about cells, we developed the microscopes. We have basically 4 kinds of microscopes. Light microscope, works by passing visible light through a specimen which can magnify objects about 1000 times, Electron microscope, uses a beam of electrons, which can magnify up to 100,000 times, Scanning Electron microscope, which can show a specimen with 3D, and Transmission Electron microscope, used to study the details of internal cell structure. Cell theory states that al living things are composed of cells and that all cells come from other cells.
     There are two types of cells. Prokaryotic cells, and eukaryotic cells. Prokaryotic cells compose bacteria and archaea, and eukaryotic cells compose other forms of life. The surface area of a cell is important for carrying out the cell's functions. Cells are all bounded by a plasma membrane. All have chromosomes carrying genes made of DNA. And they all contain ribosomes, tiny structures that make proteins according to instructions from the genes. The entire region between the nucleus and the plasma membrane is called the cytoplasm. There are various organelles in an eukaryotic cell. There are four different life processes in eukaryotic cells; 1) manufacturing 2) breakdown of molecules 3) energy processing, 4) structural support, movement, and communication.
     Phospholipids are the main components of biological membranes. It has two distinct regions; a negatively charged and thus hydrophilic phosphate group and two non-polar, hydrophobic fatty acid tails. Non-polar molecules such as O2 can easily pass through its hydrophobic interior. Some of these proteins form channels that allow specific ions and other hydrophilic molecules to cross the membrane.
     During a cell reproduction, as a cell prepares to divide, the DNA is copied and the thin chromatin fibers coil up. Nuclear envelope controls the flow of materials into and out of the nucleus. It connects with ER. Ribosomes are found in two locations. Free ribosomes are in the fluid of the cytoplasm, while bound ribosomes are attached to the outside of ER or nuclear envelope. Smooth ER is important in the synthesis of lipids. It is a detoxification in liver cells and also a calcium ion storage. Rough ER is a synthesis of membrane lipids and proteins, secretory proteins, and hydrolytic enzymes. It is also a formation of transport vesicles. Cell's structure and activities are organized by internal skeleton. Cytoskeleton supports the cell structure and cell motility. Microfilaments form a 3D network just inside the plasma membrane that helps support the cell's shape. Intermediate filaments serve mainly to reinforce cell shape and to anchor certain organelles. It holds nucleus as well. Microtubules are readily disassembled in a reverse manner and the tubulin subunits can then be reused in the cell. They can grow out from a centrosome. They shape and support the cell and also act as tracks along which organelles equipped with motor proteins can move. Cells have an ability to move. They have cilia which sweep.
     Three types of cell junctions are found in animal tissues. At tight junctions, the membranes of neighboring cells are every tightly pressed against each other, knit together by proteins. Anchoring junctions function like rivets, fastening cells together into strong sheets. Gap junctions are channels that allow small molecules to flow through protein-lined pores between neighboring cells.

KEY TERMS:
-Nucleoid: the region where the DNA of a prokaryotic cells is coiled
-Flagella: longer projections that help attach prokaryotes to surfaces
-Cellular metabolism: many of the chemical activities of cells that occur within organelles
-Chromatin: a material that makes up eukaryotic chromosomes
-Vesicles: the transfer of membrane segments that connect physically the membranes such as endo-membrane system
-Golgi apparatus: a structure of a cell that packages substances and send them out
-Lysosome: a digestive system of a cell
-Vacuole: digestion; storage of chemicals; cell enlargement; controls water balance
-Endosymbiosis: hypothesis of it proposes that mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells
-Granum: a stack for thylakoids

This is a diagram of a cell. As you can see, there are various structures in a cell. Those structures are grouped in four types as I mentioned in summary.

1) Manufacturing

-Nucleus: DNA synthesis; RNA synthesis. Nucleolus is inside.

-Ribosomes: protein synthesis. 

-Smooth ER: produces lipid. Detoxification in liver cells. Calcium ion storage.

-Rough ER: produces mainly protein. Has ribosomes attached. 

2) Breakdown

-Lysosomes: only in animal cells. Digestive system of cells. Recycles food.

-Vacuoles: Digestion. Storage of chemicals, cell enlargement, water balance.

-Peroxisomes: Diverse metabolic processes with breakdown of H2O2 by-product.

3) Energy Processing

-Mitochondria: makes chemical energy. 

-Chloroplasts: only in plant cells and some protists. produces light energy to chemical energy sugars

4) Support, Movement, and Communication Between Cells

-Cytoskeleton: including cilia, flagella, and centrioles in animal cells. maintains cell shape. anchorage for organelles: movement of organelles within cells and also cell itself. mechanical transmission of signals from exterior of cell to interior. communication between cells.

-Extracellular Matrix: only in animal cells. Binding of cells in tissues; surface protections; regulation of cellular activities.

-Cell junctions: communication between cells. binding of cells in tissues

-Cell walls: only in plants, fungi, and some protists. maintains the cell shape and skeletal support. protects surface. binding of cells in tissues.


5 Facts:
1) There are many structures in a cell. They all perform the important functions for a cell.
2) There are two different kinds of cell. Prokaryotic, and Eukaryotic. Prokaryotic cells are simpler than Eukaryotic.
3) Manufacturing, breaking down of molecules, energy processing, and structural support, movement, and communication are the main life process for eukaryotic cells.
4) Animal cells have lysosome and they do not have cell wall. Not having cell walls make it easier for animals to move. They have plasma membrane instead.
5) Plant cells have chloroplast, and cell wall.