Enzymes and stuff.

Objs:
-What are enzymes
- Describe models to illustrate functions
-What do enzymes do?

Starch + Water = Amylase = Maltose

Lipid + Water = Lypase = Fatty Acid + Glycerol

Protein + Water = Protease = Amino Acids

Sucrose + Water = Sucrase = Fructose and Glucose

Maltose + Water = Maltase = Glucose

Big molecules being broken down into smaller ones = hydrolysis reaction, hydro: there should therefore, before the reactant should be water.

Substrate reacted with an enzyme = Products.

Enzyme = Biological Catalyst = speeds up reaction in living organisms

The body produces Hydrogen Peroxide. It is toxic for us, but we have an enzyme, catalayse, which breaks it down to make water and oxygen.

Molecules have more kinetic energy, collide more, but this is by heating. Can't heat up hydrogen peroxide, is in body, is why enzymes are handy.

An enzyme works by lowering the acitivation energy needed, which is a barrier to the rate of reation, therefore, the enzymes speed it up. (See catalyst.)

What do enzymes do?

Speed up reactions by lowering activation energy needed, which acts as a barrier.

Why are Enzymes Catalysts?

Substrate Energy is always higher then product energy. The barrier gets lowered with an enzyme. Enzymes are catalysts as they lower the activation energy required to drive a reaction.

The nature of Enzymes:

They are globular proteins. Globular proteins have a globular shape. If the shape is wrong, it won't function properly, if the tertiary structure is wrong. The tertiary fold relies on primary, as it is defined by the sequence of amino acids.

Enzymes are usually quite large, only a small area is important though. The active site: a specific shape due to the way it folds up. If something affects the active site, the enzyme will not be functional.

Enzyme + Substrate = Enzyme Substrate Complex + Products.

The substrate and enzyme have COMPLIMENTARY shapes. Like jigsaw pieces, they fit together, but they aren't identical.

At the end, the enzyme is unchanged and can be reused, whereas products diffuse away.

Enzyme + Substrate = Enzyme Substrate Complex, REACTION TAKES PLACE = Enzyme + Products.

Enzymes are:

• Proteins of high molecular weight.
  
• A bio-catalyst.
  
• Sensitive to temperature changes.
  
• Sensitive to pH
  

Enzyme and substrate have to hit at right force AND be of complimentary shape.

Models...

Lock and Key model, 1894, if there's not a specific key in the lock, the door won't open style metaphor. In an enzyme catalysed reaction the enzyme bonds to the substrate to form a complex.

Induced Fit Model, a glove is vaguely the same shape as a hand, when a hand is in the glove the fit 'induces' to fit it. Explains that the enzyme changes shape, and takes into account that they have some flexibility.

Once the substrate has bound to the enzyme, that bind tells the enzymes to change the shape to therefore become a perfect fit. Therefore, a reaction can't take place until the induced fit has happened.

Oh, and this was a side note, 'Saw chancges take place with x-ray defraction, therefore, better model.' Don't have a clue what I was on about. Suggestions?

-Nin.

A homework that I thought may be of use. Osmosis and that,

Active Transport - is energy requiring transport of molecules pr ions against a concentration gradient. It needs energy from respiration. An example is the resorption of Na in the kidney.

Exocytosis - is a process exporting large molecules from the cell. A secretory vessel is formed, and it is a type of bulk transport. An example of this is the secretion of digestive enzymes by cells in the pancreas.

Facilitated Diffusion- is diffusion through hydrophyllic protein channels. A protein carrier transports the molecules down a concentration gradient. It is a passive process. An example is the movement of glucose into cells.

Osmosis- is the net movement of water molecules down a water potential gradient through a partially permeable membrane. It is a passive process. An example of this is a red blood cell losing water when placed in a hypertonic solution.

Simple diffusion - is the net movement of molecules from a region of higher concentration to lower concentration down a concentration gradient. The molecules or ions move down a concentration gradient. Therefore it is a passive process. An example of this is the movement of respiratory gases between the alveoli and blood capillaries.

Phagocytosis- is the uptake of solid material into a cell. It is a type of bulk transport and a phagocytotic vessle is formed. An example of which is a white blood cell engulfing bacterium.

Pinocytosis- is the uptake of liquid into cell. It is a type of bulk transport, and small vacuoles or vesicles are formed. An example of this is a human egg taking up nutrients that surround it.

Proteins and Protein Structure. :D

Two types of proteins, Globular and Structural.

Enzymes are catalysts that specifically increase reaction rates by as much as 10 (to the power of) 6. They are proteins. Other examples are Regulatory Proteins, Contractile and Motile Proteins, which allow cell and tissue movement. Actin and Mysoin in muscles. Protective Proteins, like antibodies. The little sea creatures, muscles, have proteins that allow the to attach to rocks. Fish have proteins that allow them to swim if freezing temperatures. Hemoglobin is in red blood cells, it transports oxygen to tissues, and Fibrin aids in blood clotting.

Amino Acids are the building blocks of proteins. They are monomers. 'Mono' means 'Single'. 'Mer' means 'Unit'. (Can you kinda see how the name applies?)

A chain of these is a polypeptide. 'Poly' meaning many.

Some proteins can be more then one polypeptide. Like Hemoglobin which is four combined together.

Lipids aren't polymers, they are big, but aren't lots of repeating units.

Amino Acids...

• Carbon
• Nitrogen
• Oxygen
  
• Hydrogen.
  

All have those basic elements. Some many have different ones such as Sulfur or Phosphorus.

Approximately 20 naturally occurring amino acids exist, so there is huge variation in polypeptide chains.

The basica structure of a amino acid is as follows: On the left, an Amino group (Nitrogen, with 2 single bonded hydrogen.) This is singley bonded to a Carbon, which is single bonded to a hydrogen, the R Group, which I will desribe next, and on the right, singley bonded to a Carboxylic Acid group. (As said before this is a singley bonded carbon and 'OH' with a double bonded oxygen.

The R group is the variable. It vaires from one amino to the next to give the different function or proerties. It can be as simple as just 'H' (Glycine), or CH3 (Adenine). They give different, specific properties like size, shape, charge, etc.

They are joined in a condensation reation. (Read a few posts below for my comment about those.)

The way they bond is that a bond goes from the carbonto the nitrogen in the condensation reaction. This is called a peptide bond.

Two amino acids joining together is a Dipeptide.


So, comment and coreect me or whatever. Critism is welcomed, help is to. Aiming for an A in this overall so any useful info is good. D:
-Nin. ^__^

Homework Notes. :D Mito and such.

Mitochondria:

1. Site of respiration that produces ATP.
   
2. Epithelial Cells use a lot of respiration due to active transport.
   
3. They are for absorption and products of digestion, this is the purpose of the cell, mito aids this.
   

Bile: Neutralises stomach acid, making the conditions alkaline, This allows the enzymes in the small intestine to work properly ,as they one work in small pH ranges.

Conditions of Centrifugation:

1. Cold: Reduces the ezyme activity that could damage organelles. Also stops bacterial Growth.
   
2. Isotonic: Maintains same water potential inside and outside of cell to prevent it from bursting or shrinking.
3. Buffer: To maintain pH, as enzymes only work in a certain pH range.
   

You divide by 1000 to get um into mm

Stuff about osmosis, water potential and active transport, in a big bulk of notes. ^_^

Distilled water has a higher water potential. It would be less of a negative water potential then in say... potato cells. Therefore, it diffuses in by osmosis, and the potato cells would swell and become turgid.

Turgid is once again, another one of those happy words that examiners would seem to dote on. xP

Yay. (:

Sucrose has a lower water potential then in the same potato cells, therefore, water would diffuses out of the potato cells by osmosis, and the cells will shrink and become plasmolysed. (Yes, that is another of those 'words'.)

Anymore water diffusing in by osmosis on a cell that has reached maximum turgidity will be forced the opposing pressure of the cell wall.

In sucrose, little or no water would remain in these potato cells. The cell wall would not be able to shrink any further.

The rate of change would be determined from an initial part of a graph as the initial part is linear, so it will be constant, and as time goes on the water potential of the cell will change and therefore slow, so it would be easier to compare all from the beginning.

Active Transport :

With diffusion, osmosis and facilitated diffusion, they are all passive, and it moves in/out of the cell. Active transport is different in that it is not passive, it requires ATP (see previous posts), it is definitively more complex, and it goes against a concentration gradient.

It is carrier assisted, which means protein carriers are present. It requires energy to move the molecules against their concentration gradient.

What whats to go through, fits on to the carrier with the specific gap/shape. The ATP comes along and splits into ADP + Pi + energy. The energy attaches and changes the shape, and then the thing that wants to go through goes through.

Endocytosis means going in ti the cell. If it is a solid it is called phagocytosis, and if it is a liquid/fine suspension, it is pinocytosis. Exocytosis means going out of the cell.