Testing cohesion

Cohesion is a term that scientists use to say that something sticks together, for example, water is very cohesive. Water molecules tend to be attracted to each other. In a recent lab we did in class, we tested how far we could push water cohesion!

In the first lab we tried to cut water in half with a toothpick. First, I put a couple drops of water onto a piece of wax paper. Then, when I tried to cut the water with the toothpick, the water won. The cohesion with the water is what made the water win because the water really likes itself :).


During the second part of the lab we saw how many droplets of water we could get onto a penny. The results were very close in numbers. The max we could fit onto the penny was about 40-43. Again, that proves that water likes water!


The third part of the lab, we tested how fat you could fun water down a string to get from one end to the other end. When we mastered one length of string, you could get a longer piece of string and once mastered that, then you get a longer string, etc. Water sticks to itself thats all thats to it.

And in this lab, we learned that water always will stick to itself by cohesion.

Bugs and corn lab

With this lab,  we used a virtual simulation to gather info and interpret data. This dealed with growing two different types of corn in two different ways in pods. Then we added bugs to the different pods and also the amount of bugs were different then we just watched the corn grow over a period of 140 days that were simulated. After the corn grew you picked the corn and weighed it and last but not least we put the data in the table that we had and recorded it all. This lad taught me that there are different effects on corn from bugs and the amount of them.

Cell Membranes

Cell membranes are a barrier to most substances, and this property allows materials to be concentrated inside cells, excluded from cells, or simply separated from the outside environment. This iscompartmentalisation is essential for life, as it enables reactions to take place that would otherwise be impossible. Eukaryotic cells can also compartmentalise materials inside organelles. Obviously materials need to be able to enter and leave cells, and there are five main methods by which substances can move across a cell membrane:

1. Lipid Diffusion
2. Osmosis
3. Passive Transport
4. Active Transport
5. Vesicles     
   
   
   
   
   
   
   Lipid Diffusion:        
   
   
   a passive diffusion process, no energy is involved and substances can only move down their concentration gradient. Lipid diffusion cannot be controlled by the cell, in the sense of being switched on or off.
   
   
   
   
   Osmosis:
         
   
   
   Osmosis is the diffusion of water across a membrane. It is in fact just normal lipid diffusion, but since water is so important and so abundant in cells (its concentration is about 50 M), the diffusion of water has its own name - osmosis. 
   
   
   
   
   Passive Transport:     
    
   
   
   Passive transport is the transport of substances across a membrane by a trans-membrane protein molecule. The transport proteins tend to be specific for one molecule (a bit like enzymes), so substances can only cross a membrane if it contains the appropriate protein.
   
   
   
   
   Active Transport:  
       
   
   
   
   
   Active transport is the pumping of substances across a membrane by a trans-membrane protein pump molecule. The protein binds a molecule of the substance to be transported on one side of the membrane, changes shape, and releases it on the other side.
   
   
   
   
   Vesicles:
       
   The processes described so far only apply to small molecules. Large molecules (such as proteins, polysaccharides and nucleotides) and even whole cells are moved in and out of cells by using membrane vesicles.
   
   

Biomolecules

A biomolecule is any of the organic molecules produced by living organisms.

	Carbohydrates	Fats	Protein
Simplest form	Monosaccharides	· Saturated fatty acids Unsaturated fatty acids  · Glycerol	Basic unit: amino acids
Structure/ Types	· Monosaccharides: single sugar molecules, reducing sugars  · Disaccharides:double sugar molecules  · Polysaccharides: made from condensing many similar monosaccharides	· Neutral fats and oils  o Monoglyceride  o Diglyceride  o Triglycerids: contains 1 glycerol and 4 fatty acid molecules  · Phospholipids:  o Hydrophilic head and hydrophobic tail (polar molecules) form a lipid bilayer – plasma membrane  o Consist of organic group, phosphate group, glycerol and fatty acid	· Primary: Amino acids linked to form a polypeptide chain  · Secondary: Polypeptides are folded in various ways  · Tertiary: Folding of secondary structure into a complex shape  · Quarternary: Aggregation of polypeptide chains (alpha, beta chain, prosthetic group)
Function/Role	· starch: concentrated form of energy  · form supporting structures (e.g. cellulose cell wall)  · formation of nucleic acids  · synthesis of lubricants  · Fibre: Provides bulk to intestinal contents  · Aids in peristalsis	· Effective source and storage of energy  · Insulating material as it is just under the skin  · Solvent for fat soluble vitamins (A, D, E, K) and hormones (eg: sex hormones)  · Restricts water loss from surface of the skin  · Constituent of protoplasm, especially in membranes	· Source of energy  · Catalytic (enzymes)  · Transport  · Structural role in cells: synthesis of protoplasm (growth and repair of worn out cells  · Formation of antibodies to combat diseases
Bonds	Glycosidic bonds	Tryglycerides – Ester bonds	· Amino acids - Peptide bonds  · Fibrous protein- Hydrogen bond  · Globular protein – disulfide bond
Properties		· Group of organic compounds with an oily, greasy or waxy consistency  · Insoluble  · Water repelling	· Fibrous  o Water insoluble  o Parallel polypeptide chains  · Globular  o Easily water soluble
Molecular formular	CnH2nOn	R-COOH or CH3(CH2)nCOOH
Deficiency			· Kwashiokor  · Edema
Excess		Obesity