Enzymes Video Review

Enzymes are biological catalysts that speed up chemical reactions without being changed in the end. This is achieved by the enzymes providing an alternative pathway with a lower activation energy. Activation energy is the minimum amount of energy needed for a reaction to occur. This can be seen using an energy profile diagram. Most enzymes are protein molecules although some are RNA molecules called ribozymes.

Enzymes are important as they allow metabolic reactions necessary for the sustenance life to occur in seconds. Without them, these reactions would occur to slow for life to be sustained. During these reactions the substrate’s bonds are broken to form the product. The highest energy arrangement of atoms that contains a structure intermediate between that of the reactants and products is referred to as the Transition State. The distinctive features of enzymes include their catalytic power, their regulation and their specificity. The number of molecules of substrate converted to product per enzyme molecule per second is called the turnover number or Kcat.

Enzymes are named based on their substrates, based on the action they perform and some just end in ‘ase’. Enzyme names usually end in ‘ase’, however there are a few exceptions. They are given numbers called enzyme commission numbers (EC), based on their class, subclass and sub-subclass. There are six classes of enzymes, oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases, each with categorizing functions. Enzymes need non-protein components to help them work called cofactors. This can be subdivided into inorganic cofactors and organic cofactors. Organic cofactors can be transiently associated in which case they are Cosubstrates or permanently associated in which case they will be Prosthetic groups.

Apoenzyme- inactive protein part

Cofactor- non-protein part

Haloenzyme- active enzyme

The apoenzyme with the cofactor gives the haloenzyme .

Inorganic catalyst can be compared to enzymes by looking at industrial processes such as the haber and contact process .These inorganic catalysts, unlike enzymes which work at normal body temperature, require very high temperatures and pressures in order to work. Enzymes are more efficient and due to their specificity and like inorganic catalysts, they do not have any side reactions occurring, thereby ensuring 100% product manufacture. Inorganic catalyst cannot be regulated are may be poisonous.

This video was very informative and well put together. I appreciated the use of colour to highlight important point and also as a separator, as a person who gets bored quickly it helps. there was one badly coloured part however, the equation with sucrose, where I found it difficult to follow, and had to really focus to read it. I’m not sure if this was the intention of the individual, but if so, mission accomplished. the beginning of the video was also a bit unclear as I could not clarify the names of the scientist being mentioned and therefore went on a google hunt with the bits of name that I could make out. I would have also preferred if the photo of the scientist was a little bigger, although I am aware that they are not apart of the major topic, but I would have still preferred to see their ingenious faces. Generally I enjoyed the video, despite these one or two issues, it did what it was intended to which makes it very successful in my eyes.

Enzyme Classes – Shhhhh!!! Class is in session. . .

Six major classes of enzymes

enzyme classes wordle

Oxidoreductases – catalyses oxidation- reduction reactions

Transferases – catalyses the transfer of C,Nor Pcontaining groups

Hydrolases – catalyses the cleavage of bonds by the addition of water

Lyases – catalyses the cleavage of certain C-C, C-S and certain C-N bonds

Isomerases – catalyses the racemization of optical and geometrical isomers

Ligases – catalyses the formation of bonds between carbon and O, S, N coupled to hydrolysis of high energy phosphate. 


Enzyme inhibitors are molecules that bind to enzymes and decrease the velocity of enzyme-catalysed reaction. There are irreversible inhibitors that permanently bond to enzymes through covalent bonds, as well as    reversible inhibitors that temporarily bond through non-covalent bonds. Reversible inhibitors comprise of competitive, non-competitive, mixed and uncompetitive inhibitors.

Competitive Inhibitor



  • Similar shape to substrate
  • Binds to active site
  • Vmax (max velocity) remains the same
  • Km increases

Non-competitive Inhibitor



  • Does not resemble substrate
  • Binds either to free enzyme or enzyme substrate complex (ES)
  • Vmax decreases
  • Km remains the same

Mixed Inhibitor

  • Binds the same as a noncompetitive inhibitor, either to the free enzyme or ES cmplex, except the EIS cmplex has residual enzymatic activity.
  • Vmax decreases
  • Km  can either increase or decrease



Uncompetitive Inhibitor

  • Binds ONLY to the EIS complex
  • Both Vmax and Km are reduced by the same amount








                                                                                                                                       FIGURE 4.





6 – type of enzyme with more than one active site

8 – inhibitor that produces residual enzyme activity

9 – inhibitor that binds to the ESI

11-non-protein components that help enzymes work

12-substances that diminishes velocity of an enzyme-catalysed rxn

13-catalyses chemical reactions

14-molecular recognition based on structural complementarity


1 – enzymes are what type of biological molecule

2 – binds with active site to form product

3 – point at which all active sites are occupied with substrate

4 – inhibitors that bind permanently

5 – catalyses cleavage of bonds by addition of water

6 – location where substrate binds

7 – numerically equal to the [s] at which rxn velocity is equal to half vmax

10-number of moles of substrate converted to product per enzyme mol per second 



Carbohydrates are the most abundant class of organic compounds found in living organisms. They originate as products of photosynthesis, an endothermic reductive condensation of carbon dioxide requiring light energy and the pigment chlorophyll.

n CO2   +   n H2O   +   energy      CnH2nOn   +   n O2

Bio-significance of carbohydrates

  • Energy Source
  • Structure
  • Precursor Molecule
  • Storage

What are monosaccharides?

Monosaccharide is a simple sugar consist only of one unit. They serve as building blocks for more complex carbohydrate forms.

Examples:Glucose, Fructose and Galactose

Ribose and Deoxyribose – they are constituents of nucleic acids, ribonucleic acids (RNA) and deoxyribonucleic acids (DNA)

What are disaccharides?
Disaccharides are a group of sugars composed of two monosaccharide groups linked together through covalent bonds.
Examples: Maltose, Sucrose and Lactose
What are polysaccharides?
Polysaccharides are complex carbohydrates composed of numerous monosaccharides combined through the loss of water molecules.
Examples:Starch, Amylose, Amylopectin, Glycogen

The Cell Theory- The Wacky History of the Cell Theory

As a person with a short attention span I always need to find ways to spice up my studying. As it was stated in this video, “if something bores you, DIG DEEPER!!!“, you’ll probably find out something awesome!

I enjoyed researching the cell theory, but for you guys who couldn’t help falling asleep, please take in this video. You’ll be glad you did cause its kinda funny lol and who can’t resist animations. The narrations were my favorite part, so listen up and enjoy learning……I surely did.

Summary for yall who still didn’t get it :


• Plants are composed of cells
• Animals are composed of cells
• Cells originate from pre-existing cells

Although the cell theory was researched and developed by many different scientist feeding off of each other’s ideas, there were three main cofounders -:

• Matthias Schleiden
• Theodor Schwann
• Rudolf Virchow

Matthias Schleiden (15th April 1804-23rd June 1881) was a German botanist who preffered to study the structure of plants under the microscope. In 1838 he wrote, “Contributions to Phytogenesis”, in which he stated that the different parts of plant organisms are composed of cell or cell derivatives. He later concluded that plants were made up of cells.

Theodor Schwann (7th Dec 1810- 11th Jan 1882) was a German physiologist who advanced the cell theory in plants and moved over to animals. In 1839 he proposed that all organisms are composed of cells.

Rudolf Virchow was a German doctor, anthropologist, pre-historian, pathologist and politician (seems to me like somebody was a bit indecisive) who stated that all cells arise from cells. He showed that cells originated from pre-existing cells.









Radiation source(source of illumination) is light

Radiation source is electrons
Wavelength – 400-700nm Wavelength – about 0.005nm
Lens are made of glass Lens is electromagnetic
Not affected by magnetic fields Affected by magnetic fields
Max magnification 1500-2000 X Max magnification 1,60,000 to 2,50,000 X
Resolving power 0.1 – 0.2 nm Resolving power 200 – 300 nm
Image is coloured Image is black and white
Can view living cells

Living tissues destroyed by intense electron beams


The major difference in practice is the resolution– the amount of detail that can be discerned in the image.