Biomolecules 5 Flashcards
what are enzymes what is their structure
Almost all enzymes are proteins.
An enzyme like any protein has a primary structure, i.e.,
amino acid sequence of the protein. An enzyme like any protein has the
secondary and the tertiary structure. When you look at a tertiary structure
(Figure 9.4 b) you will notice that the backbone of the protein chain folds
upon itself, the chain criss-crosses itself and hence, many crevices or
pockets are made.
what is the pocket or crevice
The active site is the crevice or pocket in the enzyme where the substrate molecule gets binded or attached. Thus enzymes,
through their active site, catalyse reactions at a high rate.
differentiate organic enzyme ( biocatslyst) and inorganic catalyst
organic
-proteinaceous
-get denatured at high temperature and pressure
-involved in biological or biochemical reacns
inorganic
- inroganic
- remains effective at high temps
- involved in industrail aprocess
are there any heat resistant enzymes
However, enzymes isolated from organisms who normally
live under extremely high temperatures (e.g., hot vents and sulphur
springs), are stable and retain their catalytic power even at high
temperatures (upto 80°-90°C). Thermal stability is thus an important
quality of such enzymes isolated from thermophilic organisms.
what are ribozyme
Sometimes nucleic acids( RNA) can also act as enzymes. they help in pepetid ebond formtaion
what are chemical and physical reacn
-physical reacn is just a change in shape without breaking bonds. aolso change of state of matter
- chemocal reacns involve breaking of bonds as well as formation of new bonds resulting in newly formed products.
what is the rate of reacn
Rate of a physical or chemical
process refers to the amount of product formed per unit time.
Rate =δP/δt
how is reate of reacn afftected by temperature
Rates of physical
and chemical processes are influenced by temperature among other
factors. A general rule of thumb is that rate doubles or decreases by half for every 10°C change in either direction.
When enzyme catalysed
reactions are observed, the rate would be vastly higher than the same but
uncatalysed reaction. explain with example
CO2 + H2O <—– carbonic anhydrase—–> H2CO3
In the absence of any enzyme this reaction is very slow, with about
200 molecules of H2CO3
being formed in an hour. However, by using the
enzyme present within the cytoplasm called carbonic anhydrase, the
reaction speeds dramatically with about 600,000 molecules being formed
every second. The enzyme has accelerated the reaction rate by about 10
million times.
what is a metabolic pathwqy
A multistep chemical reaction, when each
of the steps is catalysed by the same enzyme complex or different enzymes,
is called a metabolic pathway.
give an example of metabolic pathway
C6H12O6 + O2 → 2C3H4O3 + 2H2O
metabolic pathway in which glucose becomes pyruvic acid
through ten different enzyme catalysed metabolic reactions. At this
stage you should know that this very metabolic pathway with one or two
additional reactions gives rise to a variety of metabolic end products. In
our skeletal muscle, under anaerobic conditions, lactic acid is formed.
Under normal aerobic conditions, pyruvic acid is formed. In yeast, during
fermentation, the same pathway leads to the production of ethanol
(alcohol). Hence, in different conditions different products are possible.
what is a subtrate
The chemical which is converted into a product is
called a ‘substrate’.
substrate ‘S’ has to bind the enzyme at
its ‘active site’ within a given cleft or pocket. The substrate has to diffuse towards the ‘active site’. There is thus, an
obligatory formation of an ‘ES’ complex. E
stands for enzyme. This complex formation is
a transient phenomenon. During the state
where substrate is bound to the enzyme active
site, a new structure of the substrate called
transition state structure is formed. after the expected bond breaking/making is
completed, the product is released from the
active site. In other words, the structure of
substrate gets transformed into the structure
of product(s). The pathway of this
transformation must go through the so-called
transition state structure.
what if reacn is endothermic or exothermic
If ‘P’ is at a lower level than ‘S’, the reaction
is an exothermic reaction. One need not supply energy (by heating) in
order to form the product. However, whether it is an exothermic or
spontaneous reaction or an endothermic or energy requiring reaction,
the ‘S’ has to go through a much higher energy state or transition state.
what is activation energy
For an y reacn to occur, some amount of minimum start up energy is required for the substrate molecule tof orm the enzyme-substrate complex, which is the first stage of the Transition state leading to the fomrtation of a specific product. This start up energy is called activation Energy.
Since there are many chemical reacns taking place within a living system, there is an enormous demand for energy which cannot be fulfilled by any living system.
Enzymes increase the kinetic energy of substrate molecule and leading them to collide, forming the enzyme-substrate complex.
enzymes lower activation energy required for a n reacn ti start.
