Short Answer Questions – work check

Unit 1 Objectives:

Unit 1 Objectives
1. The inner body temperature of humans is an excellent illustration of homeostasis. When a
person is fit, their body temperature stays near around 98.6 degrees Fahrenheit (37
degrees Celsius). Humans are warm-blooded organisms and can regulate their internal
temperature to maintain a comfortable range. Your body temperature typically fluctuates
by a few degrees if you’re resting in the summer heat or enjoying the winter snow. That is
an instance of homeostasis in action. Whether you feel shivering in the cold or
perspiration in the heat, your body is attempting to preserve equilibrium.
2. Specificity: Every transport protein exclusively attaches to/transports a specific category
of chemical.
Example: The antibody-antigen interaction is an instance of a protein-ligand combination
whose binding action could be very selective. Generally, affinity maturation results in
extremely specialized interactions, whilst naïve antibodies are promiscuous as well as
attach a greater number of ligands.
Competition: When two highly related molecules with a similar structure attach to the
similar transport protein, the substance with the higher concentrations or that adheres
quite easily will travel through the membrane quicker.
Example: Thrombin joins thrombomodulin (TM) at anion binding exosite 1, an allosteric
region located distant from the active region of thrombomodulin. A monoclonal antibody
(mAb) that fights with TM for attaching to thrombin had been isolated.
Saturation: The pace of transport is restricted to the carrier proteins that are accessible.
After all binding spots are taken, the speed stays stable. For instance, if a protein has two
binding spots for the single ligand and therefore is “50% saturated,” just one of the 2
spots would be filled by ligand on mean in the total protein populace; in alternative terms,
just half the spots will be filled, thus Ya = 0.5, or 50%.
3. Enzyme specificity: • Enzymes are certain biological catalysts which could accelerate the rate of a
reaction by lowering the activation energy of a reaction.
• Activation energy is the energy that is required to reach the transition state.
• So, enzymes could convert reactants/substrates into products by lowering the
activation energy.
• Enzyme specificity is the ability of an enzyme to choose its correct substrate.
• There c
could be several similar molecules, so an enzyme should be able to
bind specifically to its own substrate.
• The mechanism is mainly molecular based on structural complementarity.
• Like a lock and key enzyme must have correct substrate.
• So, an enzyme must be very specific in selecting the substrate and the reaction
which is to be catalyzed.
Enzyme competition:
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It is a type of enzyme inhibition
When certain molecules bind to enzymes its activity lowers and that is called
enzyme inhibition.
It could be reversible or irreversible.
In reversible inhibition, the enzyme inhibitor binding would be very weak (weak
interactions).
In irreversible, once bound the inhibitor cannot be released.
Enzyme competition is a type of reversible inhibition.
Here inhibitor and the substrate are structurally similar hence there would be a
competition between them to bind to the enzyme’s active site.
Enzyme saturation
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So, in a system when all the available enzymes are bound to its substrate and no
free enzyme is available, we could call it enzyme saturation.
• So, this happens when substrate concentration is high as enzyme concentration.
4. Fluid mosaic model.
a. It is the most widely accepted model which explains the architecture of cell
membrane.
b. It was proposed by Singer and Nicholson in the year 1972.
c. According to them, the plasma membrane is a two-dimensional Quasi fluid
system or solution, which contains lipids and membrane proteins.
d. Quasi fluid is the dynamic state of plasma membrane.
e. The membrane lipids and proteins could undergo lateral diffusion.
f. The lipids/phospholipids are continuously arranged like two parallel rows of
sheets, hence known as lipid bilayer.
g. Phospholipids have a polar head and non-polar tail; it is oriented in such a way
that the polar head faces toward the aqueous phase and the non-polar fatty acid
chain forms a hydrophobic barrier
h. The membrane lipids and proteins interact with each other and provide stability.
5. Tonicity and osmolarity are two notions that are similar but not identical. Tonicity and
osmolarity are both measuring the concentrations through the semi-permeable
membranes. Through a semipermeable membrane, tonicity measures just the
concentration of non-penetrating solutes. However, in the case of osmolarity, the total
concentration of penetrating and non-penetrating solutes is measured.
a. Osmolarity
i. The osmotic pressure of a solution is measured by its osmolarity.
ii. It’s an approximate estimate of how much solute is in a solution.
b. Tonicity
i. It refers to the ratio of solute particle concentration inside a cell to the
concentration outside the cell.
6. SIMPLE DIFFUSION, FACILITATED DIFFUSION and ACTIVE TRANSPORT are
discussed together since they are almost similar. Only some differences are present.
a. Similarities:
i. Ions crosses cell membrane for transport.
ii. The concentration gradient is present.
b. Differences:
i. In simple diffusion, no need for membrane channels and membrane carrier
proteins, and lipophilic molecules crosses the cell membrane.
ii. In facilitated diffusion-Requires Membrane channels, lipophobic
molecules cross the cell membrane via channel proteins and lipophilic
molecules via the cell membrane.
iii. In Active Transport-Requires Membrane carrier proteins, ATP molecules
as source of energy for moving ions against a concentration gradient,
lipophobic and lipophilic molecules cross the cell membrane.
7. The cell needs channels for passive transport by diffusion which does not require any
career protein and transport through a concentration gradient. The cell needs career
proteins for transport by facilitated diffusion and active transport also. The substances
which can’t directly transport through channels can be transported by these proteins with
concentration gradient as in facilitated diffusion and against concentration gradient as in
active transport.
8. Specificity, saturation, and competition are the three distinguishing features of a receptorligand interaction. Carrier-mediated transport exhibits specificity, competitiveness, and
saturation.
Specificity refers to the ability of a transporter to transfer either one form of molecule or
only a set of closely associated molecules. The transporter cannot just transfer some sort
of molecule. An example of precision is the GLUT transporter that is unique for naturally
occurring 6-carbon monosaccharides.
Competition refers to substrates interacting with one another for binding sites on the
transporters.
Saturation is where there is a small number of carriers. In a set number of carriers, as the
substrate concentration increases, the transport rate increases up to a cap, the point at
which all carrier binding sites are loaded with the substrate. At saturation, carriers are
operating at their optimum rate, and a further rise in substrate concentration would have
no effect.
9. The core concept of flow-down gradients is also a general model of how things, whether
animate or inanimate, move in the physical world. Flow is the movement of stuff (small
molecules, ions, blood, air, heat) from one point in a system to another point in a system.
Flow occurs because of the existence of an energy gradient between two points in the
system. The magnitude of the flow is a direct function of the magnitude of the energy
gradient that is present – the larger the gradient, the greater the flow. Happens
spontaneously. Four Major Types of Gradients in the Body:
a. Pressure Gradients
b. Concentration Gradients
c. Electrical Gradients
d. Thermal Gradients
10. Artificial cell communication is based on a well-established scientific understanding of
biological cell signaling, referring to a cell’s ability to receive, process, as well as transmit
messages. Although signals can come from anywhere, cell-to-cell interaction requires
four elements: a sender as well as a recipient cell, a signal, as well as a medium through
whom it can travel. The sender cell creates, codes, and sends a message that travels via a
medium and prompts a reaction in a recipient cell via transduction signaling cascades that
decipher and analyze the message. Cells perceive and utilize a wide range of signals,
comprising electrical impulses, mechanical stimuli, and heat, although chemical signaling
is the most common type of cell communication, in which diffusible chemical
messengers operate as signals to communicate data. Cells are very complex chemical
systems capable of easily synthesizing, degrading, and processing substances via
biochemical or adhesion processes.

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