Category: Biology Questions

Mitochondria refer to the membrane-bound organelles that are present in the eukaryotic cell’s cytoplasm, which produces adenosine triphosphate (ATP) that is the primary energy molecule utilized by the cells.

While talking about mitochondria, it is essential to get familiar with everything concerning it. Let us begin with the definition first.

What are Mitochondria?

Mitochondria are well known by the name “powerhouse of the cell”. These are the double membrane-bound organelle that is usually found in most eukaryotic organisms inside the cytoplasm and essentially work as a cell’s digestive system.

Mitochondria play a crucial role in breaking down the nutrients while generating energy-rich molecules for the cells. Several biochemical reactions involved in cellular respiration occur within the mitochondria.

The term mitochondrion is derived from the Greek words namely “mitos” and “chondrion”, which means thread and granules like respectively.

Why is Mitochondria known as the powerhouse of the cell?

It is because these are the cell’s organelles that are further responsible for producing ATP and the energy currency of the cell.

Structure of Mitochondria

Here in the diagram, the points mentioned refers to

• 1 for granules
• 2 for ribosomes
• 3 for Cristae
• 4 for Inter membrane space
• 5 for Matrix
• 6 for ATP Synthase Particle
• 7 for Inner membrane
• 8 for Outer Membrane
• 9 for Deoxyribonucleic Acid (DNA)

While talking about the structure of mitochondria, it has a double membrane and a rod-shaped structure that is found in both animal and plant cells.

• Its size ranges from 0.5 to 1.0 micrometre in diameter.
• Its structure includes an inner membrane, an outer membrane, and a get-like material known as a matrix.
• Its inner and outer membrane are comprised of proteins and phospholipid layers separated by intermembrane spaces.
• The outer membrane covers the mitochondrion’s surface and has a large number of porins that are unique proteins.
• It is freely permeable to nutrients, molecules, ions, AP molecules, and energy molecules like ADP.

Mitochondria Functions

An essential function of mitochondria is to produce energy via the oxidative phosphorylation process. However, apart from this important function, it is also involved in the following processes.

1. It regulates a cell’s metabolic activity
2. It promotes the cell multiplication and growth of new cells.
3. It plays an essential role in programmed cell death or apoptosis.
4. It helps in detoxifying the ammonia in the liver cells.
5. It is also responsible for building specific parts of the blood and several hormones like oestrogen and testosterone.
6. It facilitates in maintaining the calcium ions adequate concentration with several compartments of the cell.
7. It is also involved in several cellular activities like cell signalling, cellular differentiation, cell senescence, cell growth, and controlling the cell cycle.

However, any irregularity in mitochondria functioning can directly affect human health, but it is challenging to identify that as symptoms may vary from person to person. And the disorders can be pretty severe in several cases that it can even lead to causing the organ to fail. Several mitochondrial disorders include Barth syndrome, Alpers diseases, Kearns Sayre Syndrome.

Enzymes are the well-known magical proteins essential for life. But how do these enzymes’ function? How do they catalyze only specific biochemical reactions? How do they speed up biochemical reactions so quickly? But before that, let us start with the definition.

What are enzymes?

Enzymes refer to the biological molecules that act as catalysts and aid the complex reactions to take place everywhere in life.

For instance, you ate a piece of meat. Then proteases will go to function and facilitate them breaking down the peptide bonds among the amino acids. So, does that mean that all the enzymes break down all the substances? Well, no, since the enzymes are specific catalysts, so they function to complete one task.

Functioning of enzyme

Like all the other catalysts, enzymes function by lowering down the chemical reaction’s activation energy.

A substance that speeds up the chemical reaction devoid of being a reactant is known as a catalyst. The catalysts for the biochemical reactions that occur in living organisms are known as enzymes. And enzymes are proteins.

While considering the enzyme’s functioning, enzymes perform a crucial task of lowering down the activation energy of a reaction that refers to the amount of energy that must be used to put in for a reaction to begin. Activation energy basically refers to the energy required for a chemical reaction.

Enzymes function by binding to reactant molecules and holding them so that the chemical bond-forming and bond-breaking processes take place more readily.

The reaction represented here by this graph is a combustion reaction that involves the reactants Oxygen and Glucose. And the reactants products here are Water and Carbon Dioxide, and energy is also released during it.

The enzymes here speed up the reaction by lowering down the activation energy required to begin.  Compare the activation energy levels with and without enzymes.

Enzymes Action

Enzymes bring the reactants together so that they do not have to expend the energy to move until they collide at random.

Enzymes bind both the reactant molecules known as substrates at a site on enzyme molecules known as an active site.

By binding the chemical reaction’s reactants at an active site, enzymes also position the reactants appropriately so that they do not have to overcome the intermolecular forces that would push them apart otherwise.

This step enables the molecules to interact even with less energy.

They may also enable the reactions to take place in diverse pathways that have lower activation energy levels.

Here in the below-mentioned diagram, the active site is specific for biochemical reaction’s reactants, the enzyme catalysts, and just like the puzzling pieces fitting together, the active site only binds particular substrates.

These enzyme molecules bind the reactant molecules known as substrates at their active site forming an enzyme-substrate complex. This, in turn, brings up the reactants altogether and then positions them appropriately so the reaction can take place.

After the reaction completion, the products are released from the enzyme’s active site, which frees up the enzyme so that it can catalyze the other reactions.

However, the activities of these enzymes depend on the ionic conditions, the pH of the surroundings, and the temperature. Several enzymes function best at acidic pH while, in contrast, other function best in neutral environments.

Cells are the fundamental and structural unit of life that is also known as the most basic and smallest biological unit of living organisms. Based on the cellular organization, cells are further classified as prokaryotic and eukaryotic. But the animal and plant cells fall under the eukaryotic category.

What are animal cells?

An animal is defined as the type of eukaryotic cell that lacks a cell wall and has a true membrane-bound nucleus and several other organelles.

Key points about animal cells

• Animal cells range a few microscopic microns to a few millimetres in size.
• The shape of animal cells varies.
• The giant animal cell is an ostrich egg that can stretch over 5.1 inches and weighs about 1.4 kilograms.

Four main components of an animal cell

• Cell membrane

A cell membrane is also known as the plasma membrane that is found in the cells. It separates the cell’s interior from the outside environment. Cell membrane performs the essential function of allowing the movement of molecules in and out of the cell. It also regulates the materials transportation exiting or entering the cell.

• Nucleus

The nucleus comprises genetic information or DNA. It controls and regulates the cell’s activities. It carries the structures and genes that contain genetic information.

• Cytoplasm

The cytoplasm is the water-based filing of the cell. It is basically a semi-fluid substance of a cell that is internal to the cellular membrane and external to the nuclear membrane, which is further described as the non-nuclear content of protoplasms. In the case of the eukaryotes, the cytoplasm component contains all the organelles.

• Mitochondria

Mitochondria create the energy for cells through respiration. Mitochondria are basically the membrane-bound cell organelles that produce most of the chemical energy required to power a cell’s biochemical reactions. The chemical energy generated by the mitochondria is stored in a small molecule known as adenosine triphosphate (ATP).

Apart from these, the Structure of an animal cell includes several components. An animal cell is generally smaller than plant cells. A typical animal cell consists of several cell organelles. These include

• Nuclear Membrane

A nuclear membrane is a double membrane structure that surrounds the nucleus.

• Centrosome

A centrosome is a small organelle located near the nucleus that has a thick centre with radiating tubules.

• Lysosome

Lysosomes are round-shaped organelles that are surrounded by a membrane containing the digestive enzymes that aids in digestion, cell renewal, and excretion process.

• Golgi Apparatus

It’s a smooth layered, flat, and sac-like organelle located near the nucleus. It is involved in storing, manufacturing, transporting, and packing the particles throughout the cell.

• Ribosome

Ribosomes are tiny organelles made up of RND-rich cytoplasmic granules.

• Vacuole

A vacuole is a membrane-bound organelle present within a cell that is involved in storing water, food wastes, maintaining shapes, etc.

• Endoplasmic Reticulum

The endoplasmic reticulum is a cellular organelle that consists of a thin and winding network of membranous sacs coming from the nucleus.

• Nucleopore

Nucleopore are the tiny holes present within a nuclear membrane that are involved in nucleic acid and protein’s movement within a cell.

Respiration refers to a biochemical process where an organism’s cells acquire energy by combining glucose and oxygen, resulting in the release of ATP, Water, and Carbon Dioxide.

Respiration releases the energy from glucose in ATP form that occurs in all the living cells. The respiration process occurs in all living cells.

Aerobic respiration that is with oxygen releases more energy as compared to anaerobic respiration that is without oxygen.

Both anaerobic and aerobic respiration involves the chemical reaction that takes place in the cell to produce energy, and this energy is essentially required for the active processes.

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Aerobic respiration

Aerobic respiration refers to respiration using oxygen to break down the food molecules. The glucose molecule is the primary respiratory substrate that is used for respiration. It is oxidized to release its energy.

The general word equation for aerobic respiration is denoted as

Glucose + Oxygen ———–> Carbon Dioxide + Water + Energy released

Symbol equation for aerobic respiration

C6H12O6 + 6O2 ——–> 6CO2 + 6H2O

Respiration is generally a series of processes, but this equation summarizes the overall process.

During a respiratory process, the first stage occurs in the cell’s cytoplasm, but most of the energy is generally released in the mitochondria. In contrast, in the aerobic respiration process, 38 ATP molecules of chemical energy are produced.

While talking about aerobic respiration, anaerobic respiration is not separate as both of them take place in the cell to produce energy. So, let us get familiar with anaerobic respiration also.

Anaerobic Respiration

Many organisms cannot respire devoid of oxygen, but several tissues and organisms can continue to respire even if the oxygen runs out. These tissues and organisms use the anaerobic respiration process.

During this type of respiration, glucose oxidation is incomplete, and therefore the reaction requires less energy. The energy needed by anaerobic respiration is about a nineteenth of energy release during the aerobic respiration process. And only two ATP molecules are generated.

Even human muscles can respire anaerobically but for shorter time periods only.

Here the glucose is converted into lactic acid

Glucose ———> Lactic Acid + Energy released

The word equation for anaerobic respiration is denoted by

Glucose ———-> Ethanol + Carbon Dioxide + energy released

Anaerobic respiration takes place only in the cell’s cytoplasm.

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Difference between aerobic and anaerobic respiration

RNA and DNA, both carry genetic information but there are a few key differences between them. But before moving to key differences let us first get familiar with the definitions.

What is DNA?

DNA is an acronym for Deoxyribonucleic acid is a nucleic acid, which functions as the original blueprint for protein synthesis. It comprises the phosphates, sugar deoxyribose, and a unique sequence of nitrogenous bases guanine (G), adenine (A), thymine (T), and Cytosine (C).

What is RNA?

RNA is an acronym for Ribonucleic acid is a nucleic acid that is directly included in protein synthesis. It is an essential nucleotide with nucleic acids long chains present in all the living cells.

RNA’s primary role is to act as a messenger that conveys instructions from DNA for controlling the synthesis of proteins.  It comprises phosphates, the sugar ribose, and nitrogenous bases including guanine (G), Adenine (A), Uracil (U), Cytosine (C).

RNA and DNA share the nitrogenous bases G, C, and A. But thymine is usually present in DNA only whereas Uracil is present in RNA only.

Key differences between RNA and DNA

The primary difference between the competitive and non-competitive Inhibition is that the binding of the inhibitor to the active enzyme’s site refers to the competitive Inhibition whereas, in the case of non-competitive Inhibition, it refers to the inhibitor binding to enzyme at a point other than the active site.

We will get through all the differences between competitive and non-competitive Inhibition but first, let us go through its definitions.

What is competitive Inhibition?

Competitive Inhibition refers to a type of reversible Inhibition where the inhibitor molecules bind to the enzyme’s active site. For this binding to happen, the inhibitor molecules have to compete with substrate molecules, and therefore, the inhibitor molecules’ conformation is similar to the substrate molecule.

Also, they are chemically similar to substrate molecules, and therefore, they can bind to the enzyme active site chemically. However, the inhibitor molecule binding blocks the enzyme’s active site resulting in substrate accumulation while increasing the substrate concentration.

What is non-competitive Inhibition?

Non-Competitive Inhibition refers to a type of reversible Inhibition where the inhibitor molecules bind to the enzyme-substrate complex at an allosteric site other than the active one. In this type, the inhibitor molecule binding to the allosteric site results in a conformation modification in the enzyme’s active site.

It changes the active site’s specificity to a corresponding substrate while making the active site unavailable for the binding process. As the non-competitive inhibitors do not directly compete with the substrate, they do not even modify the substrate concentration.

Key Differences between competitive and non-competitive Inhibition

Bottom Line!

Competitive Inhibition is a reversible enzyme inhibition where the inhibitor competes with the substrate to bind the enzyme’s active site and increases the substrate’s concentration.

On the contrary, the non-competitive Inhibition is also a reversible enzyme inhibition where the molecules bind to the enzyme-substrate complex at some other site instead of the active site and change the active site’s conformation while dissociating the enzyme-substrate complex before the formation of the product.

Therefore, the primary difference between both is the type of binding of the inhibitor molecule to the enzyme.