Biology for Engineers

Unit 1

1. Give similarities and differences between biology and engineering.

Similarities:

1. Problem-solving: Both disciplines involve problem-solving processes. Biologists and engineers

often encounter complex challenges that require creative and analytical thinking to address.
2. Interdisciplinary nature: Both fields intersect with various other disciplines. Biology integrates
with fields like chemistry, physics, and medicine, while engineering interfaces with physics,
mathematics, and technology.
3. Innovation: Both biology and engineering contribute to innovation. Biologists innovate through
discoveries in genetics, ecology, and biotechnology, while engineers innovate by designing new
technologies, systems, and infrastructure.
4. Research and experimentation: Both biologists and engineers conduct research and experiments
to advance their respective fields. They rely on empirical evidence and data analysis to develop
new theories, technologies, and applications.

Differences:

1. Focus: Biology primarily focuses on the study of living organisms, their structure, function,
behavior, and evolution, while engineering focuses on designing, building, and optimizing
systems, structures, and processes to meet specific needs.
2. Methodology: Biologists often use methods such as observation, experimentation, and statistical
analysis to understand natural phenomena, while engineers employ principles of mathematics,
physics, and design to develop practical solutions.
3. Scale: Biology operates at various scales, from molecular and cellular levels to ecosystems and
the biosphere, while engineering typically deals with macroscopic scales, designing structures,
machines, and systems for human use.
4. Ethical considerations: Biologists often grapple with ethical considerations related to animal
welfare, conservation, and genetic manipulation, while engineers face ethical dilemmas
concerning safety, sustainability, and the societal impact of their creations.

2. Write about the significance of biology.

Biology holds profound significance in our lives, influencing everything from individual health
to global ecosystems. Here are several key aspects highlighting its importance:

1. Understanding Life: Biology is the study of life and living organisms. It delves into the
structure, function, growth, origin, evolution, and distribution of living organisms. By
comprehending the intricate mechanisms that govern life, we gain insights into our own
existence and the diversity of life on Earth.
2. Health and Medicine: Biology plays a central role in healthcare and medicine. It helps us
understand the causes of diseases, how they spread, and how they can be treated or prevented.
From discovering new drugs to developing vaccines, biology guides medical advancements that
enhance human health and prolong life.
3. Ecological Balance: Biology is essential for understanding ecosystems and the delicate balance
of nature. It helps us comprehend the interdependence of organisms and their environments,
including the flow of energy, nutrient cycles, and the impact of human activities on biodiversity.
By studying biology, we can develop strategies for conservation and sustainable resource
management to preserve the health of our planet.
4. Biotechnology and Innovation: Biology serves as the foundation for biotechnology, which
harnesses biological processes and systems to develop products and technologies that benefit
society. From genetic engineering to bioinformatics, advancements in biology drive innovations
in agriculture, pharmaceuticals, energy, and beyond, addressing pressing challenges and
improving quality of life.
5. Evolutionary Insights: Biology provides insights into the process of evolution, shaping our
understanding of how species adapt and diversify over time. By studying evolutionary biology,
we can trace the origins of life, unravel the evolutionary history of organisms, and explore the
mechanisms driving evolutionary change. This knowledge has implications for fields ranging
from medicine to conservation biology.
6. Ethical Considerations: Biology raises ethical questions regarding our treatment of living
organisms, including humans, animals, and plants. Issues such as genetic engineering, cloning,
and biodiversity conservation prompt ethical debates about the responsible use of biological
knowledge and technology, highlighting the need for ethical frameworks to guide scientific
research and technological development.

3. Draw similarities between eye and camera functions

The eye and a camera share several similarities in their functions, despite being quite different in
their structures. Here are some parallels:

1. Lens: Both the eye and a camera have a lens that focuses incoming light onto a sensitive surface.
In the eye, this surface is the retina, while in a camera, it's the film or digital sensor.
2. Iris: The iris in the eye and the aperture in a camera control the amount of light entering the
system. They adjust their size to regulate the intensity of light reaching the sensitive surface.
3. Retina/Sensor: The retina in the eye and the sensor in a camera capture the incoming light and
convert it into electrical signals. These signals are then processed by the brain in the case of the
eye and by electronic circuits in the case of the camera.
4. Focus: Both systems can adjust their focus to bring objects at different distances into sharp
focus. In the eye, this is achieved by changing the shape of the lens, while in a camera, it's done
by moving lens elements or adjusting the distance between them.
5. Depth of Field: Both the eye and a camera can control their depth of field, which determines
how much of the scene is in focus. This is influenced by factors like aperture size and distance to
the subject.
6. Peripheral Vision: Just like a camera has a field of view, the eye has peripheral vision, which
allows it to detect motion and objects outside the central focus area.
7. Image Processing: Both the eye and modern cameras perform some level of image processing.
In the eye, this occurs in the brain, where visual information is interpreted and analyzed. In a
camera, this is done by onboard processors or external software.

4. Briefly write about discoveries in biology.

In recent years, biology has witnessed remarkable discoveries across various domains. Here are a
few notable ones:

1. CRISPR-Cas9: This revolutionary gene-editing tool allows precise modification of DNA

sequences, offering immense potential in medical research, agriculture, and biotechnology. Its
discovery has opened up new avenues for treating genetic disorders and understanding the
genetic basis of diseases.
2. Stem Cell Advancements: Researchers have made significant progress in understanding and
harnessing the potential of stem cells for regenerative medicine. From induced pluripotent stem
cells (iPSCs) to advancements in organoid technology, these discoveries hold promise for
treating a wide range of diseases and injuries.
3. Microbiome Research: The human microbiome, comprising trillions of microbes living in and
on our bodies, has been a focus of intense study. Discoveries in this field have revealed the
crucial role of these microbes in health and disease, impacting areas such as digestion, immunity,
and even mental health.
4. Genomics and Personalized Medicine: Advances in DNA sequencing technologies have led to
the widespread adoption of genomic medicine. By analyzing an individual's genetic makeup,
researchers can tailor treatments and interventions to suit their unique genetic profile, leading to
more personalized and effective healthcare.
5. Synthetic Biology: The field of synthetic biology has seen significant progress, with researchers
engineering biological systems to perform novel functions. This includes designing synthetic
organisms, metabolic pathways, and genetic circuits for applications ranging from
biomanufacturing to environmental remediation.
 Unit 2

1. Describe the mode of nutrition of the Five Kingdoms.

 Animalia (Animals): Animals are heterotrophic organisms, meaning they cannot

produce their own food and must obtain it from other organisms. They typically ingest
organic matter, such as plants or other animals, and then digest it internally to extract
nutrients.
 Plantae (Plants): Plants are autotrophic organisms, meaning they can produce their own
food through the process of photosynthesis. They use chlorophyll and other pigments to
capture sunlight, which is then used to convert carbon dioxide and water into glucose and
oxygen.
 Fungi: Fungi are heterotrophic organisms, similar to animals, in that they cannot produce
their own food. However, unlike animals, fungi do not ingest their food. Instead, they
absorb nutrients from their surroundings through the process of external digestion. Fungi
secrete enzymes that break down organic matter into simpler compounds, which they
then absorb.
 Protista: Protists encompass a diverse group of organisms, and their mode of nutrition
can vary widely. Some protists are autotrophic, capable of photosynthesis like plants.
Others are heterotrophic, obtaining nutrients by ingesting organic matter or through
absorption, similar to animals and fungi.
 Monera (Bacteria and Archaea): Bacteria and Archaea also exhibit diverse modes of
nutrition. Many are heterotrophic, obtaining nutrients from organic matter in their
environment through absorption or by breaking down complex molecules. However,
some bacteria and archaea are autotrophic, capable of synthesizing their own organic
compounds through processes like photosynthesis or chemosynthesis.

2. Explain the components of Modern Cell Theory.

Modern Cell Theory is an extension of the original Cell Theory proposed by Matthias Schleiden
and Theodor Schwann in the 19th century. It encompasses our current understanding of cells and
their role in living organisms. The components of Modern Cell Theory include:

1. All living organisms are composed of cells: This component states that all living organisms,
whether they are unicellular or multicellular, are made up of one or more cells. Cells are the
basic structural and functional units of life.
2. Cells are the basic units of structure and function in living organisms: This component
highlights the fundamental role of cells in carrying out the processes necessary for life. Cells
perform various functions, such as metabolism, growth, reproduction, and response to stimuli.
3. Cells arise from pre-existing cells through cell division: This component emphasizes that new
cells are formed from pre-existing cells through the process of cell division. Cells replicate their
genetic material and divide to produce daughter cells, ensuring the continuity of life.
4. Cells contain hereditary information (DNA) that is passed from cell to cell during cell
division: This component recognizes the importance of genetic material, usually DNA, in cells.
Genetic information is passed from parent cells to daughter cells during cell division, ensuring
the transmission of traits from one generation to the next.
5. All cells are similar in chemical composition and metabolic activities: This component
highlights the biochemical unity of cells. Despite the diversity of cell types and functions, all
cells share fundamental biochemical processes and components, such as DNA, RNA, proteins,
and metabolic pathways.

3. Give the differences between DNA & RNA.

DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid) are two types of nucleic acids that
play essential roles in the storage, transmission, and expression of genetic information. Here are
the key differences between DNA and RNA:

1. Sugar Backbone:
 DNA contains deoxyribose sugar in its backbone.
 RNA contains ribose sugar in its backbone.
2. Bases:
 DNA contains adenine (A), thymine (T), cytosine (C), and guanine (G) as its bases.
 RNA contains adenine (A), uracil (U), cytosine (C), and guanine (G) as its bases. (In
RNA, thymine is replaced by uracil.)
3. Structure:
 DNA typically forms a double-stranded helix structure, with two complementary strands
running antiparallel to each other and held together by hydrogen bonds between
complementary base pairs (A-T and C-G).
 RNA is usually single-stranded, although it can form secondary structures such as hairpin
loops due to intramolecular base pairing.
4. Function:
 DNA functions primarily as the genetic material, carrying the hereditary information that
determines the traits of organisms. It serves as a template for the synthesis of RNA.
 RNA plays various roles in gene expression, including messenger RNA (mRNA), which
carries the genetic information from DNA to the ribosome for protein synthesis, transfer
RNA (tRNA), which brings amino acids to the ribosome during protein synthesis, and
ribosomal RNA (rRNA), which forms part of the ribosome and catalyzes the assembly of
amino acids into proteins.
5. Stability:
 DNA is generally more stable than RNA due to the presence of the more chemically
stable thymine and the absence of a hydroxyl group on the 2' carbon of its sugar
backbone.
 RNA is more susceptible to degradation because of the presence of the hydroxyl group on
the 2' carbon of its sugar backbone, which makes it more prone to hydrolysis.
6. Location:
 DNA is found primarily in the cell nucleus, where it is organized into chromosomes.
 RNA is found in various cellular locations, including the nucleus (where it is transcribed
from DNA), the cytoplasm (where it functions in protein synthesis), and other organelles
such as mitochondria and chloroplasts.
 4. What are essential and non-essential amino acids in human food? Give one example
of each type.

Essential amino acids are those that the human body cannot synthesize on its own and must be
obtained from the diet. There are nine essential amino acids:

1. Histidine: Found in foods like meat, poultry, fish, dairy, and grains.
2. Isoleucine: Present in foods such as meat, fish, poultry, eggs, dairy, and soy products.
3. Leucine: Abundant in foods like meat, poultry, fish, dairy, legumes, and nuts.
4. Lysine: Found in significant amounts in meat, poultry, fish, dairy, eggs, and some plant sources
like legumes and quinoa.
5. Methionine: Present in foods like meat, poultry, fish, dairy, eggs, and some plant sources like
nuts and seeds.
6. Phenylalanine: Found in foods such as meat, poultry, fish, dairy, eggs, and some plant sources
like soybeans and peanuts.
7. Threonine: Abundant in foods like meat, poultry, fish, dairy, eggs, and some plant sources like
nuts and seeds.
8. Tryptophan: Present in foods such as meat, poultry, fish, dairy, eggs, and some plant sources
like pumpkin seeds and soybeans.
9. Valine: Found in foods like meat, poultry, fish, dairy, legumes, and some grains.

Non-essential amino acids, on the other hand, can be synthesized by the body, so they do not
need to be obtained directly from the diet. Examples include:

1. Alanine: Can be synthesized from pyruvate and is found in a variety of foods including meat,
fish, poultry, dairy, eggs, nuts, and seeds.
2. Asparagine: Synthesized from aspartate and is found in many foods, particularly high-protein
ones like meat, dairy, eggs, nuts, and legumes.
 Unit 3

1. What do we inherit from our parents? Genotype or Phenotype?

We inherit both genotype and phenotype from our parents, but they're distinct concepts.
Genotype refers to the genetic makeup of an organism, which includes all the genes inherited
from parents. Phenotype, on the other hand, refers to the observable characteristics or traits
of an organism, which result from the interaction between its genotype and the environment.
While genotype provides the blueprint for an organism's traits, the phenotype is the actual
expression of those traits. So, in short, we inherit our genotype from our parents, which
influences our phenotype.

Genotype: The genetic makeup of an organism, including all the genes inherited from parents.
It's like the blueprint or instructions for building an organism.

Phenotype: The observable characteristics or traits of an organism, resulting from the interaction
between its genotype and the environment. It's like the actual expression of those genetic
instructions.

2. What are the main functions of the cell wall?

The cell wall serves several important functions in plant cells:

1. Structural Support: The cell wall provides structural support and shape to the cell, helping it
maintain its integrity and resist mechanical stress. It prevents the cell from collapsing under its
own weight and provides rigidity.
2. Protection: It acts as a barrier, protecting the cell from physical damage, pathogens, and harmful
substances. The tough outer layer of the cell wall helps shield the delicate cellular contents from
external threats.
3. Regulation of Water Content: The cell wall regulates the movement of water into and out of
the cell, helping to maintain turgor pressure. This is crucial for maintaining cell shape and
overall plant structure.
4. Transport: It facilitates the movement of water, nutrients, and other molecules between cells
through specialized channels called plasmodesmata. These channels allow for communication
and transport between adjacent cells, enabling coordination within plant tissues.
5. Support for Growth: As plants grow, new cell wall material is added, contributing to cell
expansion and growth. The cell wall provides a scaffold for cell enlargement and division.
3. There is no life without enzymes. Justify the statement.

The statement "There is no life without enzymes" highlights the fundamental role that enzymes
play in biological systems. Enzymes are proteins that act as catalysts, speeding up biochemical
reactions within cells. Without these catalysts, many essential cellular processes would occur too
slowly to sustain life. Here's a breakdown of why enzymes are indispensable for life:
1. Catalysis of biochemical reactions: Enzymes facilitate chemical reactions by lowering the
activation energy required for them to occur. Without this catalytic activity, crucial metabolic
processes such as digestion, respiration, and DNA replication would be too slow to sustain life.
2. Specificity: Enzymes are highly specific, each catalyzing a particular reaction or set of reactions.
This specificity ensures that biochemical pathways proceed efficiently and accurately. Without
enzymes, the specificity required for the precise regulation of cellular processes would be
lacking.
3. Regulation: Enzyme activity can be regulated in response to cellular conditions, allowing
organisms to adapt to changes in their environment or metabolic needs. This regulation ensures
that energy and resources are utilized efficiently and that cellular processes occur in a
coordinated manner.
4. Energy metabolism: Enzymes play a crucial role in energy metabolism, including the
breakdown of nutrients such as carbohydrates, fats, and proteins to produce energy for cellular
activities. Without enzymes, organisms would not be able to extract and utilize energy from their
surroundings effectively.
5. Synthesis of biological molecules: Enzymes are involved in the synthesis of complex biological
molecules such as proteins, nucleic acids, and lipids. These molecules are essential for the
structure, function, and regulation of cells and organisms.
6. Cellular homeostasis: Enzymes participate in maintaining cellular homeostasis by regulating
pH, ion concentrations, and other critical parameters within cells. Without enzymes to mediate
these processes, cells would be unable to maintain the stable internal environment necessary for
life.

4. What is the chemical basis of enzyme catalysis?

Enzyme catalysis relies on the chemical properties of enzymes, which are specialized proteins
that act as catalysts to speed up chemical reactions in living organisms. The key features
underlying enzyme catalysis include:

1. Active Site: Enzymes have a region called the active site, which is a pocket or cleft where the
substrate(s) bind. This site has a specific shape and chemical environment that complements the
substrate molecules, allowing them to bind with high specificity.
2. Substrate Binding: Enzymes bind to their substrate(s) through various types of interactions,
including hydrogen bonds, ionic interactions, hydrophobic interactions, and van der Waals
forces. The specificity of substrate binding is crucial for the enzyme to catalyze specific
reactions.
3. Induced Fit Model: Upon substrate binding, enzymes may undergo conformational changes that
further optimize the fit between the enzyme and the substrate(s). This induced fit can stabilize
the transition state of the reaction, lowering the activation energy required for the reaction to
proceed.
4. Catalytic Groups: Within the active site, enzymes often contain specific amino acid residues or
cofactors that participate directly in catalysis. These catalytic groups can facilitate the conversion
of substrate(s) into product(s) by stabilizing transition states, promoting the formation of reactive
intermediates, or facilitating the transfer of functional groups.
5. Transition State Stabilization: Enzymes accelerate reactions by stabilizing the transition state,
which is the high-energy state that the reactants must pass through before forming products. By
 lowering the energy barrier associated with the transition state, enzymes increase the rate of
reaction.
6. Proximity and Orientation Effects: Enzymes bring substrate molecules into close proximity
and proper orientation, increasing the likelihood of productive collisions between reactants. This
proximity effect accelerates the formation of transition states and enhances reaction rates.
7. Regulation: Enzyme activity can be regulated through various mechanisms, including allosteric
regulation, covalent modification, and changes in enzyme concentration. These regulatory
mechanisms allow cells to control the rates of specific metabolic pathways in response to cellular
conditions and signals.
 Unit 4

1. What is Chargaff’s rule?

Chargaff's rule, formulated by biochemist Erwin Chargaff in the late 1940s, states that in DNA,
the amount of adenine (A) is roughly equal to the amount of thymine (T), and the amount of
cytosine (C) is roughly equal to the amount of guanine (G). In other words, in a double-stranded
DNA molecule, the ratio of A to T and the ratio of C to G are approximately 1:1. This
observation was a crucial clue in the discovery of the structure of DNA, ultimately leading to the
proposal of the double helix model by James Watson and Francis Crick.

2. Explain different types of DNA repair.

DNA repair mechanisms are essential for maintaining the integrity of the genetic material within
cells. These mechanisms correct damage to DNA caused by various factors such as
environmental agents, spontaneous errors during replication, and metabolic processes. There are
several types of DNA repair mechanisms, each specialized for different types of damage:

1. Base Excision Repair (BER):

 BER primarily repairs small, non-helix-distorting lesions such as damaged or
inappropriate bases.
 It starts with the recognition and removal of the damaged base by a DNA glycosylase
enzyme, leaving an apurinic/apyrimidinic (AP) site.
 The AP site is then processed by other enzymes to remove the damaged nucleotide and
replace it with the correct one.
2. Nucleotide Excision Repair (NER):
 NER deals with bulky lesions that distort the DNA helix, such as those caused by UV
radiation or certain chemicals.
 It involves recognition of the damaged region, followed by excision of a segment of
single-stranded DNA containing the lesion.
 The gap is then filled in by DNA polymerase using the undamaged strand as a template.
3. Mismatch Repair (MMR):
 MMR corrects errors that occur during DNA replication, such as mismatches and small
insertion-deletion loops that are not corrected by the proofreading activity of DNA
polymerase.
 It involves the recognition of the mismatch, excision of the incorrect nucleotide-
containing strand, and resynthesis using the correct template.
4. Homologous Recombination (HR):
 HR is involved in the repair of double-strand breaks (DSBs) in DNA, which can arise
from various sources such as ionizing radiation or replication fork collapse.
 It uses an undamaged homologous DNA sequence as a template to repair the break.
 After DNA resection to generate single-stranded DNA ends, the damaged DNA strand is
repaired using the intact sister chromatid or homologous chromosome as a template.
5. Non-Homologous End Joining (NHEJ):
 NHEJ is another pathway for repairing DSBs, particularly in the absence of a
homologous template, such as during G1 phase of the cell cycle.
  It involves the direct ligation of broken DNA ends, often resulting in loss or addition of
nucleotides at the repair site.
 NHEJ is quicker than HR but tends to be more error-prone.
6. Translesion Synthesis (TLS):
 TLS is a bypass mechanism that allows DNA replication to proceed past damaged bases
that would otherwise stall replicative DNA polymerases.
 Specialized DNA polymerases with low fidelity can insert nucleotides opposite damaged
bases, allowing replication to continue.
 TLS can be error-prone, leading to mutations, but it prevents replication fork collapse and
allows for cell survival in the presence of DNA damage.

3. State the salient features of the genetic code.

The genetic code is the set of rules by which information encoded in genetic material (DNA or
RNA sequences) is translated into proteins, which are the building blocks of life. Here are the
salient features of the genetic code:

1. Triplet Code: The genetic code is a triplet code, meaning that three consecutive nucleotides
(codons) in the mRNA sequence correspond to a specific amino acid or a stop signal. There are
64 possible codons formed by combinations of four nucleotide bases (A, U, G, and C), with each
codon encoding either an amino acid or a stop signal.
2. Degeneracy: Degeneracy refers to the redundancy in the genetic code, where multiple codons
can code for the same amino acid. This redundancy allows for some flexibility and tolerance
against mutations. For example, most amino acids are encoded by more than one codon, except
for methionine and tryptophan.
3. Start and Stop Codons: The genetic code includes special codons that serve as signals to start
and stop protein synthesis. The start codon, AUG (encoding methionine), initiates translation,
while the stop codons (UAA, UAG, and UGA) signal the termination of translation.
4. Universal: The genetic code is nearly universal across all living organisms, from bacteria to
humans, with few exceptions. This universality allows for the transfer of genetic information
between different species and is a fundamental principle in biotechnology and genetic
engineering.
5. Non-Overlapping and Commaless: The genetic code is non-overlapping, meaning that each
nucleotide is part of only one codon and is read sequentially during translation. Additionally,
there are no gaps (commas) between codons in the mRNA sequence.
6. Conserved: The genetic code is highly conserved throughout evolution, with minor variations
occurring rarely. This conservation underscores its fundamental importance in the functioning of
all living organisms.

4. Explain the different functions of proteins.

Proteins are incredibly diverse molecules that play numerous critical roles in living organisms.
Their functions can be broadly categorized into several key roles:
1. Enzymatic Function: Proteins serve as enzymes, which are biological catalysts that accelerate
chemical reactions within cells. Enzymes facilitate various biochemical processes, such as
digestion, metabolism, and DNA replication.
2. Structural Function: Proteins provide structural support to cells, tissues, and organs. Structural
proteins like collagen, keratin, and actin form the framework of cells and tissues, maintaining
their shape and integrity. For example, collagen provides strength and elasticity to skin, tendons,
and bones.
3. Transport Function: Proteins facilitate the transport of molecules across cell membranes and
throughout the body. Transport proteins, such as hemoglobin, carry essential substances like
oxygen, ions, and nutrients in the bloodstream. Channels and carriers in cell membranes are also
protein-based and regulate the passage of ions and molecules into and out of cells.
4. Hormonal Function: Some proteins act as hormones, which are chemical messengers that
regulate various physiological processes and signaling pathways in the body. For instance,
insulin regulates blood sugar levels by promoting the uptake of glucose into cells, while growth
hormone stimulates growth and development.
5. Immune Function: Proteins play a crucial role in the immune system by recognizing and
neutralizing foreign invaders like pathogens (e.g., viruses, bacteria) and toxins. Antibodies, also
known as immunoglobulins, are specialized proteins produced by immune cells that bind to
specific antigens, marking them for destruction by other immune cells.
6. Contractile Function: Certain proteins are involved in muscle contraction, allowing for
movement and locomotion. Examples include myosin and actin, which are essential components
of muscle fibers and enable muscle contraction by sliding past each other.
7. Storage Function: Proteins can serve as storage molecules for essential nutrients and ions. For
example, ferritin stores iron in cells, while casein stores calcium in milk.
8. Regulatory Function: Proteins regulate gene expression and control various cellular processes.
Transcription factors are proteins that bind to DNA and modulate the transcription of specific
genes, thereby regulating the synthesis of messenger RNA (mRNA) and protein production.
9. Signaling Function: Proteins act as signaling molecules that transmit information within and
between cells. Signaling proteins, such as receptors and second messengers, relay signals from
the extracellular environment to the cell's interior, triggering responses like gene expression,
metabolism, and cell growth.
 Unit 5

1. Give a classification of enzymes based on nomenclature

Enzymes are classified based on the reactions they catalyze, which is often reflected in their
systematic names. The International Union of Biochemistry and Molecular Biology (IUBMB)
has established a nomenclature system for enzymes based on the type of reaction they catalyze.
Here's a broad classification based on this nomenclature system:

1. Oxidoreductases: These enzymes catalyze oxidation-reduction reactions, transferring electrons

from one molecule (the reductant) to another (the oxidant). Examples include dehydrogenases,
oxidases, and reductases.
2. Transferases: These enzymes transfer functional groups (such as methyl, acyl, or phosphate
groups) from one molecule to another. Examples include kinases, methyltransferases, and
transaminases.
3. Hydrolases: Hydrolases catalyze the hydrolysis of various bonds by adding water molecules.
Examples include proteases (hydrolyze peptide bonds in proteins), lipases (hydrolyze ester bonds
in lipids), and glycosidases (hydrolyze glycosidic bonds in carbohydrates).
4. Lyases: Lyases catalyze the removal of groups from substrates without hydrolysis or oxidation,
resulting in the formation of double bonds or the addition of groups to double bonds. Examples
include decarboxylases and dehydratases.
5. Isomerases: Isomerases catalyze the rearrangement of atoms within a molecule, leading to the
formation of isomeric forms. Examples include racemases, epimerases, and mutases.
6. Ligases (Synthetases): Ligases catalyze the joining of two molecules, often coupled with the
hydrolysis of ATP or another high-energy molecule. Examples include DNA ligases and
aminoacyl-tRNA synthetases.

2. Difference between cellular respiration and photosynthesis.

Cellular respiration and photosynthesis are two fundamental processes that occur in living
organisms, particularly in plants and animals. While they are interconnected in the biosphere
through the carbon cycle, they are essentially opposite processes with distinct purposes and
mechanisms.

1. Cellular Respiration:
 Definition: Cellular respiration is the process by which cells break down glucose and
other organic molecules to produce energy in the form of ATP (adenosine triphosphate).
It occurs in the mitochondria of eukaryotic cells and cytoplasm of prokaryotic cells.
 Inputs: Glucose (sugar) and oxygen (O2).
 Outputs: Carbon dioxide (CO2), water (H2O), and ATP.
 Formula: C6H12O6 (glucose) + 6O2 (oxygen) → 6CO2 (carbon dioxide) + 6H2O
(water) + Energy (as ATP).
 Purpose: The main purpose of cellular respiration is to extract energy stored in organic
molecules (such as glucose) and convert it into a usable form (ATP) for various cellular
processes, including growth, reproduction, and movement.
  Location: Cellular respiration primarily occurs in the mitochondria of eukaryotic cells,
although some steps may occur in the cytoplasm.
2. Photosynthesis:
 Definition: Photosynthesis is the process by which green plants, algae, and some bacteria
convert light energy into chemical energy stored in glucose and other organic molecules.
It occurs in the chloroplasts of plant cells and in certain bacteria.
 Inputs: Carbon dioxide (CO2), water (H2O), and light energy.
 Outputs: Glucose (C6H12O6) and oxygen (O2).
 Formula: 6CO2 (carbon dioxide) + 6H2O (water) + light energy → C6H12O6 (glucose)
+ 6O2 (oxygen).
 Purpose: The primary purpose of photosynthesis is to produce glucose and other organic
molecules, which serve as energy sources for the organism and as building blocks for
cellular structures.
 Location: Photosynthesis primarily occurs in the chloroplasts of plant cells, where
chlorophyll, the green pigment, captures light energy and converts it into chemical
energy.

Key Differences:

 Purpose: Cellular respiration releases energy stored in organic molecules, while

photosynthesis stores energy in organic molecules.
 Reactants and Products: Cellular respiration uses glucose and oxygen as reactants and
produces carbon dioxide, water, and ATP as products, whereas photosynthesis uses
carbon dioxide, water, and light energy as reactants and produces glucose and oxygen as
products.
 Location: Cellular respiration occurs in the mitochondria (and cytoplasm) of cells, while
photosynthesis occurs in the chloroplasts of plant cells.
 Energy Flow: Cellular respiration involves the breakdown of complex molecules to
release energy, whereas photosynthesis involves the synthesis of complex molecules
using light energy.

3. What are catabolism and anabolism?

Catabolism and anabolism are two fundamental processes in metabolism, the collective term for
all the biochemical reactions that occur within an organism to sustain life.

1. Catabolism: This process involves the breakdown of complex molecules into simpler ones,
usually accompanied by the release of energy. For instance, during the digestion of food, large
molecules such as carbohydrates, proteins, and fats are broken down into smaller units like
glucose, amino acids, and fatty acids, respectively. This breakdown releases energy that the
organism can use for various cellular activities, such as movement, growth, and maintenance.
2. Anabolism: In contrast, anabolism is the process of building complex molecules from simpler
ones, requiring an input of energy. It's essentially the opposite of catabolism. Anabolic processes
include the synthesis of proteins from amino acids, the synthesis of glycogen from glucose, and
the synthesis of lipids from fatty acids and glycerol. These processes consume energy to create
the necessary molecules for growth, repair, and other cellular functions.

Together, catabolism and anabolism maintain the balance of energy and biomolecules within an
organism, allowing it to grow, reproduce, and function properly.

4. Write a short note on the ecological aspects of the single-celled organism

5. Single-celled organisms, while often microscopic, play crucial roles in ecological
systems. These organisms, including bacteria, archaea, protists, and some fungi,
contribute significantly to nutrient cycling, energy flow, and ecosystem stability.
6. One key ecological aspect of single-celled organisms is their role in nutrient cycling.
They decompose organic matter, breaking it down into simpler compounds that can be
utilized by other organisms. For example, bacteria and fungi play essential roles in the
decomposition of dead organic material, releasing nutrients like nitrogen, phosphorus,
and carbon back into the environment, where they can be taken up by plants and other
organisms.
7. Additionally, single-celled organisms are important primary producers in many
ecosystems. Photosynthetic bacteria and protists harness sunlight to produce organic
molecules through photosynthesis, serving as the base of the food chain. These organisms
are critical for transferring solar energy into forms that can be consumed by other
organisms, ultimately supporting the entire ecosystem.
8. Moreover, single-celled organisms play roles in symbiotic relationships with other
organisms. For instance, certain bacteria form mutualistic associations with plants,
helping them fix nitrogen from the atmosphere, which enhances plant growth. Other
single-celled organisms, like certain protists and bacteria, live as symbionts in the guts of
animals, aiding in digestion or providing essential nutrients.
9. Furthermore, single-celled organisms are essential in maintaining ecosystem balance and
resilience. They regulate populations of other organisms, such as controlling harmful
bacteria or algae blooms. Additionally, they can serve as indicators of environmental
health; changes in the abundance or diversity of certain microorganisms can signal shifts
in environmental conditions or pollution levels.