Instructor: Touseef Zahra
 Biology is the study of everything that is, or was once, alive —
whether it's a plant, animal or microorganism.
 Biology is the study of life. The word "biology" is derived from the
Greek words "bios" (meaning life) and "logos" (meaning "study"). In
general, biologists study the structure, function, growth, origin,
evolution, and distribution of living organisms.
 Biology is important because it helps us understand how living things
work and how they function and interact on multiple levels,
we recognize life by what living things do:
1. Order: organisms are highly organized structure that consist of one or more
cells.
2. Sensitivity or Response to Stimuli: For example, plants can bend toward a
source of light or respond to touch. Even tiny bacteria can move toward or away
from chemicals (a process called chemotaxis)
3. Growth and Development: Organisms grow and develop according to specific
instructions coded for by their genes. These genes provide instructions that will
direct cellular growth and development, ensuring that a species’ young will grow
up to exhibit many of the same characteristics as its parents
4. Regulation: organisms require regulatory mechanisms to coordinate internal
functions, such as the transport of nutrients, response to stimuli, and coping with
environmental stresses. For example, organ systems such as the digestive or
circulatory systems perform specific functions like carrying oxygen throughout the
body, removing wastes, delivering nutrients to every cell, and cooling the body.
5. Energy Processing: butterfly obtain fuel in form of nectar from flowers. And
will use chemical energy for work or when needed.
 Some organisms capture energy from the sun and convert it into chemical energy
in food; others use chemical energy from molecules they take in.
6. Reproduction: the ability to reproduce and pass genetic information onto their
offspring.
 1. Organization
 2. Information (Genetics)
 3. Energy and matter
 4. Interaction
 5. Evolution
 6. Scientific Process
 Organization refers to the hierarchical structure that exists in living organisms, from the
simplest level to the complex. Here are some levels:
1.
Cell: basic structural and functional and biological units of life. Cell can replicate itself.
All living things are made of cells; the cell itself is the smallest fundamental unit of
structure and function in living organisms. A cell is enclosed by a plasma membrane,
which forms a selective barrier that allows nutrients to enter and waste products to
leave. Each cell contains nucleus.
• Cells are building blocks of human life, containing organelles that enable the body to
produce ATP (adenosine triphosphate) for energy, proteins for growth and repair, DNA for
defining features and the breaking down of harmful substances amongst others.
• Together trillions of cells make up the human body.
Some organisms consist of a single cell (unicellular) and others has multiple cells
(multicellular). Cells are classified as prokaryotic or eukaryotic.
A. Eukaryotic : any cell that possesses a clearly defined nucleus and membrane
bound organelles. These are large, complex and mostly reproduce sexually. (plants,
animals, humans).
B. Prokaryotic: small, simple, nucleus is absent, these unicellular organisms are
mostly invisible to the naked eye, hence, they are also referred to as microscopic
organisms. (Bacteria, amoeba) do not have a membrane-bound nucleus or
organelles
Nucleus:
Well organized, large, have
protective layer
Nucleoid:
poorly organized, small, no
protection layer
Ribosomes:
Found inside the living cells, that produce
proteins
2. Molecule: when two or more atoms combine together chemically they form a
molecule. Here are some examples of molecules:
 H2O (water)
 N2 (nitrogen)
 CO2 (carbon dioxide)
Types of Molecules
 Molecules are classified according to their composition:
Monoatomic molecule – made up of only one atom. (He,Ne)
Diatomic molecule – A diatomic molecule consists of two atoms (H2, N2)
Polyatomic molecule – A polyatomic molecule consists of more than three atoms.
Triatomic molecule – made up of three atoms.
Macromolecule – huge molecules that are made up of more than 10000 or more
atoms. (carbohydrates, Nucleic acids, proteins)
3. Organalles: specialized structure found within cells that perform various functions
necessary for the cell survival and function. Example: Nucleus (stored genetic
information), Mitochondria (Powerhouse/ produced chemical energy)
 Organelles without membrane: The Cell wall, Ribosomes, are non-membrane-
bound cell organelles. They are present both in the prokaryotic cell and the
eukaryotic cell.
 Single membrane-bound organelles: , Lysosome, Golgi, endoplasmic present only
in a eukaryotic cell.
 Double membrane-bound organelles: Nucleus, mitochondria and chloroplast are
double membrane-bound organelles present only in a eukaryotic cell.
Golgi complex: responsible
for transporting, modifying, and
packaging proteins and lipids to
targeted destinations
4. Tissues: the body tissue is an aggregation of cells that function together to
perform specific functions within body.
There are 4 types of tissues.
Epithelial tissues: covers the surface of the organ including skin, digestive tract,
reproductive tract. Covering or protective tissue. Tightly packed
Nervous tissues: found in brain and spinal cord.
Muscle tissues: responsible for body movement
skeletal muscle: voluntary
smooth muscles: involuntary (digestive tract)
cardiac muscles: found in heart
Connective tissues: provide structural support to the body and connect different
body parts. (blood)
5. Organs: complex structure that is made up if different tissues and has specific
functions in the body.
Parts of body that perform particular job
e.g Heart, lung, brain, leaves.
6. Organisms: individual(single) living thing are called organisms that capable of
carrying out life processes (grow, reproduce….,)
7. Population: A number(group) of organisms of same species that lives in a particular
area at the same time.
Example: human population consists of human livings on earth and can be vary on
basics of age, gender, location…
8. Communities: A community is the term used to describe two or more populations of
different species that occupy the same space at the same time. For example Forest
community include population of trees, plants, birds, mammals and more.
9. Ecosystem: An ecosystem is the term used to describe both the biotic (living) and
abiotic (nonliving) factors in a specific area that interact with each other.
A change in temperature will affect the plant growth.
10. Biosphere: defined as region on, above and below earth surface where life exists.
The entire part of earth’s land, soil, water and atmosphere in which living organisms
are found is called Biosphere.
DNA (deoxyribonucleic Acid): is macromolecule made up of small units called
Nucleotides. Found in nucleus of a cell.
Definition:
“DNA is a group of molecules that is responsible for carrying and transmitting the
hereditary materials or the genetic instructions from parents to offspring's.”
Structure:
The DNA structure can be thought of as a twisted ladder. This structure is described as
a double-helix, running in opposite direction, it is a nucleic acid, and all nucleic acids
are made up of nucleotides. The DNA molecule is composed of units
called nucleotides, and each nucleotide is composed of three different components
such as sugar, phosphate groups and nitrogen bases.
 The basic building blocks of DNA are nucleotides, the
sugar and phosphate groups link the nucleotides
together to form each strand of DNA. Adenine (A),
Thymine (T), Guanine (G) and Cytosine (C) are four
types of nitrogen bases.
 These 4 Nitrogenous bases pair together in the
following way: A with T, and C with G. These base
pairs are essential for the DNA’s double helix
structure, which resembles a twisted ladder.
 Composition of nitrogen bases (Purine/double ring)
(Pyrimidine)
 The order of the nitrogenous bases determines the
genetic code or the DNA’s instructions
 James Watson and Francis Crick proposed this
double strand DNA structure.
 Among the three components of DNA structure, sugar found is
called deoxyribose that binds naturally to a phosphate molecule to
become the sugar phosphate backbone of DNA , linking with a
nitrogen base in order to form a nucleotide. These links in pairs in
great numbers forming the Double helix shape of DNA.
Phosphate: A phosphate backbone is the portion of DNA double
helix that provides structural support to the molecule. The
phosphate backbone is the outside of the ladder when you see a
picture of DNA . And they have this remarkable property in that
phosphate backbones link the chemical building blocks of
DNA, the nucleotides, together in a very, very stable way, and
so that it is very difficult to break those bonds
The two strands of DNA are coiled in a right-handed fashion and are
anti-parallel to each other i.e. one strand runs from 3’-5’ end while
the other strand runs from 5’-3’ end.
In DNA (double helix) there are two antiparallel strands of
polynucleotides that are linked together by hydrogen bonds
between nitrogenous bases. Purine pairs with pyrimidine base,
A pairs with T and G pairs with C by two and three hydrogen
bonds respectively.
 1. DNA Replication: it occurs during cell division also known as semi
Conservative replication during which DNA makes a copy of itself.
How is DNA replicated?
 Replication occurs in three major steps: the opening of the double helix and
separation of the DNA strands, and the assembly of the new DNA segment.
 During separation, the two strands of the DNA double helix uncoil at a specific
location called the origin of Replication(where A=T). Several enzymes and
proteins then work together to prepare, or prime, the strands for duplication.
Finally, a special enzyme called DNA polymerase the main function of the DNA
polymerase is to synthesize DNA by the process of replication.
 Stages:
1. Initiation ( Replication Fork Formation)
Before DNA can be replicated, the double stranded molecule must be “unzipped” into
two single strands. in order to unwind DNA, the interactions between base pairs must
be broken. This is performed by an enzyme known as DNA helicase. DNA helicase
disrupts the hydrogen bonding between base pairs to separate the strands into a Y shape
known as the replication fork. This area will be the template for replication to begin.
the replication fork is bi-directional; one strand is oriented in the 3' to 5'
direction (leading strand) while the other is oriented 5' to 3' (lagging strand).
 2. Elongation: Enzymes known as DNA polymerases are responsible creating the
new strand by a process called elongation.
 One of the template strands is read in a 3’ to 5’ direction, therefore the new strand
will be formed in a 5’ to 3’ direction. This newly formed strand is referred to as
the leading strand.
The lagging strand begins replication by binding with multiple primers. Each primer
is only several bases apart. DNA polymerase then adds pieces of DNA,
called Okazaki fragments, to the strand between primers. This process of replication
is discontinuous as the newly created fragments are disjointed.
 3. Termination: Once both the continuous and discontinuous strands are formed, an
enzyme removes all RNA primers from the original strands. These primers are then
replaced with appropriate bases. Another enzyme called DNA ligase joins Okazaki
fragments together forming a single unified strand.
In the end, replication produces two DNA molecules, each with one strand from the
parent molecule and one new strand.
 Is a vital process that takes place within cells and essential mechanism for
determining cell structure and function. Protein synthesis takes place within the
nucleus and ribosomes of a cell and is regulated by DNA and RNA. This process
consists of two steps.
1, Transcription 2, Translation
1. Transcription: the process of copying genetic information from one strand of
DNA into RNA is transcription. Only one strand of DNA is copied during the
process of transcription known as the template strand
DNA → RNA
Main enzyme involved in transcription is RNA polymerase. It uses single strand
DNA to synthesize a complementary RNA strand. It forms 5 to 3 direction on
template strand.
The DNA strand having 3’ to 5’ polarity acts as a template strand (synthesis
RNA) and the DNA strand having 5’ to 3’ polarity is called the coding strand.
Stages of Transcription
 Initiation
RNA polymerase attaches to the DNA molecule with the help of sigma factor and
moves along the DNA strand until it recognizes a promoter sequence. These are known
as the transcription start sites. This acts as a template for a new mRNA strand.
 Elongation
Ribonucleotides are added to the template strand that enables the growth of mRNA
growth.
 Termination
Attached to RO factor, RNA polymerase encounters a terminator sequence and the
transcription stops. RNA polymerase then releases the DNA template.
 2. Translation:
RNA
protein
In translation, the mRNA is "decoded" to build a protein (or a
chunk/subunit of a protein) that contains a specific series of amino
acids.
Translation occur within a cell organelle called ribosomes. mRNA
makes its way to and connects within the Ribosome RNA (RRNA)
and enzymes.
Ribosomes are very important because they are protein factory of
cell.
 In an mRNA, the instructions for building a polypeptide come in
groups of three nucleotides called codons. Here are some key
features of codons to keep in mind as we move forward:
 There are different codons for amino acids
 Three “stop” codons mark the polypeptide as finished
 One codon, AUG, is a “start” signal to kick off translation (it also
specifies the amino acid methionine)
 These relationships between mRNA codons and amino acids are
known as the genetic code.
Messenger RNA
(abbreviated mRNA) is a
type of single-stranded
RNA involved in protein
synthesis
The role of mRNA is to
carry protein information
from one part to another.
Stages:
Initiation:
 Initiation ("beginning"): in this stage, the ribosome gets together with
the mRNA and the first tRNA so translation can begin.
 Elongation ("middle"): in this stage, amino acids are brought to the
tRNA
Bring aminoacid
to mRNA
ribosome by tRNAs and linked together to form a chain.
 Termination ("end"): in the last stage, the finished polypeptide is
released to go and do its job in the cell.
 Polypeptide:
The result of protein synthesis is a chain of amino acids that have
been attached link by link in specific order.
rRNA Ribo
Bond with
special protein
to form
ribosomes.
 The ribonucleic acid has all the components same to that
of the DNA with only 2 main differences within it. RNA
has the same nitrogen bases called the adenine, Guanine,
Cytosine as that of the DNA except for the Thymine
which is replaced by the uracil. Adenine and uracil are
considered as the major building blocks of RNA and
both of them form base-pair with the help of 2 hydrogen
bonds.
Functions: facilitate the translation of DNA into proteins
Functions as an adapter molecule in protein synthesis,
 Serves as a messenger between the DNA and the
ribosomes.
 They are the carrier of genetic information in all living
cells
 Promotes the ribosomes to choose the right amino acid
which is required in building up of new proteins in the
body.
 DNA Mutation occur when there are changes in the
Nucleotides sequence that makes up a strand of DNA.
These alterations can be caused by random mistakes in
DNA replication or by environmental influences such as
UV rays and chemicals.
 Changing even just one nitrogen base in a sequence can
alter the amino acid that is expressed by that DNA
codon, which can lead to a completely different protein
being expressed.
 Internal causes: when DNA fails to copy accurately
 External causes: exposed to chemical radiation.
Types:
1. Point mutation:
 A point mutation—the change of a single nitrogen base in
a DNA sequence—is usually the least harmful type of DNA
mutation.
 At most, a point mutation will cause a single amino acid in a
protein to change. it may cause issues with that protein's
folding pattern
 Sickle cell anemia
 Red blood cells are usually round and flexible, so they move
easily through blood vessels. In sickle cell anemia, some red
blood cells are shaped like sickles or crescent moons. These
sickle cells also become rigid and sticky, which can slow or
block blood flow.
2.Frameshift Mutations
 Frameshift mutations are generally much more serious, in this the
single base is either completely deleted or an extra one is inserted
into the middle of the DNA sequence. This change in sequence
causes the reading frame to shift—hence the name "frameshift"
mutation.
 A reading frame shift changes the three-letter codon sequence. That
not only changes the original amino acid but all subsequent amino
acids as well. This significantly alters the protein and can cause
severe problems, even possibly leading to death.
Insertions
 One type of frameshift mutation is called insertion. As the name
implies, an insertion occurs when a single nitrogen base is
accidentally added in the middle of a sequence
Deletions
 Deletion is one last type of frameshift mutation and occurs when a
nitrogen base is taken out of the sequence. Again, this causes the
entire reading frame to change. It alters the codon and will also
affect all amino acids that are coded for after the deletion.
(Crohn’s disease, cystic fibrosis, and certain types of cancer are due
to frameshift mutations)
1.
Auto Immune disease:
DNA mutations can sometimes trigger autoimmune disease. In these conditions the
immune system mistakenly targets and attacks the body owns cells and tissues.
Example: Rheumatoid Arthritis (swelling and deformities of joints)
2. Immunodeficiency: some mutations can weaken the immune system, making
individuals more susceptible to infections.
Here are two types of immunodeficiency disorders: those you are born with
(primary), and those that are acquired (secondary).
Examples: Secondary (AIDS, Hepatitis, Cancers)
 Cancer (Leukemia): is a cancer of white Blood cells. WBC’s are the
vital part of immune system. They protected body from the viruses,
bacteria and abnormal cells. they normally grow and divide in an
orderly way, as your body needs them. But in people with leukemia,
the bone marrow produces an excessive amount of abnormal white
blood cells, which don't function properly.
 Tumors: is a mass or growth of abnormal cell in brain is tumor.
1. Benign:
Do not contain cancerous cell, remove and rarely grow back.
Have an obvious edge
Do not spread t the other part of body
But I can press on sensitive areas of brain
If found in brain then might be life threatening
With the passage of time it became malignant
Examples: Lipomas, Fibroid
 2. Malignant (Cancerous): also called brain cancer contain cancerous cells.
threat to life, Rapid growth, no obvious edge, spread to other parts of brain but
rarely to body.
Some cancer cells can travel through the bloodstream to other parts of the body.
This spreading process is called Metastasis.
 Cancerous tumors can occur anywhere in the body. The most frequently
diagnosed malignant tumors worldwide include breast cancer, lung cancer.
 One characteristics of living organism is their use of energy to carry out different
activities of life (moving, growing….)
 The input of energy, primarily from the sun and the transformation of energy from
one to another form make life possible.
Autotrophs/Producers : They can produce their own food, through process of
photosynthesis. “self feeders”. Like plants, bacteria
Heterotrophs/Consumers: They rely on other organisms (plants and animals) for
nutrition. Like humans, animals and insects.
 Photosynthesis: Photosynthesis is the process by which plants use sunlight, water, and carbon
dioxide to create oxygen and energy in the form of sugar. They also used chlorophyll (green
pigment present in the leaves of plants) This pigment captures the sun’s energy which is used
to prepare food from carbon dioxide and water (absorb light).
 Process: the photosynthesis process takes place in cell organelles called chloroplasts that
contains chlorophyll. light energy is absorbed by chlorophyll molecule whereas carbon
dioxide and oxygen enter through the tiny pores of stomata (stomata opens during sunlight
that’s why carbon dioxide enter into leaves). From roots water reaches to the leaves through
Xylem (long tube which help water to reach) when water and carbon dioxide both reaches to
the leaves they combine and in response to their reaction oxygen and Glucose produced. Then
sugar are sent to the roots, stems, leaves, fruits, seeds and flowers. These sugar are used by
plants as an energy source which help them to grow.
 Chemicals that a plant absorbs from the air and the soil may be incorporated into
plant’s body and then passed to an animal that eats the plant. Eventually these
chemicals will be returned to the environment by decomposers such as bacteria and
fungi that breakdown waste products in the bodies of dead organisms. The chemical
are then available to be taken up by plants again, thereby completing the cycle.
 Refers to various ways in which living organisms, such as plants, animals
and microorganisms affect one another within an eco system.
 Each organism also interact continuously with physical factors in its
environment. The leaves of the tree absorb light from the sun, take in carbon
dioxide from the air and release oxygen to the air. Like other organisms, we
humans interact with our environment for example: human have greatly
increased the burning of fossil fuels (coal, oil, gases). This practice release
large amounts of carbon dioxide and other gases into the atmosphere causing
increased heat, due to all this climate is changing day by day.
 Types :
1. Mutualism: benefit to both organisms,
Example: oxpecker (bird) land on zebra and eat ticks and parasites
that live on zebra skin. Bird get food and zebra get rid of these
parasites.
2. Commensalism: one is benefit while the other is neither
harmed not helped.
Example: certain birds may build nest in trees, using them as a
shelter without causing harm to the tree.
3.Competition: when organisms compete for the same resources,
such as food, space, or mates
 Evolution is the process by which living organisms, over successive generations, undergo
genetic changes that result in the development of new species and the modification of
existing ones. This process is driven by mechanism such as natural selection, genetic
mutation and genetic flow. Charles Darwin’s theory of natural selection is a central
concept in this field.
 According to Darwin “the idea that species change over time, give rise to new species, and
share a common ancestor” .
 like Darwin, Lamarck believed that organisms adapted to their environments and passed
on those adaptations. He thought organisms did this by changing their behavior and,
therefore, their bodies — like an athlete working out and getting stronger and that those
changes were passed on to offspring.
 For example, He thought that giraffes originally had shorter necks but that, as trees around
them grew taller, they stretched their necks to reach the tasty leaves and their offspring
gradually evolved longer and longer necks.
 science is a systematic and logical approach to discovering how things in the universe
work. science aims for measurable results through testing and analysis, a process
known as the scientific method.
Scientific process:
 1. Observation:
Let's suppose that you get two slices of bread, put them into the toaster, and press the
button. However, your bread does not toast.
 Two types of Observation:
1. Overt: aware that you are being observed
2. Covert: not aware
3. Participant observation
4. Naturalistic
The information that we gather is known as data.
Two types of data
1.
Qualitative data: Interpretations, descriptions, how? Why? Interview and observation.
2.
Quantitative data: Numbers, countable, measurable, fixed, tables, graphs.
 2.Ask a question.
Why didn't my bread get toasted?
 3 Propose a hypothesis.
A hypothesis is testable solution to problem, For example, our hypothesis in
this case could be that the toast didn't toast because the electrical outlet is
broken.
This hypothesis is not necessarily the right explanation. Instead, it's a
possible explanation that we can test to see if it is likely correct.
 4. Make predictions.
A prediction is an outcome we'd expect to see if the hypothesis is correct. In
this case, we might predict that if the electrical outlet is broken, then
plugging the toaster into a different outlet should fix the problem.
 5. Test the predictions.
 To test the hypothesis, we need to make an observation or perform an
experiment associated with the prediction. For instance, in this case, we
would plug the toaster into a different outlet and see if it toasts. If the
toaster does toast, then the hypothesis is supported—likely correct.
 If the toaster doesn't toast, then the hypothesis is not supported—likely
wrong.
 Inductive reasoning aims at developing a theory while deductive aims at testing an
existing theory.
 Inductive: specific to general, provide conclusion based that are nor certain but
based on the probability of the observed patterns.
Example: dark clouds lead to rain
 Deductive: general to specific
logically conclusions. If this true then conclusion must true.
Example: all birds have feathers
Robins are birds
Therefore Robins have feathers.