He is credited as one of the first scientists to

investigate living things at microscopic scale in

1665, using a compound microscope that he
designed.

Hooke refined the design of the compound

microscope around 1665 and published a book
titled Micrographia which illustrated his
findings using the instrument.
 was proposed by Matthias Jakob Schleiden and
Theodor Schwann. This theory proposed that “all
living beings whether plants or animals are
composed of a group of cells which arise from the
pre-existing cells.”
All living things are composed of cells.

Cells are the structural and functional unit

of life.

New cells are made from preexisting cells,

which divide into two
• Cell define as the “most basic” unit of life,
hence, it is structurally and functionally
complex

• A cell can be a mini-organism consisting

of tiny organs called organelles.
• It is the movement of substances across the
cell membrane either into or out of the cell.
Sometimes things just move through the
phospholipid bilayer.
• Cell transport may require energy.
 - it requires energy in the form of Adenosine triphosphate(ATP),
substances from lower concentration to higher concentration transport
through cell membrane.

- it does not require any energy and it transmits substances from high
concentration to lower concentration through transport through cell
membrane.
•

The larger molecules or large substances of

extracellular fluid will enter into the cell through
the process of endocytosis.

•
The vesicle present inside the cell moves outside of
the cell membrane This is commonly occurring,
when the cell needs to export a molecule, enzymes
and hormones .
The transport mechanisms across the cell membrane are vital for maintaining cellular
functions and homeostasis. Intrinsic proteins facilitate various types of transport—
passive diffusion for small molecules and active transport for larger or charged
particles—ensuring that cells can efficiently uptake nutrients and expel waste
products while regulating internal environments.
 is the set of chemical reactions that
occur in living organisms in order to
maintain life. Cellular metabolism
involves complex sequences of
controlled biochemical reactions,
better known as metabolic pathways.
These processes allow organisms to
grow and reproduce, maintain their
structures, and respond to
environmental changes.
Anabolic process or anabolism is
the biosynthetic pathways that
generate complex macromolecules
such as nucleic acids, proteins,
polysaccharides, and lipids.
Catabolism is the set of metabolic
processes that break down large
molecules. These more complex
molecules are broken down to
produce energy necessary for
various functions of the body.
• is a process by which cells duplicate
their contents and then divide to yield
multiple cells with similar, if not
duplicate, contents.

• Cells reproduce by a cycle of growing

and dividing called the cell cycle.
• Cell division is the process in which one cell, called the parent cell, divides to form
two new cells, referred to as daughter cells. How this happens depends on whether
the cell is prokaryotic or eukaryotic.
• Cell division is simpler in prokaryotes than eukaryotes because prokaryotic cells
themselves are simpler. Prokaryotic cells have a single circular chromosome, no
nucleus, and few other organelles.

• The cell cycle is a repeating series of events that include growth, DNA synthesis, and
cell division. The cell cycle in prokaryotes is quite simple: the cell grows, its DNA
replicates, and the cell divides. This form of division in prokaryotes is called asexual
reproduction. In eukaryotes, the cell cycle is more complicated.
Growth Phase 1 (G1). The cell spends most of its life in the first gap (sometimes referred
to as growth) phase. During this phase, a cell undergoes rapid growth and performs its
routine functions.
G0 phase. The G0 phase is a resting phase where the cell has left the cycle and has
stopped dividing. These cells may remain in G0 for long periods of time, even
indefinitely, such as with neurons.

Synthesis Phase (S). For two genetically identical daughter cells to be formed, the cell’s
DNA must be copied through DNA replication.
Growth Phase 2 (G2). The second gap (growth) (G2) phase is a shortened growth period in
which many organelles are reproduced or manufactured. Parts necessary for mitosis
and cell division are made during G2, including microtubules used in the mitotic spindle.

Mitotic Phase. Before a eukaryotic cell divides, all the DNA in the cell’s multiple
chromosomes is replicated. Its organelles are also duplicated. This happens in the
interphase. Then, when the cell divides (mitotic phase), it occurs in two major steps,
called
a. mitosis, division of nucleus and
b. cytokinesis, division of cytoplasm
The cell cycle is controlled mainly by regulatory proteins. These proteins control the cycle by signaling
the cell to either start or delay the next phase of the cycle. They ensure that the cell completes the
previous phase before moving on. Regulatory proteins control the cell cycle at key checkpoints,

The mitosis
The G1 checkpoint: just DNA synthesis checkpoint: This
before entry into the S Checkpoint: The S checkpoint ensures
phase, makes the key checkpoint determines that all the
decision of whether the if the DNA has been chromosomes are
cell is big enough to divide. replicated properly. properly aligned before
the cell is allowed to
divide.
Mitosis is a process by which a single cell divides to produce two identical daughter
cells. It plays a crucial role in growth, development, and the replacement of worn-out or
damaged cells in the body.
The process in which the
nucleus of a eukaryotic cell
divides is called mitosis. During
mitosis, the two sister
chromatids that make up each
chromosome separate from
each other and move to
opposite poles of the cell.
Mitosis occurs in four phases.
The phases are called prophase,
metaphase, anaphase, and
telophase
The first and longest phase of
mitosis is prophase. During
prophase, chromatin condenses
into chromosomes, and the nuclear
envelope (the membrane
surrounding the nucleus) breaks
down.
During metaphase, spindle fibers fully
attach to the centromere of each pair of
sister chromatids. The spindle fibers
ensure that sister chromatids will
separate and go to different daughter
cells when the cell divides.
During anaphase, sister chromatids
separate and the centromeres divide.
The shortening of the spindle fibers
pulls apart the sister chromatids. One
sister chromatid moves to one pole of
the cell, and the other sister chromatid
moves to the opposite pole .At the end
of anaphase, each pole of the cell has a
complete set of chromosomes
During telophase, the chromosomes
move to opposite ends of the cell and
start to unwind back into a loose form
called chromatin. New nuclear
envelopes form around each set of
chromosomes, and structures called
nucleosomes appear in the newly
formed nuclei.
Cytokinesis is the final stage of cell
division in eukaryotes as well as
prokaryotes. During cytokinesis, the
cytoplasm splits in two and the cell
divides. The process is different in plant
and animal cells, in animal cells, the
plasma membrane of the parent cell
pinches inward along the cell’s equator
until two daughter cells form. In the plant
cells, a cell plate forms along the equator
of the parent cell.
The ultimate goal of the process of meiosis is to reduce the number
of chromosomes by half to produce gametes. This must occur prior
to sexual reproduction. The final products of meiosis, four daughter
cells, each contain one chromatid from each original homologous
pair, for a total of two chromosomes.

Haploid- (n) one set of chromosomes-half diploid

Diploid- (2n) two sets of chromosome

01 Meiosis- A two phase nuclear division that results in the eventual
production of gametes with half the normal number of chromosomes.

Gamete - specialized cell (egg or sperm) used in sexual reproduction

02 containing half the normal number of chromosomes of a somatic
cell.

Gene Recombination-A natural process in which a nucleic acid

03 molecule (usually DNA but can be RNA) is broken and then joined to
a different molecule; a result of crossing-over.
 are the fundamental DNA from all The human genome (total Genes are specific
structural and organisms is made up composition of genetic sequences of bases that
functional units of every of the same chemical material within a cell) is encode instructions for
known living organism. units (bases) called packaged into larger units how to make proteins. The
Instructions needed to adenine, thymine, known as chromosomes— DNA sequence is the
direct activities are guanine, and cytosine, physically separate particular side-by-side
contained within a DNA abbreviated as A, T, G, molecules that range in arrangement of bases
(deoxyribonucleic acid) and C length from about 50 to along the DNA strand (e.g.,
sequence. 250 million base pairs. ATTCCGGA).
 Mendelian inheritance, established by Gregor Mendel in the 19th
century, describes how traits are passed from parents to offspring
through discrete units called genes.
 GENES

• Genes are contained in chromosomes, which are in

the cell nucleus.

• Genes are segments of deoxyribonucleic acid

(DNA) that contain the code for a specific protein
that functions in one or more types of cells in the
body or the code for functional ribonucleic acid
(RNA) molecules.
 CHROMOSOMES
• Chromosomes are structures within cells that
contain a person's genes.
• Chromosomes are threadlike structures made of
protein and a single molecule of DNA that serve to
carry the genomic information from cell to cell. In
plants and animals (including humans),
chromosomes reside in the nucleus of cells.
• The human cells contain 46 chromosomes, which
contain DNA that makes each cell unique.
 ALLELE
• An allele is defined as one of two or more
versions of a DNA sequence at a specific
location (locus) on a chromosome.
• Each individual inherits two alleles for any
given gene, one from each parent.
• If both alleles are identical, the individual is
described as homozygous;
• If they are different, the individual is
heterozygous that can either be dominant
or recessive.
 ALLELE
• Dominant: A dominant allele is one that
expresses its trait even when only one copy
is present in the genotype. This means that
if an individual has at least one dominant
allele for a trait, that trait will be expressed
in the phenotype.
• Recessive: only expresses its trait when
two copies are present in the genotype
(homozygous recessive). If an individual
has one dominant allele and one recessive
allele, the dominant trait will mask the
expression of the recessive trait.
 BLOOD TYPE
• Blood type is a genetic characteristic
determined by the presence of specific
antigens on the surface of red blood cells.
The ABO blood group system is particularly
significant in human genetics and is
governed by a single gene that has three
main alleles: A , B , O
Genotype (or genome) is a Phenotype is the actual
person’s unique combination of structure and function of a
genes or genetic makeup. Thus, person’s body. The phenotype
the genotype is a complete set of is how the genotype
instructions on how that manifests in a person—not all
person’s body synthesizes the instructions in the
proteins and thus how that body genotype may be carried out
is supposed to be built and (or expressed).
function.
 GENE
INHERITANCE
 MULTIPLE ALLELE & MULTIPLE
GENES

• Mendel’s concept of inheritance

contemplated that a gene has two
alternative forms or allele, one being
dominant and other recessive.

• Multiple alleles may exist at the population

level such that many combinations of two
alleles are observed.
 CHROMOSOME THEORY OF
INHERITANCE
The chromosomal theory of inheritance
was given by Boveri and Sutton in the
early 1900s. It is the fundamental
theory of genetics. According to this
theory, genes are the units of heredity
and are found in the
chromosomes.Chromosomal Theory of
Inheritance came into existence long
after Mendelian genetics.
 GENE INHERITANCE
• A Punnett square is a graphical tool
used in genetics to predict the possible
genotypes and phenotypes of offspring
resulting from a cross between two
parents.
• Named after Reginald C. Punnett, this
method simplifies the understanding of
inheritance patterns by organizing
genetic information.
 GENE INHERITANCE
• How to Create a Punnett Square
• Draw the Grid: Start by drawing a square and dividing it
into four equal boxes for a monohybrid cross (two traits
can be organized in a 4x4 grid for dihybrid crosses).

• Label the Parents: Write one parent's genotype across

the top and the other parent's genotype down the left
side. For example, if one parent is heterozygous (Aa) and
the other is homozygous recessive (aa), label
accordingly.
 GENE INHERITANCE
• Fill in the Boxes: Each box represents a possible
genotype of the offspring. Fill in the boxes by combining
the alleles from each parent.
For instance:
From parent 1 (Aa): A and a
From parent 2 (aa): a and a
• The resulting combinations would be:
AA
Aa
Aa
aa
 GENE INHERITANCE
• Calculate Probabilities: Analyze the completed square to
determine the probabilities of each genotype and
phenotype.

In this example, there would be:

50% chance of Aa (heterozygous)
50% chance of aa (homozygous recessive)
 DEOXYRIBONUCLEIC ACID (DNA)

DNA is a fundamental molecule that carries the genetic instructions

necessary for the growth, development, functioning, and reproduction of
all known living organisms and many viruses. It is often described as the
blueprint of life.

DNA (deoxyribonucleic acid) is the cell’s genetic material, contained in

chromosomes within the cell nucleus and mitochondria. The DNA
molecule is a long, coiled double helix that resembles a spiral staircase.
 RIBONUCLEIC ACID (RNA)

RNA is primarily single-stranded and has a backbone composed of

ribose sugars and phosphate groups. RNA serves as the intermediary
between DNA and protein synthesis. It transcribes genetic information
from DNA during transcription and translates that information into
proteins during translation.
DEOXYRIBONUCLEIC ACID (DNA)
Pairing
There are 22 pairs of nonsex (autosomal) chromosomes and one pair of
sex chromosomes. Paired nonsex chromosomes are, for practical
purposes, identical in size, shape, and position and number of genes. The
23rd pair is the sex chromosomes (X and Y).

Sex chromosomes
The pair of sex chromosomes determines whether a fetus becomes male
or female. Males have one X and one Y chromosome. A male’s X comes
from his mother and the Y comes from his father. Females have two X
chromosomes, one from the mother and one from the father.
• A person may have an abnormal number of chromosomes or have
abnormal areas on one or more chromosomes. Many such abnormalities
can be diagnosed before birth.

• Abnormal numbers of nonsex chromosomes usually result in severe

abnormalities. For example, receiving an extra nonsex chromosome
may be fatal to a fetus or lead to abnormalities such as Down syndrome,
which commonly results from a person having three copies of
chromosome 21. Absence of a nonsex chromosome is fatal to the fetus.
Incomplete dominance pertains to the
genetic phenomenon in which the
distinct gene products from the two
codominant alleles in a heterozygote
blend to form a phenotype
intermediate between those of the two
homozygotes.
Codominance, as it relates to
genetics, refers to a type of
inheritance in which two
versions (alleles) of the same gene
are expressed separately to yield
different traits in an individual.
 THEORY OF EVOLUTION

-is the unifying theory of biology, meaning

it is the framework within which biologists
ask questions about the living world. Its
power is that it provides direction for
predictions about living things that are
borne out in experiment after
experiment.“Nothing makes sense in
biology except in the light of evolution”
(Dobzhansky, 1964).
Evolution by natural selection describes a mechanism for how species change over time.
There are two levels to this change;

MICROEVOLUTION MACROEVOLUTION

Refers to changes in the Refers to changes within whole

frequency of a gene in a taxonomic groups over long
population. These changes can periods of time. This can be
occur in short periods of time seen as the formation of a new
and may not be visible until trait or feature, the creation of
enough data is collected over new species, or the loss of
several generations species via extinction events.
• Natural selection is a fundamental mechanism of
evolution described by Charles Darwin. It explains how
certain traits become more common in a population
over time due to their advantages in survival and
reproduction.

• Natural selection is a mechanism of evolution.

Organisms that are more adapted to their environment
are more likely to survive and pass on the genes that
aided their success.
The process involves several key components:
• Variation: Individuals within a population exhibit
variations in traits (e.g., size, color, speed).
• Competition: Resources such as food, mates, and habitat
are limited, leading to competition among individuals.
• Survival and Reproduction: Individuals with traits that
provide a survival advantage are more likely to survive
and reproduce, passing those advantageous traits to
their offspring.
The phrase "survival of the fittest," coined by
philosopher Herbert Spencer, is often associated with
natural selection. However, it can be somewhat
misleading.
Here's what it really means:

"Fittest" Defined: In this context, "fittest" refers not necessarily to the

strongest or fastest individuals but to those best suited to their environment.
This can include various traits such as camouflage, disease resistance, or
reproductive success.

Adaptation: Over generations, the traits that enhance survival and

reproduction become more prevalent in the population. This process leads to
adaptation, where species become better suited to their environments.

Not Just Survival: While survival is important, reproduction is equally crucial.

An individual may survive longer than others but may not reproduce
successfully. Thus, "fitness" encompasses both survival and reproductive
success.
 Second, more
First, most Third, offspring
offspring are
characteristics of vary among each
produced than are
organisms are other in regard to
able to survive, so
inherited, or their
resources for
passed from characteristics and
survival and
parent to those variations are
reproduction are
offspring. inherited
limited
• May produce a phenotype It leads to genetic diversity:
with a beneficial effect on when two parents reproduce,
fitness unique combinations of alleles
assemble to produce the
• Will also have no effect on unique genotypes and thus
the fitness of the phenotypes in each of the
phenotype; these are offspring.
called neutral mutations
When two species evolve in diverse
directions from a common point

where similar traits evolve independently

in species that do not share a common
ancestry.
 It refers to any difference between Refers to the passing of genetic factors
the individuals in a species or from parents to offspring or from one
groups of organisms of any species. generation to the next.

the survival and reproduction of refers to the extended periods over

individuals with certain genotypes which evolutionary processes occur,
(genetic compositions), by means of allowing for gradual changes and
natural or artificial controlling factors. adaptations
• During his journey, Darwin found the bones of an
extinct giant sloth, Megatherium. He realized that
animals can become extinct and that life is not
unchanging, and he also saw similarities between
extinct and living animals.

• Darwin and scientists today have discovered that the

ancient organisms whose remains they find look like
organisms alive today because they are the living
organisms' ancestors or evolved from a common
ancestor.
• Fossil layers are fossils that formed in
sedimentary rock. Sedimentary rock is rock
that is formed in layers by the depositing
and pressing of sediments on top of each
other.
• Once thing that Darwin noticed on his
travels, and that people continue to notice
today, is that fossils in the bottom layers are
very different from the organisms alive
today;
• From this, Darwin concluded that organisms
have not remained the same since earth's
beginning, and that they have changed a lot,
gradually becoming more and more
complex.
One type of evidence for evolution (evidence
that organisms are related, descended from a
few common ancestors, and change to adapt to
their environments) is that organisms are
similar to each other, but not exactly the same.
Similar organisms have differences that help
them adapt to their environments.
The study of one type of evidence of
evolution is called embryology, the
study of embryos. An embryo is an
unborn (or unhatched) animal or human
young in its earliest phases. Embryos of
many different kinds of animals:
mammals, birds, reptiles, fish, etc. look
very similar and it is often difficult to
tell them apart. The embryos of this
hippo and frog all looked very similar in
their early stages of development.