COURSE : CELL BIOLOGY
CREDIT HOURS : 2 CREDITS
SEMESTER/SESSION : 2nd SEMESTER; 2022/2023
EUKARYOTIC CELL
• Eukaryotic, whose members are known as eukaryotes, is a device domain of
organisms whose cells have a nucleus.
• All animals, plants, fungi and many unicellular organisms, are eukaryotes. They
belong to the group of organisms eukaryotes or eukaryote, which is one of the
three domains of life.
• Defined as cells containing organized nucleus and organelles which are
enveloped by membrane-bound organelles.
• Examples of eukaryotic cells are plants, animals, protists, fungi. Their genetic
material is organized in chromosomes.
• Eukaryotic cells have a nucleus enclosed within the nuclear membrane and
form large and complex organisms. Protozoa, fungi, plants, and animals all have
eukaryotic cells. They are classified under the kingdom eukaryote.
• They can maintain different environments in a single cell that allows them to
carry out various metabolic reactions. This helps them grow many times larger
than the prokaryotic cells.
Characteristics of Eukaryotic Cells
• The features of eukaryotic cells are as follows:
• Eukaryotic cells have the nucleus enclosed within the nuclear membrane.
• The cell has mitochondria.
• Flagella and cilia are the locomotory organs in a eukaryotic cell.
• A cell wall is the outermost layer of the eukaryotic cells.
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• The cells divide by a process called mitosis.
• The eukaryotic cells contain a cytoskeletal structure.
• The nucleus contains a single, linear DNA, which carries all the genetic
information.
Structure of Eukaryotic Cell
Plasma Membrane
• The plasma membrane separates the cell from the outside environment.
• It comprises specific embedded proteins, which help in the exchange of
substances in and out of the cell.
Cell Wall
• A cell wall is a rigid structure present outside the plant cell. It is, however,
absent in animal cells.
• It provides shape to the cell and helps in cell-to-cell interaction.
• It is a protective layer that protects the cell from any injury or pathogen attacks.
• It is composed of cellulose, hemicellulose, pectin’s, proteins, etc.
Cytoskeleton
• The cytoskeleton is present inside the cytoplasm, which consists of
microfilaments, microtubules, and fibers to provide perfect shape to the cell,
anchor the organelles, and stimulate the cell movement.
Endoplasmic Reticulum
• It is a network of small, tubular structures that divides the cell surface into two
parts: luminal and extraluminal. Endoplasmic Reticulum is of two types:
• Rough Endoplasmic Reticulum contains ribosomes.
• Smooth Endoplasmic Reticulum that lacks ribosomes and is therefore smooth.
Nucleus
• The nucleoplasm enclosed within the nucleus contains DNA and proteins.
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• The nuclear envelo two layers the outer membrane and p consists of - the inner
membrane. Both the permeable to ions, molecules, andmembranes are RNA
material. Ribosome production also takes place inside the nucleus.
Golgi Apparatus
• It is made up of flat disc-shaped structure is absent in red s called cisternae. It
blood cells of humans and sieve cells of plants.
• They are arranged parallel and concentrically near the nucleus.
• It is an important site for the formation of glycoproteins and glycolipids.
Ribosomes
• These are the main site for protein synthesis and are composed of proteins and
ribonucleic acids.
Mitochondria
• These are also known as “ cells” because they produce energy.powerhouse of
• It consists of an outer membrane and membrane. The inner membrane an inner
is divided into folds called cristae.
• They help in the regulation of cell metabolism.
Lysosomes
• They are known as “suicidal bags “because they possess hydrolytic enzymes to
digest protein, lipids, carbohydrates, and nucleic acids.
Plastids
• These are double-membraned structures and are found only in plant cells. These
are of three types:
• Chloroplast that contains chlorophyll and is involved in photosynthesis.
• Chromoplast that contains a pigment called carotene that provides the plants
yellow, red, or orange colors.
• Leucoplasts that are colorless and store oil, fats, carbohydrates, or proteins.
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Examples of Eukaryotic Cells
• Eukaryotic cells are exclusively found in plants, animals, fungi, protozoa, and
other complex organisms. Th e examples of eukaryotic cells are
Plant Cells
• The cell wall is made up of cellulose, which provides support to the plant. It
has a large vacuole which maintains the turgor pressure. The plant cell contains
chloroplast, which aids in the process of photosynthesis.
Fungal Cells
• The cell wall is made of chitin. Some fungi have holes known as septa which
allow the organelles and cytoplasm to pass through them.
Animal Cells
• These do not have cell walls. Instead, they have a cell membrane. That is why
animals have varied shapes. They have the ability to perform phagocytosis and
pinocytosis.
Protozoa
• Protozoans are unicellular organisms. Some protozoa have cilia for locomotion.
A thin layer called pellicle provides supports to the cell.
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