A brief but complete overview of cell structure and the functions of its organelles.

1. Cell- It’s Structure and
Functions
Made by- Digvijay Singh
Class- IG-1

2. What is Cell?
 The cell (from Latin cella, meaning "small room") is the basic
structural, functional and biological unit of all known living
organisms. Cells are the smallest unit of life that can replicate
independently, and are often called the "building blocks of life".
The study of cells is called cell biology.
 Cells consist of a protoplasm enclosed within a membrane,
which contains many biomolecules such as proteins and nucleic
acids.
 Organisms can be classified as unicellular (consisting of a single
cell; including most bacteria) or multicellular (including plants
and animals). While the number of cells in plants and animals
varies from species to species, humans contain about 100
trillion (1014) cells. Most plant and animal cells are visible only
under the microscope, with dimensions between 1 and
100 micrometres.

3. Eukaryotic and Prokaryotic Cells
• Prokaryotic cells were the first form of life on Earth. They are
simpler and smaller than eukaryotic cells, and lack membrane-
bound organelles such as the nucleus. Prokaryotes include two of
the domains of life, bacteria and archaea. The DNA of a
prokaryotic cell consists of a single chromosome that is in direct
contact with the cytoplasm. The nuclear region in the cytoplasm is
called the nucleoid.
• Eukaryotic cells are about fifteen times wider than a typical
prokaryote and can be as much as a thousand times greater in
volume. The main distinguishing feature of eukaryotes as
compared to prokaryotes is compartmentalization: the presence of
membrane-bound compartments in which specific metabolic
activities take place. Most important among these is a cell nucleus,
a membrane-delineated compartment that houses the eukaryotic
cell's DNA. This nucleus gives the eukaryote its name, which
means "true nucleus."

4. The Cell Theory
• It was proposed by two German biologists, Theodor Schwann
and Matthias Schleiden in 1839
• It consists of the following points:
All known living things are made up of one or more cells.
All living cells arise from pre-existing cells by division.
The cell is the fundamental unit of structure and function in
all living organisms.
The activity of an organism depends on the total activity of
independent cells.
Energy flow (metabolism and biochemistry) occurs within
cells.
Cells contain DNA which is found specifically in the
chromosome and RNA found in the cell nucleus and
cytoplasm.
All cells are basically the same in chemical composition in
organisms of similar species .

5. Plasma Membrane
• The cell membrane (also known as the plasma membrane or
cytoplasmic membrane) is a biological membrane that separates the
interior of all cells from the outside environment.
• The cell membrane is selectively permeable to ions and organic
molecules and controls the movement of substances in and out of
cells.
• The basic function of the cell membrane is to protect the cell from its
surroundings.
• It consists of the phospholipid bilayer with embedded proteins. Cell
membranes are involved in a variety of cellular processes such as
cell adhesion, ion conductivity and cell signalling and serve as the
attachment surface for several extracellular structures, including the
cell wall, glycocalyx, and intracellular cytoskeleton. Cell membranes
can be artificially reassemble
• It helps in exocytosis and endocytosis

6. Cell Organelles
• Organelles are parts of the cell which are adapted
and/or specialized for carrying out one or more vital
functions, analogous to the organs of the human body
• Different Organelles
Mitochondria
Endoplasmic reticulum
Golgi apparatus
Lysosomes and Peroxisomes
Ribosomes
Centrosome
Vacuoles
Nucleus
Plastids

7. Cell Organelles- Functions
• Mitochondria
 Energy conversion
 Performs Pyruvate and the citric acid cycle
 NADH and FADH2: the electron transport chain
 Heat production
• Endoplasmic reticulum
 Protein transport
 Synthesis Lipids, Steroids
 Performs detoxification reactions
 Synthesis proteins

8. Cell Organelles- Functions (contd.)
• Golgi apparatus
 Synthesis Carbohydrate and Glycoprotein
 Modify, sort, and pack macromolecules
 Transports material around the cell
 Helps in exocytosis
• Lysosomes and Peroxisomes
 Break down waste materials and cellular debris
 Destroy foreign particles
 Helps in apoptosis
 Breaks down very long chain fatty acids

9. Cell Organelles- Functions (contd.)
• Centrosome
 Helps in cell division
 Assures equal distribution of
chromosomes in both daughter cells
• Ribosomes
 Translates mRNA into protein

10. Cell Organelles- Functions (contd.)
• Vacuoles
 Act as a transport in exocytosis and endocytosis
 Regulates the movements of ions around the cell
 Isolates materials that are harmful to cell
 Acts as a ‘store house’ of the cell
• Plastids
 Performs photosynthesis
 Synthesis pigments
 Monoterpene synthesis
 stores and modifies protein

11. Cell Organelles- Functions (contd.)
• Nucleus
 Cell compartmentalization
 Helps in Gene expression
 Process pre-mRNA
 Transfers genetic material from
parents to offspring
 Doesn't let genetic material to
flow into cytoplasm
 Helps in cell division
 Synthesis DNA and RNA (genetic material)

12. Cell Division
• Cell division is the process by which a parent cell divides
into two or more daughter cells.
• Cell division usually occurs as part of a larger cell cycle.
In eukaryotes, there are two distinct type of cell division:
a vegetative division, whereby each daughter cell is
genetically identical to the parent cell (mitosis), and a
reductive cell division, whereby the number of
chromosomes in the daughter cells is reduced by half, to
produce haploid gametes (meiosis). Meiosis results in
four haploid daughter cells by undergoing one round of
DNA replication followed by two divisions: homologous
chromosomes are separated in the first division, and
sister chromatids are separated in the second division.

13. Animal Cell

14. Plant cell

15. The End