This document discusses cell structure and types of cells. It begins by defining the cell as the basic unit of life and describes single-celled and multicellular organisms. The components of cells are then outlined, including the cell membrane, nucleus, cytoplasm, and organelles. The two main types of cells - prokaryotic and eukaryotic cells - are also summarized. Prokaryotic cells lack a nucleus and organelles, while eukaryotic cells have membrane-bound nuclei and organelles.

1. Cell structure
BSc II ZOOLOGY
Dr. G.D.HANDE
Assistant Professor
Dept. of Zoology
SHRI SHIVAJI SCIENCE COLLEGE
AMRAVATI

2.  Cell, in biology, the basic membrane-bound unit that
contains the fundamental molecules of life and of which
all living things are composed.
 A single cell is often a complete organism in itself, such
as a bacterium or yeast. Other cells acquire specialized
functions as they mature.
 These cells cooperate with other specialized cells and
become the building blocks of large multicellular
organisms, such as humans and other animals.
Cells are often called the "building blocks of life".

3.  Although cells are much larger than atoms, they are still
very small.
 All cells are made from the same major classes of organic
molecules: nucleic acids, proteins, carbohydrates, and
lipids.
 A cell consists of three parts: the cell membrane, the
nucleus, and, between the two, the cytoplasm.
 Within the cytoplasm lie intricate arrangements of fine
fibers and hundreds or even thousands of miniscule but
distinct structures called organelles.

4. FUNCTION OF CELL
The seven processes are movement, reproduction,
response to external stimuli, nutrition, excretion,
respiration and growth.
Cells provide six main functions
They provide structure and support, facilitate growth
through mitosis, allow passive and active transport,
produce energy, create metabolic reactions and aid in
reproduction.

5. The Four Main Types of Cells
Epithelial Cells. These cells are tightly attached to one another.
Nerve Cells. These cells are specialized for communication.
Muscle Cells. These cells are specialized for contraction. ...
Connective Tissue Cells.

6. Two Types of Cells
There are two cell types: prokaryotes and eukaryotes. Prokaryotic cells
are usually single-celled and smaller than eukaryotic cells. Eukaryotic
cells are usually found in multicellular organisms, but there are some
single-celled eukaryotes.

9. All cells, whether prokaryotic or eukaryotic, share these four features:
1. DNA
2. Plasma membrane
3. Cytoplasm
4. Ribosomes

10. Prokaryotes are unicellular organisms that lack membrane-bound
structures, the most noteworthy of which is the nucleus. Prokaryotic cells
tend to be small, simple cells, measuring around 0.1-5 μm in diameter.
While prokaryotic cells do not have membrane-bound structures, they do
have distinct cellular regions. In prokaryotic cells, DNA bundles together
in a region called the nucleoid.

11. Prokaryotic cell features
Here is a breakdown of what you might find in a prokaryotic
bacterial cell.
Nucleoid: A central region of the cell that contains its DNA.
Ribosome: Ribosomes are responsible for protein synthesis.
Cell wall: The cell wall provides structure and protection from the
outside environment.
Most bacteria have a rigid cell wall made from carbohydrates and
proteins called peptidoglycans.

12. Cell membrane: Every prokaryote has a cell membrane, also
known as the plasma membrane, that separates the cell from the
outside environment.
Capsule: Some bacteria have a layer of carbohydrates that
surrounds the cell wall called the capsule. The capsule helps the
bacterium attach to surfaces.
Fimbriae: Fimbriae are thin, hair-like structures that help with
cellular attachment.
Pili: Pili are rod-shaped structures involved in multiple roles,
including attachment and DNA transfer.
Flagella: Flagella are thin, tail-like structures that assist in
movement.

13. Examples of Prokaryotes
Bacteria and archaea are the two types of prokaryotes.
Do prokaryotes have mitochondria?
No, prokaryotes do not have mitochondria. Mitochondria are only
found in eukaryotic cells. This is also true of other membrane-bound
structures like the nucleus and the Golgi apparatus (more on these
later).
One theory for eukaryotic evolution hypothesizes that mitochondria
were first prokaryotic cells that lived inside other cells. Over time,
evolution led to these separate organisms functioning as a single
organism in the form of a eukaryote.

15. Eukaryotic cell features
Within a eukaryotic cell, each membrane-bound structure carries out specific
cellular functions. Here is an overview of many of the primary components
of eukaryotic cells.
Nucleus: The nucleus stores the genetic information in chromatin form.
Nucleolus: Found inside of the nucleus, the nucleolus is the part of
eukaryotic cells where ribosomal RNA is produced.
Plasma membrane: The plasma membrane is a phospholipid bilayer that
surrounds the entire cell and encompasses the organelles within.

16. Cytoskeleton or cell wall: The cytoskeleton or cell wall provides
structure, allows for cell movement, and plays a role in cell division.
Ribosomes: Ribosomes are responsible for protein synthesis.
Mitochondria: Mitochondria, also known as the powerhouses of the cell,
are responsible for energy production.
Cytoplasm: The cytoplasm is the region of the cell between the nuclear
envelope and plasma membrane.
Cytosol: Cytosol is a gel-like substance within the cell that contains the
organelles.

17. Endoplasmic reticulum: The endoplasmic reticulum is an organelle
dedicated to protein maturation and transportation.
Vesicles and vacuoles: Vesicles and vacuoles are membrane-bound sacs
involved in transportation and storage.
Other common organelles found in many, but not all, eukaryotes include
the Golgi apparatus, chloroplasts and lysosomes.

18. Comparing prokaryotes and eukaryotes
All life on Earth consists of either eukaryotic cells or prokaryotic cells.
Prokaryotes were the first form of life.
 The primary distinction between these two types of organisms is that
eukaryotic cells have a membrane-bound nucleus, prokaryotic cells do
not.
 The nucleus is where eukaryotes store their genetic information.
 In prokaryotes, DNA is bundled together in the nucleoid region, but it is
not stored within a membrane-bound nucleus.
 The nucleus is only one of many membrane-bound organelles in
eukaryotes.
 Prokaryotes, have no membrane-bound organelles.
 Eukaryote DNA consists of multiple molecules of double-stranded linear
DNA, while that of prokaryotes is double-stranded and circular.

19. Prokaryotes are microscopic organisms that have neither a
membrane-bound nucleus nor membrane-bound organelles.
Some cell biologists consider the term "organelle" to describe
membrane-bound structures only, whereas other cell biologists
define organelles as discrete structures that have a specialized
function.
 Prokaryotes have ribosomes, which are not surrounded by a
membrane but do have a specialized function, and could therefore
be considered organelles.
All metabolic functions carried out by a prokaryote take place in the
plasma membrane or the cytosol.

20.  All prokaryotes have a cell wall that adds structural support, acts
as a barrier against outside forces and anchors the whip-like
flagella.
 Some prokaryotes have an extra layer outside their cell wall
called a capsule, which protects the cell when it is engulfed by
other organisms, assists in retaining moisture, and helps the cell
adhere to surfaces and nutrients.
 Pili are hair-like structures on the surface of the cell that attach to
other bacterial cells or surfaces.

21. The primary distinction between these two types of organisms is that
eukaryotic cells have a membrane-bound nucleus and prokaryotic cells do
not. The nucleus is where eukaryotes store their genetic information.
Prokaryotes, on the other hand, have no membrane-bound organelles.

22. THANK YOU