College of Biotechnology
Medical Biotechnology department and
Agricultural Biotechnology department
Second Stage
No. (1)
Cell Structure & Function
Asst. lecturer
Ahmed Ghdhban Alziaydi
MSc. Biochemistry
11/15/2015
1
What is a cell?
A cell is the basic unit of life, from which larger structures
such as tissue and organs are made.
 Unicellular organisms,
such as bacteria, consist of
just a single cell.
 Multicellular organisms
consists of many cells –
humans are made from an
estimated 50 trillion cells!
A cell is the smallest unit that is
capable of performing life functions.
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Specialized cells
Most plants and animals are multicellular. The human
body is made up of around 200 different types of cell, all
working together.
Most cells are specialized, meaning
that each type of cell has a specific
structure and function.
All cells with a nucleus contain the
same genes, but different cells
activate different genes so they only
produce the proteins they need.
However, all cells have certain
common features and structures
called organelles.
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What do cells contain?
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How do plant cells specialize?
Unlike animals, many plant cells retain the ability to
differentiate and specialize throughout their life. These
cells are found in tissues called meristems.
meristem cell
root cell
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leaf cell
sieve cell
© Boardworks Ltd 2007
How do animal cells specialize?
In animals, the first type of cells in the developing embryo
are stem cells. These are unspecialized cells that go on to
form all the different cell types in the adult.
red blood cell
nerve cell
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stem cell
sperm cell
muscle cell
© Boardworks Ltd 2007
Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
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AGT
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How do cells get their energy?
All organisms need energy
to survive.
Animals obtain their energy
from the food they eat, but
plants can make their own
food by photosynthesis.
In both cases, however,
energy must first be converted
into a form that can easily be
used by cells. This process is
called respiration.
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Prokaryotic
• Do not have
structures
surrounded by
membranes
• Few internal
structures
• One-celled
organisms,
Bacteria
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AGT
http://library.thinkquest.org/C004535/prokaryotic_cells.html
9
Eukaryotic
• Contain organelles surrounded by membranes
• Most living organisms
Plant
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http://library.thinkquest.org/C004535/eukaryotic_cells.html
Animal
10
“Typical” Animal Cell
http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif
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Animal Cell
Plant Cell
“Typical” Plant Cell
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http://waynesword.palomar.edu/images/plant3.gif
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Cell Parts
Organelles
Surrounding the Cell
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Cell Membrane
• Outer membrane of cell
that controls movement
in and out of the cell
• Double layer
http://library.thinkquest.org/12413/structures.html
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AGT
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Cell
Membrane
• A cell membrane keeps all the parts of the
cell inside.
• It controls what enters and exits the cell
such as water, nutrients and waste and
thereby protects and supports the cell.
• It is the outermost layer in the animal cell.
What is a cell wall?
All plant cells have a cell wall –
a rigid layer that surrounds the
cell membrane.
The plant cell wall is made
from cellulose, a carbohydrate
polymer. The purpose of the
cell wall is to:
 maintain the shape and structure of the cell
 protect the cell’s contents from pathogens
 prevent damage to the cell caused by excess water intake.
Unlike the cell membrane, the cell wall is freely
permeable to water and other molecules.
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Cell Wall
• Most commonly found
in plant cells &
bacteria
• Supports & protects
cells
http://library.thinkquest.org/12413/structures.html
10/25/2015
AGT
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Inside the Cell
Nucleus
• Directs cell activities
• Separated from cytoplasm by nuclear
membrane
• Contains genetic material - DNA
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Nucleus
• The nucleus is located in the cytoplasm of the
cell.
• It controls and regulates all cell activities. It is
the "control center" of the cell and it contains
the cell's DNA.
• It has a similar function to the brain of the
body which is helping to control eating,
movement, and reproduction.
Nuclear Membrane
• Surrounds nucleus
• Made of two layers
• Openings allow
material to enter and
leave nucleus
http://library.thinkquest.org/12413/structures.html
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Chromosomes
• In nucleus
• Made of DNA
• Contain instructions
for traits &
characteristics
http://library.thinkquest.org/12413/structures.html
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Nucleolus
• Inside nucleus
• Contains RNA to build
proteins
http://library.thinkquest.org/12413/structures.html
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Cytoplasm
• Inside the cell, there is a large fluid-filled
space called the cytoplasm.
• It is a jelly-like substance composed of
mainly water as well as substances like
dissolved nutrients.
• The cytoplasm fills up the space between the
nucleus and the cell membrane.
• Gel-like mixture
• Surrounded by cell membrane
• Contains hereditary material
Endoplasmic Reticulum
• Moves materials around
in cell
• Smooth type: lacks
ribosomes
• Rough type (pictured):
ribosomes embedded in
surface
http://library.thinkquest.org/12413/structures.html
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Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on ribosomes
& floating throughout
the cell
http://library.thinkquest.org/12413/structures.html
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Mitochondria
• Produces energy through
chemical reactions –
breaking down fats &
carbohydrates
• Controls level of water and
other materials in cell
• Recycles and decomposes
proteins, fats, and
carbohydrates
http://library.thinkquest.org/12413/structures.html
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Where does respiration take place?
Mitochondria are cellular organelles in which
respiration takes place.
Mitochondria use enzymes to
convert the energy from glucose
into ATP – the basic energy
source for all cells.
Mitochondria have an inner
membrane on which the
enzymes are embedded.
This membrane is highly folded to increase the surface
area on which respiration can take place.
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What are chloroplasts?
Chloroplasts are the site of photosynthesis
in plant cells.
A green pigment in chloroplasts
called chlorophyll absorbs the
energy in sunlight.
This energy is used to
convert carbon dioxide
and water into glucose
and oxygen.
thylakoids
Chlorophyll is embedded in disk-like structures called
thylakoids, which are arranged into stacks.
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Golgi Bodies
• Protein 'packaging
plant'
• Move materials within
the cell
• Move materials out of
the cell
http://library.thinkquest.org/12413/structures.html
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Lysosome
• Digestive 'plant' for
proteins, fats, and
carbohydrates
• Transports undigested
material to cell
membrane for removal
• Cell breaks down if
lysosome explodes
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http://library.thinkquest.org/12413/structures.html
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What is a vacuole?
The vacuole is a fluid–filled
sac found within plant cells
and some bacteria.
The vacuole has a range of
functions, including:
 storing waste products
 maintaining the water and pH balance of the cell
 regulating the turgor pressure of the cell.
The site of vacuoles depend on how much water the plant
has absorbed.
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Vacuoles
• Membrane-bound
sacs for storage,
digestion, and waste
removal
• Contains water
solution
• Help plants maintain
shape
http://library.thinkquest.org/12413/structures.html
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Plant cells
PLANT CELL
Chloroplast
Cytoplasm
Nucleus
Cell
Membrane
Cell Wall
• A cell membrane
keeps all the parts of
the cell inside.
Cell
Membrane
• It controls what
enters and exits the
cell such as water,
nutrients and waste
and thereby protects
and supports the cell.
• It is found just inside
the cell wall in the
plant cell.
• The cell wall is found in
plant cells but not in
animal cells.
• This is the outermost
layer in the plant cell. It is
stiff and rigid and helps a
plant keep its shape.
• Cell walls allow materials
like water and nutrients;
waste, oxygen and carbon
dioxide to pass to and
from the cell membrane.
Cell
Wall
• Chloroplasts are only
found in plant cells. They
are responsible for
photosynthesis.
• Every green plant you
see is working to convert
the energy from the sun
into sugars during the
process of
photosynthesis.
Chloroplast
• Plants are the basis of all
life on Earth. They make
sugars, and the byproduct of
photosynthesis is the
oxygen that we breathe.
• Chloroplasts are green
because of the pigment
chlorophyll.
• Inside the cell, there is
a large fluid-filled
space called the
cytoplasm.
Cytoplasm
• It is a jelly-like
substance composed
of mainly water as well
as substances like
dissolved nutrients.
• The cytoplasm is found
in both plant and
animal cells, filling the
space between the
nucleus and the cell
membrane.
• The nucleus is found in
both plant and animal
cells.
• It is located in the
cytoplasm of the cell.
• It controls and regulates
all cell activities. It is the
"control center" of the
cell and it contains the
cell's DNA.
• It has a similar function
to the brain of the body
which is helping to
control eating, movement,
and reproduction.
Nucleus
Let’s summarise:
Plant Cell - Functions
Nucleus
control centre of the cell – stores
information for cell functions
Chloroplasts
contain green pigment
chlorophyll, needed in
photosynthesis
jelly-like, where cell activities
take place
Cytoplasm
Cell
membrane
thin, controls the substances that
enter or exit the cells
Cell wall
stiff wall which gives plant cells
their shape
Let’s summarise:
Animal Cell - Functions
Nucleus
control centre of the cell
– stores information for
cell functions
Cytoplasm
jelly-like, where cell
activities take place
Cell membrane thin, controls the
substances that enter or
exit the cells
Differences between Plant and
Animal Cells
Plant Cell
Animal Cell
•Plant cells contain
chloroplasts to make
food from solar energy
during photosynthesis.
•Underground parts of
plants usually do not
contain chloroplasts.
•Animal cells do not
contain chloroplasts.
•Plant cells contain cell
wall.
Animal cells do not have
cell wall.
Glossary (1/2)
 aerobic respiration – The process of releasing energy
through the oxidation of glucose molecules.
 anaerobic respiration – The process of releasing
energy from glucose molecules in the absence of oxygen.
 ATP – Adenosine triphosphate, the major form of energy
used by cells.
 cell – The basic structural and functional unit of life.
 cell membrane – The partially-permeable barrier that
regulates substances entering and leaving a cell.
 cell wall – The rigid external coat that protects and
supports plant cells.
 chlorophyll – The green pigment found in chloroplasts.
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Glossary (2/2)
 chloroplast – The site of photosynthesis in plant cells.
 cytoplasm – The jelly-like material in which all a cell’s
organelles are found, and in which most cellular processes
and reactions occur.
 mitochondria – The site of energy release by respiration.
 nucleus – The location of a cell’s DNA.
 photosynthesis – The chemical reaction in which light
energy is used to convert carbon dioxide and water into
glucose and oxygen.
 ribosome – The site of protein synthesis.
 vacuole – The fluid-filled cavity found in plant cells that
stores water and nutrients.
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