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Cells and Systems
By: Manvi Thakore and Dimpi Shah
What are some characteristics of living
organisms?
Some characteristics of living organisms are:
• Energy
Living organisms need energy in order to live. They get their
energy from their food. Some living organisms make their own
food like plants. Humans and animals get their food from
plants and/or other living organisms.
• Environment
Living organisms are interacted to the environment in many
ways. For example living organisms find their food, make their
habitat and spend their whole life in that environment.
• Reproduce
Living organisms reproduce so the life cycle stay moving.
What are some characteristics of living
organisms?
• Growth
Living organisms grow gradually when the get
older.
• Wastes
All living organisms produce wastes.
What is the basic unit of all living
organisms?
Cells are the basic unit of all living organisms.
We all are made up of cells. We can think cells
as tiny dots on your body. The cell is the
smallest thing which contains life. All cells
don’t do the same function. The functions of
cells depend on where the cell is located in
the living organism. Cells take in nutrients and
convert them into their energy.
The Cell Theory
The Cell Theory is one of the principle in biology. In 1839
German botanist Matthias Schleiden and zoologist Theodore
Schwann researched about cells and combined their
observations. They made on basic hypothesis about cells that
“all living organisms are made up of cells”. German scientist
Rudolf Virchow combined his study’s with Scheiden and
Schwann. Their ideas formed and created 2 main hypothesis
called “the cell theory”.
The 2 main hypothesis are:
- All living things are made up of a single or multi cells.
- Cells are basic of a structure or function in all living organisms.
Who made the first microscope?
Zachcerias Jansen was the first person to make the compound
microscope. Zacherias and his father were spectacle makers
that once started experimenting with those lenses. They put
some lenses in a tube and made an important observation.
They noticed that lenses at the end of the tube looked
enlarged. It looked larger than any magnifying glass could do
in that period. That was the first simple compound
microscope made which had magnification power of 9x. Later
on Anton van Leeuwenhoek made a better microscope which
had magnification power of 270x. Leeuwenhoek made many
important biological discoveries with his microscope.
Microscopes Today
There are many modern microscopes
developed by design changes and better
technology. Different types of microscopes
used today are:
- Compound/Light microscopes
- Electron microscopes
Compound/Light Microscopes
Compound microscopes have 2 lenses in order
to have better magnification. Compound
microscopes can magnify many objects with a
power of magnification of 2000x.
How do they work?
Light is first given off by the light source and is
moved in by the condenser lens on the
specimen/model. Light from the specimen/model is
passed on to objective lens. The objective lens bends
the light rays and passes it to the projector lens.
Projector lens which reverses their direction so the
image doesn’t appear upside down. Then the light
rays travel to the eye piece.
Picture of compound microscope
Electron Microscopes
The electron microscope is a type of
microscope that uses a beam of electrons
andbounced off then showed to the screen. It
better of magnifications and has a greater
resolving power than a light microscope,
allowing it to see much smaller objects in
detail. Electron microscopes have a power of
magnification of 2000 000x.
How do they work?
When stream of electrons with small
wavelength allows smaller objects to be easily
seen than it would be seen with light. Stream
of electrons can be focused using metal
apertures and magnetic lenses. Beams pass
through the model and many lenses to zoom
in more detail.
Picture of electron microscope
What are the 2 categories of living things?
The 2 categories of living things are:
• Unicellular organisms (single-celled)
• Multicellular organisms (multi-celled)
Unicellular Organisms
Unicellular organisms are living organisms which are single
celled. Unicellular organisms have been on earth for 3.8
billion years. They are really small in size. You cannot observe
any type of unicellular organism with your eye. You need a
microscope in order to observe them.
Examples: Chlamydomonal, Virus and Paramecium
What are the 2 categories of living things?
Con….
Multicellular Organisms
Muticellular organisms are living organisms
which are Multi celled. They have been on
earth for a billion years. They are really large
in size.
Examples: Humans, Plants and Animals
Animal Cells
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The parts in Animal cells are:
Cell Membrane
Cytoplasm
Nucleus
Vacuoles
The Cell Membrane
The Cell Membrane surrounds all the living organism’s cell. The Cell
Membrane protects the organelles in the cell. It is like a thin wall to
protect the cell. It allows some materials to pass through like food, water
and oxygen. It doesn't let some substances to pass too. A membrane that
does let some substances pass through and some not are called selectively
permeable or semi permeable. A membrane that lets all materials pass
through is called permeable. A membrane that lets nothing pass through
is called impermeable. The other membranes that surround nucleus and
other membranes are similar to the cell membrane. The membranes are
made up of phospholipids, proteins and carbohydrates set up in a fluid
mosaic structure is a model made up by S.J Singer and Garth Nicolson in
1972 to describe the structural features of different membranes.
Cytoplasm
Cytoplasm is a substance which is filled in a
cell. It is a jelly type material which contains
80% of water and it looks clear in colour.
Cytoplasm is the largest part in the cell. It
flows through the all. Cytoplasm carries
materials so it can be transported to different
organelles in the cell. It also helps to support
many organelles.
Nucleus
A Nucleus is a large dark circular organelle which
controls the cells functions lie eating, movement,
reproduction and it also controls what passes
through the Cell membrane and the nuclear
membrane. Nucleus is not always found in the
middle of the cell. But it will always be somewhere in
the middle of the cytoplasm. Nucleus won’t to be
ever located in the edge because it will be dangerous
for the nucleus. Nucleus has a membrane called
nuclear membrane to protect the nucleus.
Vacuoles
Vacuoles are big circular looking just like big
soft sacs. The soft sac looking spaces called
vacuoles contain food storage, wastes and
other materials which are kept as extras. In
animal cells the vacuoles are usually small.
Vacuoles in plant cells are large because they
play a big role. When a plant is watered,
water collects in those vacuoles making the
plant stronger.
Vacuoles
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The materials in a vacuole depend on the
organism but mostly they contain:
Atmospheric gases
Inorganic salts
Organic acids
Sugars
Pigments
What are the main differences between
plant and animal cells?
The main differences between plants and animal cells are:
• Plant cells have 2 extra organelles than animal cells called The
Cell wall and Chloroplast.
Cell Wall
Cell walls are really helpful structures in plant cells. The cell
wall is so strong. It is more stronger and thicker than the cell
membrane. Cell wall is a big reason why there are differences
between plant and animal cell function’s. Cell wall keeps the
plant rigid and in shape. Plants don’t have nervous systems,
immune systems and mobility because of cell walls. Cell walls
are made up of cellulose fiber, polysaccharides, and proteins.
A picture of the cell wall
Chloroplasts
Chloroplasts is another important organelle in the
plant cell. Chloroplasts contain chlorophyll .
Chlorophyll absorbs the sunlight and converts it to
chemical energy during photosynthesis.
The chloroplast is surrounded by two membranes.
Internal membranes in the chloroplast are folded
into disks called thylakoids. Stacks of thylakoids are
called the grana. Grana is surrounded by the stroma
(thick fluid).
Picture of chloroplast
I have a video to show
• http://www.britannica.com/EBchecked/media
/16440/Chloroplasts-circulate-within-plantcells
Why are cells small? Do they increase in size
when living organisms grow?
Cells don’t increase in size when living organisms
grow. Instead they divide the cells in their body and
produce more cells. That happens because of the
cell’s function. For example if the cell was larger in
size it would take longer to transport all the materials
/ substances to other organelles that it needs. That
process would easily make the cell tired. That could
cause the cell to use lots of food and water
compared to a smaller cell and that would produce
more waste. There would be multiple problems if the
cell would be large. So it is better that cells are small
in the size.
Process of fluids and nutrients moving in
and out of a cell
There are 3 ways that fluids and nutrients move
through the membrane. The 3 ways are:
• Active transport
• Passive transport (diffusion)
• Osmosis
Active Transport
Active transport requires the energy to transfer the
fluids and nutrients through the membrane like food,
water and oxygen.
Passive transport
Passive transport
Passive transport does not require energy from
the cells. It occurs naturally.
Passive transport is basically diffusion.
Diffusion is tendency of particles from a higher
region/area of concentration to a region/area
of lower concentration. In simple words
diffusion is the process of spreading out.
Picture of diffusion
Osmosis
Osmosis is a part of diffusion. Osmosis is a
process in which a fluid passes through a semi
permeable membrane. To remind you again
semi permeable membrane means some
substances are allowed to pass through the
membrane and some are not allowed.
Picture of Osmosis
Specialized cells in humans
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There are over 100 specialized cells in human.
I am going to talk bout 5 cells in humans. The
5 cells are:
Neurons
Muscle cells
Sperm cells
Red blood cells
Leukocyte
Neurons
A neuron is a nerve cell that is the basic building
block of the nervous system. neurons are similar
to other cells in the human body in a number of
ways, but there is one key difference between it.
Neurons are specialized to transmit information
throughout the body.
Picture of the neuron design
Muscle Cells
Muscle cells are specialized to contract and
relax. They have several unique protein
molecules (actin, myosin, etc.) that interlock and
are responsive to the local concentration of
calcium. When calcium levels go up, the muscle
proteins contract, when it gets down the muscle
proteins relax.
Picture of muscle cell
Sperm cells
A sperm cell’s job is to penetrate the women’s
egg and keep it fertilized so the cells multiply to
make a baby.
Picture of sperm cells
Red Blood cells
Red blood cells are the most common type of
blood cells and the vertebrate organisms
principle means of delivering oxygen to the body
tissues and the blood flow through the
circulatory system. They take up oxygen in the
lungs and release it while squeezing through the
body’s capillaries.
Picture of red blood cells
Leukocyte
White blood cells fight disease, kill bacteria,
combat allergic reactions, destroy old and
damaged cells, kill invalid organisms and are
attracted to the immune system.
Picture of Leukocyte
What do living things have in common from the
smallest to the largest?
Living organisms have many things in common.
Some are mentioned below:
• Cells
• Tissues
• Organ
• Systems
How can we make sense of the vast
diversity of living things?
As you have seen all living organisms have
many things in common like cells, tissues,
organs and systems. But each of those things
work differently depending on it’s function.
For example the skin cell functions differently
than eye cells. The brain cell works differently
than the stomach cell.
How do scientists classify living organisms?
Scientists classify living things to understand
to understand all the living things on earth
better. Scientists classify them into kingdoms
another word for large groups. Scientists think
there are 5 kingdoms for all living organisms
on earth. The 5 kingdoms are the monera, the
protoctista, the plants, the fungi and the
animals.
The structure and functions of living things
The structure and function of each living
organism depends on what type of organism it
is and what organs it contains. The stem does
a different function than the skin cell in a lion.