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 TodayThere 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 MicroscopesCompound 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 MicroscopesThe 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 OrganismsUnicellular 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 CellsThe parts in Animal cells are:

• Cell Membrane• Cytoplasm• Nucleus• Vacuoles

The Cell MembraneThe 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.

CytoplasmCytoplasm 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.

NucleusA 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.

VacuolesVacuoles 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.

VacuolesThe 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 WallCell 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

ChloroplastsChloroplasts 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-plant-cells

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 TransportActive transport requires the energy to transfer the fluids and nutrients through the membrane like food, water and oxygen.

Passive transportPassive transportPassive 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

OsmosisOsmosis 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 humansThere 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

NeuronsA 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 CellsMuscle 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 cellsA 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 cellsRed 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

LeukocyteWhite 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.

Thanks for Watching

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