The Big Discussion on Cells

Introductory Video

https://www.youtube.com/watch?v=X6N82No4Nz8&noredirect=1

Living Things

• All living things have a cellular organization, contain similar chemicals, use energy, grown and develop, respond to their surroundings, and reproduce.

• These are the 7 major characteristics of life!

Cell Sizes can vary

• Most cells are small, about 40 human cells would fit on the dot of this letter i.

• Some cells are big, the yolk of a chicken egg is a single cell.

• The smallest cells are so tiny that you could fit over a million of them on the period at the end of this sentence.

How do we look at Cells?

• The invention of the microscope made it possible for people to discover and learn about cells.

• A microscope is an instrument that makes small objects look larger.

• A light microscope that has more than one lens is called a compound microscope.

Who discovered that we have Cells?

• The first people to observe cells was the English scientist Robert Hooke.

• In 1665, Hooke observed the structure of a thin slice of cork using a compound microscope.

• To Hooke the cork looked like rectangular rooms, which he called cells.

Who discovered that we have cells?

• In 1673 Leeuwenhoek looked at pond water he saw tiny single celled organisms.

• Called them animalcules=‘little animals’

• Today they are called protists

In 1838 Matthias Schleiden discovered that all plants are made

of cells.

In 1839 Theodor Schwann discovered

that all animal tissues are made of cells.

In 1858 Rudolf Virchow stated that all cells come from

other cells.

The Cell Theory

• Observations from these scientists led to the development of the cell theory.

• The cell theory states:• All living things are

composed of cells.• Cells are the basic unit of

structure and function in living things.

• All cells are produced from other cells

https://www.youtube.com/watch?v=4OpBylwH9DU

Animal or Plant Cells

• Animal and Plant cells both have a nucleus so we call their cells eukaryotic or the organisms

eukaryotes.

Bacterial Cells

• Bacterial cells are smaller than plant or animal cells.

• Bacterial cells do have a cell wall and membrane but they do not have a nucleus.

• Organisms whose cells lack a nucleus are called prokaryotic or the organsims prokaryotes.

Looking Inside Cells

• Cells contain even smaller structures inside of the cell called organelles.

• Organelles were called organelles because early scientists thought they looked like “inner organs” kind of like our heart, kidneys, or brain.

Parts of the Cell: Nucleus• The nucleus is a large

oval structure inside the cell.

• The nucleus is the cell’s control center that directs all of the cells activities.

• It’s really the Brain of the Cell!

Parts of the Cell: Nucleus

• Inside the nucleus you have DNA (Deoxyribonucleic acid) This is what helps cells reproduce and tells them what they should do and look like

• This is why you look like a combination of your mother and father because you have DNA from both of your parents.

Parts of the Cell: Cell Membrane• The cell membranes main function is “P(a)ss”– Protection– Shape – Support

• It is a semi-permeable membrane (like a strainer)• Made of hydrophobic (water fearing) and hydrophilic

(water loving) parts

Nutrients, water and waste can pass through

It is sometimes referred to as the lipid-bilayer

Parts of the Cell: Cytoplasm

• The region between the cell membrane and the nucleus is known as cytoplasm.

• This is a clear, thick, gel-like fluid.

• Many of the cell’s organelles are found in the cytoplasm.

Parts of the Cell: Mitochondria

• rod shaped structures• Mitochondria are called

the powerhouses of the cell because they produce most of the energy the cell needs to carry out its functions.

• Muscle cells rely heavily on mitochondria.

• Produce ATP—adenosine triphosphate

Parts of the Cell: Endoplasmic Reticulum

• The endoplasmic reticulum (ER) looks like a giant maze of passageways.

• Rough ER moves proteins from one part of the cell to another.

• Smooth ER makes lipids and breaks down toxic material.

Parts of Cells: Ribosomes

• Attached to the outer surface of the endoplasmic reticulum are small grain-like bodies called ribosomes.

• Ribosomes function as factories that produce proteins for the cell.

• From the ribosomes and endoplasmic reticulum the proteins are transported to the golgi apparatus.

Parts of the Cell: Golgi Bodies

• Within the endoplasmic reticulum you will find a flattened collection of sacs and tubes. These are called Golgi Bodies.

• The Golgi Bodies are like the cells mailroom. They receive proteins , package them, and distribute them to different parts of the cell.

Parts of the Cell: Lysosomes

• Lysosomes are small round structures that contain chemicals that break down large food particles smaller ones.

• Lysosomes also break down old cell parts and release the substances so they can be used again

Parts of the Cell: Vacuoles

• Throughout the cell you can find large water-filled sacs floating in the cytoplasm.

• These sacs are called vacuoles. Vacuoles store food and other materials needed by the cell.

• All plant cells have a large central vacuole.

Connection to everyday...Why do plants start to wilt when

they don’t get water?

Parts of the Cell: Cell Wall• The Cell Wall is a rigid layer of

nonliving material (sugar—cellulose or chitin) that surrounds the cells of plants and some other organisms.

• Cell Walls look rectangular and shape and are only found in plant cells.

• A plants cell wall helps to protect and support the cell. It provides a rigid support stand for the cell and also helps keep out some harmful substances.

Parts of the Cell: Chloroplasts

• Only plant cells and other protist type cells have chloroplasts.

• The chloroplasts help capture energy from sunlight and use it to produce food for the cell.

• The chloroplasts give plants their green color.

• They are responsible for photosynthesis.

Bacteria vs. Plant vs. Animal Cell

How are Plant Cells and Animal Cells Different?

• Plant Cells are rectangular in shape due to their Cell Walls.

• Plant cells have chloroplasts which perform photosynthesis.

• Plant cells have a large central vacuole. This helps regulate how much water the plants lets in or keeps out. It regulates osmosis!

Draw an Animal Cell

Draw a Plant Cell

The Importance of Cells• Think about every time you

need energy to move your cells have to actively be working so that you can move.

• Think about every time you breathe in your individual cells have to take in oxygen and use it to make energy.

• All of our energy needs are met by small tiny parts of our body that we barely even think of.

Transport within Cells• Diffusion is the movement of

molecules from a high concentration to low concentration.

• Diffusion does not require energy use. It’s kind of like riding your bicycle down hill. You still get somewhere and you still move but you don’t have to use the pedals.

• Diffusion is a type of passive transport.

• Sometimes protein channels can help in moving materials into the cells. They are embedded in the cell membrane.

Transport within Cells• Active transport is the

movement of materials through a cell membrane using energy.

• By doing so cells have move molecules into the cell that they need but this requires energy because there is not a concentration difference.

• This type of transport is kind of like riding a bicycle up hill you get to your destination but it requires energy to do so.

Osmosis and Diffusion• Remember that diffusion is

when you have particles move from high concentration to low concentration.

• Remember that osmosis is when you have water move from high to low concentrations.

• This is important when plants regulate their water supplies.

• Red Blood Cells can burst if they don’t use osmosis correctly.

What causes Diffusion?• Molecules are always moving.

As they move, the molecules bump into one another. The more molecules there are in an area, the more collisions there will be.

• Collisions cause molecules to push away from one another.

• Over time, the molecules of a substance will continue to spread out.

How Many Cells Make Up Organisms?

• Organisms can be composed of only one cell or many cells.

• Unicellular or single celled organisms include bacteria the most numerous organisms on Earth.

• Multi-cellular organisms are composed of many cells.

• You are made up of trillions of cells.

• You have specialized cells in your body that perform specific functions.

Cell Size

• Cells are made of molecules– Molecules are tiny

particles of matter.• Molecules are made up of

atoms.– The atom is the basic

fundamental unit of matter.» Atoms are made

up of protons, neutrons and electrons.