Cells What is a cell?

Cells

What is a cell?

Cells are the stuff of life

• All living things are made from cells

• Cells are often described as building blocks but it not that simple

• Cells gather fuel, create energy, grow , reproduce, and even die

• Every cell also carries a complete set of instructions

• In a plant cell, it determines things like leaf size

• In a human cell, it gives us features like height and eye color

• It also decides whether an organism turns into a plant, a tiger or a human

• In other words, cells contain the master code that makes all living things what they are

http://www.youtube.com/watch?v=ZiK2c8DJBxY

What is the relationship between atoms, molecules and cells?

• Atoms are the most basic elements of the universe

• Molecules are atoms that are bonded together – water – H2O

• Cells are the most basic units of life

How are unicellular and multicellular creatures alike and different?

• Single cell creatures made up of one cell are unicelluar. The amoeba is a single-celled organism that constantly changes shape.

Cells Groups

• Many identical unicellular creatures work so closely together with each other that they appear to be one larger creature

• Even bacteria can communicate with each other to coordinate their behavior

Plant Cells

• Plants have specialized cells

• Roots and stem cells

• Stem support cells

• Transporting food and water

http://www.youtube.com/watch?v=I8uXewS9dJU

Types of Animal Cells

• Blood

Types Animal Cells

• Nerve

Types of Animal Cells

• Muscle

Types of Animal Cells

• Fat

Types of Animal Cells

• Skin

Types of Animal Cells

• Bone

Zooming into a cell

• 1664 English scientist Robert Hooke views a thin slice of cork through an early microscope

• Cork cells look like dozens of tiny rectangular compartments.

• He calls them cells from the Latin cella, meaning small room.

• Scientists can’t see much in the cell, just a jelly substance that they call protoplasm.

What’s in a cell?

• Water = 90%

• Protein molecules (amino acids) = 5%

• Carbohydrates (sugars burned for energy) = 2.5%

• Nucleic Acids (DNA & RNA) = 1.5%

• Fats, oils and waxes called lipids = 1%

– (mostly in cells outer membrane)

http://www.youtube.com/watch?v=Fzj6TRnXmps

• Parts of a Animal Cell

Animal Cell diagram

What does everything do?

• Nucleus – cells control center or brain (DNA)

• Ribosome – protein producing factories. Proteins produce chemical messages that run a cell

• Golgi – stores and transmits newly made proteins until they can be released through the cell membrane

What does everything do (continued)

• Vacuole – storage area for fat and other things

• Endoplasmic Reticulum – smooth and rough tubes that move and store materials made by the cell

• Cell membrane – made up of a double layer of fatty material called lipids. It allows some materials to pass into and out of a cell at thousands of places across its surface

What does everything do (continued)

• Cytoplasm- jellylike fluid between nucleus and cell membrane, where most of the cell’s innards or organelles are found (little organs)

• Lysosome – where digestion of cell nutrients takes place

• Mitochondrion – produces energy for cell to use by breaking down substances

What is in a hair follicle?

• Hair follicles like this one are made of proteins. About half of your body is made of protein

• Every person has about 500,000 different proteins working at any one time

• Most serve as switches that turn chemical reactions on and off when needed

• Proteins are made by organelles which also turn food into energy and move molecules around

What about plant cells?

• Have a stiff outer covering instead of a fatty one

• Most contain organelles called chloroplasts

• Use chlorophyll and sunlight to combine carbon dioxide and water to make sugar in a process called photosynthesis

What is DNA?

http://www.youtube.com/watch?v=zwibgNGe4aY

DNA – The Code of Life

• Deoxy – no oxygen

• Ribo – type of sugar

• Nucleic – in the cells nucleus or core

• Acid – sour chemical, like vinegar or OJ

What is the structure of DNA?

• DNA is found in the cell’s nucleus. It carries the instructions the body needs in order to function. It forms supercoils and then coils up in a small ball.

Structure and components of DNA

• Chromosomes are made up of tightly wound strands of DNA. Chromosomes are found in the cell’s nucleus.

Structure cont.

• Histones are protein molecules. They act as spools around which DNA winds. Histones play an role in gene regulation.

Double-stranded DNA

• If you stretched out 1 DNA strand, it would look like a spiral ladder , a shape that scientists call the double-helix.

• The rungs that hold it together are made of pairs of molecules called bases.

Bases (Letters) of the Genetic Code

• These bases are Adenine, Thymine, Guanine and Cytosine

• The code of life depends on which base pairs follow which along the ladder. These patterns form the code and are called genes.

How many genes?

• The human cell nucleus has 25,000 genes which are the most basic unit of heredity.

• They carry the traits you inherit from your parents. One gene is just a section of DNA on a chromosome that tells the cells to make a particular protein.

• One gene might produce a single trait but they usually work together.

Is that all? Show me the basics!

• Prokaryotes were earth’s first life forms.

• They appeared about four billion years ago.

• Look Mom! No nucleus.

• Single strand of DNA.

• Prokaryotes today are mainly one-celled bacteria.

Still not done! We have eukaryotes!

• These cells with a nucleus appeared 1.6 billion years ago.

• They are thought to form from prokaryotes and be more complex with up to 1000 strands of DNA.

• Most multi-cell forms of life are eukaryotes.

• http://www.youtube.com/watch?v=ct9B3GH_IAg

Cells make up tissues that make up organs that make up systems that make up organisms!

• Things just keep getting bigger and more complicated!

• Let’s look at 4 tissue types!

• http://www.youtube.com/watch?v=tKWTJ3_-1E8

Connective Tissues

• These are the most abundant tissues in the body

• Loose

• Fibrous

• Adipose

• Cartilage

• Bone

• Blood

Epithelial Tissues

• This tissue form the covering or lining of all of the body’s surfaces

Nerve

• This tissue controls and coordinates all of the body’s function

Muscle

• This tissue is responsible for movement. It makes up voluntary and involuntary muscles.

• Skeletal

• Cardiac

• Smooth

Wow! What else is going on here?

Cells can do math! They can divide!

• Mitosis • Meiosis

Mitosis

• Each human cell has 23 pairs of chromosomes or 46 altogether

• These carriers of genetic information copy themselves over and over.

• During mitosis, a cell splits itself into two.

• The two new cells are identical to the “parent” cell and to each other.

• http://www.youtube.com/watch?v=C6hn3sA0ip0

Meiosis

• Female and male sex cells are different from the rest of your cells in your body.

• They are made by a special kind of cell division called meiosis.

• A cell’s 46 chromosomes are copied once.

• The cell then divides into two and segments of DNA are exchanged.

• Each cell divides again making 4 different cells.

Meiosis continued• Each has only 23 chromosomes.

• During reproduction, the female and male sex cells fuse to form a normal 46 chromosome cell called a zygote.

• This goes through mitosis to develop into an embryo, then a fetus and finally a baby.

• The baby gets 1/2 of its DNA from its mother and the other 1/2 from its father.

• https://www.youtube.com/watch?v=toWK0fIyFlY

Yea, this is still meiosis

• http://www.youtube.com/watch?v=PY8IZDz1JFA

• Just a different look at what happensin Meiosis 1 and Meiosis 2.

Wait! There’s More!• Food is the fuel that drives the body

• Metabolism is the process by which food in broken down in the body

• In anabolism new cells are created and tissues maintained

• In catabolism, energy is produced for physical activity and body temperature maintained

What impacts our DNA?• Diseases caused by bacteria and viruses

• Bacteria cells release poisons into the body

• Viruses are not cells. They are just bits of DNA or RNA wrapped in protein which latch on to a cell

• They make copies of themselves which then infect other cells

• http://www.youtube.com/watch?v=s-HThHRV4uo

What do these guys look like?

Bacteria Viruses

What cells fight the bad cells?

• Skin cells are the body’s first line of defense

• If the nasty guys get by our skin, then the immune system triggers white blood cells to attack the invading bacteria or viruses.

• This can take days but our body remembers it and “memory cells” give us immunity.

• Some cells remember the invader and unleash an attack that destroys it more quickly the next time.

White Blood Cells to the rescue!http://www.youtube.com/watch?v=n8

AACdUD-is

Who’s who in the cell business?

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

How did we find out all this stuff?

• Around 1590 the Dutch lens makers Hans and Zacharias Janssen put 2 glass lenses in a tube and created the first microscope.

• 60 years later, Robert Hooke uses it to study cork from a tree.

•

Who’s next?

• Leeuwenhoek becomes the first to see living cells. They include bacteria in plaque that he scraped off his teeth.

1831 Comes Around

• Scottish biologist Robert Brown shows that the nucleus is a key part of each cell.

Here comes “The Cell Theory of Life”

• In 1839 two German scientists advance the “cell theory of life”. It states that all life on Earth is composed of cells.

• But there is a part 2 of this theory!

More on Cell Theory• 1859 Rudolph

Virchow states that all cells come from other living cells.

• This conflicts with the belief that life can spontaneously generate

Moving ahead to 1859

Louis Pasteur disproves spontaneous generation through experiments.

This adds support to the cell theory of life.

1860’s

• Walther Flemming stains cells with dye to make them easier to see.

• He is now able to discover how they reproduce.

More in the 1860’s

• Austrian monk Gregor Mendel uses pea plants to show how genes control heredity.

• His work is ignored for 40 years

Mendel’s Rules of Heredity

• Individuals carry two factors (genes) for each trait, but pass down only one

• One factor (gene) is dominant over the another

• https://www.youtube.com/watch?v=d4izVAkhMPQ

Can we finally see cells?

• Yes – 1931 and the invention of the electron microscope make it possible to see the inner workings of cells.

DNA Discovery - 1953

• Watson and Crick show that DNA is a double helix structure. This paves the way for other breakthroughs in genetics.

So what’s left to find out?

• 1977 – Scientists find out that prokaryotes are really made of two distinct groups: bacteria and archaeawhich look like bacteria but their DNA is different and they live in weird places

1997 – Send in the clones!

• Scottish scientists create Dolly, a clone or genetic copy of another sheep

It is 2000. Aren’t we finished yet?

• The Human Genome Project finishes a draft map of the entire human genome. Now doctors can prevent, diagnose and treat illnesses at the cellular level.

What? Not done yet?

Wow! We really know a lot now!

Gregor Mendel, Father of Genetics

• Humans first tamed wild animals about 12,000 years ago. They found they could change animals over time by breeding them. Same thing with plants.

Improved animals and plants

• Yet for years nobody could explain how the process really worked.

Here comes heredity

• In the late 1800s, scientists discover the secrets of heredity – the passing of genes from generation to generation

The work of Mendel

• From the gardening skills of Mendel grew genetics. By observing more then 30,000 pea plants, he unraveled the mystery of why tall plants don’t always produce tall plants, etc.

What did Mendel find?

• A tall plant is crossed with a short plant. Offspring get one gene for a given trait. The different traits do not blend, leading to two tall plants.

And we move along

• When the two tall plants in the second generation are crossed, the result is 3 tall plants and 1 short plant.

Huh?• We get this

because tall is a dominant trait and short is a recessive trait for the peas Mendel was working on.

https://www.youtube.com/watch?v=xrDjN_4HKf0

So how different are we?

• About 99.8% of your genetic information is the same as everyone else on the earth! It is the final 0.2% that makes you special.

How alike are animals to humans?

• If we start with a human at 100%,

• chimpanzees would be 99% genetically,

• mice would rate about 88%,

• chickens at 60%

• fruit flies at 60%

What about birth defects?

• During ancient times, birth defects were thought to be a punishment from the gods. Today we know that many birth defects are caused by genetic factors.

• We know that a child with Down Syndrome is born with an extra copy of one chromosome.

So what can we do about it?• Genetic engineering

makes changes in an organism’s genetic material.

• https://www.youtube.com/watch?v=zlqD4UWCuws

Everyone wants to cure cancer!

• https://www.youtube.com/watch?v=5SC2EoxUOXo

Therapy can work but also cause problems.

• How do we know GM food is safe? https://www.youtube.com/watch?v=j4n6AQMFGvE&list=PL362AAFAE994AFAC1

• There are also ethical concerns.

• https://www.youtube.com/watch?v=jY-868_HDbs

How can this knowledge help us?

• Some cancers are caused by outside factors. Smoking is know to trigger lung cancer. Others mostly depend on genes.

Genetic testing• Genetic testing

can now identify people likely to develop certain cancers and other inherited diseases.

• http://www.youtube.com/watch?v=8JTw2RpDo9o

Life span of a cell

• Skin 1-34 days

• Stomach lining 2 days

• Red blood 120 days

• Bone 25-30 years

• Some nerve cells –Forever or until we die

• Human cells are preprogrammed to die through a process called apoptosis.

Cell Reproduction

• Most types of human cells only reproduce themselves. Muscle cells can only give off more muscles cells.

• Stem cells can change into other types of cells. This allows them to act as a repair system for the body.

Embryonic Stem Cells

Embryonic stem cells can produce all 216 kinds of human cells. An embryo is an organism at any time before full development.

More on Embryonic Stem Cells

• The embryos from which human stem cells come from are typically 4-5 days old and are called a blastocyst

What can they do?

• They may one day help treat people with spinal cord damage or Alzheimer’s disease but many people are against the use of stem cells as previously stated.

• http://www.youtube.com/watch?v=s19eFX5gYcE