All living things are made up of

cells….• The cell is the smallest unit of a

living thing.

If an organism is multicellular, different cells have different jobs and they all work together.

If an organism is unicellular, all functions of life happen within that one cell.

• Cells can be specialized (have a certain function)

• The size and shape of a cell relates to its job or function.

• Cells are made of different structures that perform differentfunctions that keep a cell alive.

Level 1 : Cells

Cells are small

• Click link below:• http://learn.genetics.utah.edu/content/beg

in/cells/scale/

Level 2: Tissues• Tissue = group of cells that work together

to do a specific job• Ex: Heart muscle tissue

is made of heart muscle cells

• Animals have 4 types of tissue: nerve, muscle, connective, protective

• Plants have 3 types of tissue : transport, protective, ground

Level 3: Organs• Organ = structure that is made up of 2 or more tissues working

together to get a specific job done

• Ex: Stomach – muscle tissue moves food, special tissues make chemicals to digest food, connective tissue holds stomach together, nervous tissue sends messages back and forth between the stomach and brain

Level 4: Organ Systems• Organ system = group of organs working

together to perform a specific function• Each organ system has a specific job• Ex: Digestive system is made of several

organs including the stomach and intestines

• Cells• Tissues• Organs• Organ Systems• Organism

Cells Tissues Organs Organ Organism

Systems

Levels of Organization

Organism

•Anything that can live on its own

•Means “organized”

–Unicellular–multicellular

Unicellular Organisms• “uni-” = one• Prokaryotes are unicellular organisms• Some algae, some protists, and some

eukaryotes (yeasts), are unicellular• Can still do everything they need to

stay alive

Multicellular Organisms• “multi-” = more than one• Plants, animals, some protists, and

most fungi are multicellular• Start as a single cell many cells

cells differentiate (change) into different types of cells cells group together

• Advantages- can grow larger and have specialized cells for different functionsLink:

http://www.teachersdomain.org/resource/tdc02.sci.life.stru.different/

Why do we hear so much about stem cells & what are they?

• The human body is composed of many different types of cells– e.g. muscle cells, skin cells, liver cells,

cardiovascular cells, etc.• Not all cells have the same potential

– Some cells remain “immature”—these are stem cells

• When stem cells “mature,” or differentiate they turn into the different cells of the body (or somatic cells)

• http://www.youtube.com/watch?v=tPulEAryPO0

Stem cells are multi-talentedSelf-renew a stem cell can reproduce itself by cell division

Differentiate a stem cell can specialize into a particular type of somatic cell

There are two main types of Stem Cells—Adult & Embryonic Stem Cells

• Adult stem cells– found in adult tissue – can self-renew many times– are multipotent – they can differentiate to become only the

types of cells in the tissue they come from.• hematopoietic stem cells – give rise to blood cells• mesenchymal stem cells – give rise to cells of connective

tissues and bones• umbilical cord stem cells – a rich source of hematopoietic

stem cells• stem cells found in amniotic fluid – might be more flexible

than adult stem cells

There are two main types of Stem Cells—Adult & Embryonic Stem Cells

• Embryonic stem cells – come from embryos

• This stage embryo is called a Blastocyst – ~5 days old, a hollow microscopic ball of cells

– can self-renew forever; adult stem cells have a cell-division limit

– are pluripotent – they can differentiate to become almost EVERY cell in the body

– live in a Petri dish, not a woman's body

The Discovery of Cells

In 1665 Robert Hooke looked at cork under the microscope and described what he saw as “tiny rooms” or “cells”

Cell theory includes three principles.

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Concept #1- A polarbear is made up ofmany cells!

Concept #3- All polar bearscell came from a single livingcell. They divide and theygrow to replace old dead cells!

Concept #2- Different cells ina polar bears body doesdifferent jobs (functions). Example: Fatcells provide insulation andenergy, while red blood cellscarry oxygen.

• The main ingredient in any cell is water. A water molecule has two areas:

• The negative (–) end can attract the positive part of another substance.

• The positive (+) end can attract the negative part of another substance.

Basic Cell Substances

All cells have:

1. Cell membrane– a flexible covering that protects the inside

of a cell from the environment outside a cell.

– controls movement of materials in & out of the cell

All cells have:

2. Hereditary material- DNA

• A nucleic acid, such as DNA, contains the genetic information for a cell.

All cells have:

3. Cytoplasm- Clear, thick, gel-like fluid that contains most of the cell’s water, salts, and all organelles*It is constantly moving

cytoplasmfrom Greek kytos, means “hollow

vessel”; and plasma, means “something molded”

All cells have:

4. Organelles- • tiny membrane-

surrounded structures inside the cell that carry out specific functions.– They enable the

cell to live, grow, and reproduce

• With more advanced microscopes, scientists discovered that all cells can be grouped into two types:

• prokaryotic cells

• eukaryotic cells

Cell Types

• Most prokaryotic cells are unicellular organisms called prokaryotes.

Prokaryotes: NO NUCLEUS!

• 1st cells to evolve• Have No Nucleus!• The hereditary

information (circular DNA) is contained within the cytoplasm.

• Examples: Archaebacteria and Bacteria*”Pro” rhymes with “No”

The genetic material in a prokaryotic cell is not surrounded by a membrane.

Eukaryotes• Evolved from prokaryotes• Organisms whose cells do have a nucleus.• Hereditary information (Linear DNA) is

contained within the nucleus• Examples:

– Animals– Plants– Protists– Fungi

– *“You” are a Eukaryote.

• Plants, animals, fungi, and protists are all made of eukaryotic cells and are called eukaryotes.

• In eukaryotic cells, the genetic material is surrounded by a membrane.

Cell Types (cont.)

Why are cells so small?

Cell size is limited.-As cell size increases, it takes longer for material to diffuse from the cell membrane to the interior of the cell.

Surface area-to-volume ratio: as a cell increases in size, the volume increases 10x faster than the surface area

Cell size is limited

Cell Organelles

Can you identify the two organelles that are only found in the plant cell?

-Surrounds all cells

– In a plant cell, it lies beneath the cell wall

– In animal cells, it is the outer boundary (made of cholesterol)

– Serves as a gateway which helps to control materials going in and out of the cell

• It’s like the border of a city!

• Found in both plant and animal cells

• Centrally located in cell

•The nucleus acts as the “brain” of the cell, controls all the activities of the cell and contains genetic information stored in DNA.

• It’s like the Mayor’s Office in City Hall!

In most cells, the nucleus is the largest organelle.

Nucleus (cont.)

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• DNA in the nucleus is organized into structures called chromosomes.

• The nucleolus is also contained in the nucleus and makes ribosomes, organelles involved in the production of proteins.

• The nuclear envelope is a porous, two-membrane structure that surrounds the nucleus.

Nucleus (cont.)

• Found in both plant andanimal cells

• Network of tubes that transports materials throughout the cell

• Two types– Smooth (no ribosomes)– Rough (covered withribosomes)

It’s like a city’s subway!

• Found in both plant and animal cells

• Can be attached to the ER Membrane or floating free in the cytoplasm

• The smallest organelles

•Function: Synthesis- Produce proteins and pass them to the interior of the ER.

• It’s like the brick yardthat supplies a city withwhat it’s made of!

• Found in both plant and animal cells

• Powerhouse of the cell

• Breaks down sugar molecules to release energy

• Function: Respiration- Releasing energy stored in food food is “burned” (combined with oxygen) to produce energy for the cell in the form of ATP

It’s like a city’s powerplant!

It’s like a city’s warehouses, water towers and landfills!

• Fluid-filled sacs found in both plant and animal cells

– In plant cells: very few and very large– In animal cells: many little ones

• Store food, water and waste

• Only found surrounding plant, fungal and bacterial cells

• A cell wall is a stiff structure outside the cell membrane that protects a cell from attack by viruses and other harmful organisms.

• Made of cellulose- a tough, yet flexible material

• Provides support, structure, and protection for the cell •It’s like the

wall that surrounds a medieval city!

• Found in plant cells only

• Green in color due to a pigment called chlorophyll

•They capture energy from the sun and use it to produce food (sugar) for the cell during photosynthesis

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

It’s like the solarpanels on a city’sbuildings!

• Found in both plant and animal cells

• Coiled structures of DNA & protein; found in the nucleus

•City planning

office that works with the Mayor’s

office

• Makes Ribosomes• Found in both plant and animal

cells• It’s like a Factory!

Lysosomes• Found in both plant and

animal cells

• Function: contains digestive enzymes that digests old cell parts.

• They are the cell’s clean-up crew. They have their own membrane to protect the cell from their chemicals.

It’s like a city’s street sweeper!

Golgi Bodies (Complex)

• Found in both plant and animal cells

• Looks like a flattened stack of membranes (or pancakes!)

• They receive proteins from the ER, package them into vesicles, and distribute them out of the cell.

• Vesicles are organelles that transport substances from one area of a cell to another area of a cell.

• It’s like a city’sPost Office!

Cytoplasm• Found in both

plant and animal cells

• Clear, thick, jelly-like material

• Located beneath cell membrane

• Surrounds and protects cell organelles

• It’s like the air in a city!

Plant Cell Animal Cell

ribosomes

Golgi bodies or ER Mitochondri

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chloroplasts

Lysosomes

nucleus

Cell wall or cell membrane

vacuoles