Cells

All living things are made up of cells…. The cell is the smallest unit of a living thing. If an organism is unicellular, all functions of life happen within that one cell. If an organism is multicellular, different cells have different jobs and they all work together.

Level 1 : Cells 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 different functions that keep a cell alive.

Cells are small Click link below: http://learn.genetics.utah.edu/content/begin/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

Levels of Organization Cells Tissues Organs Organ Systems Organism Cells  Tissues  Organs  Organ  Organism Systems

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 functions Link: 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-talented Self-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 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. Getty Images

Concept #3- All polar bears cell came from a single living cell. They divide and they grow to replace old dead cells! Concept #1- A polar bear is made up of many cells! Concept #2- Different cells in a polar bears body does different jobs (functions). Example: Fat cells provide insulation and energy, while red blood cells carry oxygen.

Basic Cell Substances 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.

All cells have: 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 cytoplasm from 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

Cell Types With more advanced microscopes, scientists discovered that all cells can be grouped into two types: prokaryotic cells eukaryotic cells 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.

Cell Types (cont.) 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.

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

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

Cell Membrane • It’s like the border of a city! -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

Nucleus • 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!

EM Research Services, Newcastle University Nucleus (cont.) In most cells, the nucleus is the largest organelle. EM Research Services, Newcastle University 35

Nucleus (cont.) 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. 36

Endoplasmic Reticulum • Found in both plant and animal cells • Network of tubes that transports materials throughout the cell • Two types – Smooth (no ribosomes) – Rough (covered with ribosomes) It’s like a city’s subway!

Ribosomes • It’s like the brick yard that supplies a city with • 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 yard that supplies a city with what it’s made of!

Mitochondria It’s like a city’s power plant! • 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

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

Cell Wall It’s like the wall that surrounds a medieval city! 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!

Chloroplasts • Found in plant cells only http://www.youtube.com/watch?v=PFtzs_cUddI • 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 It’s like the solar panels on a city’s buildings!

City planning office that works with the Mayor’s office Chromosomes 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

Nucleolus 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’s Post 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

Golgi bodies or ER Mitochondria ribosomes chloroplasts Lysosomes vacuoles nucleus Cell wall or cell membrane

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