Cell Specialization, Organization and

Function

Cell Specialization

• Cells specialize to carry out specific functions in an organism.

• Cells come in a variety of shapes…

• The shape of the cell is related to its function…

STEM CELLS• Are unspecialized, jobless cells• In the lab, under the right

conditions, scientists can manipulate stem cells to be come any cell type.

• Stem cell have the ability to repair/heal any damaged, worn, or diseased cell.

• Embryonic stem cells have the ability to become any cell type

• Adult stem cells (small supply) do not have as many abilities as embryonic stem cells

Embryonic vs. Adult Stem Cells

Embryonic

• Ability to develop into almost any type of cell in the human body.

• Can replicate (multiply) at very large numbers.

• Come from the destruction of an embryo or umbilical cord.

Adult

• Ability to develop into limited types of cells.

• Are unable to grow in large numbers.

• Come from adult tissues, such as bone marrow.

How stem cells become specialized

• The stem cells receive cues (instructions) from the DNA inside of the nucleus

• The nucleus tells stem cells what cell type to become

• The process by which stem cells become specialized (get a job) is differentiation

Differentiation• Multicellular organisms

all begin as an undifferentiated mass of cells (embryo-blastocyst).

• Variations in DNA and gene expression determine the function and structure of each cell as it becomes “specialized.”

Differentiation

• Nearly all cells in a multicellular organism have exactly the same chromosomes & DNA. Because of this, all undifferentiated cells have the potential to become ANY type of cell.

• Once a cell differentiates, it CANNOT be reversed!

Differentiation

• During differentiation, only specific parts of the DNA are activated. The parts that are activated determine the function and structure of the specialized cell.

• Different parts of the DNA are also used in different types of cells. This is influenced by the cell’s environment and past history.

Differentiation

• Chemical signals may be released by one cell to influence the development and activity of another cell.

Cell Structure and Function

• Cells vary in size.Longest cell – nerve cells (up to 2 meters long)

• Cells vary in shape. Shape is often related to function. Blood cells are smooth, round, and flow easily through the blood vessels

Human Red Blood CellsNotice the rounded shape of red blood cells

What is the function of red bloodcells?

How does the rounded shape help Red blood cells do their job?

Carry O2

Rounded shape helps blood cells move easily through blood vessels

Bone Cells

Notice the “tree-ring” pattern of bone cells

What is the function of bone cells?

Provide protection to soft tissue & organs

How does the shape of bone cells help its function?Forms a network of strength to provide protection

Nerve Cells

What is the function of nerve cells?

Communication; receiving & transmitting info through the body from organ to organ

How does function relate to shape?

Long thin “fibers” for transmitting information

Muscle Cells

• What is the function of muscle cells?

• Movement

• How does its shape relate to its function?

• Muscle cells are long & elastic to allow for contraction & expansion which creates movement

There are 3 types of muscle cells

SKELETAL MUSCLE CARDIAC MUSCLE

SMOOTH MUSCLE

Sperm Cells

What is the function of sperm cells?

Fertilize the female egg

How is their shape related to their function?

Have long tails (flagella) to swim to egg

Plant transport tissue- Xylem

• What is the function of the xylem?

• To transport water and minerals from roots to top of plant.

• How does its shape relate to its function?

• Tube shape with no interference which allows for continuous water flow.

Plant transport tissue- Phloem

• What is the function of the phloem?

• Transports food and nutrients from the leaves to storage areas.

• How does its shape relate to its function?

• Long tube shapes with sieve walled tubes inside. Allows for up and down movement of material.