1. Chapter 5: Sections 4 & 5

2. KEY CONCEPT Many organisms reproduce by cell division.

3. Binary fission is similar in function to mitosis.
Asexual reproduction is the creation of offspring from a single parent.
Binary fission produces two daughter cells genetically identical to the parent cell.
Binary fission occurs in prokaryotes.
parent cell
DNA
duplicates
cell begins
to divide
daughter
cells

4. Bacterial Cells Divide to Reproduce
Bacteria reproduce by a type of cell division called binary fission.
Binary fission: a form of asexual reproduction that produces identical offspring. - single parent passes exact copies of all its DNA to its offspring.

5. Binary Fission
First stage: the DNA is copied, so that each new cell will have a copy of the genetic information.
Second stage: the cell divides, by pinching into two independent cells, each containing one of the circles of DNA and is a complete functioning bacterium.

7. Some eukaryotes reproduce through mitosis.
Budding forms a new organism from a small projection growing on the surface of the parent.
bud
Hydra
Yeast

8. Fragmentation is the splitting of the parent into pieces that each grow into a new organism.
Vegetative reproduction forms a new plant from the modification of a stem or underground structure on the parent plant.

9. Cell Differentiation
Stem cells

10. Cell Differentiation The various types of cells arrange into tissues
Organized into organs  organ systems
Ex. Blood, muscle, epithelial cells

11. Multicellular organisms depend on interactions among different cell types.
vascular
tissue
leaf
stem
lateral
roots
primary
root
SYSTEMS
root system
shoot system
Tissues are groups of cells that perform a similar function.
Organs are groups of tissues that perform a specific or related function.
Organ systems are groups of organs that carry out similar functions.
CELL
TISSUE
ORGAN

12. The various types of cells (such as blood, muscle, or epithelial cells) arrange into tissues which are organized into organs, and, ultimately, into organ systems.

13. Multicellular Organisms
Single cell (fertilized egg) gives rise to many different types of cells
Each cell: different structure & function

14. Cell Differentiation
Fertilized egg gives rise to large # of cells through cell division
lead to increasing # of identical cells

15. Cell Differentiation As cell division proceeds: Cells increase in #
Undergo differentiation
Become specialized in structure & function

16. Cell Differentiation Chromosomes DNA
All cells of multicellular organisms have exactly the same:
Chromosomes
DNA

17. Cell Differentiation During differentiation:
Specific parts of DNA are activated
Activated parts determine function & structure of cell

18. Cell Differentiation
Cells initially have the potential to become any type of cell
Because all cells contain same DNA
Once differentiation occurs, process cannot be reversed

19. Because all cells contain the same DNA, all cells initially have the potential to become any type of cell.
Once a cell differentiates, the process can not be reversed.
Stem cells are unspecialized cells that continually reproduce themselves and have, under appropriate conditions, the ability to differentiate into one or more types of specialized cells.

20. Stem Cells Unspecialized cells Continually reproduce themselves
Under appropriate conditions:
ability to differentiate into 1 or more types of specialized cells

21. Stem Cells Two types: Embryonic Adult
Scientists recently demonstrated both types of stem cells differentiate into specialized cells
With the right lab culture conditions

22. Embryonic Stem Cells Embryonic cells
Not yet differentiated into various cell types

23. Adult Stem Cells Unspecialized cells found in adults
commonly in bone marrow

24. Embryonic cells, which have not yet differentiated into various cell types, are called embryonic stem cells.
Stem cells found in adult organisms, for instance in bone marrow, are called adult stem cells.
Scientists have recently demonstrated that stem cells, both embryonic and adult, with the right laboratory culture conditions, differentiate into specialized cells.

25. Stem cells come from adults and embryos.
Adult stem cells can be hard to isolate and grow.
The use of adult stem cells may prevent transplant rejection.
The use of embryonic stem cells raises ethical issues
Embryonic stem cells are pluripotent and can be grown indefinitely in culture.
First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.

26. The use of stem cells offers many currently realized and potential benefits.
Stem cells are used to treat leukemia and lymphoma.
Stem cells may cure disease or replace damaged organs.
Stem cells may revolutionize the drug development process.