Kingdoms and DomainsSec 1.3

Crash Course! https://www.youtube.com/watch?v=vAR

47-g6tlA

Structural diversity All species on Earth shared certain fundamental

similarities such as being made up of cells and having DNA.

However, if biologists were to study the structural diversity (the diversity based on the external and internal structural forms in living things) of all living things, it would be too immense a topic.

Therefore, biologists study the similarities and differences at a higher taxonomic rank such as kingdoms and domains.

Kingdoms over time 1800’s – Kingdoms were the highest rank of

classification and plants and animals were the only taxons.

1860’s – Single-celled organisms were added through the Kingdom Protista.

1930’s – Single-celled organisms without a nucleus were classified under the Kingdom Bacteria.

1960’s – Fungi were so different they eared their own kingdoms.

1990’s – New genetic information led to the splitting of the Bacteria Kingdom into Bacteria and Archaea.

Two Major Cell Types There are two main cell types that are

significant for the kingdom classification. Prokaryotic cells – a smaller simple type of

cell that does not have a membrane-bound nucleus.

Prokaryotic – before the nucleus Eukaryotic cells – a larger and complex type

of cell that does have a membrane-bound nucleus.

Eukaryotic = true nucleus

Domains As scientists continued analyzing organisms in

the kingdoms, the differences between the two groups at the genetic and cellular levels were so great that each group was elevated to a new rank, higher than kingdom – domain.

As a result of reclassifying these kingdoms as domains, the remaining 4 kingdoms were reclassified into a domain of their own – Eukarya (because all organisms have eukaryotic cells).

Main characteristics Distinctions can be made between the kingdoms based

on several characteristics: Cell type Cell wall – absent in animals but the composition varies in

other organisms. Nutrition

Autotroph – an organism that obtains energy by making its own food.

Heterotroph – consumes other organisms to obtain energy – yielding food.

Reproduction – asexual reproduction can be found in all kingdoms, however sexual reproduction can be found in al kingdoms, however sexual reproduction is a trait that only occurs in Eukarya.

Domain Bacteria Archaea Eukarya

Kingdom Bacteria Archaea Protista Plantae Fungi Animalia

Cell Type Prokaryote Prokaryote Eukaryote Eukaryote Eukaryote

Eukaryote

# of cells Unicellular Unicellular Both Multi - cellular

Mostly Multi - cellular

Multi - cellular

Cell wall material

peptidoglycan

Not peptidoglyc

an or no cell

wall

Cellulose or no cell

wall

Cellulose Chitin No cell wall

Nutrition A and H A and H A and H A H H

Reproduction (Primary)

Asexual Asexual Asexual and

Sexual

Sexual Sexual Sexual

And now….Viruses!

Viruses A Structure that contains strands of DNA

or RNA surrounded by a protective protein called capsid.

There is a debate in the scientific world about whether viruses are living or non living

Viruses – Evidence for non-living Functionally dependent on the internal

working of cells (prokaryotic or eukaryotic). Cannot live independently outside of cells

(they are dominant). Must invade cells and use the host cell’s

machinery for survival and reproduction. Are not cellular – have no cytoplasm,

membrane-bound organelles or cell membranes.

Viruses – Evidence for Living Have genetic material. Reproduce. Affect the lives of other organisms.

Cause diseases in plants and animals which can affect population, species, and ecosystems.

Uncontrolled infection can lead to food shortages around the world.

Other viruses affect humans lead to severe illness (polio, HIV, H1N1)

Used in biotechnology to clone copies of genes.

Classifying Viruses Since viruses can’t unanimously be

determined as living organisms, they are not classified using the Linnaeus system.

Viruses are classified by the size and shape of their capsid.

Viruses are also grouped by the types of diseases they cause.