Lecture 2 Flashcards
What is biodiversity?
With about 1.9 million species identified today, biodiversity is the total range of species diversity and relationships among species.
What is taxonomy? what is it based on
The science of taxonomy helps grouping species into taxons. Classification into taxons is a subjective and rapidly changing field biology.
Recognizing the important characteristics used to differentiate organisms into taxons has some value, and forms the basis of the science of Taxonomy.
Based on:
- physical appearance
-biological appearance
-genetic similarities
Story of classification.
At one point, classification what is mainly based on morphology, visible traits of an organism. With the evolution of technology however, classification is turning into molecular biology. Organism are redefined based on similarities in their chemical components (DNA,RNA and proteins organization).
What is the ranking order of taxonomic groups (from most to least inclusive)?
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Specie
Dumb Kings Play Chess On Fine Graine Sand
Organism in the same kingdom are very broadly similar ; those in the same phylum or more similar than those of another phyla.
How is organized taxonomy?
Since the 90s, the various species found on the Earth are divided into three domains:
-Domain Eukarya
-Domain Archea
-Domain bacteria
How are bacteria and archea different from eukaryotic cells ?
Mainly because they are prokaryotic ( meaning that they don’t have a membrane bound nucleus) and also for those 4 reasons :
1. Prokaryotic DNA is not contained within a membrane-bound nucleus and no membrane bound organelles.
2. The DNA in Prokaryotic cells is mostly circular
3. Prokaryotic cell wall composition is biochemically different than eukaryotic cells
4. The size of prokaryotic cells is considerable smaller than eukaryotic cells
Domain Eukarya main characteristic and division
All organisms within the domain:
- share the same complex, compartmentalized cell called a eukaryotic cell.
- have multiple linear chromosomes
- have many specialized compartments known as organelles, including a nucleus which is membrane-bound and contains the nuclear material.
The domain is divided into 3 main Kingdoms:
-Plantae
-Animalia
-Fungi
All Eukarya that do not belong to the Kingdom Plantae, Animalia or Fungi are called Protists.
Characteristic common to Protista?
(Ex: algae, Protozoa, slime molds)
All eukaryotes that do not fit in the three other kingdoms of the domain eukarya
-mostly unicellular (can be multi but very simple)
-no specialized tissue
-Live in water and have various ways of nutrition (may be heterotrophic or photosynthetic or mixotrophs)
- paraphyletic ( descend from a common evolutionnary ancestor)
Protist are often grouped:
-photoautrophic algae (plant-like protists)
-heterotrophic protozoans(animal-like protists)
- saprotrophic slime molds (fungus-like)
This group of extremely interesting organisms provides evidence that plants, animals, and fungi evolved from a common eukaryotic ancestor.
Characteristic common to the Kingdom fungi
Mostly multicellular, cell wall made of chitin, absortive heterotrophe and absorb nutrient with no photosynthesis.
Consist of mycelia
Can be:
- Saprophytes (live on dead organismic matter)
Most saprophytic fungi secrete digestive enzymes onto their food and then absorb the products of extracellular digestion.
-parasites (feed of living things)
-mutualist: absorn nutrients from another organism but reciprocate with functs beneficial to their partners in some way
Reproduction = sexual or asexual (spores (haploid cells) are produced in both cases)
- sporangia: where spores are protected before dispersion
Kindom plantae
- composed of those organisms that are eukaryotic, multicellular, photosynthetic autotrophs. Their photosynthetic pigments are contained within membranous organelles called chloroplasts.
- well-defined cell wall made of cellulose
-sexual reproduction
-non-mobile
Domain eukarya supergroups
-SAR
- Archeaplastida
-Excavata
-amoebozoa
-opisthonka
Kingdom animalia
-eukaryotic, multicellular, heterotrophic organisms
-mobile and sessile (non-mobile for part of their life cycle) in certain stages of their development.
- reproduction (sexual or asexual)
-kingdom is so broad that it is divided into phyla.
-nervous system coordinates responses to stimuli
Domain Bacteria (most abundant organisms on earth)
- Cell wall composed of petidoglycan
- Prokaryotic (no nucleus) and unicellular
- Either autotrophs or heterotrophs
Some beneficial activities : - produce oxygen
- decompose organic material
Kingdom= Eubacteria
How are called bacteria that cause disease ?
pathogenic
Domain Archea
- unicellular
-mostly anaerobic (dont require oxygen) - few cause disease
- cell wall
- plasma membrane made of different types of lipid (no peptidoglycan)
Kingdom= archeabacteria
