Flashcards in Dr Gilmour Deck (33):
1
What are the three high level divisions in the eukarya?
-Fungi and animals
-Primary endosymbiotic algae and plants
-Protists
2
What are the Opsithokonta?
-Animals, true fungi and microsporidia
-Named for backward pointing flagellum in animal spermatozoa and fungi zoospores
-Choanoflagellates similar to choanochytes in sponges
3
What are the primary endosymbiotic algae?
-Early eukaryote cells that had already acquired mitochondria used cyanobacterial cells as feedstocks. One of these was not digested and became the chloroplast
4
What are the Chlorophyta (Green algae)?
-Part of the primary endosymbiotic algae
-Unicellular, two anterior flagella that move the cell forward by a breast stroke swimming action
5
What are the Rhodophyta (Red algae)?
-Part of the primary endosymbiotic algae
-Many multicellular, but also filamentous and unicellular
-Coloured red by phycoerythrin
6
What are the protists?
-Mixture of groups previously divided into algae and protozoa
7
What are the secondary endosymbiotic algae?
-Part of the protists
-Have more than two membranes surrounding the chloroplast
-Widespread mixotrophy or heterotrophy, using many organic compounds
8
What are the diatoms?
-Part of the secondary endosymbiotic algae
-Frustules (Silica cell walls) produce diatomaceous earth
-Asexual cell division reduces cell size
-Either centric with radial symmetry or pennate with bilateral
9
What are the brown algae?
-Part of the secondary endosymbiotic algae
-Seaweeds
-Possess vacuoles of oily liquid (leucosin) for energy storage
10
What are the haptophytes?
-Part of the secondary endosymbiotic algae
-Coccolithophores produce an exo-skeleton of coccoliths made of CaCO3
11
What are the dinoflagellates?
-Secondary endosymbiotic algae
-Grouped in Alveolates as have alveoli
-Swim via spinning motion as have two flagella
-Can be toxic
12
What are the Alveolates?
-Part of the secondary endosymbiotic algae
-Have flattened vacuoles (alveoli) beneath outer membrane
13
What are the Apicomplexans?
-Parasites with an apicoplast derived from the endosymbiotic chloroplast. Used for fatty acid metabolism
-Have apical complex for entry to host
14
What are the amoebas and slime moulds?
-Amoebas move using pseudopodia which flow
-Slime moulds are amoebas that aggregate into a fruiting body
15
What are the Euglenozoa?
- E.g. Euglena: SEA but can lose flagella and grow heterotrophically
-E.g. Trypanosomes: Obligate parasites which produce major diseases
16
What are the Metamonada?
-Largely parasites
-Lost mitochondria (degenerative evolution)
17
What are the four theories on the origin of life?
-Chemical origin (Prebiotic Soup)
-Panspermia
-RNA world
-Hydrothermal vents
18
What are the earliest forms of life still existing on Earth?
Bacterial communities called stromatolites
19
What are stromatolites made of?
Layers of microorganisms, outermost organisms are photosynthetic and inner layers are anaerobic supporting sulphate-reducing bacteria
20
What are the requirements of life?
-Essential elements (C, H, N, O, Mg, Ca, Na, K, Fe): Available on early Earth, no free O2 in atmosphere
-Temperature: Between boiling and freezing points of water
-Source of energy: Reduced minerals, sunlight
21
What is the evidence of life?
-Stromatolites
-Isotope ratios: Limestone depleted of CO2 with 13 Carbon isotope
-Microfossils
22
How does limestone being depleted of 13CO2 provide evidence of life?
Carbon-12 is released from cells so if there is little Carbon-13, it shows more Carbon-12 is being released by decomposition
23
What is the evidence for O2 in the biosphere?
Fe2+ is soluble but Fe3+ is insoluble and forms precipitates of Fe2O3. Banded iron formations suggest periods of alternating oxygen-rich and anoxic conditions
24
What are the two functions a cell must have for reproduction and growth?
Coding functions and machine functions
25
What are the coding functions a cell must have for reproduction and growth?
DNA replication, gene expression, transcription, RNA translation and protein formation
26
What are the machine functions a cell must have for reproduction and growth?
-Energy: ADP + Pi -> ATP
-Metabolism: generation of precursors of macro-molecules (sugars, amino acids, fatty acids...)
-Enzymes: Metabolic catalysts
27
What is a proto-cell?
The formation of an enclosed shape that becomes the membrane for a cell
28
What is the RNA World theory of life?
RNA the first information macromolecule as:
-Simplicity: Only four nucleotides not 20 amino acids
-Better candidate than DNA: Less energy to form and degrade and uracil is formed early in biochemical pathways
-Genetic material of some viruses
29
What was the key breakthrough in the RNA world theory?
-The discovery that RNA molecules can act like enzymes - called ribozymes
-Splices introns and regulates gene expression
-Key step of protein synthesis (peptide bond synthesis) catalysed by activity found in ribosomal RNA not in ribosomal proteins
30
What was the problem with the prebiotic soup and RNA wold theories that lead to the hydrothermal vent theory?
No obvious source of energy to drive RNA polymerisation and UV light and lightning are not a stable continuous source of energy
31
Why is generation of a proton motive force a fundamental requirement for life?
Cells gain energy using proton gradients across cell membranes (Bacteria, Archaea) or across membranes in chloroplasts and mitochondria (Eukarya)
32
What are the properties of black smoker hydrothermal vents?
-Volcanic in origin
-Super heated waster (350C) and pH 1 to 2 percolates up through the rock and emerges through cracks in the ocean floor
-Generates a proton gradient between the hydrothermal fluid in the black smoker and the pH 6 seawater
-Temperature too high and black smokers too unstable to generate life
33