Origins Flashcards
What are the 3 main groups?
Bacteria. Archeae. Eukaryote.
What does a phylogeny tree show?
Confirms how organisms are related to each other via DNA
What are the two significant evolutionary events?
Eukaryotes acquired chloroplasts and mitochondria by endosymbiosis. Bacteria are responsible.
How many groups are there?
Definitely 7, thought to be 8
How many groups have the capacity to photosynthesis?
6
Describe endosymbiosis (first event)
- Bacteria engulfed by a prokaryotic host
- Genes transferred conversion to organelle
- Produced mitochondria
Describe endosymbiosis (second event)
- Eukaryotic like cell engulfs a prokaryotic photosynthetic cyanobacterium
- Transfer genes and conversion to organelle
- Produces a chloroplast
How did eukaryotes acquire photosynthesis?
Acquired it multiple times by repeated endosymbiosis
What were the three clades that rose from the first eukaryotic organism?
Glaucocystophyte. Green Algae. Red Algae.
How did endosymbiosis contribute to diversity on the planet?
Increased diversity. Helped evolution of multicellular organisms. Diverse groups of multicellular organisms.
What needs to be overcome for multicellularity?
Cell communication - cell signalling.
What are some key events in evolution?
Photosynthesis. Endosymbiosis. Diversification. Multicellularity.
What did green algae evolve into?
Land Plants
How did Land Plants help to change the atmosphere?
Caused a massive reduction in CO2. Falling levels of CO2 caused lower temperatures. This initiated a terrestrial ecosystem and triggered evolution. Lower temperature = plants with broader leaves = increased oxygen levels
How can evolutionary trees be used to explain diversity of life on the planet?
Show how the acquisition of photosynthesis by endosymbiosis led to radiation and diversification
Where do animal and plants originate from?
Aquatic life
What are some features of eukaryotic cells?
Nucleus, cytoskeleton
What is an Amoeba?
Engulfs. Single celled celled but still eukaryotic
What are some features of complex multicellularity?
Evolved many times. Molecular mechanisms of cell adhesion. Cell communication. Different cells and tissues. Regulatory genes. Reproduction. Internal and external environment.
What are some examples of complex response?
Cell signalling (histamine). Opsonization (phagocytosis)
What is a constraint of a multicellular organism?
Getting oxygen to all the cells.
Why was there original multicellular organisms in an aquatic environment?
Oxygen existed in the ocean so multicellular organisms evolved.
What features did sponges have?
Pores
What features did Cnidarians have?
(jellyfish and sea anemone). Two cell layers. Able to stick.
What is rotational symmetry?
Property of a shape when it looks the same after rotation. Sphere is the simplest
What is radial symmetry?
Basic body plan where the organisms can be divided into similar halves by passing a plane along ny angle of the central axis eg sea anemone and starfish
What is bilateral symmetry?
Symmetrical arrangement of an organisms along a central axis. Divided by one plane
What do the levels of symmetry show?
Increases planes of symmetry to make an organism more complex. Simple axes determine the structure of organisms. Planes of symmetry determined by regulatory genes
What is a Gastrula?
Embryo with an inside endotherm and outside ectotherm - Diploblastic
What is Tripoblastic?
Ectoderm. Mesoderm. Endoderm. Bilateral symmetry.
What are Destromas?
- Blastopore becomes anus
- CNS down back
- SImple
- Progressive evolution of backbones with a dorsal hollow
What are Protosomes?
- Blastopore becomes mouth
- CNS down the front
What genes are crucial in animal development?
Hox genes
What are vertebrates?
- Bones, vertebrates and skills
