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17 Cards in this Set
- Front
- Back
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Fossils |
- sequence of life forms through geological history - Some linages more clear to see. the younger the assemblage the more similar to today Relative - assuming younger are above the older Absolute - measuring radioactive decay - Sink in water, be buried by sediment, oxygen poor environment - Biased and incomplete |
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Geology |
- Conditions on earth that are relevant - continental drift, celestial bodes, geochemistry - Early earth - little or no oxygen, violent, unsustainable for life |
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Organisms today |
- Observing and comparing - Shared inherited traits used to reconstruct common ancestor |
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Biogeography |
- Distribution of life on earth - Occurred over length of time - islands formed by volcanoes - unbalanced, population of animals not balance with world population of certain species |
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Oxygenic photosynthesis |
- Photosynthesis began by cyanobacteria 3.5 m years ago, continued by algae and land plants - Oxygen by photosynthesis built up, no longer absorbed by iron. Toxin that damages organic molecules, strips electrons and breaks chemical bonds - Organisms figured out how to detoxify oxygen |
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Evolution of eukaryotic cells |
- Large and complicated, nucleus and organelles - Evolved 1.2 - 2 billion years ago - Mitochondria (cellular respiration in animals, plants, fungi) arose from bacteria that used oxygen in the oxidation of glucose - Chloroplast - photosynthesis in plants. After cell had developed mitochondria - Cyanobacterium could perform oxygenic photosynthesis |
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Multicellularity |
- Arouse several times, independently - Composed of many different cell types Pros - mobility, protection, defence, specialization, attachment - Arose in brown algae, red algae, green algae, fungi, animals |
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Snowball earth |
- Evidence that earth was encased in ice - Cryogenic period, 850-635 million years ago - 4 phases of cooling - Life survived in hydrothermal vents and ice free refuge |
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Appearance of animals |
- Diverged from a common ancestor 1 b - 700 m years ago - Might have been stimulated by termination of snowball earth - Colonial choanoflagellate - might resemble common ancestor of all animals, cell found in some animals. Rapid diversification after snowball earth - Doushantou - earliest animal fossil. 600 m years ago. Looks like animal embryos - Ediacaran - first large multicelluar organisms in fossil record. 585 m years ago |
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Cambrian explosion |
- 535 million years ago - Any animal phyla first appeared in fossil record or earlier diversified during this period - Oxygen levels high, supporting active metabolisms. Predator and prey species apply selection pressure on each other - Hox genes - effect development pathways, body parts. Produce proteins that lay out plan for development in embryos then turn off forever |
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Where are genes |
- On chromosome in the nucleus - Exceptions - mitochondria genes and chloroplast genes |
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Chromosomes |
- DNA - 50% by weight, protein 50% by weight - Contain genetic information - Some proteins perform functions on DNA, others as packing material - Long DNA molecule with associated proteins - Histone protein - packing peanuts, protect DNA. DNA wound around them - Linear array oof genes |
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Gene |
- Segment of DNA that has meaning - Not as distinct part of the DNA molecule - Continuous - Order is the same except for mutations |
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Homologous chromosome |
- PP - homozygous for dominant allele - aa - homozygous for recessive allele - Bb - heterozygous with one dominant, one recessive - Same characteristics but different trait - 46 chromosomes in humans, 22 pairs and XX for female, XY for male |
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Mitosis |
- Part of cell cycle, function of making more cells - Equational division of nuclei an it's contents - Results in daughter nuclei with the same number of chromosomes and same genetic information - Bore this happens, chromosome must duplicate in S phase |
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Stages of mitosis |
- Membrane around nucleus disintegrates, chromosomes condense - Replicated chromosomes line up on metaphase plate of dividing cell, microtubules move things around - Sister chomatids separate and move to opposite poles of the cell. Equal genetic material - New nuclear envelope forms around new chromosomes and chromosomes decondense |
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Cytokenisis |
- Division of cell as a whole - Can have mitosis without, becomes one cell with multiple nuclei |
