24 terms

Bio 2 exam


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prebiotic soup model
proposes that certain molecules were synthesized from gases in the atmosphere or arrived via meteorites. afterwards they would have condensed with rain and accumulated in oceans

1. simple molecules were present in the atmosphere of ancient earth

2. energy in sunlight drove reactions among the simple molecules

3. stimulated by heat, the products formed more complex molecules
surface metabolism model
suggests that dissolved gases came in contact with minerals lining the walls of deep-sea vents and formed more complex, organic molecules.
some people prefer this model because they believe the prebiotic soup model would not work because molecules would be diluted i. the ocean, whereas this model has them concentrates in a single area.

-one type of hydrothermal vent is a black smoker found in mid atlantic that has thin crust snd magna shooting out of the water and gas at high pressures
-hydrogen sulfide can be broken apart to make co2, which can be used to make sugars

1. simple molecules were present in early oceans and hydrothermal vents

2. vent minerals catalyzed spontaneous reactions among high energy molecules

3. stimulated by heat and concentration, the products formed more complex molecules
why was formaldehyde synthesis important in early life?
researchers have shown that molecules of formaldehyde can react with one another to produce large organic compounds including energy rich sugars that require a large input of energy.
in earth earth, there was no ozone layer so large quantities of high energy photons could enter earth
why is the synthesis of acetic acid from co2 and h2o important in the chemical evolution?
1) acetic acid can be formed under conditions that simulate a hydrothermal vent environment
2) it is a key intermediate in an ancient metabolic pathway that produces acetyl coA, a molecule used by cells
bacterial organelle functions
storing calcium ions, holding crystals if mineral magnetite (helps cells swim in a directed way), and organizing enzymes responsible for synthesizing complex carbon compounds from co2
Parts of a prokaryotic cell
DNA, cell wall, plasma membrane, ribosomes, cytoskeleton, cell wall, flagella
what are types of eukarotic?
protists, fungi, plants, animals
Prokaryotic vs. Eukaryotic
Prokaryotes: circular dna, cell membrane, cell wall, no major organelles, binary fission
-absorb inorganic nutrients, do not use phagocytosis
-some are phototrophs, that get energy from photosynthesis. ex: cyanobacteria
-some are autotrophs, fixing carbon from CO2
-some are heterotrophs, getting organic compounds from other organisms
-some have special pathways that allow them to absorb nitrogen or sulfur containing compounds
-use aerobic and anaerobic respiration

Eukaryotes: complex cell, has own dna, larger than prokaryotes, has a nucleus, paired sets of chromosomes, and cell organelles
How did eukaryotes evolve?
They evolved from prokaryotes that engulfed other cells. The chloroplast/mitochondria used to be free-living bacteria but have their own DNA and are double membranes in cells. This is supported in the endo-symbiosis theory.
what were 2 hypotheses about heredity?
1) blending inheritance: mother and father traits blend together

2) inheritance of acquired characters: traits present in parents are modified through use and passed to offspring
what features about peas made them good for the experiment?
1) he could control which parents were involved with mating
2) individuals were available that offered easily recognized traits
3) self fertilization
Principle of Segregation
During meiosis, chromosome pairs separate into different gametes such that each of the two alleles for a given trait appears in a different gamete. the segregated alleles present in the gametes come together ay fertilization to produce a zygote
genetic correlation
When a single gene controls/affects more than one trait. ex) selection for increased beak depth caused for increased beak width as a result
how did scientists test early life?
in our bodies, we have fixed amounts of carbon. scientists put methane, co2, ammonia, and sulfur compounds in a sealed flask, heated it, and exposed it to electrical energy. the outcome was organic compounds such as amino acids, simple sugars, and nucleic acids
what were early indications of life?
earth life believed to be 3.8 billion years ago
-specific ratios of carbon trapped in rocks were always associated with life (C12,C13, C14) and carbon dating showed ages.
-fossil evidence: stromatolites looked like bacteria, they got covered with sediments and eventually fossilized
evidence darwin used to support that organisms evolved over time
-artificial selection: selective breeding

-biogeography: groups of species in geographic areas had similar advantageous traits for that area

-comparative anatomy—> homolgy: modifications of existing structures for different purposes, such as: forelimbs of mammals, reptiles, birds, amphibians

-comparative embryology: our development is similar to that of other species

-fossil record
Example of vestigial structure
wings on flightless birds

appendix: remains of a structure that most herbivores have
mendel's ideas
strengthened darwin's argument

-traits in an individual are determined by 2 alleles, one inherited by mother and one from father
symbiotic relationships
mutualism: both benefit. ex; bacteria that protect us from pathogens
commensalism: one benefits but does not harm the other. ex: tree frogs using plants for protection
parasitism: one benefits and one suffers consequences. ex: ticks
why males?
to avoid competition between mitochondria, which can only be passed on by females
advantages and disadvantages to sex
-greater variety
-maybe both parents could provide resources to ensure survival of offspring

-not a clone
-each offspring only has half of parents dna
-requires energy to find a mate
argument against why sex is to produce greater variety
cloning is often a good strategy for many forms of bacteria
Red Queen Hypothesis
hypothesis for sex that states sexual selection allows hosts to evolve at a rate that counters the rapid evolution of parasites and pathogens

-pathogens could kill us easier if they had the code on our cell surfaces that allowed them to enter and reproduce
Great Oxidation Event
the change of Earth's atmosphere from reducing to oxidizing, brought about by oxygen-generating photosynthesis (cyanobacteria). created ozone layer