lecture 3 brief hist. life on earth Flashcards
what are the three domains of life
bacteria, eukaryotes and Archaea
what are the six kingdoms
archaea, bacteria, protists, fungi, plantae, animalia
wha are the four kingdoms from eukaryotes (domain)
protists, fungi, plantae, animalia
what are archaea
prokaryotes that lack a peptidoglycan cell wall, e.g. extreme halophiles, thermophiles and methanogens
what are bacteria
– prokaryotes with a peptidoglycan cell wall, e.g. cyanobacteria, soil bacteria, nitrogen-fixing bacteria and pathogenic bacteria
what are protists
eukaryotic, primarily unicellular organisms, (algae are multicellular) They are
heterotrophic or photosynthetic organisms eg. amoebas and paramoecia.
what are fungi
eukaryotic, mostly multicellular, (yeasts are single celled). They are heterotrophic,
usually nonmotile, with chitin cell walls – eg mushrooms.
what are plantae
eukaryotic, multicellular, non-motile, usually terrestrial, photosynthetic organisms
such as trees, grasses, and mosses.
animalia
- eukaryotic, multicellular, motile, heterotrophic organisms such as sponges, spiders, newts, penguins, and humans.
what was the first form of life? when did it appear and when was it dominant
Prokaryotes were the first forms of life – they appeared 3.8 billion years ago. They were the
dominant form of life between 3.5 and 2 billion years ago
when did cells with nuclei come about
1.7 billion years ago
what happened with cyanobacteria around 3.5 billion years ago?
They are oxygen-generating algae. These photosynthetic algae: Raised atmospheric oxygen levels (over >billion years!) Enabled the ozone layer to form Protected the Earth from U. V. rays
what evolved 1.5 -2.1 billion years ago
eukaryotes
what are eukaryotes
Eukaryotes are larger and more complex than prokaryotes. They have a nucleus, chloroplasts and mitochondria. It is thought that these evolved as a result of endosymbiotic relationships between bacteria
what is the pathway of early eukaryotic evolution
Ancestral prokaryote
• Infoldings of plasma membrane
• Engulfing of aerobic heterotrophic prokaryote
• Engulfing of photosynthetic prokaryote
• Endosymbiotic relationships between bacteria
how did evolution of multicellular eukaryotes occur?
y single-celled eukaryotes living in association
with each other. This lead to the development of specialised cells. Most organisms were aerobic,
and sexual reproduction was generally well developed, and this generated variation and lead to an
increase in the rate of evolution
fusion of gametes lead to——which generates——-
genetic reecombination
variation, enabling evolution
what eukaryotes evolved next 600 million years ago
jellyfish and worms
what ocurred 570 million years ago
early cambrian period
what occured 500 million years ago
land colonised by plants fungi and animals
what did the movement from aquatic to terrestrial require
numerous adaptations
when were most of the orders of modern mammals established?
50 to 60 million years ago
when did human lineage diverge from other primates
5-6.5 million years ago
what is a good example of adaptive radiation
A
good example of adaptive radiation is seen in Darwin’s finches (see below). The original ancestral
finch colonised the Galapagos Islands. In the absence of competition from other birds, the finches
evolved by natural selection (and adaptive radiation) to occupy various niches, according to the
available food supply.
what is the genearal thing to be taken from this lecture
organisms react with the environment and they shape eand impact each other
