Lesson 1 Flashcards
What are the basic characteristics of life?
cellular organisation
reproduction
metabolism
homeostasis
heredity
response to stimuli
growth & development
adaption through evolution
what is the origin of life?
there is no known origin there are only theories which cannot be definitively proven:
1. generation of complex biomolecules due to complex early atmosphere/deep sea hypothermal vents
2. generation of replicating organisms via an RNA world/chelation by mineral clays
3. panspermia - life from space
how long have cells been on earth?
earth formed 4.5 billion years ago
evidence of cells date back to 3.4 billion years ago
things that are still alive today date back to 3.2 billion years ago
units and what they are used to measure
micron/micrometers (μm) = cells & organelles; 1μm = 1/1000 mm
nanometres (nm) = subcellular components; 1nm = 1/1000 μm
define biomass
biomass is a measure of weight of an organism based upon the amount of carbon within the organism
- there are 450 Gt C within plants across the globe
- 2 Gt C in animals
define evolution
what factors are necessary?
evolution is a process of biological change in which species accumulate differences from their ancestors as they develop characteristics which are more suitable to their environments
1. variation within individuals
2. inheritance of genetic material
3. selection pressures
4. time
what is the naming system of a species?
1st part - genus
2nd part - unique to species
what are the two major points made by Charles Darwin?
what observations led to them?
Main points:
1. species adapt to different environments over time & accumulate differences
2. natural selection is a primary cause of descent with modification (evolution)
Observations:
- individuals in a population vary in their traits
- a population can produce more offspring than can survive to produce their own offspring
- species are generally adapted to their environments
define natural selection
natural selections is a mechanism for evolution wherein individuals with inheritable traits that are more advantageous to the local environment are more likely to survive & reproduce resulting in the frequency of these traits increasing in the population’s gene pool
3 purposes of phylogenetic trees
- show relation of species through shared characteristics
- show how closely related species are
- allows for classifications into domains
explain the endosymbiosis theory
An early ancestor of eukaryotic cells (a heterotroph) engulfed an oxygen-using non-photosynthetic prokaryotic cell. an endosymbiotic relationship formed. due to evolution the host cells & endosymbiont merged resulting in a eukaryotic cell with a mitochondrion
what evidence supports the endosymbiosis theory?
- mitochondria & chloroplasts are double membraned
- mitochondria & chloroplasts contain ribosomes & circular DNA molecules (like bacterial chromosomes)
- they are autonomous (somewhat independent) so can grow & reproduce within the cell
give order of creation for mitochondria & chloroplasts
what prokaryote was their origin?
mitochondria - proteobacteria (1st)
chloroplasts - cyanobacteria (2nd)
what are the three domains of life?
prokaryotes or eukaryotes?
subgroups - how are they classified?
- bacteria - most diverse & widespread; prokaryotic; multiple kingdoms; occupy all environments
- archaea - prokaryotic; multiple kingdoms; occupy extreme environments
- eukarya - eukaryotic; four subgroups classified by modes of nutrition: (1) kingdom plantae - photosynthesis, (2) kingdom fungi - absorb nutrients from external sources, (3) protists - unicellular & classification still debated, (4) kingdom animalia - ingest other organisms
comparison of the domains of life?
nuclear envelope - present only in eukarya
membrane-enclosed organelles - only in eukarya
peptidoglycan in cell wall - only in bacteria
circular chromosom - in bacteria & archaea
growth @ temps > 100 degrees C - only archaea
