Mid Term Flashcards
What are sources of energy used by life?
- ) light
- ) inorganic compounds (h2,h2s)
- ) organic compounds (starch, fat)
Autotroph
And two examples of autotrophs
“Self feeding”
Uses inorganic compounds + outside E to make organic molecules
Ex photo autotrophs: use light and Co2 to make glucose
Chemoautotrophs: use chemical E, CO2 to make glucose
Heterotroph
And two examples of heterotrophs
“Different feeding”
Use organic compounds such as carbon source to make organic molecules
Ex.) chemoheterotrophs: consume organic molecules as both energy source and C source to transfer into other molecules (animals fungi many bacteria)
Photoheterotrophs: use light as energy but get C from food ( some bacteria)
Why is life so diverse?
Evolution
How did life start?
- ) early pre O2 atmosphere & zap with lightning
- ) this forms monomers (amino acids, nucleotides, sugars)
- ) place monomers in favourable locations for condensation reactions (clay shores, hydrothermal vents, hot pools)
- ) RNA before DNA -simpler -acts as a catalyst
- ) lipids naturally form bilayer spheres which encapsulate RNA providing a more stable environment
- ) self replication structure -> nucleus acid inside the nucleotides on outside
Evolution
Genetic change in population of organisms over successive generations
How do scientists work out evolutionary relationships?
Look for similarities and differences:
- fossil record
- morphological comparisons
- development
- molecular analyses
- behaviour
Why is chocking so common in humans?
Because the lungs evolved from the esophagus
Clade:
A monophyletic group (includes ancestral group and all its descendants)
What are the 3 universal characteristics of life?
- ) transform energy to synthesize new molecules (energy transformation)
- ) make nearly faithful copies of themselves (reproduce)
- ) regulate internal environment (maintain homeostasis) in response to external changes.
Taxon:
a named group of organisms at any level of a phylogenetic tree, eg mammals or Homo sapiens
Polytomy:
Populations likely split very rapidly from each other, making it hard to resolve which split off earlier or later
Paraphyletic
Common ancestor group missing a descendant
Polyphyletic
Group where a descendant doesn’t belong
Monophyletic:
Common ancestor group with all descendants included
Homology
Shared ancestry (homology)
Homoplasy
Similarity due to convergent evolution -similar function
Physical changes over time
- movement of continents = continental drift
- volcanic activity, meteorite collisions
- rise and fall of sea levels
- changing temperature
- increase in O2
Life is affected by physical changes to earth, but life itself also brings about physical changes to earth
- no O2
- O2 = light E splits h2o & free electrons are used to reduce co2 to build organic molecules
- O2 is waste product
- leads to aerobic respiration
- supports more complex life (eukaryotic, multicellular)
Cyanobacteria
Photosynthetic prokaryotes
Formed stromatolites
Cambrian explosion
- oxygen levels made big, mobile animals possible
- the evolution of predation exerted selection for hard parts, exoskeletons, and rapid movement
- animals moved from ocean floor which led to development of new habits
- new genes, new bodies hox genes evolved
What are the earths oldest organisms?
Bacteria
Defining characteristics of archaea
Absence of peptidoglycan in cell wall
Distinctive lipids present in their cell membrane
Plasmid
Extra-chromosome DNA, small rings, easily exchanged during sex
Bacterium structure includes :
Capsule Cytoplasm Ribosomes Nucleoid Plasma membrane Flagellum Peptidoglycan Outer membrane
Gram positive :
Gram negative:
Thick cell wall
Thin cell wall between 2 membranes ( typically antibiotics are ineffective against gram negative bacteria )
The three challenges of a bacteria
- ) make nearly faithful copies of themselves (reproduce)
- ) respond to the outside environment by resisting internal changes in physical and chemical environments ( maintain homeostasis
- ) transform energy to synthesize new molecules (energy transformation)
Reproduction in bacteria
Rapid short generation times
Asexual reproduction = binary fission
Exchange of genetic material in bacteria 3 methods
Conjugation: genes on plasmids are easily transferred ( genes transferred through sex pilus
Transformation: (uptake of free genetic material)
Transduction (via viruses: bacteriophages)
Maintain homeostasis
Respond to harsh environmental conditions
Move toward or away from chemicals
Endospores
Protect bacteria from adverse conditions ( auto cave must be use to kill them)
Biofilms
Bacteria form surface- coating communities
- form polysaccharide gel trapping debris and other cells
- can be hundreds of cells thick
- composed of single or many species
Chemotaxis
Bacteria are able to move toward or away from chemical signals
- use flagella (different than eukaryotes)
- made from different proteins
- thinner & more numerous
- also glide roll use gas floats inside cell
Paleozoic
Marine organisms
Ended with massive extinction 75% because of sea level and ocean temperature drop
Silurian
Marine life rebounded
Animals swim and feed a
Optimal hydration
Avoid dehydration of the body
What is diversity?
- ) genetic variation
- ) Species composition
- ) function (eg biochemical pathways)
Paleozoic
Marine organisms
Ended with massive extinction 75% because of sea level and ocean temperature drop
Silurian
Marine life rebounded
Animals swim and feed a
Optimal hydration
Avoid dehydration of the body
What is diversity?
- ) genetic variation
- ) Species composition
- ) function (eg biochemical pathways)
Vestigial trait
A reduced structure no function anymore
Developmental homology
Recognized in embryos
