- category of organisms categorized by the absence of a true nucleus and other membrane-bounded organelles; Chromosomes are single circular DNA molecule
- often have cell wall
- reproduce quickly through binary fission
- exchange genetic material through conjugation
- unicellular but most live in clusters or colonies
- chemically diverse with many options for metabolism
- includes bacteria and archea
- category of organisms whose cells are characterized by the presence of a membrane- bounded nucleus and other membrane-bounded organelles; chromosomes are multiple linear DNA molecule
- also have cytoskeleton and mitochondria
- includes plants, animals, fungi, algae, and protozoa
- In biological taxonomy, a domain is the highest taxonomic rank of organisms
- 3 domains: bacteria, Achaea eukarya
- one of 2 groups of prokaryotes
- includes most of the commonly encountered single-celled, non-nucleated organisms that we have traditionally referred to as bacteria
- one of 2 groups of prokaryotes
- include many species that live in extreme habitats on Earth (such as salty , acidic and hot environments) and have very diverse metabolic strategies
- category of organisms whose cells are characterized by the presence of a membrane- bounded nucleus and other membrane-bounded organelles
- includes plants, animals, fungi, algae, and protozoa
how does archaea resemble bacteria?
they resemble bacteria in cell size and gross structure, in their method of cell division (binary fission), and in many aspects of basic metabolism and enzyme content
how does archaea resemble eukaryotes?
resemble many details of DNA replication, transcription, RNA processing and initiation of protein synthesis
second highest taxonomic rank below domain
Difference between organic and inorganic
- organic means a molecule has a carbon backbone with some hydrogen; living creatures are made of various kinds of organic compounds
- inorganic molecules are composed of other elements
small organic molecule that serves as a subunit in the assembly of a macromolecule
are large molecules composed of many similar smaller molecules (monomers) linked together like a long chain
5 carbon sugar present in DNA
5 carbon sugar present in RNA and in important nucleoside triphosphate such as ATP and GTP
- direct transfer of DNA from one bacterial cell to another bacterial cell through a pilus
- transferred DNA is plasmid
what process drives the momentum of evolution?
What are the 9 steps in the evolution of the first eukaryotic cell?
- 1. formation of organic molecules
- 2. development of polymers
- 3. molecular replication
- 4. encapsulation
- 5. replication
- 6. molecular co-operation
- 7. development of an internal membrane system
- 8. endosymbiosis
- 9. multicellularity
what were the 3 main conditions of early earth?
- lots of H2O, CO, CO2, N2 and CH4
- little atmospheric oxygen
- plenty of energy in the form of UV and volcanic activity
1.what are some small organic molecules that are important to the cell?
2. why was is important that there was no oxygen on the early earth?
- 1.amino acids, lipids, nucleotides, carbohydrates
- 2. because oxidizing elements will break reactions apart appose to build them up
what was the significance of the Miller-Urey Experiment? (7)
- It replicated the early earth
- started with a warm flask of water to simulate the primeval sea
- the atmosphere had inorganic substances (H2, CH4 and NH3)
- sparks were discharged to mimic lightening
- a condenser cools the atmosphere which resulted in a rain that carried water and any dissolved gases the miniature sea
- flask becomes brown ad material circulates through solution
- after a week contents of solution analyzed and 20 amino acids, lipids, nitrogenous bases, ribose/deoxyribose found (organic substances)
briefly describe the other 4 theories that describes the origin of biological molecules.
- The deep sea vent theory: molecules were formed in underwater volcanoes
- Extraterrestrial origins: molecules formed in space in the reactions of the stars and came to earth via meteors
- Radioactive Beach Hypothesis: Rx provides sufficient energy to generate organic molecules such as amino acids and sugars, from acetonitrile in water
- Wachtershauser's hypothesis: the energy released from redox reactions from metal sulfides promoted the synthesis of organic molecules and polymers
what polymers are important to cell?
how do they come apart?
how do they form?
- DNA, protein, nucleic acid, lipids, carbohydrates
- hydrolysis reactions
- form by dehydration/condensation reactions
what was the significance of the Sydney Fox's Thermal theory?
Sidney Fox showed that splashing amino acids under hot, dry conditions caused them to instantly polymerize into proteins
What was the significance of James Ferris and the Clay Catalyst?
- clays have a structure that can absorb organic molecules and catalyze their synthesis into polymers
- on early earth, rain or waves may have splashed organic monomers onto fresh lava or hot rocks, enabling polymers to form abiotically
what is the RNA world hypothesis?
short sequences of RNA molecules will assemble spontaneously from nucleotide monomers using aqueous solution of ammonium cyanide or hydrogen cyanide subjected to heating or bombardment with ultraviolet radiation
what happens when a sequence of RNA is added to a solution of RNA monomers?
new RNA strands are formed that are complimentary to parts of the original strand
- RNA that have enzymatic activity
- scientists presume that RNA molecules may have acted as early enzymes to allow for RNA replication and other enzymatic activity
why was RNA the most important biopolymer in early life on earth? (4)
- RNA can store genetic info in its sequence of bases
- RNA can act as an enzyme and catalyze the transformation of RNA's and other compounds
- chemically manufactured RNA can evolve in test tubes to molecules with catalytic function
- can replicate and form spontaneously
what does the Hydrothermal Vent theory state? (3)
- hydrothermal vents possess the elements and energy source necessary for synthesis of organic molecules
- some minerals can catalyze the stepwise formation of hydrocarbon tails of fatty acids from hydrogen and CO gases released from hydrothermal vents
- fatty acids eventually released into water or aerosolized
in aqueous environment certain molecules especially lipids and polypeptides can self assemble into spheres filled with fluid. what chemical characteristic might drive this process?
why would if be advantageous to trap molecules in compartments?
- start the formation of macromolecules
- lipid molecules that arrange themselves in a spherical form in aqueous solutions
- this formation is due to the amphipathic nature of fatty acids
what is flip-flop?
when fatty lipids move back and forth which pushes particles inside
what is the pre-cell hypothesis?
RNA served as a molecule that could direct the synthesis of forming a double helix and eventually being able to store info (formation of DNA)
how did the nucleus and endomembrane system of eukaryotes form?
why do you think it's advantageous to evolve this elaborate internal membrane system?
- probably evolved from infolding of the plasma membrane of ancestral prokaryotes
- it's protections, compartmentalization, more surface are that will allow reactions to occur more efficiently
one of the symbiotic organisms lives inside the other
what did Ivan Wallin come up with?
he extended the idea of an endosymbiotic origin to mitochondria in the 1920's
what are the evidence that mitochondria and chloroplasts arose from ancient endosymbiosis of bacteria? (5)
- just about the same size as bacteria
- reproduce only through process similar to binary fission
- surrounded by 2 or more membranes (taken in through phagocytosis)
- contain DNA that is diff from that of the cell nucleus and that is similar to that of bacteria
- these organelle's ribosomes is similar to one in bacteria
- have several enzymes and transport systems similar to those of prokaryotes
involves the engulfment of a bacterium by another free living organism
occurs when the product of primary endosymbiosis is itself engulfed and retained by another free living eukaryote
what does it take to be multicellular? (5)
- division of tasks
- cellular differentiation
- cell adhesion
- cell to cell communication
what are the 2 types of development of multicellularity?
clonal and aggregative development
what are the advantages of muticellularity?
- size: predatory, storage, nutrient acquisition, compartmentalization
- functional specialization: divide labour in place and time
- metabolic co-operation: allows incompatible reactions to happen at once
- Motility and Mitosis trade offs: improves the efficiency of nutrient use