Chapter 1 Flashcards
What is is biology?
The study of life.
The science of life and of living organisms, including their structure, function, growth, origin, evolution, and distribution.
What is life
The property or quality that distinguishes living organisms from dead organisms and inanimate matter manifested in functions such as metabolism, growth, reproduction, and response to stimuli or adaptation to the environment originating from within the organism.
A system in which proteins and nucleic acids interact in ways that allow the structure to grow and reproduce
What did Aristotle and NASA say about life?
Life is something that grows, is self-sustaining and reproduces
Self-sustaining system capable of Darwinian evolution
What do Anishinaabe people refer to Earth and Rocks?
Mama Aki (mother) and Grandfathers
What does Pimachiowin Aki mean in the Ojibwe language Anishinaabemowin?
the Land that Gives Life, is a gift from the Creator to share with the world – a healthy boreal forest and all life that emerges from and flows across it.
What are the Creator’s Gifts?
Sun, water, wind, rain, fire, rock, soil, plants, and animals.
Why is hard to define life?
No universally accepted definition of life, very variable, A lot of things found in nature are also considered living (rivers, trees), Different questions involve different disciplines of life (scientists, astrobiologists, artificial life)
What are the differences between parasites and viruses?
Parasites
- Require a host to live, reproduce and grow
Viruses
- Don’t have their own metabolism
-Don’t respire or carry out photosynthesis
- Evolve rapidly by natural selection (nucleic acid)
- Can’t complete the life cycle without invading living cells.
- Does not have own protein-making factories (ribosomes, enzymes to replicate)
- Rickettsia is considered to be alive despite not being able to live outside a host cell.
Are viruses living organisms?
Similarities
* Can store and transmit information (reproduce)
* Evolve over time
Differences
* Viruses lack cellular machinery and metabolism
* Viruses can’t break down chemical compounds and obtain/transform energy on their own
* They require cells as hosts in order to replicate and use the information in their genetic material
What are the characteristics of life?
Displays order
Harnesses and utilizes energy
Reproduces
Responds to stimuli
Exhibits homeostasis
Grows and develops
Evolves
Could RNA be able to possess all the 7 characteristics of life?
Yes
Why do many scientists consider viruses NOT to be a form of life?
They lack ribosomes
Which characteristics of life are able to regulate their internal environment such that conditions remain relatively constant? Sweating is one way in which the human body attempts to remove heat and thereby maintain a constant
Exhibit homeostasis
Which characteristics of life describe organisms that can make adjustments to their structure, function and behaviour in response to changes in the external environment? A plant can adjust the size of the pores (stomata) on the surface of its leaves to regulate gas exchange.
Respond to stimuli
Definition of Display Order?
All forms of life, including this flower, are arranged in a highly ordered manner, with the cell being the fundamental unit that exhibits all properties of life
The Seven Characteristics of Life Are…
Emergent
An emergent property is a new characteristic that only results from the combination of other properties
What does it mean to be emergent?
More than the sum of their parts, but the organism is fundamentally different than the collection of individual characteristics
They come about, or emerge, from many simpler interactions, that on their own would not confer the properties
What does the Termite cathedral show
How properties can do things and individuals cannot
When did earth form?
4.6 bya
What is Radiometric dating?
Looks at specific isotopic ratios in rocks and knowledge of their rate of decay.
Timeline of the earth?
The earliest humans were 150,000 years ago
Earliest eukaryotes 2 bya
Oxygen in the atmosphere is 2.5 bya
Earliest porkaryotes and fossils 3.5 bya
Earth formed 4.6 bya
What was early earth like?
The original atmosphere of Earth contained lots of water vapour and large quantities of hydrogen, carbon dioxide, ammonia, and methane. Lack of oxygen
What are the 4 biologically important marcomlecules that are important for all forms of life and are constantly being synthesized within cells by various biochemical pathways and metabolic pathways?
Nucleic acids (DNA and RNA)
Proteins
Lipids
Carbohydrates
What is abiotic synthesis?
The production of organic compounds in the absence of life
Which polymers are not made up from
simpler building blocks and all are made within cells by complex metabolic pathways
Lipids
What was the Oparin-Haldane Hypothesis?
Oparin-Haldane Hypothesis: Organic molecules essential for life formed through abiotic synthesis
(production of organic compounds in absence of life) given conditions on the primitive earth.
Reducing the atmosphere (lack of hydrogen, methane and ammonia) that lacked oxygen favoured the formation of organic molecules
Lack of O2 = no ozone layer (O3) = UV light w/ lightning able to reach lower atmosphere =
gave energy for the formation of biologically important molecules
What is the Miller-Urey Experiment
Miller-Urey Experiment: a first experiment that demonstrates that organic molecules can be synthesized under conditions simulating primordial earth using MU apparatus (abiotic formation of molecules critical of life)
Hydrogen, methane and ammonia were placed in a closed apparatus and exposed to an energy source (sparking electrodes Water vapour was added to the “atmosphere” which condensed back into the water by cooling another part of the apparatus. One week after, organic molecules such as urea, amino acids, lactic, formic and acetic acids were found in condensed water.
Abiotic synthesis of biologically important molecules s/a amino acids, urea, lactic acid
Adding HCN and CH2O produced amino acids, fatty acids, purines/pyrimidines, sugars and
phospholipids
What are the basic requirements for life?
Biologically important molecules and macromolecules
System for storing, replicating and passing on information
Ability to capture and utilize (i.e. transform) energy
Separate these systems and processes from the surrounding environment in the distinct compartment(s)
What is the difference between a reducing atmosphere and oxidizing atmosphere?
Reducing atmosphere - lots of water vapour, presence of H2, CO2, NH3, + CH4, lack of O2 = no
ozone layer (O3)
Oxidizing atmosphere - ↑ O2 = O2 primary e- acceptor from organic molecules = reduced to H2O =
complex e- rich molec not formed
Why did the Oparain-Halden hypothesis support the Miller-Urey experiment?
Proved that early earth could produce biologically
important molecules can be synthesized outside living cells but cannot produce polymers (nucleic acids, proteins, lipids, carbs)
Which key macromolecules of life that are polymers were not formed by the Miller-Urey experiment?
Proteins and nucleic acids
Why is it unlikely that polymers would form in an aqueous environment, but instead polymerization reactions could have occurred on solid surfaces such as clay?
Polymerization on solid surfaces s/a clay - charged, thin, microscopic, layered structure which can also store potential energy for polymerization reactions = formation of short polymers of proteins/nucleic acids long enough
impart a specific function, allowing molecular adhesion forces to bring monomers together in orientation to lead to polymer formation.
What are monomers and polymers?
Monomer: simpler and easier to synthesize (amino acids, nucleotides) than the key chemical components of life.
Polymers: macromolecules formed from bonding together of individual monomers (nucleic acids and proteins). Synthesizes by dehydration synthesis, sufficient length to impart specific function (like protein) or store sufficient information (like nucleic acid) to make formation advantageous.
Nucleic acids = polymers of nucleotides
Proteins = polymers of amino acids
Polysaccharides (starch, cellulose) = polymers of simple sugars
What is the process of the Central Dogma?
Information is stored in DNA (deoxyribose nucleic acid provides cells with the instructions necessary to function.) - THROUGH TRANSCRIPTION, the information in DNA is copied into RNA - THROUGH TRANSLATION, the information in RNA guides the production of proteins
Why proteins?
Proteins provide structure and carry out many essential activities in a cell.
Such a sophisticated system couldn’t have been instantly established with the initial abiotic synthesis of simple organic macromolecules and the development of the first cells
Which of the following is essential to the Oparin– Haldane hypothesis of the nature of Earth’s early atmosphere?
The near absence of O2
What was the significance of the 1953 Miller–Urey experiment testing the Oparin–Haldane hypothesis?
The synthesis of complex biological molecules is possible in a reducing atmosphere.
In what ways are ribozymes similar and different from enzymes?
Ribozymes - RNA molecules have the ability to catalyze rxns
Discovered by Thomas Cech + Sidney Altman
Similarities
● Carry out critical reactions relative to gene function
● Proteins
● Tertiary, 3-D structure (structure affects function)
● Have catalytic activity
● Can self-replicate
Differences
● Ribozymes catalyze slower vs enzymes catalyze faster
● Ribozymes RNA molecules vs enzymes protein molecules
● Ribozymes less abundant vs enzymes more abundant
● Ribozymes in ribosomes vs enzymes in the cytoplasm, mitochondria, Golgi complex
Ribozymes < proteins < enzymes
Functions of RNA Ribozymes?
Some RNA molecules are not just long and linear molecules, but mot all RNA. Molecules are like that. Some fold up into 3D structures. Enzymes fold up into a specific 3D object as well.
Ribo(RNA)- zymes (enzymes): RNA that has Catalytic activity
Even In the absence of proteins, ribozymes can still catalyze reactions
RNA molecules can self-replicate, ribozymes self-replicating ribozymes
Ribozymes allow for early metabolic processes to occur
Ribozymes are involved in many biological processes (The CRISPR-Cas9 gene editing system relies on ribozymes)
Process of ribozyme?
Messenger RNA - Ribioenzyme-mediated cut (cleaved part is important in cells such as during transcription) - cut (cleaved) messenger
Why are Proteins and DNA evolutionarily advantageous compared to RNA?
DNA (information storage) and proteins (catalysis) are far better than RNA by themselves.
DNA is double-stranded and more stable than RNA and thus evolved as better repository of genetic information
Proteins became the dominant structural and functional macromolecule of all cells
* Greater diversity
* Much higher rate of catalysis the ribozymes
What are three reasons why proteins are more versatile than RNA molecules and more dominant structural and functional molecules of a modern cell?
- Catalytic power of enzymes is greater than a ribozyme(catalyze the same reaction using a poll of substrate molecules thousands of times a second)
- Cell synthesis of a huge array of different proteins. Twenty different kinds of amino acids, in different arrangements, can be incorporated into a protein, whereas an RNA molecule is composed of different combinations of only four nucleotides.
- Amino acids can interact chemically with each other in more complex and varied bonding arrangements which are not possible between nucleotides.
The difference between DNA and RNA?
- RNA is single-stranded, DNA is double-stranded (structurally complex)
- RNA has an extra oxygen
- DNA is more stable
- 20 different amino acids that makeup proteins which means you can catalyze more different reactions than ribozymes can
- Proteins that are enzymes are better catalyzers than enzymes
- DNA has sugar deoxyribose which is more difficult to synthesize than ribose in RNA.
Uracil in RNA, Thymine in DNA.
What is the “RNA World” Hypothesis?
- RNA World Hypothesis - RNA initially served as an info carrier and structural/functional molecule
similar to proteins in early earth
No DNA or protein yet so everything is done by RNA
DNA eventually replaced RNA as an information storage molecule and proteins mostly replaced RNA as structural and catalytic molecules
Once the DNA copies were made, selection may have favoured DNA, as it is a much better way to store information than RNA, for three main reasons: Each strand of DNA is chemically more stable and less likely to degrade, than a strand of RNA.
Possible scenarios for the Evolution of Flow Information?
The first cells may have contained only RNA, which was self-replicating and catalyzed a small number of reactions for survival
Some RNA molecules evolved to catalyze the production of proteins
The evolution of DNA followed next
RNA may have been the first information-carrying molecule, but it was replaced by DNA. Why?
Each strand of DNA is chemically more stable and less likely to degrade, than a strand of
RNA.
The base uracil found in RNA is not found in DNA; it has been replaced by thymine. This
may be because the conversion of cytosine to uracil is a common mutation in DNA. By utilizing thymine in DNA, uracil is easily recognized as a damaged cytosine that needs to be repaired.
DNA is double-stranded, so in the case of a mutation to one of the strands, the information contained on the complementary strand can be used to correctly repair the damaged strand.
The stability of DNA is illustrated by the fact that intact DNA can be successfully extracted from tissues that are many thousands of years old. By comparison, RNA needs to be isolated quickly, even from freshly isolated cells, using a strict protocol to prevent its degradation.
Greater diversity (RNA = 4 diff nitrogenous base variations, proteins = 20 diff amino acid variations)
Evolution of metabolism?
Metabolic reactions today are catalyzed by enzymes
Enzymes speed up reactions that can also take place on their own, and are reversible, they do not enable new chemical reactions.
Citric Acid (Kreb’s) Cycle: serves to oxidize organic molecules (acetate), releasing CO2 and water.
Explain the difference between the forward citric acid cycle and the reverse citric acid cycle (Krebs cycle)
Forward Krebs cycle - oxidative mode
● oxidizes organic molecules s/a acetate to produce CO2 + H2O
● synthesizes important precursor molecules, including those needed for the synthesis of
amino acids and fatty acids
● Input - complex organic molecules
● Output - chemical energy
Reverse Krebs cycle - reductive mode
● take in energy in the form of high energy e- from geologically produced H2 & use e- to
reduce CO2 into more complex organic molecules, s/a metabolic intermediates pyruvate and acetate
● Input - chemical energy
● Output - complex organic molecules
What are the characteristics of an alkaline hydrothermal vent (Deep Sea Hypothesis for Origin for Life)?
Alkaline Hydrothermal vent hypothesis - by mixing alkaline and acidic fluids while providing
source of energy, mineral-rich chimneys facilitate chem reactions between H+ + CO2 to form complex organic compounds
- Vents found around tectonic or volcanic activity
Characteristics:
● Ocean water high in H+ + oxidized CO2 + HCO-
● Chimneys formed from CaCO3 around hydrothermal vents = provide microscopic pores
where vent water interacts w/ ocean water
● Vent water hot, low in H+, high in reduced H2, NH3, + CH4
Sources of energy in the environment:
● H+ concentration gradient used to produce ATP by ATP synthase
● Redox rxns
What are organic molecules? What does carbon have to do with them?
- Organic molecules are complex molecules that contain the element carbon bonded with other elements.
□ Substances that do not contain Carbon are inorganic molecules - Carbon is a versatile element that can form bonds with hydrogen, oxygen, nitrogen, or other carbon atoms, to form huge carbon chains.
- Some small C-containing molecules such as CaCO3 (mineral) and CO2 (gas) are inorganic.
Define chemiosmosis
Using the difference in proton (H+) concentration across a membrane to do work
How was the proton gradient within the earliest cells produced?
Earliest cells evolved in the environment of alkaline hydrothermal vents = the gradient generated by geological processes
Water out of vents has a low concentration of H+ (they are alkaline)
Surrounding ocean water has an H+ concentration estimated to be about 1000-fold greater
What are the first cells? What is the process and theory about them?
Honeycombed, microscopic pores of hydrothermal vent chimneys
provide a model for the evolution of early cells.
Earliest cell membranes were an inorganic casing composed of metal sulphides (NiS, FeS)
□ Would trap and concentrate organic molecules and allow complex chemical reactions
□ An environment conducive to an early metabolic process mimicking the reverse citric acid cycle
- the chemiosmotic synthesis of ATP from ADP and Pi is a reaction that is catalyzed by a sophisticated membrane-localized enzyme system ATP synthase that harnesses the energy present in the proton gradient.
Why was the cell membrane essential to the development of life?
Lipids form liposomes (vesicles) spontaneously in (aq) environment, Lipid bilayers (membranes) surrounding an aqueous compartment
Abiotically produced organic molecules trapped by lipid membrane/membrane-like structure would
form cell-like structure
Precursor of cells because
● polar/hydrophilic head + non-polar/hydrophobic tail form in on itself to form the lipid bilayer
● Order - head, tail, tail, head
● Lipid bilayer protects inside of cells (cytoplasm + all organelles) from the external environment
for metabolic reactions to take place
Clay may have played an important role in what aspect of the development of life?
Formation of polymers such as short peptides or nucleic acids
Which statement best describes ribozymes
A. They are composed of RNA*
B. They are able to catalyze reactions faster than enzymes
C. They are found only in ancient cells
D. They are polymers of amino acids
Which statement best describes why DNA is thought to have replaced RNA as the means to store genetic information?
A. The sugar ribose, which is presented in DNA but not RNA is less prone to breakdown.
B. DNA contains uracil, which is more stable than the thymine present in RNA
C. Unlike RNA, DNA can exist in very complex 3-dimensional shapes, which are very stable
D. The pressure of complementary strands in DNA means that mutations in one strand can be readily repaired *
What was The Tree of Life like Fifty Years Ago?
All life was divided into two groups: eukaryotes and prokaryotes
Eukaryotes—animals, plants, fungi
□ Organisms with cells that contain a nucleus and membrane-bound organelles (single-celled or multicellular)
Prokaryotes—bacteria
□ Single-celled organisms of metabolic complexity without a nucleus or membrane-bound organelles
What is the updated The Tree of Life like?
For centuries, organisms had been grouped based primarily on how they looked (morphology).
A more objective approach to building phylogenetic trees was proposed: Use differences in DNA sequences.
□ Need to pick a gene that all organisms have
□ Gene needs to be long in sequence
Carl Woese suggested using ribosomal RNA (rRNA gene) to investigate organismal differences and develop a more accurate tree of life.
* His research team showed that life could be grouped into three domains:
□ Bacteria
□ Archaea
□ Eukarya
What is another key development in the evolution of early life aerobic respiration?
Oxygenation of the atompshere
How did oxygenation of the atmosphere begin?
Atmospheric oxygen began increasing by approximately 2.5 BYA
- Oxygen came from cyanobacteria — evolved able to oxidize water (H2O) instead of H2S or Fe2+ as the source of electrons for photosynthesis
□ O2 produced as a by-product
□ Oxygenic photosynthesis
The explosion of cyanobacterial growth turned the planet green
Common Attributes for all Forms of Cellular Life
- Lipid molecules form a membrane bilayer that defines the cell
- A genetic system based on DNA
- A system of information transfer: DNA to RNA to protein
- A system of protein assembly using messenger RNA and transfer RNA using ribosomes to polymerize the amino acids into peptides
- Reliance on proteins as the major structural and catalytic molecule
- Use of ATP as the molecule of chemical energy
The breakdown of glucose by the metabolic pathway of glycolysis to generate ATP (chemiosmosis, substrate-level phosphorylation)
We have moved recently from a 3-domain tree of life to a 2-domain tree of life. What caused the shift in thinking?
Despite the morphological similarities of the bacteria and archaea, molecular evidence tells us that the eukarya and archaea are more closely related
- 3 domain tree of life - bacteria, archaea, eukarya
● Prokaryotes - bacteria + archaea
● Eukaryotes - eukarya
● however w/ archaea - no nucleus, diff from bacteria, similar to eukarya more than
prokaryotes - Analysis of Asgard DNA (a new group of archaeans) suggests eukarya evolved from within archaea
- Asgard archaeans contain genes previously thought to be present only in eukaryotes (genes for proteins involved in building the cytoskeleton, the process of phagocytosis, and fundamental cellular processes).
- 2 domain tree of life - bacteria, archaea ( most widely accepted in future)
● eukarya branching off from archaea
Early forms of Life?
The earliest forms of life were likely prokaryotes (bacteria and archaea)
□ Earliest fossil evidence: ~3.5 billion years ago
□ Indirect evidence (carbon isotope ratios): ~3.9 BYA
How they obtained carbon (food, energy)
□ Heterotrophs are organisms that obtain carbon from organic molecules (most bacteria)
□ Autotrophs obtain carbon from inorganic forms of carbon (CO2)
- Since the early atmosphere contained very little oxygen, the earliest organisms relied on anaerobic (in absence of oxygen) respiration to
extract energy.
Glycolysis and fermentation
What are bacteria, archaea, eukarya common set of features?
- cells defined by a membrane composed of a bilayer of lipid molecules
- a genetic system based on DNA
- a system of information transfer: DNA to RNA to protein
- ribosomes as the central feature of a protein assembly machinery that uses the information in messenger RNA (mRNA) and transfer RNA (tRNA) to produce peptide chains from a pool of amino acids.
- reliance on proteins as the major structural and catalytic molecule.
- use of ATP as the currency of chemical energy.
common pathways of energy transformation (e.g., glycolysis, substrate-level phosphorylation, chemiosmosis).
Two distinguishing between eukaryotes and prokaryotes?
- the separation of DNA and cytoplasm by a nuclear envelope
- the presence in the cytoplasm of membrane-bound organelles with specialized functions: mitochondria, chloroplasts, the endoplasmic reticulum (ER), and the Golgi complex, among others.
LUCA wasn’t the first form of life to develop, so why is it so important to our understanding of the evolution of life?
LUCA (Last Universal Common Ancestor) - common ancestor from which all present-day organisms descended
- Important to the understanding of the evolution of life b/c proves that LUCA complex in structure + function = possible that life arose many times on early Earth, each form perhaps having only some of the seven attributes listed = similarities across all domains of life present today indicate, however, that only one of these primitive life forms has descendants that survive today
- Lived in absence of CO2 (anaerobic)
- Fixed CO2 into organic molecules (autotrophic)
- Possessed metabolic pathway similar to the reverse Krebs cycle
- Depended on H2 as its source of H+ + e-
- Converted N2 into ammonia (NH3)
- Lived in hot environments
- Biochem depended on FeS complexes
What is the Theory of Endosymbiosis?
- prokaryotic ancestors of modern mitochondria and chloroplasts were engulfed by
larger prokaryotic cells, forming a mutually advantageous relationship called symbiosis. - - Slowly, over time, the host cell and the endosymbionts became inseparable parts of the same single-celled organism. - Chloroplasts were once photosynthetic bacteria
- Vertical gene transfer - a genetic inheritance from one generation to the next w/in species
● Passing on genetic info - Horizontal gene transfer - genetic inheritance b/w unrelated species
● Shaped evolution of eukaryotic cells
What are the major lines of evidence in support of the theory that mitochondria and chloroplasts are descendants of prokaryotic cells?
Morphology (the oldest piece of evidence)
Reproduction
Genetic Information
Transcription and Translation
Electron Transport
DNA sequence analysis
Define Morphology, reproduction and genetic information.
Morphology - shape/size similar to those of prokaryotic cells.
Reproduction - cell cannot synthesize a mitochondrion or chloroplast, new mitochondria +
chloroplasts derived from the division of preexisting organelles
● both divide by binary fission (how prokaryotic cells divide)
Genetic information - both free-living cells = contain their own DNA, which contains both protein-coding and non-coding genes essential for organelle function.
● One gene to one protein
● w/ prokaryotic cells, DNA molecule in most mitochondria and chloroplasts is circular
(plasmids)
● DNA molecules in the nucleus are linear.
Define Transcription and Translation, Electron Transport and DNA sequence analysis
Transcription and translation - Both contain complete transcription and translational machinery
● contain ribosomes and tRNAs that are necessary to translate organelle mRNAs into proteins.
Electron transport - similar to free-living prokaryotic cells, both have e- transport chains and the enzyme ATP synthase = used to generate chemical energy
● ETC’s of bacteria and archaea found associated w/ plasma membrane.
Sequence analysis - Sequencing of the genes encoding RNA component of the ribosome (ribosomal
RNA or rRNA) establishes that these organelles belong on the bacterial branch of the tree of life
● sequence of chloroplast rRNA most closely matches that of cyanobacteria,
● sequence of mitochondrial rRNA is most similar to that of heterotrophic bacteria.
What is the Endomembrane System?
Another characteristic feature of eukaryotic cells
· Collection of internal membranes dividing the cell into structurally and functionally distinct regions
These regions include the nuclear envelope, the endoplasmic reticulum (ER), and the Golgi complex
· All inter-connected via vesicular trafficking pathway
The Earth’s atmosphere contains 21% O2. Where did that oxygen come from?
- The O2 source was cyanobacteria (a group of photosynthetic bacteria)
- photosynthetic organisms used light energy to extract H atoms and e- from compounds s/a H2S.
- H atoms and e- are used to fix CO2 into carbohydrates.
- Instead of using H2S, cyanobacteria developed the ability to oxidize water (b/c more abundant) = cyanobacteria a huge ecological advantage over other photosynthetic organisms that relied on H2S b/c meant they could thrive almost anywhere on the surface of Earth.
● Originally used it but stopped using H2S b/c water was more abundant - photosynthetic oxidation of H2O not only released valuable e-, also released as a by-product
molecular oxygen (O2) - O2 began to accumulate in the atmosphere = aerobic respiration.
What is vertical gene transfer? Horizontal gene transfer?
Vertical gene transfer—a genetic inheritance from one generation to the next within a species → passing on genetics. info
Horizontal gene transfer—genetic inheritance between unrelated species
► Shaped evolution of eukaryotic cells
→ exchange of genet. info b tw (unrelated) species → all the time in bacteria
→ facilitated by viruses in bacteria + other organisms
Process of Horizontal gene transfer?
Some protein-coding genes once located in the chloroplasts or mitochondrial genomes relocated tot he nuclear genome
Following transcription fo these genes, translation occurs in the cytosol before proteins are imported unit the mitochondrion or chloroplast
Solving an Energy Crisis
· Ability of early eukaryotes to generate more energy led to remarkable changes—cells could become larger and more complex → more energy = more possibilities
· Eukaryotes contain several mitochondria, each converting energy into ATP
Solving an Energy Crisis
· Ability of early eukaryotes to generate more energy led to remarkable changes—cells could become larger and more complex → more energy = more possibilities
· Eukaryotes contain several mitochondria, each converting energy into ATP
Evolution of Multicellular Eukaryotes
Multicellular organisms contain cells that are structurally and functionally distinct
Multicellular eukaryotes probably evolved by the differentiation of cells of the same species that congregated into colonies.
Colonies gave rise to the division of labour leading to structural and functional distinction among cells.
Define Multicellularity
Thought to have evolved several times, producing lineages of several algae and ancestors of fungi, plants, and animals.
all cells are structurally and functionally autonomous (independent).
key trait of more advanced multicellular organisms: division of labour. structurally and functionally distinct.
For example, some cells may have specialized in harvesting energy, whereas others developed a role related to the motility of the organism.
What biological materials are the most likely to fossilize?
Fossils mostly form in sedimentary rocks
- Lower the strata of sedimentary = older the fossil
- Most likely to fossilize -
● Skeletons, Shells, Stems, Leaves, Flowers
Why does the fossil record provide an incomplete portrait of life in the past?
- Only represents a small fraction of organisms that once lived on earth
- Only really represents a record of the most successful of organisms:
● those that were very abundant
● had wide distributions
● possessed hard parts that could be fossilized - Soft-bodied organisms with small geographic distributions that lived in environments where erosion was a dominant process are underrepresented in the fossil record
What sorts of information can paleobiologists discern from the fossil record?
allowed scientists to see how species have changed over time through the proliferation and extinction of
evolutionary lineages
provides data on the geographical distribution of extinct species
Stromatolites?
The earliest evidence of life in the fossilized remains of structure (3.5 billion years ago). Layered rock forms when microorganisms bind particles of sediment together, forming thin sheets. Formed by the action of a specific group of Photosynthetic bacteria called cyanobacteria.
What does the fossil record represent?
The fossil record only really represents a record of the most successful of organisms; those that were very abundant had wide distributions and possessed hard parts that could be fossilized.
Soft-bodied organisms with small geographic distributions that lived in erosion-dominant environments are underrepresented in fossils.
Fossilization?
dissolved minerals replace parts molecule by molecule, leaving fossils made of stone.
Which is not one of the seven characteristics:
Uses photosynthesis- not all living things us photosynthesis such as humans (homeostasis is maintaining balance of things in the body)
Which is not a characteristic of life?
Deteriorates
True or false: abiotic synthesis refers to the production of organic compounds in the absence of life?
True ( no oxygen and no living molecules, Urey-miller experiment)
What was not on early earth?
Oxygen
Which is not one of the 4 major types of macromolecules important for life?
DNA (nucleic acid is DNA and RNA)
What type of atmosphere was talked about in the Oparin-Haldane Hypothesis?
Reducing (reducing reactions)
Which was not a key part of the Oparin-Haldane Hypothesis?
Clay (Oparin-Haldane had to do with abiotic synthesis of monomers and clay had to do with polymerization (making chains of biotic molecules)?
Stimulating conditions on the early earth, what compounds did not result from the Miler-Urey Experiment?
Carbohydrates (polymer)
After adding HCN and CH20, what compounds were not formed?
Proteins (polymer)
What substance helps with the polymerization of molecules?
Clay
What is the order of events in the central dogma?
DNA-RNA-Protein (DNA is the blueprint and then transcription in order to get to RNA the translation to get to proteins)
Why is DNA evolutionarily advantageous compared to RNA?
Double stranded, less mutations, more stable
In the “deep sea hypothesis for the origin of life”, ocean water is said to be high in?
H+ (deep-sea hydrothermal vents were and when mixed with ocean water…had alkaline water in them which was high in pH, when interacted with the ocean water and pores opened
Which is not a domain on the tree of life?
Prokaryote (are bacteria and archaea)
What is not a feature of LUCA?
Aerobic (LUCA did not need oxygen, early earth did not need oxygen)?
A plant is a?
Photoautotroph (uses the sun to produce its own energy)
- What organisms were responsible for the oxygenation of the atmosphere?
Cyanobacteria
Did oxygen result from cyanobacteria oxidizing H2S for energy?
False (start using water which is more abundant which created oxygen, evolved to use water because it is more abundant and present)
According to the theory of endosymbiosis, chloroplasts were once?
Photosynthetic bacteria (theory of endosymbiosis is a prokaryote ate a prokaryote that could make energy and they worked together as protection and energy making, small prokaryote either evolved into mitochondria or chloroplasts)
What is no evidence to support the theory of endosymbiosis?
Fossils (morphology- shape and looks of certain things, genetic information- contain their own DNA.
Electron transport chains are present in mitochondria and chloroplasts.
True
