Chapter 1 Flashcards

Question

Which polymers are not made up from simpler building blocks and all are made within cells by complex metabolic pathways

Answer 1

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

Answer 2

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

Answer 3

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)

Answer 4

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

Answer 5

Proved that early earth could produce biologically important molecules can be synthesized outside living cells but cannot produce polymers (nucleic acids, proteins, lipids, carbs)

Answer 6

Proteins and nucleic acids

Answer 7

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.

Answer 8

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

Answer 9

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

Answer 10

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

Answer 11

The near absence of O2

Answer 12

The synthesis of complex biological molecules is possible in a reducing atmosphere.

Answer 13

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

Answer 14

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)

Answer 15

Messenger RNA - Ribioenzyme-mediated cut (cleaved part is important in cells such as during transcription) - cut (cleaved) messenger

Answer 16

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

Answer 17

1. Catalytic power of enzymes is greater than a ribozyme(catalyze the same reaction using a poll of substrate molecules thousands of times a second) 2. 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. 3. Amino acids can interact chemically with each other in more complex and varied bonding arrangements which are not possible between nucleotides.

Answer 18

- 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.

Answer 19

- 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.

Answer 20

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

Answer 21

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)

Answer 22

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.

Answer 23

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

Answer 24

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

Answer 25

* 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.

Answer 26

Using the difference in proton (H+) concentration across a membrane to do work

Answer 27

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

Answer 28

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.

Answer 29

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

Answer 30

Formation of polymers such as short peptides or nucleic acids

Answer 31

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

Answer 32

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 *

Answer 33

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

Answer 34

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

Answer 35

Oxygenation of the atompshere

Answer 36

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

Answer 37

1. Lipid molecules form a membrane bilayer that defines the cell 2. A genetic system based on DNA 3. A system of information transfer: DNA to RNA to protein 4. A system of protein assembly using messenger RNA and transfer RNA using ribosomes to polymerize the amino acids into peptides 5. Reliance on proteins as the major structural and catalytic molecule 6. 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)

Answer 38

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

Answer 39

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

Answer 40

1. cells defined by a membrane composed of a bilayer of lipid molecules 2. a genetic system based on DNA 3. a system of information transfer: DNA to RNA to protein 4. 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. 5. reliance on proteins as the major structural and catalytic molecule. 6. use of ATP as the currency of chemical energy. common pathways of energy transformation (e.g., glycolysis, substrate-level phosphorylation, chemiosmosis).

Answer 41

1. the separation of DNA and cytoplasm by a nuclear envelope 2. the presence in the cytoplasm of membrane-bound organelles with specialized functions: mitochondria, chloroplasts, the endoplasmic reticulum (ER), and the Golgi complex, among others.

Answer 42

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

Answer 43

- 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

Answer 44

Morphology (the oldest piece of evidence) Reproduction Genetic Information Transcription and Translation Electron Transport DNA sequence analysis

Answer 45

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.

Answer 46

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.

Answer 47

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

Answer 48

- 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.

Answer 49

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

Answer 50

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

Answer 51

· 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

Answer 52

· 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

Answer 53

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.

Answer 54

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.

Answer 55

Fossils mostly form in sedimentary rocks - Lower the strata of sedimentary = older the fossil - Most likely to fossilize - ● Skeletons, Shells, Stems, Leaves, Flowers

Answer 56

- 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

Answer 57

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

Answer 58

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.

Answer 59

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.

Answer 60

dissolved minerals replace parts molecule by molecule, leaving fossils made of stone.

Answer 61

Uses photosynthesis- not all living things us photosynthesis such as humans (homeostasis is maintaining balance of things in the body)

Answer 62

Deteriorates

Answer 63

True ( no oxygen and no living molecules, Urey-miller experiment)

Answer 64

DNA (nucleic acid is DNA and RNA)

Answer 65

Reducing (reducing reactions)

Answer 66

Clay (Oparin-Haldane had to do with abiotic synthesis of monomers and clay had to do with polymerization (making chains of biotic molecules)?

Answer 67

Carbohydrates (polymer)

Answer 68

Proteins (polymer)

Answer 69

DNA-RNA-Protein (DNA is the blueprint and then transcription in order to get to RNA the translation to get to proteins)

Answer 70

Double stranded, less mutations, more stable

Answer 71

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

Answer 72

Prokaryote (are bacteria and archaea)

Answer 73

Aerobic (LUCA did not need oxygen, early earth did not need oxygen)?

Answer 74

Photoautotroph (uses the sun to produce its own energy)

Answer 75

Cyanobacteria

Answer 76

False (start using water which is more abundant which created oxygen, evolved to use water because it is more abundant and present)

Answer 77

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)

Answer 78

Fossils (morphology- shape and looks of certain things, genetic information- contain their own DNA.