Questions and Answers
Describe the relationship between a living organism and its surroundings in terms of both matter and energy.
Living organisms are open systems and exchange both matter and energy with their surroundings.
How do cells accomplish the formation of a protein from individual amino acids despite it being an endergonic reaction?
The endergonic reaction is coupled to an exergonic reaction through a shared intermediate.
Explain how instant cold packs can get cold when the contents are mixed.
The dissolution reaction is spontaneous with a negative ΔG and absorbs heat, thus ΔH is positive.
What is meant by feedback inhibition and why is it important?
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How is genetic information encoded in DNA and synthesized?
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Explain the balance between stability and change in hereditary transmission of genetic information.
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Discuss how a mutation in DNA could be harmful or beneficial to an organism.
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Describe Stanley Miller's experiment (1953) and its relevance.
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What is the 'RNA world' hypothesis?
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How did the rise of O2-producing bacteria influence aerobic organisms?
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What is meant by endosymbiotic association?
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Which is a list of organelles?
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The catalog of all proteins functioning in a cell is the:
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Identify the correct statement: Carnivores are ___ and herbivores are ___.
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When two genes in an organism share detectable sequence similarity, they are said to be:
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What is the difference between cytosol and cytoplasm?
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Explain why macromolecules diffuse slower in cytosol compared to dilute solutions.
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Describe the functions of proteins, nucleic acids, polysaccharides, and lipids.
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Why is an asymmetric carbon atom called a chiral center?
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Differentiate between configuration and conformation.
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What is optical activity?
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Why is it important for a chemist to separate enantiomers of a racemic mixture?
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Explain why living organisms can produce specific chiral forms of biomolecules compared to laboratory synthesis.
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Why don't protein molecules in a living cell lead to cell destruction?
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What is meant by feedback inhibition and why is it important in a living organism?
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How is the genetic information encoded in DNA and how is a new copy of DNA synthesized?
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Explain how hereditary transmission of genetic information reflects a balance between stability and change.
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How could a mutation in DNA be harmful or beneficial to an organism?
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Describe Stanley Miller's experiment (1953) and its relevance.
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Describe the 'RNA world' hypothesis.
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How might the rise of O2-producing bacteria have led to the predominance of aerobic organisms?
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What is meant by endosymbiotic association?
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In which reaction does water not participate as a reactant?
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When mixing sodium hydroxide with an acetate buffer at pH 4.76, what happens?
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What does the Henderson-Hasselbalch equation relate?
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Where is DNA located in a bacterial cell?
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What was a major change occurring in the evolution of eukaryotes from prokaryotes?
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What encloses the nucleus in eukaryotes?
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What is the range of lengths and diameters of living cells?
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Which group of single-celled microorganisms has many members found growing in extreme environments?
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The bacterium E. coli requires simple organic molecules for growth and energy. What is this characteristic?
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Which of the following has components arranged in order of increasing size?
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Which of the following is not considered a noncovalent interaction?
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Which of the following is not among the four most abundant elements in living organisms?
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What geometry do the four covalent bonds in methane (CH4) form?
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What functional groups are present on a specific molecule?
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The macromolecules that serve in the storage and transmission of genetic information are:
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Stereoisomers that are nonsuperimposable mirror images of each other are known as:
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In a bacterial cell, the DNA is in the:
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A major change occurring in the evolution of eukaryotes from prokaryotes was the development of:
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In eukaryotes, the nucleus is enclosed by a double membrane called the:
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Except for highly elongated cells, living cells usually have lengths and diameters in the range of:
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Which group of single-celled micro-organisms has many members found growing in extreme environments?
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The bacterium E. coli requires simple organic molecules for growth and energy—it is therefore a:
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Which one of the following has the cellular components arranged in order of increasing size?
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Which one of the following is not considered a noncovalent interaction?
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Which one of the following is not among the four most abundant elements in living organisms?
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The four covalent bonds in methane (CH4) are arranged around carbon to give which one of the following geometries?
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What functional groups are present on this molecule?
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The macromolecules that serve in the storage and transmission of genetic information are:
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Stereoisomers that are nonsuperimposable mirror images of each other are known as:
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The enzyme fumarase catalyzes the reversible hydration of fumaric acid to l-malate, but it will not catalyze the hydration of maleic acid. This is an example of:
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Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it. This is an example of a(n):
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If heat energy is absorbed by the system during a chemical reaction, the reaction is said to be:
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If the free energy change ΔG for a reaction is -46.11 kJ/mol, the reaction is:
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The major carrier of chemical energy in all cells is:
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Enzymes are biological catalysts that enhance the rate of a reaction by:
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Energy-requiring metabolic pathways that yield complex molecules from simpler precursors are:
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Hereditary information (with the exception of some viruses) is preserved in:
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When a region of DNA must be repaired by removing and replacing some of the nucleotides, what ensures that the new nucleotides are in the correct sequence?
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The three-dimensional structure of a protein is determined primarily by:
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According to Oparin's theory for the origin of life, the prebiotic atmosphere:
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What six characteristics distinguish living organisms from inanimate objects?
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What is the function of the plasma membrane?
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How is E. coli determined to be a gram-negative bacterial species?
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How do gram-negative bacteria differ structurally from gram-positive bacteria?
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What is the function of the cell wall in higher plants?
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List the types of noncovalent interactions important for macromolecule stability.
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Why is it important that noncovalent interactions are weak?
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What is the underlying biochemical principle that accounts for similarity in living organisms?
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How are living organisms able to produce particular chiral forms of biomolecules?
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Why doesn't the number of protein molecules become too great in a living cell?
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Study Notes
Structure of Bacterial Cells
- Bacterial DNA resides in the nucleoid.
- Eukaryotes evolved from prokaryotes primarily through the development of the nucleus.
Eukaryotic Cell Structure
- The nucleus is surrounded by a nuclear envelope, a double membrane.
Size and Dimensions of Cells
- Living cells typically measure between 0.3 um to 100 um, influenced by biomolecule functions and diffusion rates.
Micro-organisms and Environments
- Archaea thrive in extreme conditions, distinct from typical bacteria.
Nutritional Classification
- E.coli is classified as a chemoheterotroph, relying on organic molecules for energy.
Cellular Component Sizes
- The increasing size order of cellular components: Amino acid < protein < ribosome < mitochondrion.
Noncovalent Interactions
- Key noncovalent interactions maintaining macromolecule structure include hydrogen bonds, ionic interactions, van der Waals interactions, and hydrophobic interactions.
- Carbon-carbon bonds are not noncovalent.
Abundant Elements in Organisms
- Four most abundant elements in living organisms: Carbon, Hydrogen, Nitrogen, and Oxygen.
- Phosphorus is notable but less abundant.
Molecular Geometry
- The geometry around carbon in methane (CH4) is tetrahedral.
Macromolecules
- Nucleic acids store and transmit genetic information.
- Proteins perform diverse functions including catalysis, structure, and signaling.
Optical Activity
- Chiral centers refer to asymmetric carbon atoms that cannot be superimposed on their mirror images, leading to stereoisomers.
Enantiomers and Biological Activity
- Stereoisomers can have different biological effects; thus, separating enantiomers is crucial for therapeutic efficacy.
Chiral Synthesis
- Living organisms produce chiral biomolecules due to the nature of enzymes as chiral catalysts.
Dynamic Steady State
- Cells maintain a dynamic steady state through ongoing synthesis and degradation of proteins.
Energy and Matter Exchange
- Living organisms are open systems, continually exchanging matter and energy with their environment.
Coupling Reactions
- Endergonic reactions can be driven by coupling to exergonic reactions via shared intermediates, yielding an overall exergonic process.
Spontaneous Dissolution and Energy
- The formation of cold packs demonstrates a spontaneous reaction where heat is absorbed (endothermic) despite negative free-energy change, explained by significant entropy change during dissolution.
Enzymatic Reactions
- Enzymes enhance reaction rates by lowering the activation energy, facilitating biological processes efficiently.
Biological Complexity
- Living organisms show chemical complexity and organizational structure that distinguish them from non-living entities, enabling self-replication and evolution over generations.### Reaction Energetics
- An exergonic reaction releases energy, characterized by a negative change in free energy (ΔG).
- The presence of an enzyme can lower the activation energy, promoting a more efficient reaction pathway.
Feedback Inhibition
- Feedback inhibition regulates biochemical pathways by using the end product to inhibit earlier steps.
- This mechanism prevents unnecessary energy and resource expenditure in organisms.
Genetic Information and DNA Synthesis
- Genetic information is stored in the linear order of four deoxyribonucleotides in DNA.
- DNA replication involves unwinding the double helix, where each strand acts as a template for synthesizing a new strand.
Stability and Change in Hereditary Transmission
- DNA replication is highly accurate, maintaining stability in genetic information crucial for species characteristics.
- Mutations, though infrequent, generate genetic diversity, enabling species adaptation over generations.
Impact of DNA Mutations
- Mutations can be detrimental, resulting in nonfunctional proteins or enzymes critical for survival.
- Conversely, some mutations create advantageous traits, enhancing function or stability in specific environments.
Stanley Miller's Experiment
- Miller's 1953 experiment simulated early Earth conditions, generating organic compounds, including amino acids.
- Findings supported the hypothesis of abiotic synthesis of biomolecules in specific environments.
RNA World Hypothesis
- RNA molecules likely functioned as both genetic material and catalysts in early life forms.
- Over time, some RNA replicated and gave rise to DNA, which became the primary genetic storage.
Evolution of Aerobic Organisms
- The emergence of O2-producing bacteria enhanced atmospheric oxygen levels, favoring aerobic organisms.
- Aerobic organisms utilize oxygen as an electron acceptor, improving survival compared to anaerobic counterparts.
Endosymbiotic Association
- Endosymbiosis describes the mutualistic relationships between primitive eukaryotic cells and engulfed bacteria.
- This association led to the development of mitochondria and chloroplasts, enabling aerobic metabolism and photosynthesis in eukaryotic cells.
Organelles and Cell Functions
- Common organelles include mitochondria, endoplasmic reticulum, and peroxisomes, essential for cellular processes.
- The proteome encompasses all proteins within a cell, while a proteasome functions to degrade unneeded proteins.
Distinct Types of Organisms
- Chemoheterotrophs (carnivores and herbivores) obtain energy from organic sources.
- Non-covalent interactions such as hydrogen bonds and van der Waals interactions stabilize macromolecular structures.
Cytosol vs. Cytoplasm
- Cytoplasm is the entire internal volume of a cell, while cytosol is the aqueous component.
- Macromolecule diffusion in cytosol is slower due to crowded, gel-like conditions caused by macromolecular interactions.
Chiral Centers and Optical Activity
- Asymmetric carbon atoms, or chiral centers, can lead to stereoisomers that are non-superimposable.
- Optical activity is the ability of substances to rotate plane-polarized light, significant in the study of biomolecules.
Dynamic Steady State in Cells
- Cells continuously synthesize and degrade proteins, maintaining a balance to prevent overaccumulation.
- Living organisms maintain a dynamic interaction with their environment, exchanging energy and matter to sustain life.
Coupling of Reactions
- Cells can drive endergonic processes by coupling them with exergonic reactions, creating an overall negative free-energy change.
- This principle illustrates the efficiency of cellular energy management through shared intermediates.### Endosymbiotic Association
- Endosymbiotic association involves the envelopment of one organism by another, creating a mutually beneficial relationship.
- Primitive eukaryotic cells likely formed associations with photosynthetic and aerobic bacteria.
- Aerobic bacteria evolved into mitochondria, while photosynthetic bacteria became chloroplasts in modern eukaryotic cells.
Biochemical Reactions
- In the reaction to produce gaseous carbon dioxide from bicarbonate, water does not act as a reactant.
- An acetate buffer at pH 4.76 maintains its pH when mixed with sodium hydroxide, but the ratio of acetic acid to sodium acetate decreases.
- The Henderson-Hasselbalch equation connects pH to pKa and the concentrations of acid and conjugate base.
Cellular Components and Structures
- Bacterial DNA is located in the nucleoid.
- A key evolutionary advancement from prokaryotes to eukaryotes was the development of the nucleus.
- The nucleus in eukaryotes is encased by a nuclear envelope, a double membrane structure.
Cell Dimensions and Microbial Groups
- Living cells typically have dimensions ranging from 0.3 µm to 100 µm, determined by minimum biomolecules for function and diffusion rates.
- Archaea, a group of single-celled microorganisms, thrive in extreme environments.
Energy and Growth Requirements
- E. coli is classified as a chemoheterotroph, requiring simple organic molecules for energy and growth.
Cellular Organization
- The hierarchy of cellular components in order of increasing size is amino acid < protein < ribosome < mitochondrion.
- Carbon-carbon bonds are not considered noncovalent interactions; other interactions include hydrogen bonds, hydrophobic interactions, ionic interactions, and van der Waals interactions.
Abundant Elements and Molecular Geometries
- The four most abundant elements in living organisms are carbon, hydrogen, nitrogen, and oxygen; phosphorus is not among them.
- Methane (CH4) exhibits a tetrahedral geometry due to its four covalent bonds around carbon.
Functional Groups and Genetic Information
- The molecule in the query contains hydroxyl and aldehyde functional groups.
- Nucleic acids are the macromolecules responsible for the storage and transmission of genetic information.
Stereoisomers
- Stereoisomers that are nonsuperimposable mirror images are categorized as enantiomers.
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Test your knowledge on the foundational concepts of biochemistry with these flashcards from Chapter 1. Explore key differences between prokaryotes and eukaryotes and other essential terms in the field. Perfect for students seeking to reinforce their understanding of biological molecules.