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Questions and Answers
What is the first level of higher-order structure in proteins?
What is the first level of higher-order structure in proteins?
What type of bonds are responsible for forming secondary protein structures such as alpha helices and beta sheets?
What type of bonds are responsible for forming secondary protein structures such as alpha helices and beta sheets?
Which protein structure involves the overall 3D arrangement of a polypeptide chain?
Which protein structure involves the overall 3D arrangement of a polypeptide chain?
What determines a protein's specific structure?
What determines a protein's specific structure?
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What does the quaternary structure of a protein involve?
What does the quaternary structure of a protein involve?
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Which amino acid characteristic primarily defines the chemistry of proteins?
Which amino acid characteristic primarily defines the chemistry of proteins?
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What is the main feature of tertiary protein structure?
What is the main feature of tertiary protein structure?
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What can small differences in bonds between glucose molecules lead to?
What can small differences in bonds between glucose molecules lead to?
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What is the primary role of water in biological systems?
What is the primary role of water in biological systems?
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Which of the following correctly identifies a type of macromolecule that is not a polymer?
Which of the following correctly identifies a type of macromolecule that is not a polymer?
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What is the process called when water is removed to form a polymer?
What is the process called when water is removed to form a polymer?
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Which enzyme specifically catalyzes the polymerization of nucleic acids?
Which enzyme specifically catalyzes the polymerization of nucleic acids?
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Which statement is true regarding hydrolases?
Which statement is true regarding hydrolases?
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When discussing monomers, which of the following statements is accurate?
When discussing monomers, which of the following statements is accurate?
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Which type of molecule is made up of polymers of amino acids?
Which type of molecule is made up of polymers of amino acids?
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What happens to water during depolymerization reactions?
What happens to water during depolymerization reactions?
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What does resolution in microscopy refer to?
What does resolution in microscopy refer to?
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Which type of microscopy uses reflected light?
Which type of microscopy uses reflected light?
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Which statement about magnification and resolution is correct?
Which statement about magnification and resolution is correct?
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Which microscopy technique allows observation of smaller specimens clearly due to higher contrast?
Which microscopy technique allows observation of smaller specimens clearly due to higher contrast?
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What is one of the primary purposes of using differential interference contrast (DIC) microscopy?
What is one of the primary purposes of using differential interference contrast (DIC) microscopy?
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What does the cell theory state regarding the origin of cells?
What does the cell theory state regarding the origin of cells?
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Why do larger cells face challenges related to their size?
Why do larger cells face challenges related to their size?
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Which of the following statements is true about cellular organisms?
Which of the following statements is true about cellular organisms?
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What was one of the first observations of cells using a microscope in the 1600s?
What was one of the first observations of cells using a microscope in the 1600s?
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What structural adaptation might a cell develop if it requires a larger surface area?
What structural adaptation might a cell develop if it requires a larger surface area?
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In the context of cellular size, what does the trade-off refer to?
In the context of cellular size, what does the trade-off refer to?
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Which types of cells are typically larger than typical mammalian somatic cells?
Which types of cells are typically larger than typical mammalian somatic cells?
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What role does microscopy play in biology?
What role does microscopy play in biology?
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Study Notes
Molecules of Life
- Water is the solvent of life
- Water dissolves more molecules than any other solvent
- Water is a polar molecule (opposite charges on either end)
- Water dissolves other polar molecules
- Water dissolves charged molecules
Macromolecules
- Carbohydrates are polymers of sugars
- Lipids are not polymers
- Proteins are polymers of amino acids
- Nucleic acids are polymers of nucleotides
Polymers
- Chains composed of molecules called monomers
- Polymerize and depolymerize
- Polymerization/depolymerization reactions involve addition or loss of water.
- Dehydration synthesis (polymerization)
- Hydrolysis (depolymerization)
- Addition or loss of water happens at the bonds between monomers
- Enzymes catalyze the synthesis/hydrolysis of polymers
- Polymerases
- Hydrolases
- Nice trick: -ase = enzyme
Enzyme example: DNA Polymerization
- DNA Polymerase catalyzes the polymerization of DNA (a nucleic acid)
Biopolymers
- Most biopolymers are not just simple chains of monomers
- The chains usually twist and fold forming varied levels of higher-order structure
- Examples: DNA double helix, Protein folding
Higher-order Polymer Structure Example: Proteins
- 1° structure: amino acid chain
- 2° structure: ex) a-helix, β-sheet
- 3° structure: folding
- 4° structure: assembling with other proteins into a complex
Amino Acids
- Contain Nitrogen, mildly acidic
- R = sidechain
- Sidechain properties define the chemistry of proteins
Primary Protein Structure
- Amino acids are linked by covalent bonds called peptide bonds
- Proteins also known as polypeptides
Amino Acid Structure and Properties
- Earthlings use 20 different AA's
Secondary Protein Structure
- Hydrogen bonds between nearby amino acids cause the polypeptide to twist (alpha helix) or form sheets (beta sheets)
Tertiary Protein Structure
- Chemistry between sidechains causes higher-order folding
Quaternary Protein Structure
- Individual proteins interact to form complexes
- Again, determined by their structure and chemistry
Fun Fact: Chains of Glucose
- Small differences in glucose bonds create huge differences in the properties of these carbohydrates and their structure
- Cellulose, Starch, Glycogen
- All are chains of glucose
- Different bonds result in varying structures and shapes
Cell Theory
- All organisms are composed of one or more cells.
- The cell is the basic structural and functional unit of all living organisms.
- Cells arise only from the division of pre-existing cells.
First Observations of Cells using Microscopes
- Robert Hooke looked at cork cells
- Anton van Leeuwenhoek made a better microscope, and saw "many very little animacules, very prettily a-moving"
Cellular Scales
- Cells are generally pretty small
- Examples of cellular sizes are given for reference
Cell Size Scales and Visibility
- Unaided human eye
- Light microscope
- Electron microscope
Why Cells Tend to Be Small
- Surface area must be sufficient to allow exchange of stuff between the cell and its surroundings
- Larger volumes require more surface area to achieve this
- Larger volumes need more structural support
Trade-off Between Cell Surface Area and Volume
- The problem is that as volume increases, the surface area does not increase proportionately.
But what if the cell really requires a large surface area?
- Develop convoluted / branchy surface morphologies
What if the cell needs a large volume?
- Using cell walls (e.g., xylem vessels from wood)
Microscopy
- Resolution, magnification, and contrast
- Resolution- The ability of a microscope to distinguish two objects as being separate
- Higher magnification increases resolution
- Higher contrast gives more detail, but can't increase resolution
- Microscopy types: Light Microscopy (reflected light, transmitted light, and fluorescence), Electron Microscopy (transmission, and scanning)
Microscopy Types
- Brightfield, Darkfield, Phase-Contrast, Differential Interference Contrast (DIC)
- Contrast-enhancing methods
- Exploiting properties of the specimens
- Variations in specimen thickness and density
- Methods influence how light passes through
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Description
This quiz covers essential concepts related to the molecules of life, including the role of water as a solvent, the structure of macromolecules such as carbohydrates, lipids, proteins, and nucleic acids, and the processes of polymerization and hydrolysis. Test your understanding of these fundamental biological concepts.
