Biology: Molecules of Life and Polymers
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Questions and Answers

What is the first level of higher-order structure in proteins?

  • Primary structure (correct)
  • Quaternary structure
  • Tertiary structure
  • Secondary structure

What type of bonds are responsible for forming secondary protein structures such as alpha helices and beta sheets?

  • Ionic bonds
  • Hydrogen bonds (correct)
  • Disulfide bridges
  • Peptide bonds

Which protein structure involves the overall 3D arrangement of a polypeptide chain?

  • Tertiary structure (correct)
  • Secondary structure
  • Quaternary structure
  • Primary structure

What determines a protein's specific structure?

<p>Properties and order of the amino acids (A)</p> Signup and view all the answers

What does the quaternary structure of a protein involve?

<p>Interaction between multiple polypeptide chains (C)</p> Signup and view all the answers

Which amino acid characteristic primarily defines the chemistry of proteins?

<p>The properties of the side chains (A)</p> Signup and view all the answers

What is the main feature of tertiary protein structure?

<p>Interaction and folding governed by sidechain chemistry (C)</p> Signup and view all the answers

What can small differences in bonds between glucose molecules lead to?

<p>Diverse carbohydrate properties (A)</p> Signup and view all the answers

What is the primary role of water in biological systems?

<p>It acts as the solvent of life, dissolving more substances than any other solvent. (B)</p> Signup and view all the answers

Which of the following correctly identifies a type of macromolecule that is not a polymer?

<p>Lipids (D)</p> Signup and view all the answers

What is the process called when water is removed to form a polymer?

<p>Dehydration synthesis (C)</p> Signup and view all the answers

Which enzyme specifically catalyzes the polymerization of nucleic acids?

<p>DNA polymerase (C)</p> Signup and view all the answers

Which statement is true regarding hydrolases?

<p>They hydrolyze polymers into monomers. (D)</p> Signup and view all the answers

When discussing monomers, which of the following statements is accurate?

<p>Monomers are the building blocks that combine to form polymers. (C)</p> Signup and view all the answers

Which type of molecule is made up of polymers of amino acids?

<p>Proteins (D)</p> Signup and view all the answers

What happens to water during depolymerization reactions?

<p>Water is consumed. (B)</p> Signup and view all the answers

What does resolution in microscopy refer to?

<p>The ability to distinguish two objects as being separate (C)</p> Signup and view all the answers

Which type of microscopy uses reflected light?

<p>Stereomicroscope (D)</p> Signup and view all the answers

Which statement about magnification and resolution is correct?

<p>Higher magnification can increase resolution. (C)</p> Signup and view all the answers

Which microscopy technique allows observation of smaller specimens clearly due to higher contrast?

<p>Darkfield microscopy (C)</p> Signup and view all the answers

What is one of the primary purposes of using differential interference contrast (DIC) microscopy?

<p>To enhance contrast in unstained, transparent specimens (A)</p> Signup and view all the answers

What does the cell theory state regarding the origin of cells?

<p>Cells arise only from the division of pre-existing cells. (C)</p> Signup and view all the answers

Why do larger cells face challenges related to their size?

<p>Larger volumes need more surface area for exchange. (D)</p> Signup and view all the answers

Which of the following statements is true about cellular organisms?

<p>All organisms are composed of one or more cells. (B)</p> Signup and view all the answers

What was one of the first observations of cells using a microscope in the 1600s?

<p>Robert Hooke viewed cork cells. (B)</p> Signup and view all the answers

What structural adaptation might a cell develop if it requires a larger surface area?

<p>Formation of microvilli. (C)</p> Signup and view all the answers

In the context of cellular size, what does the trade-off refer to?

<p>Surface area increases at a slower rate than volume. (D)</p> Signup and view all the answers

Which types of cells are typically larger than typical mammalian somatic cells?

<p>Human egg cells. (B)</p> Signup and view all the answers

What role does microscopy play in biology?

<p>They allow for the observation of very small organisms. (C)</p> Signup and view all the answers

Flashcards

Water's role in life

Water is the primary solvent in living organisms. It dissolves more substances than any other solvent due to its polar nature.

What are macromolecules?

Macromolecules are large, complex molecules essential for life. They are composed of smaller building blocks known as monomers.

What are carbohydrates?

Carbohydrates are polymers made up of sugar monomers. They serve as energy sources and structural components in cells.

What are lipids?

Lipids, including fats and oils, are not polymers. They are hydrophobic and serve as energy stores, insulation, and structural components.

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What are proteins?

Proteins are polymers composed of amino acid monomers. They have diverse functions, including enzymes, structural components, and signaling molecules.

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What are nucleic acids?

Nucleic acids are polymers of nucleotides. They carry genetic information (DNA) and facilitate protein synthesis (RNA).

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What is polymerization?

Polymerization is the process of joining monomers to form polymers. Dehydration synthesis is the specific reaction where water is removed.

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What is depolymerization?

Depolymerization is the process of breaking down polymers into monomers. Hydrolysis is the specific reaction where water is added.

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Primary protein structure

The sequence of amino acids in a polypeptide chain.

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Secondary protein structure

The folding patterns of the polypeptide chain, such as alpha-helices and beta-sheets, formed by hydrogen bonds.

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Tertiary protein structure

The three-dimensional shape of a single polypeptide chain, arising from interactions between side chains.

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Quaternary protein structure

The arrangement of multiple polypeptide chains into a functional protein complex, involving interactions between the individual proteins.

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What determines a protein's structure?

The specific order and properties of amino acids in a protein determine its structure.

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Amino acid side chains

The side chains (R groups) of amino acids vary in their chemical properties, influencing the overall characteristics of proteins.

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Peptide bonds

The covalent bonds that link amino acids together to form polypeptides.

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Glucose chain structures

Different arrangements of glucose monomers in chains can lead to distinct properties of carbohydrates.

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Resolution

The ability of a microscope to distinguish two objects as being separate.

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Magnification and resolution

Increasing the magnification of a microscope often improves its ability to distinguish two objects as separate. But, magnification alone doesn't guarantee better resolution.

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Contrast

The ability of a microscope to make objects stand out against the background. It can enhance detail, but doesn't improve resolution.

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Reflected light microscopy

A type of light microscope that uses light reflected off the surface of an object to create an image.

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Transmitted light microscopy

A type of light microscope that uses light transmitted through an object to create an image.

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Cell Theory

The theory that all living organisms are composed of one or more cells, the cell is the fundamental unit of structure and function in all living organisms, and all cells arise from pre-existing cells.

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Cell Size

Cells are generally very small, typically measuring in micrometers (µm).

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Surface Area to Volume Ratio

The ratio of surface area to volume is crucial for cell function. As a cell grows, its volume increases faster than its surface area, making it harder for the cell to exchange materials with its surroundings.

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Surface Area Adaptations

Cells can develop convoluted or branched surface morphologies, such as microvilli, to increase their surface area and efficiently exchange materials with their surroundings.

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Large Volume Adaptation

Cells that require a large volume, like cells with multiple nuclei, often develop unique characteristics such as branching structures or multiple nuclei.

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Microscopes and Cell Discovery

The discovery of cells was made possible by the invention and improvement of microscopes.

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Early Microscope Observations

Robert Hooke observed cork cells using a microscope in the 1600s, and Anton van Leeuwenhoek improved the microscope and observed microscopic organisms.

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Types of Microscopes

Light microscopes use visible light to illuminate and magnify specimens, while electron microscopes use electrons to produce higher-resolution images of cells and their structures.

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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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Lecture 2 - Macromolecules, Cell Theory, Microscopy PDF

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.

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