Covalent Bonding in Biomolecules

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Questions and Answers

Which of the following is NOT listed as a metal important in catalyzing the chemistry of the cell?

  • Molybdenum (Mo)
  • Calcium (Ca) (correct)
  • Iron (Fe)
  • Manganese (Mn)

Which metal, when present in cells, is essential for catalyzing biochemical reactions?

  • Sodium (Na)
  • Potassium (K)
  • Cobalt (Co) (correct)
  • Magnesium (Mg)

If a cellular process requires a metal catalyst, which of the following would be a possible candidate?

  • Selenium (Se)
  • Iodine (I)
  • Phosphorus (P)
  • Copper (Cu) (correct)

Which of these elements is specifically mentioned as having a catalytic role in cellular biochemistry?

<p>Nickel (Ni) (B)</p> Signup and view all the answers

Which of the following metals is involved in facilitating chemical reactions within cells?

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

Which of the following best describes the linkage formed when phosphoric acid reacts with two different hydroxyl groups?

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

What type of bond is formed when the carboxyl group of one amino acid reacts with the amino group of another amino acid?

<p>Peptide bond (C)</p> Signup and view all the answers

Which of the following best describes the bond formed between two sugar molecules?

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

What is the key structural feature of cystine that enables it to form disulfide bonds?

<p>Thiol group (A)</p> Signup and view all the answers

How many shared electron pairs are involved in a single covalent bond formed by a carbon atom?

<p>One (B)</p> Signup and view all the answers

Which of the following elements is NOT considered one of the six core elements primarily involved in biochemical reactions?

<p>Sodium (A)</p> Signup and view all the answers

A carbon atom that is double bonded will exhibit which geometry?

<p>Trigonal planar (C)</p> Signup and view all the answers

Which type of bond allows for free rotation, influencing a molecule’s structural conformation?

<p>Single bonds (B)</p> Signup and view all the answers

What is the relationship between isomers formed by molecules with double bonds?

<p>They are not identical and do not interconvert. (A)</p> Signup and view all the answers

Functional groups, which confer specific chemical properties to a molecule, include combinations of what atoms?

<p>At least one or a combination of O, N, S, or P (B)</p> Signup and view all the answers

Which of the following best describes a carboxyl group and its deprotonated form?

<p>Acidic, then negatively charged carboxylate (B)</p> Signup and view all the answers

What is the charge of a deprotonated phosphate group in biological conditions?

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

Which reaction results in an ester?

<p>Carboxyl group + hydroxyl group (D)</p> Signup and view all the answers

A carbon atom with four single bonds will adopt which geometry?

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

Which type of bond is capable of rotation, allowing for variable bond angles?

<p>Single bond (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a functional group?

<p>It consists only of carbon and hydrogen atoms (C)</p> Signup and view all the answers

A carbon atom in a molecule with a triple bond or two double bonds as well as 2 bonding groups (no lone pairs) would adopt which geometry?

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

Which of the following functional groups contains a sulfur atom?

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

Flashcards

Metals in Cell Chemistry

Certain metal elements play crucial roles in speeding up chemical reactions within living cells.

Examples of Metals in Biological Reactions

Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), and Molybdenum (Mo) are all examples of metals involved in biological reactions.

Importance of Metals in Cellular Processes

The presence of these metals allows cells to efficiently carry out essential chemical processes, such as energy production and building molecules.

Metals in Enzymes

These metals are incorporated into enzymes, which are proteins that act as biological catalysts, speeding up chemical reactions.

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Metal Specificity in Enzymes

The specific metal required varies depending on the chemical reaction and the enzyme involved.

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Biologically Important Elements

The elements that form the foundation for complex molecules in biology, featuring key characteristics like ability to form multiple bonds and diverse structures.

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Carbon Bonding

Carbon atoms are versatile and bond in different ways, influencing the shape of molecules, which in turn determines function.

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Functional Groups

Groups of atoms attached to a hydrocarbon chain that give a molecule its unique chemical characteristics, allowing it to participate in specific reactions.

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Ester

A group that forms when a hydroxyl group (-OH) reacts with a carboxyl group (-COOH). It's a crucial linkage in biomolecules such as fats and lipids.

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Hydrogen Bonding

An atom that can form a maximum of one covalent bond.

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Oxygen Bonding

An atom that can form a maximum of two covalent bonds.

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Nitrogen Bonding

An atom that can form a maximum of three covalent bonds.

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Carbon Bonding

An atom that can form a maximum of four covalent bonds.

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Ether Bond

A chemical bond formed when two hydroxyl groups (OH) are joined through a condensation reaction, eliminating a water molecule.

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Glycosidic Bond

A specific type of ether bond formed between sugar molecules. The C1 carbon of glucose, in its hemiacetal form, participates in this bond.

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Acid Anhydride

A molecule with two carboxylic acid groups linked together by a shared oxygen atom.

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Phospho-Anhydride

A type of anhydride formed with a phosphate group. These are highly important in biochemistry, with ATP being a prime example.

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Peptide Bond

The bond formed when the amino group of one amino acid and the carboxyl group of another amino acid join together, releasing a water molecule.

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Molecular geometry

The shape formed by the bonds around a central atom, such as carbon. Examples include tetrahedral (109°), trigonal planar (120°), and linear (180°).

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Bond Rotation

A single bond can rotate, allowing for flexible bond angles. A double bond is rigid and has fixed bond angles.

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Disulfide Bond

A covalent bond formed between two sulfur atoms (-S-S-). Found in proteins and contributes to their structure.

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Phosphate Ester

A covalent bond formed between a phosphate group and a hydroxyl group. Found in many important biological molecules, including DNA and ATP.

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Study Notes

Covalent Bonding in Biomolecules

  • Some metals (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo) are vital for catalyzing cell chemistry.
  • Other elements, like iodine (I), selenium (Se), silicon (Si), fluorine (F), and boron (B), have specific roles, often in hormones or ionic balance.
  • Sodium (Na), chlorine (Cl), and potassium (K) are crucial for the ionic balance and nerve signals.
  • Six elements (H, N, C, O, P, S) form most complex biomolecules.
  • Covalent bonds form when atoms share electron pairs.
  • Covalent bonds are strong, have defined lengths, and have defined directions.
  • Hydrogen (H) forms 1 bond.
  • Oxygen (O) forms 2 bonds.
  • Nitrogen (N) forms 3 bonds.
  • Carbon (C) forms 4 bonds.
  • Sulfur (S) forms 2 bonds.
  • Phosphorus (P) forms 5 bonds.

Geometry of Carbon Bonds

  • Single-bonded carbon atoms have a tetrahedral arrangement (109.5°).
  • Double-bonded carbon atoms have a trigonal planar arrangement (120°).
  • Bonds in the plane of the page are shown as regular lines.
  • Bonds coming towards the viewer are shown as solid wedges.
  • Bonds behind the plane are shown as dashed wedges.

Functional Groups

  • Hydrocarbons alone don't typically react.
  • Functional groups are attachments to hydrocarbon chains that change their properties.
  • Common functional groups include: oxygen, nitrogen, sulfur and phosphorus atoms.
  • Alcohols can be oxidized to aldehydes, ketones or carboxylic acids.
  • Carboxylic acids can release hydrogen (H+) ions, making them acids.
  • Acyl groups are part of larger carboxylic acids.
  • Amino groups are basic and often carry a positive charge (NH₃⁺).
  • Phosphate groups are highly acidic and negatively charged (O−P=OO−).
  • Functional groups like hydroxyl, aldehyde, ketone, acetyl, sulfhydryl, and phosphate groups are vital parts of biomolecules.

Common Linking Bonds in Biomolecules

  • Esters: Formed by a carboxylic acid and an alcohol and are common in lipids.
  • Phosphodiesters: Formed by phosphoric acid and two different hydroxyl groups.
  • Phosphoric acid: Linking two hydroxyl groups.
  • Phosphodiesters and anhydrides: Important in energy transfer, exemplified by ATP.
  • Anhydrides: Formed from two carboxylic acids and are important in biochemical reactions.
  • Thiols: Can form thioesters like acetyl CoA.
  • Disulfide bonds: Formed by linking two sulfhydryl groups.

Glycosidic Bonds

  • Amino acids join to form polypeptide chains via peptide bonds.
  • Two hydroxy groups join via condensation to form an ether linkage/ glycosidic bond.
  • The glycosidic bond is essential for linking sugar molecules.

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