Cell Biology Week 2 Reading

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Questions and Answers

What is the property expressed as the amount of energy required to break 1 mole of covalent bonds?

Bond energy (correct)

Noncovalent bond energy

Ionic bond energy

Electron affinity

What type of atoms are usually part of various functional groups in biological compounds, in addition to carbon and hydrogen?

Oxygen and nitrogen and sulfur

Phosphorus and sulfur and nitrogen

Oxygen and sulfur and phosphorus (correct)

Nitrogen and phosphorus and oxygen

What is the name for mirror-image forms of the same compound?

Stereoisomers (correct)

Homologues

Isotopes

Isomers

What is the process by which carbon-containing compounds lose electrons to other molecules?

Oxidation Signup and view all the answers

What property of water accounts for its high surface tension, high boiling point, and high specific heat?

Hydrogen bond formation Signup and view all the answers

Which term describes molecules that are not very soluble in water?

Hydrophobic Signup and view all the answers

What is the specific heat of water?

1.0 calories per gram Signup and view all the answers

What type of molecules are termed hydrophilic (water-loving)?

Molecules that form hydrogen bonds with water Signup and view all the answers

Which of the following macromolecules carries specific information in its monomer sequence?

Nucleic acids Signup and view all the answers

What is the primary function of proteins in the cell?

Catalysis, signalling and support Signup and view all the answers

How are macromolecules synthesized?

Through a process involving ATP Signup and view all the answers

What is the process of removing monomers from a polymer called?

Hydrolysis Signup and view all the answers

Which macromolecule determines the 3D structure and biological activity of proteins?

Proteins themselves Signup and view all the answers

What is the main requirement for polymerization of macromolecules?

An adequate supply of the monomeric subunits and a source of energy Signup and view all the answers

What is the role of molecular chaperones in macromolecule assembly?

They assist the assembly process by preventing incorrect molecular interactions Signup and view all the answers

What holds together every protein or other macromolecule in the cell?

Strong covalent bonds Signup and view all the answers

What is the assertion of molecular self-assembly in macromolecules?

It asserts that information for folding and assembly is inherent in the polymers themselves Signup and view all the answers

What type of noncovalent bond involves weak attractive interactions between an electronegative atom such as oxygen and a hydrogen atom covalently bonded to a second electronegative atom?

Hydrogen bond Signup and view all the answers

What type of interactions occur between two atoms when they are very close to one another and are oriented approximately?

Van der Waals interactions Signup and view all the answers

Which type of interaction describes the tendency of nonpolar groups within a macromolecule to associate with each other and minimize their contact with surrounding water molecules?

Hydrophobic interaction Signup and view all the answers

What is the term for the process by which a denatured polypeptide returns to conditions in which the native conformation is stable?

Renaturation Signup and view all the answers

What is the primary function of motility proteins?

Play key roles in the contraction and movement of cells Signup and view all the answers

How do regulatory proteins contribute to cellular functions?

Control and coordinate cellular functions Signup and view all the answers

What is the main role of defence proteins?

Protect against disease Signup and view all the answers

What distinguishes globular proteins from fibrous proteins?

Fibrous proteins are involved in cellular structure Signup and view all the answers

How many amino acids are typically used in protein synthesis?

20 amino acids Signup and view all the answers

What is the name of the bond linking two amino acids?

Peptide bond Signup and view all the answers

What type of amino acids occur in proteins?

Only L-amino acids Signup and view all the answers

What is the term for the transient attraction of two nonpolar molecules?

Van der Waals interaction Signup and view all the answers

What is the primary structure of a protein based on?

Amino acid sequence and covalent peptide bond Signup and view all the answers

What is the role of molecular chaperones in protein folding?

Ensuring accurate protein folding by shielding parts of a newly synthesized protein from interactions Signup and view all the answers

What dictates the secondary, tertiary, and quaternary structures of a protein?

The primary structure Signup and view all the answers

What determines the final folded shape of a protein?

Primary structure of the polypeptide Signup and view all the answers

Which technique is used to determine accurate 3D structures of polypeptides?

X-ray crystallography Signup and view all the answers

What level of organization does quaternary structure apply to?

Multimeric proteins Signup and view all the answers

In which type of proteins are disulfide bonds involved in maintaining the tertiary structure?

Globular proteins Signup and view all the answers

Which type of bonding is common in alpha helices but can be either intramolecular or intermolecular in beta-sheets?

Hydrogen bonding Signup and view all the answers

Which amino acids are considered 'alpha helix formers' and are commonly found in alpha-helical regions?

Leucine, methionine, glutamate Signup and view all the answers

What is the primary determining factor for the shape of fibrous proteins?

Secondary structure Signup and view all the answers

What is a discrete, locally folded unit of tertiary structure that usually has a specific function in proteins?

Domain Signup and view all the answers

What is the role of ATP in the cell?

To serve as intermediates in various energy-transferring reactions Signup and view all the answers

What provides the energy needed to form each new phosphodiester bridge during nucleic acid synthesis?

High-energy nucleoside triphosphates like ATP Signup and view all the answers

What is the direction of nucleotide sequences written in by convention?

From the 5' end to the 3' end Signup and view all the answers

What property of A, T (or U in RNA), G, and C provides a mechanism for nucleic acids to recognize one another?

The base pairing of A with T (or U in RNA) and G with C Signup and view all the answers

What did Francis Crick and James Watson postulate in 1953 regarding DNA?

That DNA has an antiparallel double-stranded helical structure Signup and view all the answers

What type of bond links two glucose units in maltose?

Glycosidic bond Signup and view all the answers

Where is starch commonly stored in plant cells?

Plastids Signup and view all the answers

What is the primary structural polysaccharide found in plant cell walls?

Cellulose Signup and view all the answers

In addition to insecet exoskeletons, where else is chitin found?

Fungal cell walls Signup and view all the answers

Which macromolecule does glycogen belong to and where is it typically found?

Polysaccharides in animal cells Signup and view all the answers

What type of fatty acids have one or more double bonds resulting in a bend or kink in the chain?

Unsaturated fatty acids Signup and view all the answers

Which lipid class is important in membrane structure due to its amphipathic nature and is a key component of the bilayer structure found in all membranes?

Phospholipids Signup and view all the answers

Which type of lipids consist of a glycerol molecule with three fatty acids linked to it and are synthesized stepwise, with one fatty acid added at a time?

Triacylglycerol Signup and view all the answers

What makes trans fats resemble saturated fatty acids in both their shape and their ability to pack together more tightly than typical unsaturated fatty acids?

They contain unsaturated fatty acids with a particular type of double bond Signup and view all the answers

Study Notes

Cellular Membranes and Organic Chemistry

Membranes create cellular compartments and regulate molecular and ionic movement.
Organic chemistry focuses on carbon-containing compounds, both natural and synthetic.
Biological chemistry examines the chemistry within living organisms, integral to cell biology.

Properties of Carbon

Carbon is crucial for biological molecules due to its tetravalent nature, forming four chemical bonds.
The octet rule suggests stability is achieved with eight electrons in the outer shell.
Carbon commonly forms covalent bonds with itself, oxygen, hydrogen, nitrogen, and sulfur.

Water in Biological Systems

Water, the universal solvent, constitutes 75-85% of a cell's weight.
Cellular processes, such as protein folding, occur in water-rich environments.
Osmosis allows water movement across membranes based on solute concentration, while aquaporins facilitate faster transport.
The molecular polarity of water contributes to its cohesive properties and temperature regulation.

Macromolecules and Polymers

Cell structures comprise ordered arrays of macromolecules like proteins, nucleic acids, and polysaccharides.
Biological macromolecules originate from small organic molecules (monomers) that polymerize into larger structures.
Nucleic acids, essential for genetic information storage and transmission, are composed of nucleotide polymers.

Nucleic Acids

Two primary nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
RNA contains ribose sugar; DNA contains deoxyribose.
DNA stores genetic information, while RNA has roles in gene regulation and protein synthesis.
Nucleotides consist of a sugar, phosphate group, and nitrogenous base.

Polysaccharides

Polysaccharides are long chains of monosaccharides, serving as energy storage and structural components.
Common polysaccharides include starch, glycogen, and cellulose, built from repeating sugar units.
Sugars are categorized as aldoses (terminal carbonyl) or ketoses (internal carbonyl) based on their structure.

Common Monosaccharides

D-glucose (C6H12O6) is the most prevalent monosaccharide.
Sugars follow the general formula CnH2nOn, linked to carbohydrates by the concept of "hydrates of carbon."
Disaccharides consist of two covalently linked monosaccharide units.

Lipids

Lipids differ from other macromolecules due to their hydrophobic nature rather than polymerization.
High molecular weight and presence in cellular structures classify them as macromolecules.
Lipids are primarily nonpolar, differing in structure, chemistry, and function.
They serve key roles in cell membranes and energy storage, and can be amphipathic, containing both polar and nonpolar regions.

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Test your knowledge about cell membranes, organic chemistry, and biological chemistry with this quiz. Explore the concepts of cellular compartments, carbon-containing compounds, and the chemistry of living systems.