Cell Biology Exam 1 Chapter 2
Why are free ionic bonds of little importance and relatively unlikely to form in living organisms? 1)Cells are composed mostly of water, which interferes with ionic bonds between free ions. 2)Cells are largely hydrophobic. 3)They are crystals.
1
What is the maximum number of 100 amino acid long polypeptides that could be made?
20^100
What are the parts of a nucleotide?
5 Carbon sugar, phosphate, nitrogen base
Amino acids: A) can form peptide bonds. B) are composed of a central carbon surrounded by an amino group, a carboxyl group, a hydrogen atom and a variable side chain. C) can have side chains that are polar, nonpolar, or with unique properties. D) all of these statements are true.
D
The β -pleated sheet is characterized by orientation of ______ the molecular axis.
Hydrogen Bonds perpendicular to
A release of hydrogen ions to a solution would MOST likely do what to the pH?
Lower the PH ( more Acidic)
____________ help(s) unfolded or misfolded proteins achieve their proper three-dimensional conformation.
Molecular chaperones
Water is sometimes called the 21st amino acid because of its importance in defining protein structure. The basis for this is the so-called hydrophobic effect. Which of the following BEST describes the hydrophobic effect? Option A: Polar regions of the protein are repelled by water, driving them to the interior of the protein. Option B: Non-polar regions of the protein are repelled by water, driving them to the interior of the molecule. Option C: Water and the protein arrange themselves so that the nonpolar surface in contact with water is maximized. Option D: All of the choices are correct.
Non-polar regions of the protein are repelled by water, driving them to the interior of the molecule.
Which of the following statements about phospholipids is TRUE? Option A: Each one has three fatty acid chains. Option B: The glycerol backbone is bonded to a small nonpolar group. Option C: Their biological function remains unknown. Option D: Each one has two fatty acid chains and the glycerol backbone is bonded to a small polar group.
Option D
Which of the following structures of proteins is composed of two or more polypeptide chains? A Option A: Primary B Option B: Secondary C Option C: Tertiary D Option D: Quaternary
Quarternary
What level of structure in proteins is held together by intermolecular R group interactions?
Quaternary structure
List 3 functions of proteins
Regulation growth factors antibodies
:the specific linear sequence of amino acids that constitutes the polypeptide chain.
The primary structure of a polypeptide
What kind of noncovalent interaction is typified by interactions between two molecules that are so close together that they can experience weak attractive forces bonding them together?
Van der Waals forces
Under which circumstances would electrons be MOST likely to be shared equally?
When atoms of the same element are sharing them.
What type of protein secondary structure is characterized as being highly extensible because of its coiled structure?
alpha-helix
How do amino acids like hydroxylysine and thyroxine, which are NOT among the 20 amino acids that are inserted into proteins, get into proteins?
alteration of R groups of the 20 amino acids after their incorporation into the polypeptide.
Why do sugars tend to be highly water soluble?
because of their large numbers of hydroxyl groups
Tertiary structure can be determined using:
both X-ray crystallography and nuclear magnetic resonance spectroscopy.
What are the properties of water?
cohesion, adhesion, high specific heat, high heat of vaporization, less dense as a solid Composed of two polar bonds All three atoms in a water molecule can form hydrogen bonds\ asymmetric molecule
both the three-dimensional arrangement and the spatial organization of atoms in a molecule.
conformation
In a living organism, where are ionic bonds MOST likely to be found?
deep in a protein's core where water is excluded
Proteins are often composed of two or more distinct modules that fold up independently of one another. They often represent parts of a protein that function in a semi-independent manner. These modules are called ______.
domains
Which of the following is NOT a structural polysaccharide? Option A: chitin Option B: cellulose Option C: glycogen Option D: glycosaminoglycan
glycogen
Which interaction is MOST important in enhancing the solubility of macromolecules in water?
hydrogen bonds
Where are hydrophobic interactions MOST likely to occur?
in the core water soluble protein
Which of the following is NOT a macromolecule formed by polymerization? - proteins - lipids -polynucleotides -polysaccharides -DNA
lipids
Which amino acid is MOST likely to be found in the core of a protein?
methionine
Amino acids are to proteins as __________ are to carbohydrates.
mon0saccarides
The low-molecular-weight building blocks of polymers are called _______.
monomers
What kind of bond results from an unequal sharing of electrons?
polar covalent bond
The infectious agent for Creutzfeld-Jakob disease is a ________
protein
an inventory of all of the proteins in a tissue, cell, or cellular organelle.
proteome
Fats that remain solid at room temperature are MOST likely to be:
saturated
Scientists can produce novel proteins by modifying existing proteins using:
site directed mutagenesis
What is the consequence of placing a proline side chain within an alpha helix?
the alpha helix kinks, the proline disrupts the alpha helix
Which polysaccharide bond CANNOT be broken by mammalian enzymes that normally digest polysaccharides?
β (1—>4) glycosidic linkages
