Part I Composition of Matter and Basic Chemistry of Living Cells

Which subatomic particle is displaced when two or more atoms combine to make a molecule?

a) protons

b) neutrons

c) electrons

d) protons and neutrons

c) electrons

What type of bond is formed when atoms share electrons?

a) ionic bond

b) covalent bond

c) hydrogen bond

d) ionic and covalent bond

b) covalent bond

What determines the number of covalent bonds an atom can create?

a) the number of protons in its nucleus

b) the number of neutrons in its nucleus

c) the excess or shortage of electrons in its outermost electron shell

d) the number of protons, neutrons, and electrons

c) the excess or shortage of electrons in its outermost electron shell

Oxygen with 6 electrons in the outer electron shell (that needs 8 to be complete), can make how many covalent bonds?

a) 2

b) 6

c) 8

d) 0

a) 2

Which of the following bonds are nonpolar?

a) oxygen and hydrogen (O-2H)

b) nitrogen and hydrogen (N-3H)

c) ium and chlorine (Na+ -Cl-)

d) oxygen and oxygen (O-O)

d) oxygen and oxygen (O-O)

In water, hydrogen bonds form between:

a) hydrogen atoms

b) oxygen atoms

c) oxygen and hydrogen atoms

d) none of the other options

c) oxygen and hydrogen atoms

2.2-1 When sugars combine via covalent bond usually it happens between a -OH group form one donor sugar molecule with another -OH group t=form the acceptor sugar. What molecule is releases in this type of condensation reaction?

a) oxygen

b) hydrogen

c) water

d) hydroxyl group

c) water

2.2-2 The reverse of a condensation reaction is called:

a) de-condensation reaction

b) hydrolysis reaction

c) oxidation reaction

d) transferase reaction

b) hydrolysis reaction

2.2-3 Phospholipids form lipid bilayers spontaneously because?

a) they are hydrophobic

b) they are amphipathic (polar and nonpolar)

c) they are attached to acids (carboxylic)

d) they are linked with phosphate groups

b) they are amphipathic (polar and nonpolar)

2.2-4 What group is not present on ALL amino acids?

a) carboxylic acid (COOH)

b) amino group (NH3)

c) hydroxyl group (OH)

d) alpha carbon

c) hydroxyl group (OH)

2.2-5 The covalent linkage between two amino acids as a?

a) peptide bond

b) glycoside bond

c) phosphodiester bond

d) aminoacyl bond

a) peptide bond

2.2-6 What group is found in a nucleotide but not a nucleoside?

a) pentose sugar

b) nitrogenous base

c) phosphate

d) none, they are the same

c) phosphate

2.2-7 What type of bond links two DNA molecules together in a double helix of DNA?

a) ionic bonds

b) hydrogen bonds

c) covalent bonds

d) covalent and ionic bonds

b) hydrogen bonds

2.2-8 How do proteins, nucleic acids, and polysaccharides polymerize?

a) by condensation reactions

b) by hydrolysis reactions

c) by oxidation reactions

d) by phosphorylation reactions

a) by condensation reactions

2.2-9 Are there chemical differences between galactose, glucose and mannose? Identify the statement that is NOT TRUE.

a) they are sugars that have sweet taste

b) they differ in spatial arragement of atoms mainly positioning of hydroxyl groups

c) all three have the formula C6H12O6

d) galactose and mannose have a beta hydroxyl on carbon 3

a) they are sugars that have a sweet taste

2.2-10 What is the alpha carbon in an amino acid? Identify the statement that is NOT TRUE

a) it is the carbon where all four covalent bonds are formed between different side groups

b) it is the carbon that has an alpha hydroxyl group attached

c) it is the carbon that links the amino and carboxyl group

d) it is the carbon that isomerizes to make D and L amino acids

b) it is the carbon that has an alpha hydroxyl group attached

2.2-11 Why is it that D- amino acid are toxic?

a) D-amino acids are toxic because that are not recognized by cells as an amino acid

b) D-amino acids are toxic because they are incorporated into a protein they mix-up the hydrogen bonding pattern in alpha helices and beta sheets

c) D-amino acids are not toxic. Its a myth

d) D-amino acids ate oxidized once they enter the cell membrane and become unable to make peptide bonds

b) D-amino acids are toxic because they are incorporated into a protein they mix-up the hydrogen bonding pattern in alpha helices and beta sheets.