Practice Questions - Week 2 Flashcards
What distinguishes nucleotides from nucleosides?
a) nucleosides lack the phosphate group
b) nucleosides lack the sugar group
c) nucleosides lack a nitrogenous base
d) nucleosides have extra phosphate groups
a)
(Nucleoside is a nitrogenous base linked to a pentose)
A nucleotide of DNA may contain
a) ribose, uracil, and a phosphate group
b) deoxyribose, uracil and a phosphate group
c) deoxyribose, thymine, and a phosphate group
d) ribose, thymine, and a phosphate group
c)
(The pentose in DNA is a deoxyribose. Thymine is a nitrogenous base that only exist in DNA nucleotides, whereas Uracil only exists in RNA nuleotides. All nucleotides contain at least one phosphate group)
Which of the following nitrogenous base is a purine
a) uracil
b) adenine
c) cytosine
d) thymine
b)
(Adenine and Guanine are purines (double ring). Cytosine, Uracil and Thymine are pyrimidines (single ring))
The nucleotide sequence of DNA is which level of structure: primary, secondary, tertiary, or quaternary?
primary
(The sequence of nucleotides and their respective Nitrogenous bases are the primary structure of DNA.
The secondary structure is the double helix, tertiary structure relates to supercoiling of the helix (normally occurs in Prokaryotic DNA) and quaternary structure refers to the association of DNA with histones)
How does the double helix structure of DNA support its role in encoding the genome?
a) The sugar-phosphate backbone provides a template for DNA replication.
b) tRNA pairing with the template strand creates proteins encoded by the genome.
c) Complementary base pairing facilitates degradation of DNA
d) Complementary base pairing allows easy editing of both strands of DNA.
d)
(Complementary base pairing in DNA is important to allow easy editing of both strands of DNA to avoid mutations, so the genome is safely kept. Double helix also supports DNA duplication, and transcription of genes into mRNA. Complementary base pairing is important for DNA stability and for its function in the genome)
DNA double helix does not have which of the following?
a) antiparallel configuration
b) complementary base pairing
c) major and minor grooves
d) uracil
d)
(Uracil is a nitrogenous base present in RNA nucleotides. It does not exist in DNA nucleotides)
In eukaryotes, DNA is wrapped around
a) single-stranded binding proteins
b) polymerases
c) ribosomes
d) histones
d)
(DNA is packed in the cells by wrapping around positive proteins called histones)
If the sequence of the 5’-3’ strand is AATGCTAC, the complementary sequence has the following sequence:
a) 3’-AATGCTAC-5’
b) 3’-CATCGTAA-5’
c) 3’-TTACGATG-5’
d) 3’-GTAGCATT-5’
d)
(Base pairing follows the rule: A-T, G-C. The complementary strand has the opposite direction (i.e. 3’-5’))
Select which one is true about structural differences between RNA and DNA
a) bases, pentose, and the phosphodiester linkage
b) bases, pentose and the secondary structure
c) bases, pentose, and the glycosidic bond
d) bases, pentose, and number of phosphate groups
b)
(Structurally DNA and RNA differ in their pentose (deoxyribose vs ribose), in the nitrogenous bases (Thymine vs uracil) and in the secondary structure (double helix vs mostly single-strand))
mRNA splicing is required to remove ___________ from pre-mRNA and initiate_________
a) introns, translation
b) exons, transcription
c) exons, translation
d) introns, transcription
a)
How many nucleotides contain 12 mRNA codons?
a) 12
b) 24
c) 36
d) 48
c)
(Each codon has 3 nucleotides (3 bases); therefore, a mRNA with 12 codons has 36 nucleotides)
Match the following list of RNAs with their functions:
tRNA
mRNA
rRNA
codes for proteins
components of the ribosome
is linked to a specific amino acid
tRNA - is linked to a specific amino acid
mRNA - codes for proteins
rRNA - components of the ribosome
Select the statements that are correct.
a) Codon is a sequence of three bases in mRNA that codes for one amino acid
b) The initiation codon is AUG and codes for isoleucine
c) Each codon specifies more than one amino acid
d) Some amino acid acids may have two or more codons
e) The genetic code, the number and size of chromosomes differ for each species
a, d
(The initiation codon is AUG and codes for the amino acid methionine. Each codon specifies only one amino acid. The number and size of chromosomes differ for each species, but the genetic code is universal)
Ribosomes are complex particles containing rRNA and ___________ where protein synthesis take place. ________ molecules bind to mature ___________ and transfer ____________ one by one to start and elongate the polypeptide chain.
a) proteins, mRNA, tRNA, amino acids
b) lipids, tRNA, amino acids, tRNA
c) proteins, tRNA, mRNA, amino acids
d) mRNA, protein, tRNA amino acids
c)
