Question
click below
click below
Question
Normal Size Small Size show me how
practice exam 4
Biology- exam 4- practice exam
Question | Answer |
---|---|
In DNA, the nucleotide containing adenine always pairs with the nucleotide containing _______. | Thymine |
Chromosomes are made of macromolecules from which of the following classes? | Nucleic acids and proteins |
Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? | 8% |
Which of the following statements CORRECTLY describes the eukaryotic chromosome? | It consists of linear molecules of double-stranded DNA |
In the synthesis of a polynucleotide strand of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and which of the following atoms or molecules of the last nucleotide in the polymer? | the 3' OH |
What is meant by the description "antiparallel" regarding the two strands that make up the DNA double helix? | The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. |
Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments? | DNA polymerase I |
DNA differs from RNA in that: | RNA has a hydroxyl group attached to its 2' carbon, whereas DNA does not in the sugar of the nucleotides |
In E. coli, a type of bacteria, there is a mutation in a gene that alters the helicase that normally acts at the origin of replication. Which of the following events would be most likely to occur as a result of this mutation? | No replication fork will be formed. |
In DNA replication, the resulting daughter molecules contain one strand of the original parental DNA and one new strand. What is the explanation for this phenomenon? | DNA replication is semiconservative. |
Using the figure above, the lagging strand of DNA that is synthesized uses which strand as the template strand? | the top strand in the DNA molecule being shown |
What are telomeres? | the ends of linear chromosomes |
Which of these mechanisms ensures that DNA replication is accurate? | complementary base pairing, mismatch repair, proofreading, excision repair, all of the above |
If a cell were unable to produce histone proteins, which of the following results would be a likely effect on the cell? | The cell's DNA could not be packed into its nucleus. |
The two strands of DNA are held together by: | Hydrogen bonds |
Which of the following statements correctly describes the structure and types of chromatin? | Heterochromatin is highly condensed, whereas euchromatin is less compact. |
Which of the following processes correctly describes alternative RNA splicing? | It can allow the production of proteins of different sizes and functions from a single pre-mRNA. |
Which of the following help(s) to stabilize mRNA by inhibiting its degradation? | 5' cap and poly (A) tail |
In which of the following actions does RNA polymerase differ from DNA polymerase? | RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis. |
Which of the following molecular structures contain codons? | mRNA |
The genetic code is redundant (or sometimes also called degenerate). What is meant by this statement? | More than one codon can specify the addition of the same amino acid. |
The process of translation most directly makes what level of protein structure? | Primary |
Which of the following processes occurs in prokaryotes but NOT in eukaryotes? | coupling of transcription and translation to occur simultaneously |
Aminoacyl tRNA synthases are: | enzymes that add the correct tRNA to a specific amino acid |
A particular triplet of bases in the template strand of DNA is 3’-AGT-5’ What would be the corresponding codon for the mRNA that is transcribed? | 5'-UCA-3’ |
What are ribosomes composed of? | both rRNA and protein parts in two subunits. |
The anticodon of a particular tRNA molecule is: | complementary to the corresponding mRNA codon. |
number protein synthesis sequence. 1. An aminoacyl-tRNA binds to A site. 2. Peptide bond forms between the new amino acid and a polypeptide chain. 3. tRNA leaves P site and moves to the E site. 4. Small ribosomal subunit binds with mRNA. 5. Stop | 4, 1, 2, 3, 5 |
What is the function of the release factor during translation in eukaryotes? | It binds to the stop codon in the A site in place of a tRNA. |
The source of free energy to drive the process of translation is: | GTP hydrolysis |
What are polyribosomes? | groups of ribosomes reading a single mRNA simultaneously |
Which of the following statements is the BEST current description of a gene? | a DNA sequence that is expressed to form a functional product: either RNA or polypeptide |