Chapter 4: DNA- The Molecular Basis of Life Flashcards
Deoxyribonucleic Acid (DNA)
A double-stranded polymer of nucleotides (each consisting of a deoxyribose sugar, a phosphate, and four nitrogenous bases) that carries the genetic information of an organism.
Bacteriophage
Any bacteria-infecting virus
Isotope
Different atoms of the same element containing the same number of protons but a different number of neutrons.
Radioisotopes
Unstable isotopes that decay spontaneously by emitting radiation.
Deoxyribose Sugar
Sugar molecule containing five carbons that as lost the -OH (hydroxyl group) on its 2’ (2 prime) carbon.
Phosphate Group
Group of four oxygen atoms surrounding a central phosphorous atom found in the backbone of DNA.
Nucleotides
Molecules that consist of a five-carbon sugar (deoxyribose or ribose) with a nitrogenous base attached to their 1’ carbon and a phosphate group attached to their 5’ carbon.
Nitrogenous Base
An alkaline, cyclic molecule containing nitrogen.
Glycosyl Bond
A bond between a sugar and another organic molecule by way of an intervening nitrogen or oxygen atom.
Antiparallel
Parallel but running in opposite directions; the 5’ end of one strand of DNA aligns with the 3’ end of the other strand in a double helix.
Complementary Base Pairing
The pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand; adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).
Mitosis
Division of the nucleus of a eukaryotic cell into two daughter nuclei with identical sets of chromosomes.
Cytokinesis
Division of cytoplasm and organelles of a cell into two daughter cells.
Template
a single-stranded DNA sequence that acts as the guiding pattern for producing a complementary DNA strand.
Semiconservative
The process of replication in which each DNA molecule is composed of one parent strand and one newly synthesized strand.
DNA Helicase
The enzyme that unwinds double- helical DNA by disrupting hydrogen bonds.
Anneal
The pairing of complementary strands of DNA through hydrogen bonding.
Single- stranded binding proteins (SSBs)
A protein that keeps separated strands of DNA apart.
DNA Gyrase
The bacterial enzyme that relieves the tension produced by the unwinding of DNA during replication.
Replication Fork
The region where the enzymes replicating a DNA molecule are bound to untwisted, single stranded DNA.
Replication Bubble
The region where two replication forks are in close proximity to each other, producing a bubble in the replicating DNA.
DNA Polymerase III
The enzyme responsible for synthesizing complementary strands of DNA during DNA replication.
Deoxyribonucleoside Triphosphates
Molecules composed of a deoxyribose bonded to three phosphate groups and a nitrogenous base.
RNA (ribonucleic acid) Primer
A sequence of 10 to 60 RNA bases that is annealed to a region of single-stranded …………… not done
Adenine and guanine are pyrimidines
False; Adenine and guanine are purines.
The DNA double helix makes a complete turn every 3.4 nm along its length.
True
DNA’s backbone is held together by hydrogen bonds while the complementary bases are held together by phosphodiester bonds.
Flase; Phosphodiester bonds hold DNA’s backbone together while the complementary bases are held together by hydrogen bonds.
If the deoxynucleotide sequence in one strand of a short stretch of DNA double helix is 5’–CTGGAT–3’, then the complementary sequence in the opposite strand is 3’–GACCTG–5’.
False; If the deoxynucleotide sequence in one strand of a short stretch of DNA double helix is 5’–CTGGAT–3’, then the complementary sequence in the opposite strand is 3’–GACCTA–5’.
DNA helicase is an enzyme that ensures that the appropriate complementary base pairs have been added to the growing daughter strands during DNA replication.
False; DNA polymerase III is an enzyme that ensures that the appropriate complementary base pairs have been added to the growing daughter strands during DNA replication.
DNA replication is conservative.
False; DNA replication is semi- conservative.
Joachim Hammerling’s experiment using Acetabularia revealed that the hereditary information is found in the foot of the alga where the nucleus resides.
True
DNA polymerase III builds a complementary DNA strand during DNA replication in the 3’ to 5’ direction.
False; DNA polymerase III builds a complementary DNA strand during DNA replication in the 5’ to 3’ direction.
After one replication of double-stranded DNA, some of the daughter DNA molecules contain no parental material.
False; After one replication of double-stranded DNA, the daughter DNA molecules are comprised of 50% parental material.
Erwin Chargaff’s rules state that adenine bonds with thymine, and cytosine bonds with guanine.
True
Which of the following best describes deoxyribonucleic acid (DNA)?
It consists of a linear backbone of the sugar deoxyribose and phosphates, with nitrogenous bases attached to the sugar residues.
Which of the following is associated with only the lagging strand during DNA replication?
Okazaki fragments
The percent composition of adenine in a DNA molecule is found to be 35%. Therefore, which of the following is the percent composition of guanine?
15%
DNA replication occurs in which of the following ways?
in the 5’ to 3’ direction only
Which of the following did Matthew Meselson and Franklin Stahl’s experiment illustrate?
DNA replicates semiconservatively.
In eukaryotes, transcription occurs in the cytoplasm and translation occurs in the nucleus.
False; In eukaryotes, transcription occurs in the nucleus and translation occurs in the cytoplasm.
During transcription, RNA polymerase uses the template strand of DNA as a template to synthesize the complementary mRNA.
True
RNA comprises a ribose sugar, a phosphate, and a nitrogenous base. The nitrogenous base may be adenine, uracil, guanine, or cytosine.
True
Beadle and Tatum’s investigation of metabolism in the organism Neurospora crassa led to the one gene–one polypeptide hypothesis.
True
When a bacteria’s environment is high in lactose, the LacI protein is bound tightly to the operator of the lac operon.
False; When a bacteria’s environment is high in lactose, the LacI protein is bound to a lactose molecule.
A missense mutation results in the substitution of one or more amino acids in the protein chain.
False; A missense mutation results in the substitution of one amino acid in the protein chain.
Telomeres are examples of positive variable number tandem repeats that protect the chromosome.
True