Vocabulary: transformation, bacteriophage, base pairing, semiconservative replication, origin of replication, replication fork, helicase, primase, primer, DNA polymerase, leading strand, lagging strand, Okazaki fragments, DNA ligase, mismatch repair, excision repair, nuclease, telomere, telomerase
Complementary base pairing
Objectives:
After attending lectures and studying the chapter, the student should be able to:
1. State the function of DNA.
2. Describe the structure of the DNA double helix.
3. Describe the structure of a DNA nucleotide, including identifying the 3' and the 5' end.
4. Name the 4 nitrogenous bases in DNA nucleotides and recognize their symbols.
5. Describe the condensation synthesis of nucleotides to make strands of DNA.
6. Describe the complementary base pairing that bonds together the two strands of a
double-stranded DNA molecule.
7. Describe the antiparallel configuration of the two strands of a double-stranded DNA
molecule.
8. Relating to DNA replication:
a. Explain what is meant by DNA replication.
b. Explain what is meant by semi-conservative DNA replication.
c. Explain the role of helicase enzymes in unwinding the double-stranded DNA molecule
by initiating the formation of replication bubbles.
d. Explain the process of making a complementary copy of DNA, including the roles of the enzymes primase and DNA polymerase.
e. Distinguish between the leading strand and the lagging strand and explain why the
leading strand can be formed continuously, but the lagging strand must be formed in
Okazaki fragments.
f. Describe the process of replacing RNA primer nucleotides with DNA nucleotides.
g. Explain the role of DNA ligase in completing the lagging strand of DNA.
h. Explain why the RNA primer at the 5' end of the leading strand of DNA cannot be
replaced with DNA nucleotides.
i. Describe the structure and function of a telomere.
j. Know the function of the following enzymes: primase, ligase, helicase, DNA polymerase
| 1056876144 | Concept 16.1: DNA is the genetic material | ... | |
| 1056876145 | Transformation | (1) The conversion of a normal animal cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer. | |
| 1056876146 | Bacteriophages | A virus that infects bacteria; also called a phage. | |
| 1056876147 | Virus | An infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope. | |
| 1056876148 | Double helix | The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape. |  |
| 1056876149 | Antiparallel | Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5′ → 3′ directions). | |
| 1056876150 | Concept 16.2: Many proteins work together in DNA replication and repair | ... | |
| 1056876151 | Semiconservative Model | Type of DNA replication in which the replicated double helix consists of one old strand, derived from the parental molecule, and one newly made strand. |  |
| 1056876152 | Origins of Replication | Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides. |  |
| 1056876153 | Replication Fork | A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized. | |
| 1056876154 | Helicases | An enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands. | |
| 1056876155 | Single-Strand binding proteins | A protein that binds to the unpaired DNA strands during DNA replication, stabilizing them and holding them apart while they serve as templates for the synthesis of complementary strands of DNA. | |
| 1056876156 | Topoisomerase | A protein that breaks, swivels, and rejoins DNA strands. During DNA replication, topoisomerase helps to relieve strain in the double helix ahead of the replication fork. | |
| 1056876157 | Primer | A short stretch of RNA with a free 3' end, bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication | |
| 1056876158 | Primase | An enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parenta DNA strand as a template. | |
| 1056876159 | DNA Polymerase | An enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucleotides to the 3' end of an existing chain. There are severl different DNA polymerases; DNA polymerase III and DNA polymerase I play major roles in DNA replication in E. coli. | |
| 1056876160 | Leading Strand | The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5′ → 3′ direction. |  |
| 1056876161 | Lagging Strand | A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5′ → 3′ direction away from the replication fork. |  |
| 1056876162 | Okazaki Fragments | A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication. Many such segments are joined together to make up the lagging strand of newly synthesized DNA |  |
| 1056876163 | MisMatch Repair | The cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides. | |
| 1056876164 | Nuclease | An enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides | |
| 1056876165 | Nucleotide Excision Repair | A repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide. | |
| 1056876166 | Telomeres | The tandemly repetitive DNA at the end of a eukaryotic chromosome's DNA molecule. Telomeres protect the organisms genes from being eroded during successive rounds of replication. | |
| 1056876167 | Telomerase | An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells | |
| 1056876168 | Concept 16.3: A chromosome consists of a DNA molecule packed together with proteins | ... | |
| 1056876169 | Heterochromatin | Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed. | |
| 1056876170 | Euchromatin | The less condensed form of eukaryotic chromatin that is available for transcription. | |
| 1056876171 | Word Roots: helic- | = a spiral (helicase: an enzyme that untwists the double helix of DNA at the replication forks) | |
| 1056876172 | Word Roots: liga- | = bound or tied (DNA ligase: a linking enzyme for DNA replication) | |
| 1056876173 | Word Roots: -phage | = to eat (bacteriophages: viruses that infect bacteria) | |
| 1056876174 | Word Roots: semi- | = half (semiconservative model: type of DNA replication in which the replicated double helix consists of one old strand, derived from the parent molecule, and one newly made strand) | |
| 1056876175 | Word Roots: telos- | = an end (telomere: the protective structure at each end of a eukaryotic chromosome) | |
| 1056876176 | Word Roots: trans- | across (transformation: a phenomenon in which external DNA is assimilated by a cell) |
