DNA Replication Quiz

The cell\'s genetic instructions are encoded in the **molecule called DNA** DNA controls - the characteristics of organisms - ability of a fertilized egg to develop into an adult organism Genetic Material must contain : **Information, replication, Transmission, Variantions** The Linkage bet...

The cell\'s genetic instructions are encoded in the **molecule called DNA** DNA controls - the characteristics of organisms - ability of a fertilized egg to develop into an adult organism Genetic Material must contain : **Information, replication, Transmission, Variantions** The Linkage between the two sugar molecules and phosphate group is called [**phosphor diester linkage. Phosphate and sugars** are **the backbone**] Chromosomes are made **[of DNA and protein]** Nucleic acids are named as such because they **[release H^+^ in solutions]** DNA is a macromolecule composed of monomers called  **[nucleotides]** The building blocks of DNA are **[nucleotides]** - Which of the following statements describe purines but NOT pyrimidines? - **They have a double-ring structure.** - **They include the base adenine.** - **They include the base guanine.** A DNA strand runs 3\' to 5\' left-to-right. The complementary strand runs\-\-- 5 to 3 left to right In their DNA replication experiments, Meselson and Stahl used two isotopes of the element** N** Unavailable so that the daughter strands could be distinguished from the parental strands The experimental tool shown here generates patterns that are analyzed using mathematical theory to explain the three dimensional structure of molecules. The tool is called **[Xray diffraction]** **[DNA replication procedure: two complementary strands- template strands/parent starnds. ]** **[First N bases, covalend bond]** **[Origin of replication is starting point of replication. ]** **[DNA polymerase enzyme responsible to covalently bond nucleotides together]** **[Individual nucleotides with three phosphate group\-\--Deoxynucleoside triphosphate (dNTP) is a biomolecule that serves as the building blocks for DNA and RNA, and as an energy source for DNA replication and maintenance:]** - **[Building blocks: dNTPs are nucleotides that contain a nitrogenous base, deoxyribose sugar, and three phosphate groups. There are four types of dNTPs, each with a different nitrogenous base: dTTP, dCTP, dGTP, and dATP. ]** - **[Energy source: dNTPs provide energy in the form of GTP and ATP. ]** - **[DNA sequencing: dNTPs are used in DNA sequencing reactions, such as the Sanger method. In this method, modified dNTPs called dideoxynucleotide trip]** **[At the catalytic site, DNA polymerase breaks bonds between 1^st^ and 2^nd^ phosphate, then attach the resulting nucleotides with one phosphate group called deoxynucleoside monophosphate to the 3 end of the growing strand via phosphoester bond. The breakage of the covalent bond release pyrophosphate \-\--an exergonic reaction that provides energy to adjacent nucleotides. ]** **[The enzyme DNA polymerase attaches a nucleotide to the Blank\_\_\_\_\_\_ end of a growing strand via a Blank\_\_\_\_\_\_ bond.\-\-\--]** **[3\' ; phosphoester]** **[DNA application opening area is called replication Fork]** **[During replication, Leading strand is made in the same direction the fork is moving]** **[Lagging stands are small fragments-Okazaki , opposite direction of Fork. Happens in 5-3 direction, each of the fragments requires its own primer. ]** **[To complete synthesis of Okazaki fragments within the lagging srands, three additional events occurs:]** - **[The RNA primers are removed by DNA polymerase I]** - **[After removal, DNA polymerase I filled the vacant space]** - **[Covalent bond]** **[Telomere:]** Special sequence [ **5-GGGTTA-3**] located at the end of the eukeryotic chromosome where they protect chromosomal DNA from **[degradation]** and from **[being joined end to end i]**n the cell [ **.**] Telomeres are added by enzyme called **[Telomerase- contains internal RNA primer and reverse transcriptase enzyme.]** **[The RNA primer contains template for synthesis of Telomere, make the sequence repetitive. ]** **[Structure of eukeryotic chromosome: ]** **[The double strand is packed histone.]** **[Histone is complex and basic polypeptides rich in arginine and lysine. Role in compactly fitting DNA in nucleus of cell]** **[DNA is packed into chromosome in the nucleus\-\-\-\-\-\--chromosome is consisting of chromatin\-\-\-\--chromatin is DNA + protein\-\-\-\--chromatin is organized in nucleosim\-\--nuclepsum consist of stretch of DNA wrapped around 8 histones. ]** **[Highly compacted chromatine region interphase called heterochromatine,,, less compacted chromatine called euchromatine.]** **[When cell prepares to divide, chromosome becomes more compacted, during metaphase]** Diagram Description automatically generated **[What experiment demonstrated that DNA replication was semiconservative? Meselson and Stahl]** **[What enzyme covalently links nucleotides together? DNA polymerase]** **[Energy is generated to covalently connect adjacent molecules by breaking the bond between first and second phosphates in the dNTP.]** **[This enzyme works by breaking a bond between the first and second phosphate and attaching a nucleotide dNMP to the 3\' end of the DNA strand via a phosphodiester bond\-\-\--Polymerase]** **[What process takes place near the opening of replication forks? DNA synthesis]** **[A mouse lacking the correct form of primase will not be able to make a complementary daughter strand because primase is responsible for synthesizing RNA primers, which are essential for DNA polymerase to begin building a new DNA strand during replication; without primers, DNA synthesis cannot start. ]** **[Explanation:]** - **[Function of primase:]** **[Primase is an enzyme that creates short RNA sequences called primers on the DNA template, acting as a starting point for DNA polymerase to add nucleotides and build a new DNA strand.]** - **[Impact of lacking primase:]** **[If a mouse lacks functional primase, it cannot initiate DNA replication as DNA polymerase needs a primer to begin adding nucleotides. ]** **[Key points to remember:]** - **[Okazaki fragments:]** **[While related to DNA replication, Okazaki fragments are specifically formed on the lagging strand during replication, and their formation still requires a primer synthesized by primase. ]** - **[Histone compaction:]** **[Histone compaction is related to DNA packaging and is not directly impacted by the lack of primase. ]** - **[DNA unwinding:]** **[Although helicase is responsible for unwinding the DNA double helix, the process still requires primers to initiate replication. ]** **[So, the correct answer is: It will not be able to make a complementary daughter strand. ]** **[Which of the following statements about telomerase is INCORRECT?]** **[Question 2 options:]** **[Telomeres are found at the ends of chromosomes.]** -- ----------------------------------------------------------------------------------------------------- **[Telomeres are lengthened by telomerase.]** **[Telomeres are crucial to the viability of a cell that replicates often.]** **[Telomeres would be longer in cells of older individuals than younger individuals.]** **[Telomeres are short repeat sequences.]** **[The incorrect statement about telomerase is: \"Telomeres would be longer in cells of older individuals than younger individuals\". ]** **[Explanation: Telomeres naturally shorten with each cell division, so older individuals would typically have shorter telomeres compared to younger individuals. Telomerase is an enzyme that helps lengthen telomeres, but its activity decreases with age, leading to shorter telomeres in older cells. ]** **[Key points about telomerase:]** - **[Function:]** **[Telomerase adds repetitive DNA sequences to the ends of chromosomes, called telomeres, to prevent chromosome degradation during DNA replication. ]** - **[Importance of telomeres:]** **[Telomeres are crucial for maintaining chromosome stability and preventing cell damage when cells divide repeatedly. ]** - **[Aging and telomeres:]** **[As we age, our cells naturally divide more, leading to shorter telomeres and potentially contributing to cellular senescence. ]** **[Eukaryotic cells store their DNA in the form of linear chromosomes. This creates problems for replication of DNA at the ends of the chromosomes because]** **[Question 4 options:]** **[base pairs at the ends of chromosomes do not consist of A, C, G, or T]** -- ------------------------------------------------------------------------------------------------------------- **[DNA polymerase cannot access the nucleus, where the DNA is found]** **[by the time DNA polymerase gets to the ends, there are no more free dNTPs for replication]** **[DNA polymerase can only synthesize DNA in the 5\' to 3\' direction]** **[all of the genes are located in the middle of the chromosome]** The main reason why linear chromosomes in eukaryotes create problems for DNA replication at the ends is because DNA polymerase can only synthesize DNA in the 5\' to 3\' direction.  Explanation: When replicating DNA, the lagging strand requires primers to initiate synthesis, but at the very end of the chromosome, there\'s no space to add a primer, leading to a gap that cannot be filled, resulting in a shortened chromosome with each replication cycle.  A researcher has discovered a mouse that has two forms of DNA polymerase. One form adds bases to the 3\' end and one adds bases to the 5\' end. What does this mean for the mouse? Question 5 options: Its DNA will not be unwound for replication -- ------------------------------------------------------------- It will not be able to make a complementary daughter strand It will not make Okazaki fragments Its DNA will not be compacted around histones A mouse with two forms of DNA polymerase, one adding bases to the 3\' end and one to the 5\' end, will not be able to make a complementary daughter strand because DNA replication can only occur in the 5\' to 3\' direction, so having a polymerase adding bases to the 5\' end would disrupt the process completely.  Explanatio A telomere has a sequence at the Blank\_\_\_\_\_\_ that is termed a(n) Blank\_\_\_\_\_\_ because it does not have a complementary strand. 3\' end; overhang The repeating structural unit of eukaryotic chromatin is the nucleosomeField 1Field 1 nucleosome , Correct Unavailable  Graphical user interface, text, application Description automatically generated  Graphical user interface, text, application, email Description automatically generated  Graphical user interface, text, application, email Description automatically generated  Table Description automatically generated  A picture containing table Description automatically generated  Graphical user interface, application Description automatically generated  Table Description automatically generated  Graphical user interface, application Description automatically generated with medium confidence  Graphical user interface, text, application Description automatically generated