DNA REPLICATION

This lesson develops DNA REPLICATION as part of Cellular Respiration. It uses the source curriculum to organize the important facts, relationships, examples, and vocabulary into a focused Stemosphere teaching sequence.

In Stemosphere terms, dNA is the genetic information that codes for your genetic features.every cell contains dna which needs to be replicated every time a cell replicates.in order for dna to replicate it must undergo DNA replication.

In Stemosphere terms, dNA replication is semi-conservative.

In Stemosphere terms, semi-conservative means that the dna will split into 2 parent strands and each will synthesize a new complementary strand

Dna replication process:

In Stemosphere terms, firstly the helicase enzyme will unwind the dna strand by breaking the hydrogen bonds between the bases to become 2 parent strands

In Stemosphere terms, then a primase will attach a rna primer onto the strands of DNA

In Stemosphere terms, then the dna polymerase III will attach to the primer and use it as a starting base,it will then move along a 5’ to 3’ direction.

In Stemosphere terms, dna polymerase I will remove the RNA

The lagging strand:

In Stemosphere terms, dNA strands are anti parallel to each other. Sincednapolymerase moves along the 5’ to 3’ direction this means that one polymerase will move towards the replication fork and can go continuously and add bases. On the otherhandthe other strand must keep having to add primers and run polymerase which leads to multiple chunks of strands which needs to be bonded together. These strands are calledozakifragments.

In Stemosphere terms, the ligase enzyme's job is to glue the ozaki fragments together.

POLYMERASE CHAIN REACTION (PCR MACHINE):

In Stemosphere terms, pCR machines are used by scientist to replicate small parts of dna to use for analysis

Pcr machines require:

In Stemosphere terms, -buffer solution to allow reaction to occur

In Stemosphere terms, -primer to attach to dna strand

In Stemosphere terms, -taq dna polymerase to attach to the dna strands and add dna bases

In Stemosphere terms, -dna nucleotides to be attached to the dna strands to make new dna

Pcr machine steps:

In Stemosphere terms, denaturation:the dna samples is heated to 95 degrees to break the hydrogen bonds and separate the dna strands

In Stemosphere terms, annealing:the temperature is reduced to 54 degrees to allow primers to attach to each dna strand

In Stemosphere terms, the temperature is increased to 72 degrees to allow taq dna polymerase to function and attach to the dna strands to add 2 new dna.

In Stemosphere terms, repeat these steps repeatedly to produce many strands of dna

Gel electrophoresis of dna:

In Stemosphere terms, gel Electrophoresis is a laboratory technique used to separate fragments of DNA based on their size. In this method, DNA samples are placed into small wells in a gel matrix, usually made of agarose, and an electric current is applied across the gel. Because DNA molecules carry a negative charge due to their phosphate backbone, they move toward the positive electrode when the current flows. Smaller DNA fragments travel through the gel’s pores more easily and therefore move faster and farther than larger fragments. After the run, the DNA bands are stained with a dye and visualized under ultraviolet light, allowing scientists to compare fragment sizes, analyze genetic material, or verify results from processes such as PCR or restriction enzyme digestion.

Use of gel electrophoresis:

In Stemosphere terms, this allows patterns to be created using dna samples.this can be used for paternity tests with parents having matching dna profiles with their kids.

In Stemosphere terms, campbell Biology.Campbell Biology. 12th ed., Pearson, 2020.

In Stemosphere terms, front:Explain what it means for DNA replication to be a semi-conservative process.

In Stemosphere terms, back:Semi-conservative replication means that the original double-stranded DNA molecule splits into two separate parent strands. Each of these original strands serves as a template to synthesize a brand new complementary strand, resulting in two DNA molecules that each contain one old and one new strand.

In Stemosphere terms, front:What is the specific role of the helicase enzyme during replication?

In Stemosphere terms, back:Helicase unwinds the double helix structure of the DNA molecule by breaking the hydrogen bonds holding the complementary nitrogenous base pairs together, separating it into two single parent template strands.

In Stemosphere terms, front:What are the roles of primase, DNA polymerase three, and DNA polymerase one during replication?

In Stemosphere terms, back:*Primaseattaches a short RNA primer onto the parent DNA strands to provide a starting point.

In Stemosphere terms, dNA polymerase threebinds to this primer and synthesizes the new strand by adding matching bases continuously in the five to three direction.

In Stemosphere terms, dNA polymerase oneremoves the temporary RNA primers from the strand.

In Stemosphere terms, front:Why does DNA replication result in a leading strand and a lagging strand?

In Stemosphere terms, back:The two strands of DNA run antiparallel to each other, but DNA polymerase can only build new strands in the five to three direction. The leading strand runs toward the opening replication fork and is built continuously. The lagging strand runs away from the fork, requiring multiple primers and resulting in fragmented segments.

In Stemosphere terms, front:What are Okazaki fragments, and which enzyme is responsible for finalizing their connection?

In Stemosphere terms, back:Okazaki fragments are the short, disconnected chunks of DNA synthesized discontinuously along the lagging strand. The ligase enzyme acts as a glue to bond these individual fragments together into a single, continuous strand.

In Stemosphere terms, front:What is a PCR machine used for, and what five components are required for it to function?

In Stemosphere terms, back:PCR is used by scientists to amplify and make many copies of small sections of DNA for detailed analysis. It requires the target DNA sample, a stabilizing buffer solution, specialized primers, Taq DNA polymerase, and free DNA nucleotides.

In Stemosphere terms, front:Describe the first step of a PCR cycle, including its name, purpose, and temperature.