Module 11 - Molecular Genetics Flashcards
What is semiconservative replication?
Method of DNA replication where parental strands separate and serve as templates. It produces DNA molecules that have one strand of parental DNA and one strand of new DNA. Occurs during interphase.
What is helicase?
An enzyme that unwinds and unzips the parent double helix. breaks the hydrogen bonds between the base pairs leaving single strands of DNA
What is topoisomerase?
An enzyme that keeps the double helix from supercoiling as it is being separated and unwound.
What is RNA primase?
Adds an RNA primer on the two separated DNA strands to prepare them to be built upon
What is DNA polymerase?
Assembles nucleotides along the individual DNA strands, creating a new strand of DNA
What is ligase?
An enzyme that “glues” / seals the new strand to the original strand
Leading strand vs lagging strand
The two strands from the parental DNA go in two different directions. The one that goes from 5’ to 3’ is the leading strand and the one that goes from 3’ to 5’ is the lagging strand. That is because DNA polymerase can only build on the 3’ end of the strand, so 3’ to 5’ will have to keep going back as the DNA unwinds. But the one that goes from 5’ to 3’ can continuously be built.
What are the steps of protein synthesis?
- Transcription
- Translation
What is mRNA?
Messenger RNA, carries genetic information from DNA in the nucleas to direct protein synthesis in the cytoplasm. Formed complementary to one strand of DNA.
What is rRNA?
Ribosome RNA, associates with protein to form the ribosome.
What is tRNA?
Transfer RNA, brings amino acids to ribosomes. Smaller segments of RNA nucleotides.
What is a codon?
The three base code for amino acids in DNA or RNA
What is a peptide bond?
What is a guanine cap?
Guanine on the end of mRNA to protect it as it leaves the nucleus.
What has to happen before mRNA can leave the nucleus?
Poly-A Tail must be added, Guanine cap must be added, introns must be removed from mRNA.
What is a spliceosome?
A large RNA protein complex that removes the introns from pre-RNA
What are exons and introns?
Exons are sequences on DNA that end up on the final mRNA product after transcriptions, while introns do not end up on mRNA after transcription.
What is RNA?
A nucleic acid like DNA that has uracil instead of thymine and is single stranded.
What is transcription?
The process by which mRNA is synthesized from DNA. DNA code is transferred to mRNA. The first step in the central dogma.
What are the steps of transcription?
DNA is unzipped, RNA polymerase binds to a specific section where mRNA will be synthesized. As DNA unwinds, RNA polymerase initiates mRNA synthesis and moves along one of the DNA strands in the 3’ to 5’ direction. Eventually, the mRNA is released and the RNA polymerase detaches from the DNA.
What is RNA polymerase?
An enzyme that regulates mRNA synthesis during transcription.
Template strand vs nontemplate strand
A double helix gets split into two strands during transcription and RNA polymerase attaches to and reads one of them. That one is the template strand, and the unused strand is the nontemplate strand.
What happens to pre-mRNA to make it a mature mRNA?
Introns are removed from the pre-mRNA, a protective cap is added to the 5’ end and a poly-A tail is added to the 3’ end.
What is a poly-A tail?
A tail of many adenine nucleotides that stabilizes the mRNA, prevents it from degradation in the cytoplasm, and allows it to be exported from the nucleus.
What are somatic cells?
Any cell that isn’t a reproductive cell.
What is a polygenic trait?
A trait influenced by multiple genes
What is a pleiotropic gene?
A gene that influences multiple traits.
What is translation?
The process by which the code is read and translated to make a protein. The second part of the central dogma
What are the steps to translation?
The 5’ end of mRNA connects to the ribosome. tRNA acts as interpreters of the mRNA sequence. Activated by an enzyme that attaches a specific amino acid to the 3’ end. This creates an anticodon that will match up to one of the mRNA codons, with the corresponding amino acid.
