General Genetics
Define Allele
Alleles are alternative forms of genes
BB for brown eyes; bb for blue eyes
One double stranded DNA will make 2 strands of mRNA, one for each strand per replication cycle. (T/F)
False, bonus what is the term that describes how only one strand of DNA is used for transcription
Where does transcription occur in eukaryotes?
In the nucleus
Transcription is asynchronous with translation in prokaryotes (T/F)
False
Why are genes regulated?
To respond to their environment
Plasmids encode for essential genes T/F
False
What is the function of DNA ligase
To join DNA strands together by forming phosphodiester bonds, whether it be for DNA replication or DNA repair.
What role do sigma factors play in transcription?
They help bind RNA polymerase with DNA to during a bacteria's initiation step of transcription.
Fun fact: the eukaryotic equivalent of sigma factors are transcription factors
How is translation terminated
Stop codons signal the dissembling of the ribosome
The lac operon has gene encodes a protein that can repress the operon. What kind of feedback is this
Negative
The same phenotype can have different genotypes (T/F)
True
A eukaryotic DNA strands thats NOT replicating or transcribing will be found in this form.
they'll be wrapped around a bunch of histone proteins in the form called the nucleosome. They do this so they can fit in the tiny a** nucleus.
Where does the coding strand in DNA get its name?
It resembles the mRNA strand that is used to create polypeptides
Define Alternative Splicing
process by which exons or portions of exons or noncoding regions within a pre-mRNA transcript are differentially joined or skipped, resulting in multiple protein being encoded by a single gene
How are genes regulated Posttranscriptional?
through attenuation. ( premature stoppage)
Fun fact: this only occurs in prokaryotes due to the fact that transcription and translation is coupled.
Outside their nucleoid/nucleus, Prokaryotes and Eukaryotes can carry genes in their ___ and their ___ respectively.
Plasmid/mitochondria/chloroplast
What is the role of telomeres?
To control the number of replications a cell can do while telomerase regulates cell death. ( it also prevents premature death)
In eukaryotes, the modified portion of mRNA that ends up being translated into a polypeptide is called
exon
What does it mean for a bacteria to be polycistronic
It means that one transcribed mRNA can code for multiple gene products
What is the molecule that induces catabolite repression of the lac operon
Glucose
DNA strands are complimentary to one another and are oriented in opposite directions. What is the term for this?
Antiparallel
During replication, why does one strand have to lag?
The lagging strand is oriented in the opposite direction of where the replication fork is moving, and since nucleotides are always added 5’ to 3’, it has to lag to be able properly read and code the DNA.
Describe the two types of termination signals in prokaryotes
Rho-independent or intrinsic termination is facilitated by two sequences in the RNA
Why is Wobble and Degeneracy useful in coding for proteins?
They reduce the chance of mutations as errors in the 3rd base of a codon. As a result, a mutation here often times does not affect the resulting amino acid.
What is the purpose of the lac operon anyways and what happens when both glucose and lactose are present?
It serves to create lactase in order to break down and metabolize lactose HOWEVER Glucose is the organism's metabolite of choice meaning that the lac operon will be repressed if any glucose is present.
tldr; bacteria like glucose, if glucose there, it don't care if lactose is there or not and will not care to break it down.