Part 3 Flashcards
(12 cards)
Look at the roles of transposable elements in disease
SINES and LINEs can induce mutations that can disrupt and or provide new regulatory sequences at their integrated sites. Most mutations are expected to be harmful to cell and associated with several inherited human diseases. Movement of transposable elements plays major role in genome evolution.
Understand why eukaryotes require complex packaging mechanisms and why prokaryotes do not
Eukaryotes have condensed histones which package long DNA into tiny nucleus
More complex
Prokaryotes are much smaller and so have less DNA
Look at the overall genomic organization of prokaryotes
Circular DNA molecules, genomes contained in single chromosome
Look at the significance of sequence repeats in human kinetochores
Centromeres are characterized by heterochromatin containing highly repetitive sequences, AIT are required are required for chromosomal stability
Look at the roles of telomeres in eukaryotes and prokaryotes
Telomeres are specialized sequences required to maintain the ends of eukaryotic chromosomes.
Chromosome maintenance (prevents/buffers degradation) and replication with repetitive DNA and simple sequence repeats of TTAGGG at the ends of chromosomes
Telomere DNA loops back on itself to form a circular structure and associates with a protein complex to protect the ends of chromosomes
Understand the mechanism of retro transposition and formation of pseudogenes
transposable elements are DNA sequences that can move to different sites in DNA.
Retrotransposons are transposable elements whose movement is caused by reverse transcription. How this happens is a DNA sequence is transcribed into an RNA sequence. A reverse transcriptase enzyme turns the RNA back into DNA and this new DNA sequence is inserted somewhere else in the genome.
There are multiple copies of a single gene. Pseudogenes is when one of the multiples of a gene is no longer functional due to a mutation in the DNA sequence. They lack introns and the normal chromosomal sequence that directs transcription of a gene into mRNA. So these genes have already been processed.
1. A segment of DNA is duplicated, causing a black of DNA sequence to be relocated.
- Retrotransposition is when reverse transcription of an mRNA takes place and then it is inserted somewhere else in the genome.
Look at the role of lncRNA has in X Chromosome inactivation
lncRNA (long non coding RNA) noncoding RNAs greater than 200 nucleotides - major regulators
Key element in x chromosome inactivation is a lncRNA called Xist binds to inactive X blocking transcription
What is epigenetic inheritance?
Transfer of infomration from parent to progeny that is not based on DNA sequence Many shares information carried by histones
Understand the basic function of replication factories and transcription hubs.
Replication factories: cellular structures that allow cells to generate new genetic material (DNA using original DNA as a template
Transcription Hub: Stationary structures that reel DNA templates while extruding resulting in RNA transcripts
What is the significance of the large number of lncRNA transcripts in humans compared to other organisms?
With human genome including 50000 lncRNA and the fact that a number of lncRNA is larger than the amount of protein coding genes suggest that lncRNA make substantial contribution to the biological complexity of higher eukaryotes.
How do miRNA and lncRNA differ in the way they regulate transcription?
miRNA regulates mRNA post transcriptionally while lncRNA acts on the transcription level
miRNA binds to RISC to regulate transcription while lncRNA is able to bind directly to mRNA alone
mRNA causes mRNA degradation while lncRNA alters chromatin which affects transcription activity
miRNA prevents translations lncRNA regulatory role
Look at the organization of chromatin in nucleosomes
Chromatin is organized into nucleosomes, where DNA wraps around a histone octamer. These nucleosomes are the basic units that compact DNA, regulate gene expression, and support proper chromosome function.
