1/28/2025 Genome/Chromosome Organization Flashcards
what are the essential differences between prokaryotic and eukaryotic chromosomes
A. size of the cell
B. prokaryotic have circular genomes whereas eukaryote are linear
C. eukaryotic genomes are larger
D. prokaryotes do not have ribosomes
E. Prokaryotes don’t have internal membrane structures such as a nucleus or endoplasmic reticulum
A, B, C, and E
what is the main function of the genetic material? how does it do this?
the main function of the genetic material is to store the information required to produce an organism
the DNA molecule does this through its base sequence
what is a structural gene
a structural gene is a gene that codes for proteins that are a part of a cell’s structure or preform specific functions
what is a non-structural gene
they code for RNA molecules that are not translated into proteins
what is the final product of a non-structural gene after it is transcribed?
an RNA molecule, it is not translated and the final product is made at the transcription
what is repeat DNA
they are repetitive DNA sequences that may be functional or archaic in usage and we dont know what they do
ex. ) centromere, telomere
Viral genomes can be? (3 statements)
DNA or RNA
single stranded or double stranded
circular or linear
why are viral genome’s so small in comparison to bacterial genomes?
because viruses are stripped down and need less machinery since they hijack their hosts and need less genetic information to function
what does it mean when a virus is self assembled
during the infection process, the genetic material and capsid proteins that make up the virus will spontaneously bind and everything will be shipped out together
what type of assembly do simple viruses undergo
self assembly
what type of assembly do more complex viruses undergo
directed assembly
what happens in direct assembly of a virus
the viral genome requires proteins that may not be part of the virus itself, these are noncapsid proteins
what is the role of a noncapsid protein
they carry out the assembly process but are left behind (ie. scaffolding proteins)
they act as proteases that often cleave viral capsid proteins
what is a nucleod
it is where the DNA exists in a prokaryotic cells
when an RNA is made in a bacterial cell, why can the ribosome process it quicker than a eukaryotic cell?
there is no membrane or nucleus separating the RNA and the ribosome
why do humans and bacterial genomes have similar numbers of structural gene sequences, yet humans have much larger genomes?
bacterial genomes are optimized to be jam packed with genes and do not have much intergenic regions in between
this makes them more efficient and streamlined in replication
they also have overlapping regions on their double stranded DNA, further optimizing their space
what is an intergenic region
it is the nontranscribed space between genes on a DNA strand, humans have more space than bacterial genes
what is the first level of compaction in a prokaryotic DNA
the DNA forms loops and folds on itself and binds with stabilizing binding proteins that pinch the loops in
what is the second level of bacterial chromosome compaction
DNA supercoiling
what is positive DNA supercoiling
it is where the DNA is turned more to the right (8base pairs per turn) and it buckles in on itself to form 10 bp again
what is negative supercoiling
it is where the DNA is forced to turn in the direction opposite of its natural helix, this may cause the helix to be 12 bp per turn which will cause it to buckle in on itself to get the 10 again
if we turn a left handed helix towards the right, what kind of supercoiling is it
negative supercoiling/ underwinding
when a noncapsid protein in a viral genome acts as a protease and cleaves viral capsid proteins what happens
this yields smaller capsid proteins that assemble correctly
