Topic 4 - Dynamic Genomes Flashcards
Define synteny
The term used to describe the preserved order of genes along a chromosome, or region of chromosome, indicative of a shared common ancestral chromosome.
Define paleoploidy
The state of genome or chromosome ploidy in evolutionary common ancestral organisms implied by the genome analysis of present-day organisms.
Define paralogues
Genes within the same species that share a common ancestor through duplication event.
What features of DNA sequence contribute to the differences in C-value between organisms?
You may have thought of highly repetitive sequences (often called satellites and microsatellites), the presence of introns, RNA-encoding genes and transposons.
What are Pseudogenes?
Non-functional copies of a gene, which, if transcribed, produce an inactive protein.
What is pseudotetraploid?
The state of an organism’s genome reflecting incomplete tetraploidy, often through chromosome loss. Organisms can become tetraploid (i.e. have two sets of their diploid genome) by alloploidy (the two sets originate in ancestrally related, but separate species) or autoploidy (the two sets originating in the same species).
What is the function of histone proteins?
Histones are protein components of chromosomes; they assemble to form a multimeric complex around which the DNA winds as part of the compaction process to form a chromosome.
Within which cellular areas are ribosomes found in a eukaryote?
Ribosomes are found at the rough endoplasmic reticulum and also in the cytosol.
Recall an example of a polyploid organism
An example might be the hexaploid common wheat, and also the pseudotetraploid X. laevis.
In addition to the order of genes along a chromosome, which other feature of genes could be used for comparisons when looking for synteny? (Hint: Consider how the coding region of a gene is split.)
The position of introns and exons, as well as transcriptional orientation, in regions of synteny, would also be expected to be similar.
In addition to the order of genes along a chromosome, which other feature of genes could be used for comparisons when looking for synteny? (Hint: Consider how the coding region of a gene is split.)
The position of introns and exons, as well as transcriptional orientation, in regions of synteny, would also be expected to be similar.
Which two lines of evidence based upon gene/protein sequence and chromosome structure can provide evidence for duplication events?
Comparison programmes such as BLAST, which identify genes/proteins of similar sequence and synteny, can be used to identify conserved gene order, both indicative of duplication events.
What is the 2R hypothesis?
The hypothesis, now accepted, that the evolution of vertebrates involved two whole genome duplications (WGDs).
Recall the meaning of the term synteny.
Synteny is the shared order of genes along a stretch of an ancestral chromosome that is shared in the descendants from that common ancestor.
What are orthologues?
This term is used to describe all genes that are derived from a common ancestral gene that are found in different species. These often retain the same function in both species. For example, the human β-globin gene and the mouse β-globin genes are orthologues. Similarly, the mouse FEN1 gene and human FEN1 gene are orthologues.
