Comparative Genome Analysis Flashcards
How do plant genomes differ to animal genomes?
Plants possess nuclear, mitochondrial and plastid DNA. Genome size and chromosome number varies heavily.
Are micro/megaspores haploid or diploid?
Haploid.
Is pollen haploid or diploid?
Diploid.
What is the plastid genome responsible for?
Translation, photosynthesis and RuBisCO production.
What is the mitochondrial genome responsible for?
Translation and respiration.
How do we know the size of plant genomes?
By using flow cytometry.
How do you perform flow cytometry?
Add leaf discs to lysis buffer. Extract nuclei and remove cell debris. Place in flow cytometry machine.
What is c-value?
The constant size of the haploid genome (measured in pg).
What is the c-value paradox?
Similar species can have quite different genome sizes and does not seem to relate to the number of genes encoded.
Why are some plant genomes so large?
Some include a lot of repetitive DNA like tandem and dispersed repeats.
What are Class 1 and Class 2 transposons?
Transposons are genetic elements that can jump between locations. Class 1 (retrotransposons) move via an RNA copy. Class 2 move via DNA.
What are the functions of telomeres?
To protect the chromosome ends and avoid shortening. They attach the chromosome to the nuclear envelope.
What is the plant telomere sequence?
TTTAGGG
What is the animal telomere sequence?
TTAGGG
Aside from their sequences, how do plant and animal telomeres differ?
Plant telomeres never shorten as plant meristems express telomerase.
What is the main function of centromeres?
They are the site for spindle attachment.
Where are most genes located in a chromosome?
In chromosome arms.
What is genome downsizing?
Loss of repetitive DNA.
What is aneuploidy?
Loss of whole chromosomes.
What is fractionation?
Loss of a whole pair of chromosomes.
Define synteny.
Conservation of blocks of gene order along chromosomes amongst different related species.
Why is synteny useful?
It allows chromosomes to be mapped onto each other. This helps to understand evolution.
Define comparative genomics.
Genomic features of different organisms are compared.
What are orthologous sequences?
Sequences that share a common ancestor.
What are paralogous sequences?
Gene copies created by duplication.
Why is comparative genomics important?
Can identify conserved sequences which are essential to life. Useful for studying evolution.
