Genomes Of Prokaryotes And Eukaryotic Organelles

Question 1

pan-genome

Answer 1

represents the entire set of genes
within a species, consisting of:
A core genome
The accessory genome

Question 2

a core genome

Answer 2

containing all the genes shared
between all individuals of the species

Question 3

accessory genome,

Answer 3

the entire collection of additional genes in all strains and isolates of a
species

Question 4

Closed pan-genome:

Answer 4

Do not add many genes per each sequenced genome. Stable pangenome size. It has a large core and small accessory genome.

Question 5

Open pan-genome:

Answer 5

Adds many genes per each additional sequenced genome. It is constantly growing. Small core and large accessory genome.

Question 6

Conjugation

Answer 6

• Physical contact between two bacteria
• One-way transfer of chromosomal or plasmid DNA
• DNA transfer through narrow tube (pilus)
• Conjugative plasmids carry genes required to perform the conjugation event (e.g. F plasmid)
• F+ bacteria produces pilus that attaches to a recipient cell (F-), a ssDNA is transferred through
the pilus and both cells synthesize a complementary strand. Now both are F+.

Question 7

Transduction

Answer 7

Transfer of donor cell DNA via bacteriophage (e.g. lambda phage)

Question 8

Transformation

Answer 8

Transfer of naked DNA from dead (lysed) donor cells to recipient cell in a state of competence (induced in the lab, or in nature is a natural response to specific environmental conditions)

Question 9

The E. coli pan-genome is an…

Answer 9

Open pan-genome, because it is not stabilized yet.
Species with a closed pan-genome and few accessory genes
have a more limited ecological range

Question 10

Metagenomics

Answer 10

The study of genetic material recovered directly from environmental
samples (also “environmental genomics”, “ecogenomics”, “community genomics”).

Question 11

Extranuclear genes

Answer 11

genes located outside the nucleus.
Mitochondria and chloroplasts contain independent and distinct genomes from the nuclear genome, that are subjected to its own form of expression and regulation.

Question 12

Non-mendelian inheritance

Answer 12

Eukaryotic organelles follow Non-mendelian inheritance, a
pattern of inheritance that does not follow the Mendelian
principles of segregation (where each parent contributes to a
single allele). The distribution of alleles is random.

Extreme non-mendelial inheritance it can lead to uniparental
inheritance, when the genotype of only one parent is inherited. Maternal inheritance is very common (e.g. mammals)

Question 13

Endosymbiotic theory:

Answer 13

Mitochondria and chloroplasts are the relics of free living bacteria that formed an symbiotic association with the precursor of the eukaryotic cell, at the very early stages of evolution.

Question 14

Mitochondria and chloroplasts are endosymbionts, based in the observation that:

Answer 14

Organelle genomes are independent of and distinct from eukaryotic nuclear genomes
Gene expression and gene sequences in organelles are similar to those found in bacteria

Question 15

Mitochondrial genomes:

Answer 15

• Size: From 5 to 400 kb
• Number of genes: From 3 to 100 genes
• Content: It encodes 2 major rRNA, some tRNA (from none to all) and the
components of the respiratory complex

Question 16

Chloroplast genomes:

Answer 16

• Size: Relatively larger (60-217 kb)
• Number of genes: Around 200 genes
• Content: It encodes for all the rRNAs, all the tRNAs, photosynthetic proteins and extra proteins like RNA polymerase and ribosomal proteins.

Question 17

Production of proteins in the organelle

Answer 17

Organellar genomes produce some of the proteins found
in the organelle, but not all of them. The other proteins
are encoded from nuclear genes, synthesized in the
cytoplasm and transported into the organelle.

Question 18

Hairpin telomeres,

Answer 18

a covalently closed DNA hairpin loop at the end of the chromosome. It solves the end-replication problem
and protects DNA exposed ends.

Question 19

multipartite genome

Answer 19

a genome
divided into 2 or more DNA molecules.