Gene and genome evolution #5

Question 1

What is DNA?

Answer 1

DNA is a sequence of four repeating nucleotides that provide structural support to chromosomes.

Question 2

What are the types of genomes?

Answer 2

The types of genomes are nuclear, mitochondrial, and chloroplast (in plants).

Question 3

What are the types of DNA?

Answer 3

The types of DNA are coding and non-coding.

Question 4

Who discovered the first viral RNA genome?

Answer 4

Fiers discovered the first viral RNA genome (bacteriophage MS2) in 1976.

Question 5

Who discovered the first DNA genome?

Answer 5

Sanger discovered the first DNA genome (phage Φ-X174) in 1977.

Question 6

When was the entire genome of Watson sequenced?

Answer 6

The entire genome of Watson was sequenced in 2007.

Question 7

When was the entire Neanderthal genome sequenced?

Answer 7

The entire Neanderthal genome was sequenced in 2013.

Question 8

Is there a correlation between genome size and complexity?

Answer 8

No, there is no correlation between genome size and complexity.

Question 9

What is the relationship between total DNA and the amount of coding sequence?

Answer 9

The relationship between total DNA and the amount of coding sequence varies. Smallest size (bacterium) and largest size (amoeba) have mostly coding sequences, while unicellular eukaryotes have intermediate amounts.

Question 10

hat types of organisms have mostly non-coding DNA?

Answer 10

Most animals and plants have mostly non-coding DNA.

Question 11

What is junk DNA?

Answer 11

Junk DNA is non-coding DNA that does not code for functional genes.

Question 12

What are transposable elements (TEs)?

Answer 12

Transposable elements (TEs) are DNA segments that can move or jump within a genome.

Question 13

What is “selfish” DNA?

Answer 13

“Selfish” DNA is genetic segments that can enhance their own transmission at the expense of other genes in the genome.

Question 14

Is the complexity of an organism related to genome size or gene number?

Answer 14

No, the complexity of an organism is not related to genome size or gene number. Instead, genomes are the messy outcomes of evolutionary processes.

Question 15

What are the mechanisms of genome evolution?

Answer 15

The mechanisms of genome evolution are duplications, retrotransposition, whole genome duplication, horizontal gene transfer, de novo genes, and gene death.

Question 16

What is gene duplication?

Answer 16

Gene duplication is the duplication of any region of DNA that contains a gene.

Question 17

What is tandem duplication?

Answer 17

Tandem duplication is when gene copies are located adjacent to each other on a chromosome.

Question 18

What is retrotransposition?

Answer 18

Retrotransposition is when mRNA is transcribed to DNA and inserted back into the genome without introns.

Question 19

What is exon shuffling?

Answer 19

Exon shuffling is a process in which mixtures of exons are duplicated from genes with different functions. This can result in new genes with new functions.

Question 20

Can gene duplication lead to neofunctionalization?

Answer 20

Yes, gene duplication can lead to neofunctionalization, where one copy of the duplicated gene retains its original function while the other evolves a new function.

Question 21

What is an example of neofunctionalization?

Answer 21

An example of neofunctionalization is the RNASE1B gene in the douc langur. RNASE1 is an enzyme that aids digestion in vertebrates, while RNASE1B works in low-pH environments (i.e., monkey gut) to digest symbiotic bacteria that help with leaf fermentation.

Question 22

What is subfunctionalization?

Answer 22

Subfunctionalization is a process in which a duplicate gene and the parental copy carry out partial roles of a complete function.

Question 23

What is an example of subfunctionalization?

Answer 23

An example of subfunctionalization is foetal haemoglobin, which has a higher affinity for oxygen than adult haemoglobin. Foetal haemoglobin is shut off after birth, and adult haemoglobin takes over.

Question 24

What is whole genome duplication?

Answer 24

Whole genome duplication involves the entire genome of a single species being doubled (autopolyploid) or two species hybridizing.

Question 25

What is an example of whole genome duplication?

Answer 25

An example of whole genome duplication is the allotetraploid goatsbeard, which resulted from the hybridization of two diploid species.

Question 26

What is horizontal gene transfer?

Answer 26

Horizontal gene transfer is the acquisition of new genes from another species. This is usually between distantly related organisms and is particularly important in prokaryotes.

Question 27

What is an example of horizontal gene transfer?

Answer 27

An example of horizontal gene transfer is antibiotic resistance genes being transferred between bacteria.

Question 28

What are de novo genes?

Answer 28

De novo genes are new genes that arise from mutations in non-coding DNA, such as a mutation that turns on transcription of a downstream stretch of DNA.

Question 29

What is the fate of most new genes?

Answer 29

Most new genes are lost due to their low frequency, which often leads to their loss by random genetic drift and/or selection. Only a small fraction of new genes remain as functional genomic features, often due to their adaptive function.

Question 30

Can deletions play a role in gene trafficking?

Answer 30

Yes, deletions can play a key role in gene trafficking, which is the movement of genes to new locations in the genome. Deletions can result in a gene being moved from one location to another.