Chapter 24

Question 1

Genomics

Answer 1

Comparing genomes (entire D N A sequences) of different species provides a powerful new tool for exploring the evolutionary divergence among organisms

Question 2

Comparative Genomics

Answer 2

Genomes of viruses and bacteria evolve in a matter of days​

Complex eukaryotic species evolve over millions of years

Question 3

Plant, fungal, and animal genomes have unique and shared genes

Answer 3

3814 gene families are shared by every plant.​

Move onto land arose in 3006 new gene families.​

Moss and flowering plants very different but share 80% of developmental genes.​

Mosses to plants with internal transport required 516 more gene families.​

Transition to flowering plants required 1350 more gene families.

Question 4

Compare plants with animals and fungi

Answer 4

Of remaining genes, many are similar to those found in animal and fungal genomes

Question 5

Genome Size

Answer 5

Genome size and gene number vary greatly among eukaryote species

Question 6

Polyploidy

Answer 6

Three or more chromosome sets

Question 7

Autopolyploids

Answer 7

genome duplication within a single lineage.

Question 8

Allopolyploids

Answer 8

hybridization of two lineages followed by genome duplication

Question 9

Paleopolyploids

Answer 9

ancient polyploids

Question 10

Synthetic polyploids

Answer 10

Crossing plants most closely related to ancestral species and chemically inducing chromosome doubling.

Question 11

Polyploidy can alter gene expression

Answer 11

During early generations after polyploidization, changes in gene expression are observed

Question 12

Barbara McClintock

Answer 12

Hypothesized that transposons could be mobilized by genome shock.

Question 13

Transposable

Answer 13

(mobile) genetic elements

Question 14

Aneuploidy

Answer 14

Gain or loss of an individual chromosome

Question 15

Gene duplication

Answer 15

One of the greatest sources of novel traits

Question 16

Paralogues

Answer 16

two genes within an organism that have arisen from the duplication of a single gene in an ancestor

Question 17

Orthologues

Answer 17

reflects conservation of a single gene from a common ancestor

Question 18

Conservation of synteny

Answer 18

when the common ancestral sequence has been preserved in both species

Question 19

Gene inactivation

Answer 19

Loss of gene function

Question 20

Olfactory receptor (OR) genes

Answer 20

Inactivation best explanation for our reduced sense of smell relative to other mammals

Question 21

Noncoding D N A

Answer 21

Much of the genome is noncoding-D N A (ncD N A)​

Repetitive D N A is often retrotransposon D N A​

30% of animal and 40–80% of plant genomes

Question 22

Conserved noncoding regions (C N Cs)

Answer 22

evolve more slowly than expected assuming no function

Question 23

Horizontal gene transfer (H G T)

Answer 23

Genes hitchhike from other species​

Also called lateral gene transfer.​

Can lead to phylogenetic complexity.​

Likely most prevalent very early in the history of life.

Question 24

vertical gene transfer (V G T)

Answer 24

genes passed generation to generation

Question 25

Gene Function and Expression Patterns

Answer 25

Inferred by comparing genes in different species

Question 26

Comparing chimp and human cerebral organoids

Answer 26

383 genes up-regulated in radial glial cells ​

220 genes up-regulated in excitatory neurons. ​

285 genes down-regulated in radial glial cells​

165 genes down-regulated in excitatory neurons​

Question 27

Cerebral organoids

Answer 27

pluripotent stem cells are induced to differentiate into neural tissue that includes radial glial cells and excitatory neurons

Question 28

FOXP2 gene

Answer 28

speech and grammar but not language comprehension

Question 29

Conservation biology

Answer 29

Tasmanian devil facial tumor disease.​

Since 1996, 60% of devils have died.​

Low genetic diversity allows transmission.​

Giant panda population diversity.​

Destruction of bamboo resulting in decline of pandas.​

They lack key genes for digestion — must be in microbiome.​

Polar bear facing extinction.​

Warm temperatures melt their sea ice homes.​

Maternal line from a single brown bear 20,000 to 50,000 years ago.