The Evolution of Genes and Genomes:

Question 1

What is Parallel Phenotypic Evolution?

Answer 1

• The repeated evolution of similar traits, especially among closely related species
• Facilitated by conserved developmental genes.

Question 2

What are Hox Genes?

Answer 2

• Conserved homeotic genes found in vertebrates, Drosophila, and other animal groups.
• They contain the homeobox domain and specify pattern and axis formation in these animals.

Question 3

What is Homeobox?

Answer 3

• It is 180-Base-pair segment of DNA found in certain homeotic genes
• It regulates the expression of other genes and thus controls large-scale developmental processes.

Question 4

What is a pseudogene?

Answer 4

A DNA segment that is homologous to a functional gene but is not expressed because of changes to its sequence or changes to its location in the genome.

Question 5

What is a lateral gene transfer?

Answer 5

It is the transfer of genes from one species to another, common among bacteria and archaea

Question 6

What is a genome?

Answer 6

an organism’s full set of genes and non-coding portions of DNA.

Question 7

What is molecular evolution?

Answer 7

branch of biology dealing with the relationships between the structure of genes and the and proteins, and the functions of organisms.

Question 8

Why add a gap in an amino acid sequence?

Answer 8

accounts for insertions or deletion of amino acids.

Question 9

What is sequence homology?

Answer 9

Similarity due to sharing a common ancestor

Question 10

What is a homeodomain?

Answer 10

It is the 60 amino acids that are coded by the homeobox. It is a transcription factor that binds to a specific DNA sequence in the promoters of target genes.

Question 11

What is a genetic switch?

Answer 11

turns genes on or off (timing and spatial expression of genes)

Question 12

What is a genetic toolkit?

Answer 12

Highly conserved developmental mechanisms controlled by specific DNA sequences,

Question 13

How do genomes get more genes?

Answer 13

by lateral gene transfer ,pick up DNA fragments from the environment, viral infection, and hybridization.

Question 14

What is heterochrony?

Answer 14

genes that regulate the development of expression genes, for different durations in different species.

Question 15

A nucleotide substitution is a common mutation that can result in?

Answer 15

Change of one amino acid
=> different electrical charge of amino acid
=> change in structure of a protein
=>change the chemical/physical properties of that protein.

Question 16

Multicellular organisms have bigger genomes, but most of it is?

Answer 16

non-coding “Junk” DNA

Question 17

What are gene families?

Answer 17

different copies of genes that have undergone separate mutations, giving rise to groups of closely related genes.

Question 18

What are the four key processes that underlie development?

Answer 18

Determination (fate of cell)

• Differentiation (specific structures and functions)
• -Morphogenesis (organization and distribution of differentiated cells)
• –Growth (increase in size and body of the cell by cell division and expansion)

Question 19

Why are gaps added when comparing nucleotide and amino acid sequences between 2 or more organisms?

Answer 19

we use computers to look up and compare these . GAP accounts for insertion of amino acids or deletion.

Question 20

When nucleotide and amino acid sequences among organisms are compared, what do highly conserved sequences imply about organisms?

Answer 20

• There is similarity due to common ancestry (sequence homology)
• Have same/ if not, similar sequence variety, because DNA codes are probably the same.
• The protein was built the same way in the organism

Question 21

What observations about vertebrate embryos suggested that development genes were highly conserved among vertebrate animals?

Answer 21

• since, in the earliest stages we couldn’t tell the difference amongst the organisms; however, in the late stages, characteristics are more clear.

Question 22

Describe the effects genetic switches turning the genes on and off, in the expressions of Hox genes?

Answer 22

• it depends on organism as to which gene will be turned off
• it prevents them from being transcribed

Question 23

When genes are duplicated, the “original” copy of the gene usually functions in its normal way; there are four possible fates for the identical copy of the duplicated gene. What are those four facts?

Answer 23

1. Maintain its function-> make more gene product
2. Maintain function at different times or tissues
3. Substitutions in DNA sequences-> psuedogenes
4. Substitutions in DNA sequences-> new function

Question 24

General relationship between the “size” of an organism and the amount of “junk” DNA in that organism is:

Answer 24

Larger multicellular organisms have a lot of “junk” DNA; whereas unicellurlar organisms have little room for “junk” DNA.

Question 25

General relationship between “size” of organism and “size” of its genome:

Answer 25

• Multicellular organisms have bigger genomes

- Unicellular organisms have smaller genomes

Question 26

What is the current hypothesis about the purpose of “junk” DNA in an organisms genome?

Answer 26

• can affect degree of or timing of expression of surrounding genes
• maybe “psuedogenes”
• maintains chromosome structure

Question 27

What are methods of lateral gene transfer, that increase the number of genes in some organisms?

Answer 27

• Through transformation (picking up DNA fragments from environment)
• Through transduction (viral infection)
• Hybridization (in plants, which they can duplicate their genes)

Question 28

What are the 2 primary methods by which genes duplicate in some organisms?

Answer 28

by transformation and transduction