13. Eukaryotic Chromosome and Gene Structure

Question 1

Nucleosome

Answer 1

DNA is wrapped around a nucleosome core (octomer or histones) (Genes available)

Question 2

Solenoid

Answer 2

Nucleosomes folded into a spiral structure (Genes unavailable)

Question 3

Constitutive Heterochromatin

Answer 3

Portions of the genome that are always found in heterochromatin; includes centromeres and telomeres

Question 4

Facultative Heterochromatin

Answer 4

Portions of the genome made heterochromatic for regulatory or developmental reasons; e.g. Barr bodies

Question 5

Telomere Replication

Answer 5

Uses telomerase, which has a built-in RNA template and decreases in activity as one ages, which shortens the telomeres

Question 6

Gene Families

Answer 6

Related genes that are located near each other on a chromosome

Question 7

Pseudogenes

Answer 7

Regions that look like that they should be genes; no functional end product; often lack promoters or are transcribed and not translated; can be processed (full mRNA is retrotransposed back into genome) or nonprocessed (duplications and mutations render gene nonfunctional); termed evolutionary detritus

Question 8

Replicative Transposons

Answer 8

Transposons replicate themselves in the genome; yeast mating example

Question 9

Nonreplicative Transposons

Answer 9

Transposons leave donor DNA with a double-stranded break and then insert themselves into a new place; damaging to genome and sometimes found among viruses

Question 10

Conservative Transposons

Answer 10

Transposons move from one place to another with full conservation of DNA at both sites

Question 11

Satellites

Answer 11

Highly repetitive sequences found in heterochromatic areas; unknown function but thought to be related to centromere construction

Question 12

Multiple Copy Genes

Answer 12

Moderately repetitive sequences that are copied numerous times in a chromosomes

Question 13

Mini-Satellites

Answer 13

Short sequences (15-100 bases) with tandem repeats

Question 14

Micro-Satellites

Answer 14

Smaller sequences (<15 bases) of tandem repeats; tendency to see a lot of CA repeats

Question 15

SINES

Answer 15

Short Interspersed Elements; less than 500 bases and repeated hundreds of thousands of times; composes about 11% of human genome (e.g. Alu family)

Question 16

LINES

Answer 16

Long Interspersed Elements; several thousand bases long and copied up to 100,000 times; some contain genes for transposition; make up about 21% of human genome (e.g. L1 family makes up 14% by itself)

Question 17

Matrix Attachment Regions

Answer 17

Short sequences where protein scaffolding in the nucleus attaches to DNA

Question 18

Shape of Mitochondrial DNA

Answer 18

Circular (though most genes have migrated to nuclear genome)

Question 19

Evidence for Endosymbiont Theory

Answer 19

Circular DNA
No nucleus
Antibiotics (Prokaryotic directly effect, eukaryotic doesn’t)
rRNA is similar to prokaryotes (more similar to bacteriophages)
Intermediates: Cyanophora paradoxa, Rickettsia, and Trichomonads

Question 20

Mitochondrial Eve

Answer 20

A woman whose mitochondrial lines are the origin of all surviving mitochondrial lines