Ch 6 Lecture (Clusters and Repeats)

Question 1

Gene Family

Answer 1

A set of genes within a genome that encode related or identical proteins or RNAs

Question 2

Pseudogenes

Answer 2

Inactive but stable components of the genome derived by mutation of an ancestral active gene

Question 3

Gene Clusters

Answer 3

A group of adjacent genes that are identical or related

Question 4

Unequal Crossover

Answer 4

Recombination that occurs between sites that are similar but not perfectly aligned

Increases the number of repeats on one chromosome and decreases on the other

Question 5

Unequal crossing over within a gene cluster, but between genes, results in:

Answer 5

Increase in the number of repeats on one chromosome

Decrease in the number of repeats on the other

Question 6

If crossing over occurs within a gene, the result depends on the similarity of the genes:

Answer 6

If the genes are nearly identical, there is little change in the sequence of either gene

If the genes are not identical, the recombination genes will be different from either of the original genes

Question 7

Duplication of a gene results in:

Answer 7

Relaxation of selective pressure on one of the copies

Selective pressure diffused until one mutates

Selective pressure is refocused on the less mutated gene

Question 8

When changes accumulate more rapidly in one gene copy:

Answer 8

Pseudogene can form

Development of a new function, leading to a reduction in mutation rate
–now more advantageous to have 2 copies

Question 9

Interrupted genes:

Answer 9

Reduce the chances of unequal crossover

Question 10

rRNA

Answer 10

The primary product of transcriptional events in a cell

80-90% of cellular RNA

Question 11

Two Types of rRNA Genes in Eukaryotes

Answer 11

Small rRNA

Large rRNA precursor

Question 12

Small rRNA

Answer 12

5S rRNA tandem repeats

Question 13

Large rRNA Precursor

Answer 13

45S rRNA tandem repeats

Processed into 18S, 5.8S, and 28S rRNA

snoRNA “guide RNAs” required for processing

Question 14

Nucleolus

Answer 14

Region of nucleus where rRNA synthesis, processing and ribosomal subunit synthesis occurs

Question 15

Satellite DNA

Answer 15

Highly repetitive DNA has a very short repeating sequence and no coding function

Question 16

Minisatellites

Answer 16

Repeating unit length is 10-100 bp

Greater number of repeats than microsatellites

Rate of crossover at minisatellite loci is 10X that of other parts of the genome

Question 17

Microsatellites

Answer 17

Repeating unit length is < 10 bp

Question 18

Variable Number of Tandem Repeats (VNTR)

Answer 18

Microsatellites that have < 20 repeats and a 2-6 bp repeat

Question 19

Minisatellite variability is produced by:

Answer 19

Unequal crossing over

Question 20

Microsatellite and VNTR variability is produced by:

Answer 20

Intrastrand misfiring and slippage during replication

Question 21

4 chromosomal mutations

Answer 21

insertions
deletions
inversions
translocations

Question 22

most common gene clusters

Answer 22

rRNA and histone proteins

Question 23

how do clusters usually form

Answer 23

unequal crossing over

Question 24

why do interrupted genes reduce the chances of unequal crossing over

Answer 24

the introns are not similar enough

Question 25

number and location of rRNA in prokaryotes

Answer 25

1-10 copies
throughout the genome

Question 26

number and location of rRNA in eukaryotes

Answer 26

100+ copies
clustered by telomeres
organized as tandem repeats

Question 27

what is a use for guide RNA in the lab

Answer 27

CRISPR

Question 28

the nucleolus disappears during

Answer 28

M phase

Question 29

satelite DNA is a major constituent of

Answer 29

centromeric heterochromatin

Question 30

microsatellite and minisatellite loci can be used for

Answer 30

gene mapping and DNA fingerprinting