Vallian Ch3

Question 1

What is the main characteristic of transposable elements that transpose through an RNA intermediate?

Answer 1

They can either encode reverse transcriptase or not, with the viral family being able to do so and some nonviral families, like retropseudogenes, unable to encode reverse transcriptase.

Question 2

RNA Intermediate Transposition

Answer 2

A mechanism where transposable elements move through an RNA intermediate, which can include the ability to encode reverse transcriptase.

Question 3

How does transposition through a DNA intermediate differ from RNA-mediated transposition?

Answer 3

Transposition through a DNA intermediate involves transposons moving directly as DNA, while RNA-mediated transposition involves an RNA intermediate.

Question 4

DNA Intermediate Transposition

Answer 4

A less common mechanism of transposition where transposable elements move directly as DNA rather than through an RNA intermediate.

Question 4

What are Non-LTR retrotransposons?

Answer 4

Elements that lack long terminal repeats and contain genes for reverse transcriptase and other proteins, categorized mainly into LINEs and SINEs.

Question 5

What is a key feature of LINEs regarding their transcription?

Answer 5

LINEs are transcribed with an RNA polymerase II promoter, leading to the production of an adenine-rich transcript that prevents degradation.

Question 5

Non-LTR Retrotransposons

Answer 5

A type of retrotransposon that lacks long terminal repeats and can be classified into LINEs and SINEs, important for genome evolution.

Question 6

LINEs

Answer 6

Long Interspersed Elements that are transcribed into RNA and serve as intermediates for transposition into new genomic locations.

Question 7

How do LINEs insert into the genome?

Answer 7

They insert into AT-rich regions by cutting one DNA strand and using reverse transcriptase to synthesize and integrate themselves.

Question 8

LINEs

Answer 8

Long Interspersed Elements that are transcribed into RNA and serve as intermediates for transposition into new genomic locations.

Question 9

How do LINEs insert into the genome?

Answer 9

They insert into AT-rich regions by cutting one DNA strand and using reverse transcriptase to synthesize and integrate themselves.

Question 10

Mechanism of Insertion for LINEs

Answer 10

The process by which LINEs insert into the genome by cutting DNA strands and synthesizing retrotransposons using reverse transcriptase.

Question 10

How prevalent are LINE-1 elements in the human genome?

Answer 10

LINE-1 elements are abundant in the human genome, with around 500,000 copies.

Question 10

LINE-1 Elements

Answer 10

A type of retrotransposon found abundantly in the human genome that can disrupt genes and link to diseases like cancer.

Question 11

What products are encoded by the human LINE1 gene?

Answer 11

The human LINE1 gene encodes proteins for nucleic acid binding, protein-protein interactions, a nuclease, reverse transcriptase, and cysteine/histidine-rich proteins.

Question 12

Human LINE1 Gene Products

Answer 12

Proteins produced by the human LINE1 gene that facilitate transposition and integration into the genome, including reverse transcriptase.

Question 13

What does the structure of human L1 include?

Answer 13

The structure of human L1 includes genomic DNA, untranslated regions, and open reading frames (ORF1 and ORF2).

Question 14

Human L1 Structure

Answer 14

The composition of the human L1 retrotransposon, which consists of genomic DNA, untranslated regions, and open reading frames for functional proteins.

Question 15

What are SINEs, and how do they differ from LINEs?

Answer 15

SINEs are short interspersed elements that resemble RNA polymerase II-transcribed genes but lack reverse transcriptase and rely on LINEs for transposition.

Question 16

SINEs

Answer 16

Short Interspersed Elements that are non-coding, depend on other transposons for movement, and are typically associated with tRNA-derived sequences.

Question 17

What are Alu elements?

Answer 17

The most common SINEs in primates, about 350 base pairs long, that do not encode proteins and are implicated in various genetic diseases.

Question 18

Alu Elements

Answer 18

A type of short interspersed element prevalent in primates, significant in genetic variability and disease, and recognized by the AluI restriction enzyme.

Question 18

What are SINE-VNTR-Alus (SVAs)?

Answer 18

A unique family of retrotransposons specific to hominids, that incorporates Alu elements and contains variable repeats, shorter than LINEs but longer than SINEs.

Question 18

SINE-VNTR-Alus (SVAs)

Answer 18

A family of retrotransposons with Alu elements and variable repeats, contributing to genomic diversity, and existing in several subfamilies.

Question 19

How are SINEs involved in transposition?

Answer 19

SINEs rely on other transposons like LINEs to facilitate their transposition, as they cannot encode reverse transcriptase themselves.

Question 20

Transposition Mechanism of SINEs

Answer 20

The process by which SINEs depend on the transposition machinery of other elements, mainly LINEs, to move within the genome.

Question 21

What role do LINEs and SINEs play in genome evolution?

Answer 21

LINEs and SINEs contribute significantly to genome variability and evolution by facilitating genetic rearrangements and introducing new sequences.