DNA Reverse Complement Flashcards

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1. Kort 1

   Fråga

   In double-stranded DNA, which bases pair with adenine (A) and cytosine (C), respectively?

   Svar

   Thymine (T) pairs with A. Guanine (G) pairs with C.

2. Kort 2

   Fråga

   Two DNA strands are aligned base by base. The top strand has its 5′ end on the left. Which end of the bottom strand is on the left?

   Svar

   The 3′ end. The strands are antiparallel, so their directions are opposite.

3. Kort 3

   Fråga

   Write the complementary DNA strand directly below 5′–CATGGA–3′, pairing the bases in the same columns. Label its ends.

   Svar

   3′–GTACCT–5′

   The aligned partner runs 3′ to 5′ from left to right.

4. Kort 4

   Fråga

   A DNA strand is written 5′ to 3′. How do you get its reverse complement?

   Svar

   Pair each base, then read the paired bases in reverse order. The result gives the partner strand from its 5′ end to its 3′ end.

5. Kort 5

   Fråga

   What is the reverse complement of 5′–GTTCA–3′?

   Svar

   5′–TGAAC–3′

   The aligned partner is 3′–CAAGT–5′. Read it from the right.

6. Kort 6

   Fråga

   Which two bases fill the blanks in the bottom DNA strand, from left to right?

   5′–G C T A G–3′
   3′–C _ A _ C–5′
   

   Svar

   G, then T. They pair with C and A in the top strand.

   The completed bottom strand is 3′–CGATC–5′.

7. Kort 7

   Fråga

   Write the same DNA strand 5′ to 3′ if it is shown as 3′–TGGAC–5′.

   Svar

   5′–CAGGT–3′

   Start from the right. The bases stay the same because you're reading the same strand.

8. Kort 8

   Fråga

   Write the strand that pairs with 3′–ACCTGA–5′. Give your answer 5′ to 3′.

   Svar

   5′–TGGACT–3′

   The aligned partner already has its 5′ end on the left.

9. Kort 9

   Fråga

   Someone gives CGTGAC as the reverse complement of 5′–CAGTGC–3′. What step did they miss?

   Svar

   They still need to complement each base. CGTGAC is the original sequence read backward. The reverse complement is 5′–GCACTG–3′.

10. Kort 10

    Fråga

    A DNA strand ends with G at its 3′ end. What is the first base of its reverse complement, written 5′ to 3′?

    Svar

    C. The original 3′ end lines up with the partner's 5′ end, and C pairs with G.

11. Kort 11

    Fråga

    Write the reverse complement of 5′–ACGCTAA–3′.

    Svar

    5′–TTAGCGT–3′

    Pair the bases to get 3′–TGCGATT–5′, then read from the right.

12. Kort 12

    Fråga

    Is 5′–AGCATGCT–3′ a reverse-complement palindrome?

    Svar

    Yes. Its reverse complement is 5′–AGCATGCT–3′ again.

13. Kort 13

    Fråga

    Someone gives AGGCAT as the reverse complement of 5′–TCCGTA–3′. What step did they miss?

    Svar

    They still need to reverse the order. AGGCAT is the aligned partner read 3′ to 5′. Read it from the other end to get 5′–TACGGA–3′.

14. Kort 14

    Fråga

    A DNA strand's reverse complement is 5′–CGAACTG–3′. What was the original sequence, written 5′ to 3′?

    Svar

    5′–CAGTTCG–3′

    Taking the reverse complement a second time restores the original sequence.

15. Kort 15

    Fråga

    Find the exact + strand match to 5′–GATA–3′ on the printed + reference 5′–TCGGATACCAA–3′. Count the leftmost reference base as position 1 and include both ends of the match.

    Svar

    Positions 4–7 (+). Those bases read GATA from left to right.

16. Kort 16

    Fråga

    You split a 5′→3′ DNA sequence into a left block and a right block. Which block provides the 5′ end of the reverse complement?

    Svar

    The right block. The original 3′ end is on the right, across from the partner's 5′ end.

17. Kort 17

    Fråga

    An exact DNA query matches the + strand at reference positions 4–8. Which reference position holds the query's 5′ end?

    Svar

    Position 4. The query runs left to right on the + strand.

18. Kort 18

    Fråga

    To find a − strand match to 5′–GCTAC–3′, what sequence should you look for on the printed 5′→3′ + reference?

    Svar

    5′–GTAGC–3′

    That's the reverse complement of the query.

19. Kort 19

    Fråga

    Can a five-base DNA sequence made from A, C, G, and T equal its own reverse complement?

    Svar

    No. Its middle base would have to pair with itself, and each of those four bases pairs with a different base.

20. Kort 20

    Fråga

    Search the printed + reference 5′–ACTAGGATTCCTAGT–3′ for 5′–CTAGG–3′ on either strand. Give each exact match's strand and 1-based inclusive reference positions.

    Svar

    Positions 2–6 (+) and 10–14 (−).

    The reference has CTAGG at 2–6 and CCTAG, the query's reverse complement, at 10–14.

21. Kort 21

    Fråga

    One base in the bottom DNA strand is paired incorrectly. Which base should replace it, and at what position from the left?

    5′–A T C G C–3′
    3′–T A A C G–5′
    

    Svar

    G at position 3. The top strand has C there.

    The corrected bottom strand is 3′–TAGCG–5′.

22. Kort 22

    Fråga

    A window on the printed + reference is 5′–CGAG–3′. Does its − strand exactly match the query 5′–CTCA–3′?

    Svar

    No. The − strand at that span reads 5′–CTCG–3′. Its last base differs from the query.

23. Kort 23

    Fråga

    Find the exact − strand match to 5′–CCGA–3′ on the printed + reference 5′–GACTCGGAATC–3′. Give the 1-based inclusive reference positions.

    Svar

    Positions 4–7 (−). The printed bases at 4–7 are TCGG. The opposite strand reads CCGA in the 5′→3′ direction.

24. Kort 24

    Fråga

    An exact DNA query matches the − strand at reference positions 6–10. Which reference position holds the query's 5′ end?

    Svar

    Position 10. The query runs right to left on the − strand.

25. Kort 25

    Fråga

    A query of 5′–CGCG–3′ exactly matches the + strand at reference positions 3–6. How many strands match at that same span?

    Svar

    Two. CGCG equals its own reverse complement, so positions 3–6 match on both strands.

25 kort

DNA Reverse Complement Flashcards

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