DNA Reverse Complement Flashcards

Practice finding DNA reverse complements, reading 5′ and 3′ labels, and locating exact matches on either DNA strand.

Bu deste hakkında

Start by pairing DNA bases and labeling the ends of the complementary strand. Then find reverse complements, work backward to the original sequence, and spot when a wrong answer skipped the pairing or the reversal.

Use the same direction check to find exact matches on the + and − strands and give their positions on the printed reference. You’ll also see how a reverse-complement palindrome can match both strands at the same span.

Every sequence example is original and artificial. The cards use A, C, G, and T and exact matches so you can focus on strand direction. RNA, approximate searches, and primer design need additional rules and are outside the scope.

Bu destedeki kartlar

  1. Kart 1

    Soru

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

    Cevap

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

  2. Kart 2

    Soru

    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?

    Cevap

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

  3. Kart 3

    Soru

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

    Cevap

    3′–GTACCT–5′

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

  4. Kart 4

    Soru

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

    Cevap

    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. Kart 5

    Soru

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

    Cevap

    5′–TGAAC–3′

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

  6. Kart 6

    Soru

    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′
    

    Cevap

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

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

  7. Kart 7

    Soru

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

    Cevap

    5′–CAGGT–3′

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

  8. Kart 8

    Soru

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

    Cevap

    5′–TGGACT–3′

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

  9. Kart 9

    Soru

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

    Cevap

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

  10. Kart 10

    Soru

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

    Cevap

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

  11. Kart 11

    Soru

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

    Cevap

    5′–TTAGCGT–3′

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

  12. Kart 12

    Soru

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

    Cevap

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

  13. Kart 13

    Soru

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

    Cevap

    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. Kart 14

    Soru

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

    Cevap

    5′–CAGTTCG–3′

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

  15. Kart 15

    Soru

    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.

    Cevap

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

  16. Kart 16

    Soru

    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?

    Cevap

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

  17. Kart 17

    Soru

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

    Cevap

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

  18. Kart 18

    Soru

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

    Cevap

    5′–GTAGC–3′

    That's the reverse complement of the query.

  19. Kart 19

    Soru

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

    Cevap

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

  20. Kart 20

    Soru

    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.

    Cevap

    Positions 2–6 (+) and 10–14 (−).

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

  21. Kart 21

    Soru

    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′
    

    Cevap

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

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

  22. Kart 22

    Soru

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

    Cevap

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

  23. Kart 23

    Soru

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

    Cevap

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

  24. Kart 24

    Soru

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

    Cevap

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

  25. Kart 25

    Soru

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

    Cevap

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

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25 kart

DNA Reverse Complement Flashcards

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