Lecture 7

Question 1

DNA has … replication

Answer 1

semi-conservative

Question 2

in prokaryotes such as bacteria, DNA is … The DNA double helix separates at the …, creating a ..

Answer 2

circular; replication forks; replication bubble

Question 3

helicase … double helix by …
single stranded binding proteins: bind to strands to prevent …
topoisomerase cuts DNA to release … before helicase acts

Answer 3

unwinding; breaking H bonds; rewinding; helical stress

Question 4

DNA replication occurs in three major steps:

1. the … of the double helix and … of the DNA strands
2. the … of the template strand and
3. the … of the new DNA segment

Answer 4

opening; separation; priming; assembly

Question 5

after a stretch of the DNA is unwound by the initiatior protein, known as …, a protein known as …, breaks the H bonds between the bases, … the strand

Answer 5

topoisomerase; helicase; separating

Question 6

one each DNA strand an enzyme known as …, attaches and assembles a primer (… foundation) allowing replication to begin. A primer is essential because DNA nucleotides can only attach to ….; a strand cannot be made de novo

Answer 6

primase; RNA; existing nucleotides

Question 7

beginning at the primer sequence, … attaches to the original DNA strand and begins assembling a new, complementary strand. It uses … to build the new strand, matching each nucleotide in the template strand with its complementary nucleotide, creating an …
DNA polymerase can only add nucleotides on the … of an existing nucleic acid polymer, which is why the RNA primer is necessary

Answer 7

DNA polymerase; free-floating nucleotides; anti-sequence; 3’ end

Question 8

the newly synthesized strand must elongate in the … to … direction. The enzyme DNA polymerase adds nucleotides to the … end of each strand of DNA (same as RNA during transcription). Newly added nucleotides have bases that are complementary to those on the … strand, following base-pairing

Answer 8

5’ to 3’; 3’; template

Question 9

synthesis of the … and … strands of DNA involves a number of different proteins

Answer 9

leading; lagging

Question 10

Remember that DNA must be built in the 5’ to 3’ direction, so: the strand being replicated continuously is the …
The … must be synthesized in the direction opposite the … It is synthesized in short, separated segments called …, later joined together by …

Answer 10

leading strand; lagging strand; growing replication fork; Okazaki fragments; DNA ligase

Question 11

The joining of Okazaki fragments requires an enzyme (DNA ligase) that catalyzes the linking of the new DNA segments after the RNA primers have been

Answer 11

replaced with DNA

Question 12

eukaryotic DNA has multiple

Answer 12

origins of replication (ORI)