Biology 1201A Lecture Notes - Lecture 4: Tata Box, Trp Operon, Dna Replication

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2 Oct 2016

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Semiconservative replication: because the newly synthesized strand contains a single strand of the old dna. Helicase: unwind the dna helix, and forces the double helix into a twist. Single strand binding protein: attach to each strand of uncoiled dna to keep them separate. Topoisomerases: break and rejoin the double helix, allowing the twists to unravel to relieve knots. Dna polymerase: move in 3" 5" direction to polymerize 5" 3" complementary dna. Primase: synthesize new rna segment called rna primer. It is placed as the helix unwind and. Dna pol build from it in a 5" 3" direction; as helix is unwinded more => new rna primer is placed and dna pol will continue to build. The rna primer is later replaced with dna by dna polymerase: replication of telomere: two problems occur. Not enough template strand where primase can attach. Last primase is removed => no 3" end of okazaki fragment => dna pol cannot build after removing rna primer.

Related Questions

Multiple choice questions:

1) For DNA Polymerase III to work, which of these components has to act first? (A. Conservative replication, B. Newly replicated strand, C.Primase, D. RNA, E.Mutation rate)

2) The double helix of DNA is wrapped about 1 3/4 times around which of these components? (A. Helicase, B. DNA polymerase III, C. DNA polymerase I, D.Nucleosome, E. DNA ligase)

3) Which strand is produced more rapidly? (A.Okazaki fragment, B. Lagging strand, C. Leading strand, D. 3' , E. 5' )

4) During DNA replication in the lagging strand there is production of this component? (A. Okazaki fragment, B. mRNA, C. tRNA, D. proteins, E. none of the above)

5) Which enzyme is used first to permit DNA polymerase III to begin replicating the 3' stand? (A. Conservative replication, B. Parental stand, C. Primase, D. RNA, E. Mutation rate)

6) Which enzyme unwraps the double helix? (A. Helicase, B. DNA polymerase III, C.DNA polymerase I, D. Nuclesome, E. DNA ligase)

Thanks for any feedback, want to verify my answers.

Double check to see if I got these right? 3 questions

Some Processes Involved in DNA Replication

1.The replication origin is identified.

2 DNA primase builds RNA primer.

3Okazaki fragments are spliced by DNA ligase.

4Helicases bind and uncoil the DNA double helix.

5 RNA primer is the starting point for DNA polymerase.

6 DNA replication ends at the telomere where DNA codes fortermination.

7 DNA polymerase adds complementary nucleotides in the 5' to 3'direction in short segments called Okazaki fragments.

The sequence in which the events numbered above occur during DNAreplication of the lagging strand: Number 1 - 7 in order.

I put: 1,4,2,5,7,3,6

__________________Question 2:

Some Functions of Enzymes

Build DNA strands
Build RNA primers
Build mRNA strand
Cleave DNA strands
Splice Okazaki fragments

Enzyme:
Helicase :4
DNA ligase :5
RNA primase :1
RNA polymerase :3
DNA polymerase:2

Question 3:

like mRNA, tRNA has a ribose sugar, U instead of T, and issingle stranded. Unlike mRNA, which remains a long single strand ofnucleotides, tRNA folds so that some areas pair up.

The resulting structure has an anticodon on one end and a site foran amino acid to attach on the other end. There is basecomplementarity (A pairs with U and G pairs with C) between an mRNAcodon and tRNA anticodon.

If the amino acid tyrosine attaches to a tRNA, which of thefollowing anticodons could be at the opposite end of the tRNAmolecule?

Select one:

a. ATA and ATG

b. UAU and UAC

c. AUA and AUG

d. AGA and AGU

I picked B.

purpleturtle13

1) What is the difference between the leading strand and the lagging strand in DNA replication? Place the following steps of DNA replication in right chronological order.

1. Primase adds an ribonucleotide primer
2. Initiator proteins bind the origin of replication and helicase breaks hydrogen bonds between complementary bases of double stranded template DNA
3. DNA polymerase III extends by complementary base pairing deoxyribonucleotides to the template strands
4. Ligase phosphodiester bonds the nucleotides to connect okazaki fragments nad connect fragments at the origin and where the "crotches or forks" collide
5. DNA polymerase I removes RNA primer and replaces with Deoxyribonucleotides

2) Given the template DNA and primer sequences below, what bases will be added to the primer as DNA replication proceeds? (The bases should appear in the order that they will be added)

5'-GTCGTCTCCCTTTTTAAAAACCCCCCC-3'
5'-UUUUUAAAAAGGG-3'

3) Given the DNA sequence below, what could be a primer sequence used in its replication?
5'-CGTACGGCCCCAAAATTGCTACTCTGCTG-3'

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Biology 1201A Lecture Notes - Lecture 4: Tata Box, Trp Operon, Dna Replication

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