DNA Replication And Transcription Post-Lecture

False

They increase the probability of producing a DNA fingerprint that is unique to an individual.

50

Whether the gene is methylated.

A method to amplify a fragment of DNA.

True

False

32

Extension

Annealing.

phosphate

PCR

the DNA will move up the gel

A

the profile from suspect 2 matches the crime scene

remove supercoiling transfer into a linear form

The recombinant DNA contains two inserts.

Explanation: The pBR322 DNA was cleaved with HindIII-nuclease and ligated to a HindIII digest of human mitochondrial DNA. A recombinant plasmid was obtained and its genome was cleaved and analyzed by gel electrophoresis. The pBR322 plasmid has a single EcoRI restriction site between the HindIII and PvuI cleavage sites. The single HindIII restriction site is present between the EcoRV and EcoRI restriction sites. The plasmid and the human mitochondrial DNA insert are digested with HindIII restriction enzyme. HindIII is a type II restriction endonuclease that cleaves between palindromic sequences of two adenine nucleotides in the sequence AAGCTT from 5′ to 3′ and TTCGAA from 3′ to 5′. Palindromic sequences are sequences wherein the 5′ to 3′ sequence is the reverse of the 3′ to 5′ sequence of DNA with which it pairs. There are two HindIII restriction sites in the mitochondrial insert, as only 1.15 kb fragments are obtained after HindIII digestion of the recombinant plasmid (lane C). Each mitochondrial insert will generate two sticky ends. During ligation of the insert with linear pBR322, one sticky end of the mitochondrial fragment ligates/joins with the sticky end of the pBR322 plasmid. The other sticky end will ligate with the second mitochondrial insert.The two mitochondrial DNA fragments are inserted within the sticky ends generated by the HindIII restriction site of pBR322, both adjacent to each other.

Circular

EcoRI 0 HindII 2.0 Hpall 0.8 EcoRI 1.3

15

cleave with additional restriction enzymes cleave with HpaII plus HindIII

DNA polymerase

Primers are short sequences that allow the initiation of DNA synthesis.

Phosphate groups

Primase

They are formed on the lagging strand of DNA.

Topoisomerase

True

1. The new DNA strand that grows continuously in the 5' to 3' direction is called the leading strand. 2. The enzyme that can replicate DNA is called DNA polymerase. 3. During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a replication fork. 4. After replication is complete, the new DNAs, called daughter DNA, are identical to each other. 5. Okazaki fragmentsare the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.

Explanation: During DNA replication, each strand in the parental duplex serves as the template for the production of a daughter strand by complementary base pairing. Therefore, one cycle of replication will produce two daughter duplexes, each with one parental strand and one newly synthesized strand. During a second cycle of replication, all four strands in the two duplexes will serve as templates, resulting in four duplexes (eight strands of DNA).

A: Breaks hydrogen bonds, unwinding DNA double helix B: Synthesizes RNA primers on leading and lagging strands. C: Replaces RNA primers with DNA nucleotides. D: Catalyzes phosphodiester bond formation, joining DNA fragments. E: Lagging strand. F: Leading Strand G: Relaxes supercoiled DNA H: Coats single-stranded DNA, preventing duplex formation I: Synthesizes DNA 5' to 3' on leading and lagging strands.

CAACTGGTCCAT Explanation: The shortest fragment generated by the dideoxynucleotide DNA sequencing reaction migrates to the bottom of the gel. That fragment represents the 5' nucleotide of the sequenced strand. Therefore, the 5' to 3' sequence of nucleotides in the sequenced strand can be determined by reading the bands in all lanes from the bottom of the gel to the top: 5'-ATGGACCAGTTG-3', in this example. The template strand is complementary and antiparallel to the sequenced strand: 5'-CAACTGGTCCAT-3', in this example.

A: 5' end B: hydrogen bond C 3' end D deoxyribose sugar E nitrogenous base F phosphate group G 3' end

https://session.masteringchemistry.com/problemAsset/1943351/4/1108497_010.jpg

A: To the right B: to the right C: to the left D: to the left

Helicase: binds at the replication fork breaks H-bonds between bases Topoisomerase: binds ahead of the replication fork breaks covalent bonds in DNA backbone single-strand binding protein: binds after the replication fork prevents H-bonds between bases

leading strand: made continuously only one primer needed daughter strand elongates toward replication fork lagging strand: multiple primers needed made in segments daughter strand elongates away from replication fork both strands: synthesized 5' to 3'

Earliest- A and H. B and G F and C D and E- latest

1: pol III binds to 3' end of primer B 2: pol III moves 5' to 3', adding DNA nucleotides to primer B 3: pol I binds to 5' end of primer A 4: pol I replaces primer A with DNA 5: DNA ligase links fragments A and B

Viral RNA Viral RNA -dependent RNA polymerases lack a proofreading exonuclease, so viral RNA replication is much more error-prone than DNA replication. Some, but not all, DNA virus DNA polymerases lack proofreading, so DNA replication by some, but not all, DNA viruses is error-prone.

modified guanine nucleotide

a long string of adenine nucleotides

snRNPs and other proteins

exons

cytoplasm

1: DNA double helix unwinds to expose the nucleotide bases. 2: RNA polymerase identifies the start sequence. 3: RNA polymerase adds bases that are complementary to the DNA template. 4: RNA polymerase identifies the termination sequence. 5: mRNA strand and RNA polymerase are released. Background Image

Explanation: Only one strand of DNA acts as a template. The other strand, which may be called the coding strand or informational strand, is complementary to the template strand that is coded. Since polymerases add nucleotide bases to the 3' end through the free OH group, the DNA template strand must be read from the 3' to 5' direction, creating an mRNA strand that is read in the 5' to 3' direction and that matches the code on the DNA coding or informational strand except that thymine (T) is replaced with uracil (U). Once created, mRNA must be processed further before they leave the nucleus of the cell. Introns are cut out, and the exons containing the code to be expressed are connected in a continuous chain. It is this mRNA with the introns removed that brings the genetic information to the ribosomes in the cytoplasm of the cell. Once in the cytoplasm, ribosomes and transfer RNA (tRNA) work together to translate mRNA into a protein. A single DNA sequence can be transcribed by many RNA polymerase at once. Hence, proteins can be manufactured in large quantities.

UGAGCC

the specific sequence of bases along the DNA strands

A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA. A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA. Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.

A: same sequence as RNA transcript (except for having T instead of U) B: produces stem-loop structure in RNA transcript C: recognized be alpha subunit of RNA polymerase D: complementary to RNA transcript E: Leads to an unstable RNA-DNA complex

1 TFIID binds binds to the TATA box 2 TFIIB, TFIIF, and RNA pol II bind 3 TFIIE and TFIIH bind 5 Synthesis of the pre-mRNA begins at the +1 nucleotide 5 A 5' cap is added to the pre-mRNA 6 Spliceosome complexes carry out intron splicing 7 A poly-A tail is added to the pre-mRNA

1: mutation in a splicing signal sequence in intron 2 2: mutation in the gene's promoter sequence 3: mutations in splicing signal sequences in both intron 1 and intron 2 4: no mutation in any splicing signal sequence

7

6

The 5′, 5′ -internucleotide bond would be at the 5 ′ end, where capping occurs. The poly (A) sequence would be at the 3 ′ end - at the right end of the figure, where the RNA product does not anneal to the DNA template.

Transcription, 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane

Exon splicing

It provides a site for ribosome binding in the cytoplasm.