Chapter 12: DNA Structure, Replication and Organization Flashcards

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1
Q

Bacteriophages

A

A virus that parasitizes a bacterium by infecting it and reproducing inside it.

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2
Q

Nucleotide

A

Composed of nitrogenous bases. Nucleotides form the basic structural unit of nucleic acids such as DNA.

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3
Q

Deoxyribose sugar

A

The sugar component of DNA, phosphates that form the chains.

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4
Q

Nitrogenous base

A

A nitrogen containing molecule that has the same chemical properties as a base. They are particularly important since they make up the building blocks of DNA and RNA: adenine, guanine, cytosine, thymine and uracil.

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5
Q

Purine (adenine and guanine)

A

A substituted derivative of this, especially the bases adenine and guanine present in DNA and RNA.

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6
Q

Pyrimidine (thymine and cytosine)

A

A substituted derivative of this, especially the bases thymine and cytosine present in DNA.

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7
Q

Sugar-phosphate backbone

A

The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone.

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8
Q

Phosphodiester bond

A

Links nucleotides together

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9
Q

5’ end

A

attaches to a phosphate group

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10
Q

3’ end

A

attaches to a hydroxyl group

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11
Q

Double-helix model

A

Discovered by Watson and Crick. Anti-parallel DNA strands wind around each other, with purine and pyrimidine bases facing each other in the interior of the molecule.

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12
Q

Why are the DNA strands Antiparallel?

A

The DNA strands are antiparallel to allow for complimentary base pairing.

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13
Q

Complementary base pairing

A

Adenines pair with Thymines and Guanines pair with Cytosines.

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14
Q

Semiconservative replication model

A

DNA replication produces DNA molecules with 1 parental strand and 1 newly made strand (Watson and Crick).

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15
Q

Conservative replication model

A

DNA replication produces 1 double helix with both parental strands, and the other with 2 new daughter strands.

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16
Q

Dispersive Replication Model

A

DNA replication produces DNA strands in which segmtns of new DNA are interspersed with the parental DNA.

17
Q

4 Deoxyribonucleoside triphosphates

A

dATP, dGTP, dCTP, dTTP (ps you guys should probe look up what these are but i just couldn’t find it in my notes)

18
Q

DNA helicase

A

Separates the two strands so the nucleotides are no longer base-paired.

19
Q

Replication fork

A

The DNA uncoils during replication creating a leading an a lagging strand.

20
Q

Single-stranded binding proteins

A

Proteins which bind to the single-stranded portions of the DNA molecule.

21
Q

Topoisomerase

A

protects the rest of the DNA molecule from being wound tighter.

22
Q

RNA primer

A

Connected ot the template strand by primase to initiate a new DNA strand. Once the RNA primer is in place then the DNA Polymerase can add DNA bases, copying the template strand.

23
Q

Primase

A

An enzyme which which connects a few complimentary RNA bases to the template strand – this is called an RNA Primer

24
Q

Leading strand

A

Strand of DNA being replicated continuously. In DNA replication, the strand that is made in the 5’ to 3’ direction by continuous polymerization at the 3’ growing tip.

25
Q

Lagging strand

A

The dna strand that is replicated discontinuously from the 5’ to the 3’ direction.

26
Q

Discontinuous replication

A

The synthesis of a new strand of a replicating DNA molecule as a series of short fragments that are subsequently joined together. Only one of the new strands, the so-called lagging strand, is synthesized in this way.

27
Q

Okazaki fragments

A

Relatively short fragment of DNA synthesized on the lagging strand during DNA replication.

28
Q

DNA ligase

A

A specific type of enzyme that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond.

29
Q

Replication origin

A

A particular sequence in a genome at which replication is initiated. This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double-stranded RNA viruses.

30
Q

Base-pair mismatch

A

The presence of an uncomplimentary base in double-stranded DNA caused by spontaneous deamination of cytosine or adenine, mismatching during homologous recombination, or errors in DNA replication.