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Diagnostic Molecular Biology > Ch. 1 - DNA > Flashcards

Ch. 1 - DNA Flashcards

1
Q

Nucleotides

A

Units of DNA

Composed of a phosphorylated ribose sugar and a nitrogen base

Aka nucleoside mono- di- or tri- phosphate (i.e. ATP, adenosine triphosphate)

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2
Q

4 nitrogen bases

A

Adenine
Cytosine
Guanine
Thymine

Attached to a deoxyribose sugar, forming a polymer with other deoxyribose sugars via phosphodiester bonds

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3
Q

Nucleoside

A

Nitrogen base bound to an unphosphorylated sugar

Adenosine
Guanosine
Cytidine
Thymidine

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4
Q

DNA

A

Deoxyribonucleic acid

Macromolecule of C, N, O, P, H

Assembled in units of nucleotides

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5
Q

Pyrimidines

A

Nitrogen bases with a single ring structure

Thymine
Cytosine

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6
Q

Purines

A

Nitrogen bases with a double ring structure

Adenine
Guanine

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7
Q

Modified Nucleosides

A

Used for labeling and detection

Used in medicines for cancer and viruses

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8
Q

Nucleic acid

A

Macromolecule made up of nucleotides bound together by the phosphate and OH groups on their sugars

Chain grows by adding 5’ phosphate group of an oncoming nucleotide to the 3’ OH group of the chain

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9
Q

Sugar-phosphate backbone

A

The sugar-phosphate chain that connect the bases of DNA

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10
Q

What holds complementary base pairs together?

A

Hydrogen bonds

GC has three
AT has two

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11
Q

Hybridization

A

The formation of H bonds between two complementary strands of DNA

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12
Q

In what direction does DNA synthesis proceed?

A

5’ to 3’

DNA polymerase reads the template in the 3’ to 5’ direction, resulting in the new strand having the 5’ to 3’ orientation

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13
Q

DNA polymerase

A

The enzyme responsible for polymerizing nucleotides

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14
Q

Template

A

The guide used by DNA polymerase to determine which nucleotides to add

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15
Q

Semi-conservative replication

A

Each strand of a ds helix serves as a temple for a new strand, maintaining the correct sequence of nucleotides

Results in two ds helices each with a parent and a new strand

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16
Q

Replication fork

A

The site of DNA undergoing active replication

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17
Q

Okazaki fragments

A

Small fragments that are synthesized during replication of the 5’ to 3’ strand

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18
Q

Leading strand

A

3’ to 5’ strand where DNA replication occurs continuously

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19
Q

Lagging strand

A

5’ to 3’ strand where DNA replication occurs in a discontinuous manner via Okazaki fragments

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20
Q

Primase

A

An enzyme that synthesizes RNA primers that are needed for priming DNA synthesis on the lagging strand

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21
Q

DNA Polymerase I

A

pol I

Replaces RNA primers with DNA nucleotides

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22
Q

DNA ligase

A

Ensures binding between fragments and replaced nucleotides on the lagging strand during DNA replication

Catalyzes the formation of a phosphodiester bond between adjacent 3’-OH and 5’-P nucleotide ends

23
Q

DNA Polymerase III

A

Main polymerase

Adds nucleotides to the leading and lagging strands of DNA

24
Q

Helicase

A

Enzyme that unwinds the double helix

25
Q

SSBP

A

Single-stranded binding proteins

Stabilize the unwound single strands

26
Q

DNA gyrase

A

Enzyme that prevents supercoiling of the ds DNA outside of the replication fork

27
Q

Exonucleases

A

Enzymes that remove nucleotides from DNA or RNA from either end of the linear model (not circular DNA)

Protects the sequence of nucleotides to prevent mutations

Proofreads newly synthesized DNA

Specific

28
Q

Terminal transferase

A

Type of DNA polymerase

Can add nucleotides to the end of a DNA strand without a primer

29
Q

Endonucleases

A

Break the sugar-phosphate backbone of DNA

30
Q

Restriction enzymes

A

Endonucleases that recognize specific base sequences and break or restrict (cut) the DNA polymer at the sugar-phosphate backbone

Originate from bacteria

31
Q

Type I restriction endonucleases

A

Have both nuclease and methylase activity in a single enzyme

32
Q

Type II restriction endonucleases

A

Used most often in the laboratory
Restrict (cut) DNA in a palindromic sequence
Produce fragments of predictable size
Extremely specific

33
Q

Blunt Ends

A

No overhang at the ends of the strand after cutting

Hybridization is not easy

34
Q

Sticky Ends

A

Overhands at the ends of the DNA after cutting

Easy to hybridize here

35
Q

Double-stranded break

A

Helicase cuts the sugar-phosphate backbone of both strands of DNA

36
Q

Nick

A

A single-stranded break in the sugar-phosphate backbone (by helicase)

The nicked strand can rotate around the intact strand

The nicked ends can be digested by exonuclease activity or extended by using the intact strand as a template (nick translation)

37
Q

Nick translation

A

Nicked ends of a strand of DNA can be extended using the intact strand as a template

38
Q

DNA methyltransferases

A

Catalyze the addition of methyl groups to nitrogen bases, usually A or C in DNA strands

39
Q

Hemimethylated

A

Methylated on one strand of the double helix and not the other

40
Q

Recombination

A

Mixture and assembly of new genetic combinations

41
Q

Crossing over

A

Physical exchange between molecules

42
Q

Recombinant molecule or organism

A

One that holds a new combination of DNA sequences

43
Q

How do sexually reproducing organisms mix genes?

A

3 ways

  1. At the beginning of meiosis, duplicated chromosomes line up and recombine via crossing over, forming 4 recombined DNA duplexes
  2. Newly recombined duplexes are randomly assorted into gametes, so that each gamete contains one set of each of the recombined parental chromosomes
  3. The gamete will emerge with a gamete from the other parent carrying its own set of recombined chromosomes. The resulting offspring has a new set of genes from each parent.
44
Q

Recombinant DNA technology

A

A controlled mixing of genes

45
Q

Conjugation

A

The transfer of genetic material from one cell to another through physical contact

Requires both an F+ and an F- cell

46
Q

F+ cell

A

A cell with a plasmid containing the F factor or fertility factor

Can transfer F factor to an F- cell

47
Q

F- cell

A

A cell without a plasmid containing the F factor

Can obtain F factor after conjugation

48
Q

Hfr bacteria

A

High frequency of recombination

F factor is embedded in the chromosome instead of being in a plasmid

49
Q

Transduction

A

Transmission of viral DNA from one bacterium to another through a viral intermediate

50
Q

Hershey Chase experiment

A

Used 35S to label the viral protein and 32P to label the viral DNA

The viral protein remained outside of the bacterial cell while the viral DNA entered the cell.

51
Q

Transformation

A

Transfer of genetic material from cell to cell without physical contact, such that a new phenotype is produced in the recipient cells

52
Q

Griffith’s experiment

A

Griffith placed heat-killed virulent S strain bacteria with live avirulent R strain bacteria and infected a mouse, which died.

The virulent heat-killed S strain transformed the avirulent R strain and made it virulent.

Treatments with protease and ribonuclease did not affect transformation, but treatment with deoxyribonuclease prevented it, proving that DNA was the cause of the transformation

53
Q

Plasmid

A

Extrachromosomal DNA

Usually contains special properties like antibiotic resistance (R factors)

Diagnostic Molecular Biology (22 decks)

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