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Module 7 NUCLEIC ACID STRUCTURE AND FUNCTION > Structure and function > Flashcards

Structure and function Flashcards

1
Q

universal in living things, and are also found in viruses

A

Nucleic acid

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2
Q

compounds structurally similar to naturally occuring RNA and DNA, used as a research tool in molecular biology and/or as cure in medicine

A

Nucleic acid analogue

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3
Q

polymeric molecule composed of 4 types of monomeric units that contains the genetic information of an organism

A

DNA

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4
Q

The DNA structure as we know today was proposed by ____________ and _________ who were able to form a model of double-stranded DNA in helical form held together by hydrogen bonds

A

James watson and francis crick

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5
Q

occurs where the backbones are far apart

A

Major grooves

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6
Q

occurs where they are close together

A

Minor grooves

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7
Q

The purine and pyrimidine bases guanine (G), cytosine (C), thymine (T), and adenine (A) are held together by a phosphodiester backbone between _______________ attached to the nucleobases by an N-glycosidic bond

A

2 deoxyribosyl moieties

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8
Q

Convention dictates that a single-stranded DNA sequence is written in the _____________

A

5-3 direction

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9
Q

The common form of DNA is said to be right-handed because as one looks down the double helix, the base residues form a spiral in a __________

A

Clockwise direction

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10
Q

one strand runs in the 5’ to 3’ direction and the other in the 3’ to 5’ direction

A

Antiparallel

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11
Q

Of the 2 DNA strands, 1 is a template strand (the strand that is copied during nucleic acid synthesis), also called the

A

Non coding strand

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12
Q

The other strand is the coding strand which matches the RNA transcript that encodes the proteins

A

but containing uracil in place of thymine

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13
Q

Double-stranded DNA exists in at least six forms

A

A-E and Z

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14
Q

The G–C bonds are much more resistant to denaturation, or “melting,” than

A

A-T regions

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15
Q

G-C bonds have three hydrogen bonds hold the ______________ to ____________, whereas the other pair, the A–T pair, is held together by two hydrogen bonds only

A

Deoxyguanosine nucleotide

Deoxycytidine nucleotide

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16
Q

The double-stranded DNA structure can be separated in a solution by

A

Increasing the temperature 2. Decreasing the salt concentration

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17
Q

Separated strands of DNA will renature or will reassociate when appropriate physiologic temperature and salt conditions are achieved

A

Hybridization

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18
Q

are formed when the molecule is twisted in the direction opposite from the clockwise turns of the right-handed double helix found in B-DNA. Such DNA is said to be underwound

A

Negative supercoils

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19
Q

Negative super coil

A

Right handed

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20
Q

Positive super coil

A

Left handed

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21
Q

Enzymes that catalyze topologic changes of DNA are called

A

Topoisomerases

22
Q

The best-characterized example topoisomerases

A

Bacterial DNA gyrase

23
Q

DNA gyraseintroduces negative supercoils (or relaxes positive supercoils) using

A

ATP

24
Q

The ability of gyrase to relax positive supercoils comes into play during

A

DNA replication

25
Q

Drugs like _____________ that inhibit DNA gyrase are used as antibacterial agents

A

Quinolones

26
Q

DNA provides a template for replication and transcription •It is the source of information for

A

Protein synthesis

27
Q

Complementarity of DNA strands suggests that replication is done in a semi-conservative manner, where each strand is used to create a new

A

Daughter strand

28
Q

During a round of replication, each of the two strands of DNA is used as a _________________ of a new, complementary strand

A

Template for synthesis

29
Q

polymer of purine and pyrimidine ribonucleotides linked together by phosphodiester bridges analogous to those in DNA

A

Ribonucleic acid RNA

30
Q

Serves as template for protein synthesis

A

Messenger RNA

31
Q

For mRNA recognition prior to translation •Stabilizes mRNA

A

CAP

32
Q

The 5’ terminal of mRNA is “capped” by a

A

7methylguanosine triphosphate

33
Q

The 3’ end of mRNA has an attached polymer of adenylate residues 20-250 nucleotides in length called the

A

Poly A tail

34
Q

mechanism by which most messenger RNA molecules are terminated at their 3’ ends

A

Polyadenelation

35
Q

The polyadenosine (poly-A) tail protects the mRNA molecule from

A

Exonucleases

36
Q

important for transcription termination, for export of the mRNA from the nucleus, and for translation

A

Polyadenosine

37
Q

do not contain poly(A) tails

A

Histones

38
Q

Both the mRNA “cap” and “poly(A) tail” are added post-transcriptionally by

A

Nontemplate directed enzyme

39
Q

In mammalian cells, including cells of humans, the mRNA molecules present in the cytoplasm are not the RNA products immediately synthesized from the DNA template •Thus, in mammalian nuclei, the immediate products of gene transcription constitute a fourth class of RNA molecules. •These nuclear RNA molecules, called

A

Heterogenous nuclear RNA

40
Q

Serve as adapters for the translation of mRNA to amino acids

A

Transfer RNA

41
Q

There are at least 20 species of tRNA in each cell, at least 1 corresponding to each of the 20 amino acids required for protein synthesis

A

20 1 20

42
Q

Although tRNAs are quite stable in prokaryotes, they are somewhat less stable in

A

Eukaryotes

43
Q

tRNA stabel in________ mRNA stable in______

A

Prokaryotes

Eukaryotes

44
Q

The primary structure of all tRNA molecules allows extensive folding and intra-strand complementarity to generate a secondary structure that appears in two dimensions like a

A

Cloverleaf

45
Q

Sometimes called nodocfrom the reversed letters of the word codon •A unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA •Each tRNA contains a specific anticodon triplet sequence that can base-pair to one or more codons for an amino acid •For example, one codon for lysine is AAA; the anticodon of a lysine tRNA might be UUU

A

Aicodon

46
Q

A cytoplasmic nucleoprotein that acts as the machinery for the synthesis of proteins from mRNA templates

A

rRNA

47
Q

The 60s subunit contains subunits

A

5s, 5.8s, & 28s

48
Q

The 40s subunit contains a single

A

18 sub units

49
Q

All rRNA molecules except the _____________ are processed from a single 45s precursor RNA molecule in the nucleolus

A

5sRNA

50
Q

Found within the nucleus of eukaryotic cells. •They are involved in a variety of important processes such as RNA splicing (removal of introns from hnRNA), regulation of transcription factors and maintaining the telomeres (region of highly repetitive DNA at the end of a linear chromosome) •These elements are rich in Uridine content

A

Small nuclear RNA

Module 7 NUCLEIC ACID STRUCTURE AND FUNCTION (1 decks)

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