DNA: Nucleic Acid Structure And function

Question 0

Most common nucleic acids are

Answer 0

DNA & RNA

Question 1

Is a macromolecule composed of nucleotide chains. These molecules carry genetic information within cells. Are universal in living things, and are also found in viruses.

Answer 1

Nucleic acid

Question 2

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

Answer 2

Nucleic acid analogues

Question 3

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

Answer 3

DNA

Question 4

The discovery that genetic formation is coded along the length of polymeric molecule composed of only four types of _____________.

Answer 4

Monomeric units

Question 5

The genetic code in DNA depends on how ______ & ______ are arranged in a ______.

Answer 5

Purines & Pyrimidines. DNA strand.

Question 6

The DNA structure was proposed by whom. They were able to form a model of double-stranded DNA in helical form held together by ________.

Answer 6

James Watson & Francis Crick. Hydrogen bonds.

Question 7

One turn of B-DNA includes ________. The ________ of the double helix is indicated by the vertical cord.

Answer 7

10 base pairs. Central axis.

Question 8

Occurs where the backbones are far apart

Answer 8

Major groove

Question 9

Occurs where they are close together

Answer 9

Minor groove

Question 10

In major and minor grooves, certain protein binds to DNA to alter its structure or regulate ______(copying DNA to RNA) or _______(copying DNA to DNA)

Answer 10

Transcription. Replication.

Question 11

In major and minor grooves, It is easier for DNA binding proteins to interact with these bases (the internal parts of the DNA molecule) on the _________ side because the _______ are not in the way.

Answer 11

Major groove. Backbones.

Question 12

The purine and pyrimidine bases G, C, T & A are held together by a __________ backbone between 2’ deoxyribosyl moieties attached to the nucleobases by an _________.

Answer 12

Phosphodiester. N-glycosylic bond.

Question 13

In major and minor grooves, The backbone has _______. Convention dictates that a single stranded DNA sequence is written in the __ to __ direction.

Answer 13

Polarity. 5’ to 3’.

Question 14

The common DNA form is said to be ______ because as one looks down the double helix, the base residues from a ________ in a _______ direction.

Answer 14

Right-handed. Spiral. Clockwise.

Question 15

The two strands of the double-helical molecule, each of which possesses a polarity, are ________; ie, on strand runs in the 5’ to 3’ direction and the other in the 3’ to 5’ direction.

Answer 15

Antiparallel

Question 16

the strand that is copied during nucleic acid synthesis.

Answer 16

Template/non-coding strand

Question 17

Matches the RNA transcript that encodes the protein ( but containing _______ in place of thymine)

Answer 17

Coding strand. Uracil.

Question 18

2 DNA strands

Answer 18

Coding strand and Non-coding/Template strand

Question 19

In RNA strand segment, Double stranded DNA exists in at least

Answer 19

Six forms: A-E and Z

Question 20

In RNA strand segment, is usually found under physiologic conditions (low salt, high degree of hydration)

Answer 20

B form

Question 21

In RNA strand segment: are much more resistant to denaturation, or “melting” than A-T rich regions. This is because three hydrogen bonds hold the __________ to the _________, whereas the other pair, the A-T pair, is held together by ________ only.

Answer 21

G-C bonds. Deoxyguanosine nucleotide. Deoxycytidine nucleotide. Two hydrogen bonds.

Question 22

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

Answer 22

Increasing the temp & decreasing the salt concentration

Question 23

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

Answer 23

Hybridization

Question 24

In some organisms such as bacteria, bacteriophages, many DNA-containing animal viruses, as well as organelles such as mitochondria, the ends of the DNA molecules are joined to create a closed circle _________. This does not destroy the polarity of molecules, but it eliminates all free ___________.

Answer 24

No covalently free ends. 3' and 5' hydroxyl and phosphoryl groups.

Question 25

Closed circles exist in

Answer 25

Relaxed/Supercoiled forms

Question 26

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.

Answer 26

Negative supercoils

Question 27

Enzymes that catalyze topologic changes of DNA. Can relax or insert supercoils. Best example is BDG.

Answer 27

Topoisomerase

Question 28

Introduces negative supercoils (or relaxes positive supercoils) using ATP as energy source.

Answer 28

DNA gyrase

Question 29

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

Answer 29

DNA replication

Question 30

Drugs like _______ that inhibit DNA gyrase are used as antibacterial.

Answer 30

Quinolones

Question 31

Provides a template for replication and transcription. It is the source of info for protein synthesis. It provides info for inheritance.

Answer 31

DNA

Question 32

Complementarity of DNA strands suggest that replication is done in a ___________, where each strand is used to create a new daughter strand.

Answer 32

Semi-conservative manner

Question 33

During a round of replication, each of the two strands of DNA is used as a template for synthesis of a new

Answer 33

Complementary strand

Question 34

Is a polymer of purine and pyrimidine ribonucleotides linked together by a __________ analogous to those in DNA.

Answer 34

Ribonucleic Acid. Phosphodiester bridges.

Question 35

Sugar: Deoxyribose

Answer 35

DNA

Question 36

Sugar: Ribose

Answer 36

RNA

Question 37

Pyrimidines: cytosine & uracil

Answer 37

RNA

Question 38

Strand: double

Answer 38

DNA

Question 39

Hydrolysis by alkaline solution: not possible

Answer 39

DNA

Question 40

Pyrimidines: cytosine & thymine

Answer 40

DNA

Question 41

Strand: single

Answer 41

RNA

Question 42

Hydrolysis by alkaline solution: possible

Answer 42

RNA

Question 43

Base content: A =/ T & G =/ C

Answer 43

RNA

Question 44

Base content: A=T & G=C

Answer 44

DNA

Question 45

The ________ with a 5' to 3' polarity is complementary to the template strand with its 3' to 5' polarity.

Answer 45

RNA transcript

Question 46

The sequence in the RNA transcript and its polarity is the same as that in ________, except that the __ of the transcript replaces the __ of the gene.

Answer 46

Coding strand. U. T.

Question 47

Serves as template for protein synthesis

Answer 47

Messenger RNA

Question 48

For mRNA recognition prior to translation. Stabilizes mRNA.

Answer 48

CAP

Question 49

The 5' terminal of mRNA is "capped" by a _________ that is linked to an adjacent _________ at its 5'-hydroxyl through the three phosphates.

Answer 49

7-methylguanosine triphosphate. 2'-O-methyl ribonucleoside.

Question 50

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

Answer 50

Poly (A) Tail

Question 51

In eukaryotic organisms, __________ is the mechanism by which most messenger RNA molecules are terminated at their 3' ends.

Answer 51

Polyadenylation

Question 52

Protects the mRNA molecule from exonucleases and is important for transcription termination, for export of the mRNA from the nucleus, and for translation.

Answer 52

Polyadenosine tail

Question 53

Some mRNAs, including those for some _____, do not contain poly(A) tails.

Answer 53

Histones

Question 54

Both the mRNA cap and poly(A) tail are added _________ by _______ enzymes.

Answer 54

Post transcriptionally. Nontemplate-directed.

Question 55

In mammalian cells, including cells of humans, the mRNA molecules present in the cytoplasm are not RNA products immediately synthesized from the __________.

Answer 55

DNA template

Question 56

In mammalian nuclei, the immediate products of gene transcription constitute a

Answer 56

Fourth class of RNA molecules

Question 57

Nuclear RNA molecules that are precursors to the mature, fully processed mRNAs.

Answer 57

Heterogenous nuclear RNA (hnRNA)

Question 58

Serve as adapters for the translation of mRNA to AA. There are atleast __ species of tRNA in each cell, at least 1 corresponding to each of the 20 AA required for protein synthesis.

Answer 58

Transfer RNA (tRNA)

Question 59

Although tRNAs are quite stable in _______, they are somewhat unstable in _______. The opposite is true for mRNAs, which are quite unstable in ________ but generally more stable in _______ organism.

Answer 59

Prokaryotes. Eukaryotes. Prokaryotes. Eukaryotic.

Question 60

Allows extensive folding and intra-strand complementarity to generate a secondary structure that appears in two dimensions like a cloverleaf.

Answer 60

Primary structure of all tRNA molecules

Question 61

A unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA.

Answer 61

Anticodon/Nodoc

Question 62

Each tRNA contains a specific anticodon __________ that can base pair to one or more codons for an AA. Ex: one codon for lysine is AAA; the anticodon of a lysine tRNA might be UUU.

Answer 62

Triplet sequence.

Question 63

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

Answer 63

Ribosomal RNA (rRNA)

Question 64

On the ribosomes, the _____ & _____ molecules interact to translate into a specific protein molecule info transcribed from the gene.

Answer 64

mRNA and tRNA

Question 65

In ribosomes, larger subunit

Answer 65

60s

Question 66

In ribosomes, smaller

Answer 66

40s

Question 67

In ribosomes, The 60s subunit contains

Answer 67

5s, 5.8s & 28s

Question 68

In ribosomes, The 40s subunit contains a single

Answer 68

18s subunit

Question 69

In ribosomes, all rRNA molecules except the ______ are processed from a single ___ precursor RNA molecule in the nucleolus.

Answer 69

5srRNA. 45s.

Question 70

In ribosomes, it is independently transcribed

Answer 70

5sRNA

Question 71

Ribosomal RNA molecules are packaged in the

Answer 71

Nucleolus

Question 72

Is the target of several clinically relevant antibiotics: Erythromycin & etc.

Answer 72

rRNA

Question 73

Is the most conserved(least variable) gene in all cells. For this reason, genes that encode the rRNA (rDNA) are sequenced to identify an organism's _______, calculate related groups, and estimate rates of species divergence.

Answer 73

rRNA. Taxonomic group.

Question 74

Found within the nucleus of eukaryotic cells. They are involved in a variety of important processes such as ________, regulation of transcription factors and maintaining telomeres. These elements are rich in ________ content.

Answer 74

Small nuclear RNA (snRNA). RNA splicing. Uridine content.

Question 75

Region of highly repetitive DNA at the end of a linear chromosome.

Answer 75

Telomeres

Question 76

Removal of introns from hnRNA

Answer 76

RNA splicing