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Chapter 8
Nucleotides & Nucleic Acids
37
Biochemistry
Undergraduate 3
04/05/2016

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Term
gene
Definition
a segment of a DNA molecule that contains the information required for the synthesis of a functional biological product, whether protein or RNA
Term
ribosomal RNAs (rRNAs)
Definition
component of ribosomes (the complexes that carry out the synthesis of proteins)
Term
messenger RNAs (mRNAs)
Definition
intermediaries carrying genetic information from one or a few genes to a ribosome where the corresponding proteins can be synthesized
Term
transfer RNAs (tRNAs
Definition
adaptor molecules that faithfully translate the information in mRNA into a specific sequence of amino acids
Term
nucleotides
Definition
have 3 characteristic components:
1. a nitrogenous base
2. a pentose
3. one or more phosphates
Term
nucleoside
Definition
a nucleotide without a phosphate group
Term
What is the relationship between pyrimidine & purine?
Definition
the nitrogenous bases of nucleotides are derivatives of two parent compounds, PYRIMIDINE & PURINE
Term
What is the relationship between adenine & guanine?
Definition
both DNA & RNA contain two major purine bases, ADENINE & GUANINE, & two major pyrimidines
Term
What is the relationship between cytosine, thymine, & uracil?
Definition
in both DNA & RNA one of the pyrimidines is CYTOSINE, but the second common pyrimidine is not the same in both: it is THYMINE in DNA & URACIL in RNA
Term
deoxyribonucleotides
Definition
there are four major ones with different structures & names; the structural units of DNAs
Term
ribonucleotides
Definition
the structural units of RNAs
Term
What is the relationship between ribonucleoside 2',3'-cyclic monophosphates & ribonucleoside 3'-monophosphates?
Definition
RIBONUCLEOSIDE 2',3'-CYCLIC MONOPHOSPHATES are isolatable intermediates, & RIBONUCLEOSIDE 3'-MONOPHOSPHATES are end product of the hydrolysis of RNA by certain ribonucleases
Term
phosphodiester linkage
Definition
the linkage created when the successive nucleotides of both DNA & RNA are covalently linked through phosphate-group "bridges" in which the 5'-phosphate group of one nucleotide is joined to the 3'-hydroxyl group of the next nucleotide
Term
What is the relationship between the 5' end & the 3' end?
Definition
by definition, the 5' END lacks a nucleotide at the 5' position & the 3' END lacks a nucleotide at the 3' position
Term
oligonucleotide
Definition
a short nucleic acid
Term
polynucleotide
Definition
a longer nucleic acid
Term
base pairs
Definition
there are two types; they predominate in double-stranded DNA & RNA & have pattern caused by tautomers
Term
4 conclusions made by Chargaff after collecting data from DNAs of a great many different species
Definition
1. the base composition of DNA generally varies from one species to another
2. DNA specimens isolated from different tissues of the same species have the same bas composition
3. the base composition of DNA in a given species does not change with an organism's age, nutritional state, or changing environment
4. in all cellular DNAs, regardless of the species, the number of adenine residue is equal to the number of thymidine residues & the number of guanosine residues is equal to the number of cytosine residues
Term
What is the relationship between major groove & minor groove?
Definition
the offset pairing of the two strands creates a MAJOR GROOVE & a MINOR GROOVE on the surface of the duplex
Term
What is the relationship between parallel & antiparallel?
Definition
when Watson & Crick constructed their model, they had to decide at the outset whether the strands of DNA should be PARALLEL or ANTIPARALLEL - whether their 3',5'-phosphodiester bonds should run in the same or opposite directions
Term
2 steps determined by Watson & Crick (before confirmatory data became available) concerning DNA replication
Definition
1. separating the two strands
2. synthesizing a complementary strand for each
Term
B-form DNA
Definition
another name for the Watson-Crick structure; AKA B-DNA
Term
palindrome
Definition
a rather common type of DNA sequence
Term
inverted repeats
Definition
DNA with these are called "palindrome"; base sequences have twofold symmetry over two strands of DNA
Term
hairpin (cruciform)
Definition
can be formed by DNA sequences with inverted repeats because they are self-complementary within each strand; a type of DNA structure
Term
mirror repeat
Definition
the name given to the sequence when the inverted repeat occurs within each individual strand of the DNA
Term
triplex DNAs
Definition
formed due to Hoogsteen pairing
Term
G tetraplex
Definition
AKA the guanosine tetraplex; quite stable over a wide range of conditions
Term
transcription
Definition
the process of forming mRNA on a DNA template
Term
What is the relationship between monocistronic & polycistronic?
Definition
if it carries the code for only one peptide, the mRNA is MONOCISTRONIC; if it codes for two or more different polypeptides, the mRNA is POLYCISTRONIC
Term
anneal
Definition
the spontaneous rewinding of the unwound segments of the two strands when the temperature or pH is returned to the range in which most organisms live; yields an intact duplex
Term
hybrid duplexes
Definition
yielded when some strands of the mouse DNA associates with human DNA; segments of a mouse DNA strand forms base-paired regions with segments of a human DNA strand
Term
mutations
Definition
alterations in DNA structure that produce permanent changes in the genetic information; much evidence suggests an intimate link between the accumulation of mutations in an individual organism & the process of aging & carcinogenesis
Term
next-gen sequencing
Definition
the efficient methods (AKA next-generation) used by modern genomic sequencing
Term
nucleotide-binding fold
Definition
a protein domain; found in many enzymes that bind ATP & nucleotide cofactors
Term
second messengers
Definition
often produced due to interaction of extracellular chemical signals with receptors on the cell surface; created inside the cell to lead to adaptive changes in the cell interior
Term
adenosine 3'5'-cyclic monophosphate (cyclic AMP) (cAMP)
Definition
one of the mot common second messengers; formed from ATP in a reaction catalyzed by adenylyl cyclase (an enzyme associated with the inner face of the plasma membrane)
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