NUCLEIC ACIDS Flashcards
(81 cards)
1
Q
- Cells in an organism produce exact replicas of themselves.
- Cells have all the information on how to make complete organisms in which they are a part.
A
NUCLEIC ACIDS
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Q
- A __________ is a polymer in which the monomer units are nucleotides.
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nucleic acid
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Q
: Found within cell nucleus
* Storage and transfer of genetic information
* Passed from one cell toother during cell division
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DNA: Deoxyribonucleic Acid
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Q
- _____________responsible for such information are nucleic acids
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Molecules
2
Q
A Nucleotide has three components:
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a. Pentose Sugar: Monosaccharide
b. Phosphate Group (PO4 3-)
c. Heterocyclic Base
2
Q
Types of nucleic acids
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- DNA: Deoxyribonucleic Acid:
RNA: Ribonucleic Acid:
3
Q
Building Blocks of Nucleic Acids
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Nucleotides:
3
Q
Occurs in all parts of cell
* Primary function is to synthesize the proteins
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RNA: Ribonucleic Acid
3
Q
- Ribose is present in RNA and 2-deoxyribose is present in DNA
- Structural difference:
o a —OH group present on carbon 2’ in ribose
o a —H atom in 2-deoxyribose - RNA and DNA differ in the identity of the sugar unit in their nucleotides.
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Pentose Sugar
4
Q
- adenine (A) and guanine (G)
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Two purine derivatives
5
Q
-Containing Heterocyclic Bases
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Nitrogen
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Q
o Thymine (T) found only in .
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DNA
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Q
- thymine (T), cytosine (C), and uracil (U)
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Three pyrimidine derivatives
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Q
o Adenine (A), guanine (G), and cytosine (C) are found in
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DNA and RNA.
5
Q
- third component of a nucleotide, is derived from phosphoric acid (H3PO4)
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Phosphate
5
Q
o Uracil (U): found only in
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RNA
5
Q
- A ________________ is a nucleotide polymer in which each of the monomers contains ribose, a phosphate group, and one of the heterocyclic bases adenine, cytosine, guanine, or uracil
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ribonucleic acid (RNA)
5
Q
- DNA and RNA Primary structure is due to changes in the _______________
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bases
5
Q
checks the correct base pairing and catalyzes the formation of phosphodiester linkages
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- DNA polymerase
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Q
- Phosphate attached to C-5’ and base is attached to C-1’ position of pentose
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Nucleotide Formation
6
Q
the sequence of bases on one polynucleotide is complementary to the other polynucleotide
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DNA Sequence
6
Q
- Upon DNA replication the large DNA molecules interacts with histone proteins to fold long DNA molecules.
- is about 15% by mass DNA and 85% by mass protein.
- occur in matched (homologous) pairs.
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Chromosomes
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Q
o Complementary bases
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(A-T and G-C)
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Q
o Hydrogen bonding is stronger with
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A-T and G-C
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* Backbone: -Peptide bonds
- Proteins
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are referred to as nucleic acid backbone - Found in all
nucleic acids
Sugar-phosphate groups
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* A _______________ is a nucleotide polymer in which each of the monomers contains deoxyribose, a phosphate group, and one of the heterocyclic bases adenine, cytosine, guanine, or thymine.
deoxyribonucleic acid (DNA)
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* The __________ involves two polynucleotide chains coiled around each other in a helical fashion
secondary structure
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– A process by which DNA directs the synthesis of mRNA molecules
Transcription
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–DNA complexes are called chromosomes
histone
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* The segments are latter connected by _____________
DNA ligase
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*______________ is directly under the direction of DNA
Protein synthesis
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* Backbone: -Phosphate-Sugar
- Nucleic acids
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– a process in which mRNA is deciphered to synthesize a protein molecule
Translation
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Process by which DNA molecules produce exact duplicates of themselves
Replication
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is a single-stranded molecule;
RNA
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The base uracil found in
RNA
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The sugar unit in the backbone of DNA is ____________
deoxyribose
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* ___________ are responsible for the formation of skin, hair, enzymes, hormones, and so on
Proteins
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* Protein synthesis can be divided into two phases.
o Transcription
o Translation
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* The sugar unit in the backbone of RNA is ____________
ribose
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* The base thymine found in
DNA
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is double-stranded (double helix)
DNA
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____________ are much smaller than DNA molecules, ranging from 75 nucleotides to a few thousand nucleotides
RNA molecules
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Formed directly by DNA transcription.
Heterogeneous nuclear RNA (hnRNA)
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Carries instructions for protein synthesis (genetic information) from DNA
Messenger RNA
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converts the hnRNA to mRNA
Formation of mRNA
Post-transcription processing
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Facilitates the conversion of hnRNA to mRNA.
o Contains from 100 to 200 nucleotides
Small nuclear RNA
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: A segment of a DNA base sequence responsible for the production of a specific hnRNA/mRNA molecule
Gene
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Combines with specific proteins to form ribosomes - the physical site for protein synthesis
* Ribosomal RNA (rRNA)
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Delivers amino acids to the sites for protein synthesis
o _________ are the smallest (75–90 nucleotide units)
Transfer RNA (tRNA)
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* Two-step process in Transcription
(1) synthesis of hnRNA
(2) editing to yield mRNA molecule
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: All of the genetic material (the total DNA) contained in the chromosomes of an organism
Genome
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The _____________ is governed by RNA polymerase
unwinding process
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: Excision of introns and joining of exons
Splicing
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- a gene segment that codes for genetic information
Exon
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– a DNA segments that interrupt a genetic message
Intron
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- A process by which several different protein variants are produced from a single gene
o The process involves excision of one or more exons.
Alternative splicing
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- All of the mRNA molecules that can be generated from the genetic material in a genome.
- Responsible for the biochemical complexity created by splice variants obtained by hnRNA.
Transcriptome:
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: A three-nucleotide sequence in an mRNA molecule that codes for a specific amino acid
o Based on all possible combination of bases A, G, C, U” there are 64 possible codes
Codon
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: The assignment of the 64 mRNA codons to specific amino acids (or stop signals)
o 3 of the 64 codons are termination codons (“stop” signals)
Genetic code
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- represented by two codons
Most other amino acids
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- represented by six codons.
Arg, Leu, and Ser
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- have only a single codon.
Met and Trp
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- Codons that specify the same amino acid
Synonyms
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as intermediaries deliver amino acids to mRNA.
tRNA molecules
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- a three-nucleotide sequence on a tRNA molecule that is complementary to a codon on an mRNA molecule.
Anticodon
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– an rRNA–protein complex - serves as the site of protein synthesis:
o Contains 4 rRNA molecules and ~80 proteins - packed into two rRNA-protein subunits (one small and one large)
o ~65% rRNA and 35% protein by mass
o A _________ 's active site – Large subunit
o __________ is a RNA catalyst
o The mRNA binds to the small subunit of the ___________ .
Ribosome
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addition of specific amino acids to the 3’-OH group of tRNA.
Activation of tRNA:
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Begins with binding of mRNA to small ribosomal subunit such that its first codon (initiating codon AUG) occupies a P site (peptidyl site)
Initiation of protein synthesis:
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Adjacent to the P site in an mRNA–ribosome complex is A site (aminoacyl site) and the next tRNA with the appropriate anticodon binds to it.
Elongation:
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The polypeptide continues to grow via translocation until all necessary amino acids are in place and bonded to each other.
Termination:
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complex of mRNA and several ribosomes
Polysome (polyribosome):
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* An error in base sequence reproduced during DNA replication
* Errors in genetic information is passed on during transcription.
Mutations
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* Mutations are caused by ____________
* A ___________ is a substance or agent that causes a change in the structure of a gene:
Mutagens
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: Tiny disease-causing agents with outer protein envelope and inner nucleic acid core
Viruses
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* Inactive virus or bacterial envelope
* Antibodies produced against inactive viral or bacterial envelopes will kill the active bacteria and viruses
Vaccines
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o The study of biochemical techniques that allow the transfer of a “foreign” gene to a host organism and produce the protein associated with the added gene
Genetic Engineering (Biotechnology)
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* is a method by which the base sequence in a DNA molecule (or a portion of it) is determined.
* Discovered in 1977 by Fredrick Sanger
DNA Sequencing
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* The ____________________ is a method for rapidly producing multiple copies of a DNA nucleotide sequence (gene).
* This method allows to produce billions of copies of a specific gene in a few hours.
Polymerase Chain Reaction
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