NUCLEIC ACIDS Flashcards
- 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.
NUCLEIC ACIDS
- A __________ is a polymer in which the monomer units are nucleotides.
nucleic acid
: Found within cell nucleus
* Storage and transfer of genetic information
* Passed from one cell toother during cell division
DNA: Deoxyribonucleic Acid
- _____________responsible for such information are nucleic acids
Molecules
A Nucleotide has three components:
a. Pentose Sugar: Monosaccharide
b. Phosphate Group (PO4 3-)
c. Heterocyclic Base
Types of nucleic acids
- DNA: Deoxyribonucleic Acid:
RNA: Ribonucleic Acid:
Building Blocks of Nucleic Acids
Nucleotides:
Occurs in all parts of cell
* Primary function is to synthesize the proteins
RNA: Ribonucleic Acid
- 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.
Pentose Sugar
- adenine (A) and guanine (G)
Two purine derivatives
-Containing Heterocyclic Bases
Nitrogen
o Thymine (T) found only in .
DNA
- thymine (T), cytosine (C), and uracil (U)
Three pyrimidine derivatives
o Adenine (A), guanine (G), and cytosine (C) are found in
DNA and RNA.
- third component of a nucleotide, is derived from phosphoric acid (H3PO4)
Phosphate
o Uracil (U): found only in
RNA
- 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
ribonucleic acid (RNA)
- DNA and RNA Primary structure is due to changes in the _______________
bases
checks the correct base pairing and catalyzes the formation of phosphodiester linkages
- DNA polymerase
- Phosphate attached to C-5’ and base is attached to C-1’ position of pentose
Nucleotide Formation
the sequence of bases on one polynucleotide is complementary to the other polynucleotide
DNA Sequence
- 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.
Chromosomes
o Complementary bases
(A-T and G-C)
o Hydrogen bonding is stronger with
A-T and G-C
- Backbone: -Peptide bonds
- Proteins
are referred to as nucleic acid backbone - Found in all
nucleic acids
Sugar-phosphate groups
- 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)
- The __________ involves two polynucleotide chains coiled around each other in a helical fashion
secondary structure
– A process by which DNA directs the synthesis of mRNA molecules
Transcription
–DNA complexes are called chromosomes
histone
- The segments are latter connected by _____________
DNA ligase
*______________ is directly under the direction of DNA
Protein synthesis
- Backbone: -Phosphate-Sugar
- Nucleic acids
– a process in which mRNA is deciphered to synthesize a protein molecule
Translation
Process by which DNA molecules produce exact duplicates of themselves
Replication
is a single-stranded molecule;
RNA
The base uracil found in
RNA
The sugar unit in the backbone of DNA is ____________
deoxyribose
- ___________ are responsible for the formation of skin, hair, enzymes, hormones, and so on
Proteins
- Protein synthesis can be divided into two phases.
o Transcription
o Translation
- The sugar unit in the backbone of RNA is ____________
ribose
- The base thymine found in
DNA
is double-stranded (double helix)
DNA
____________ are much smaller than DNA molecules, ranging from 75 nucleotides to a few thousand nucleotides
RNA molecules
Formed directly by DNA transcription.
Heterogeneous nuclear RNA (hnRNA)
Carries instructions for protein synthesis (genetic information) from DNA
Messenger RNA
converts the hnRNA to mRNA
Formation of mRNA
Post-transcription processing
Facilitates the conversion of hnRNA to mRNA.
o Contains from 100 to 200 nucleotides
Small nuclear RNA
: A segment of a DNA base sequence responsible for the production of a specific hnRNA/mRNA molecule
Gene
Combines with specific proteins to form ribosomes - the physical site for protein synthesis
- Ribosomal RNA (rRNA)
Delivers amino acids to the sites for protein synthesis
o _________ are the smallest (75–90 nucleotide units)
Transfer RNA (tRNA)
- Two-step process in Transcription
(1) synthesis of hnRNA
(2) editing to yield mRNA molecule
: All of the genetic material (the total DNA) contained in the chromosomes of an organism
Genome
The _____________ is governed by RNA polymerase
unwinding process
: Excision of introns and joining of exons
Splicing
- a gene segment that codes for genetic information
Exon
– a DNA segments that interrupt a genetic message
Intron
- 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
- 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:
: 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
: 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
- represented by two codons
Most other amino acids
- represented by six codons.
Arg, Leu, and Ser
- have only a single codon.
Met and Trp
- Codons that specify the same amino acid
Synonyms
as intermediaries deliver amino acids to mRNA.
tRNA molecules
- a three-nucleotide sequence on a tRNA molecule that is complementary to a codon on an mRNA molecule.
Anticodon
– 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
addition of specific amino acids to the 3’-OH group of tRNA.
Activation of tRNA:
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:
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:
The polypeptide continues to grow via translocation until all necessary amino acids are in place and bonded to each other.
Termination:
complex of mRNA and several ribosomes
Polysome (polyribosome):
- An error in base sequence reproduced during DNA replication
- Errors in genetic information is passed on during transcription.
Mutations
- Mutations are caused by ____________
- A ___________ is a substance or agent that causes a change in the structure of a gene:
Mutagens
: Tiny disease-causing agents with outer protein envelope and inner nucleic acid core
Viruses
- Inactive virus or bacterial envelope
- Antibodies produced against inactive viral or bacterial envelopes will kill the active bacteria and viruses
Vaccines
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)
- 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
- 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
