NUCLEIC ACID Flashcards
- It is a polymer of nucleotides.
- Responsible for the storage and passage of information needed for the production of proteins
- The source of genetic information in chromosomes, which is then passed from parent to offspring.
- Biological molecules that possess heterocyclic nitrogenous bases as principal components of their structure
NUCLEIC ACID
Nucleic acids are biological molecules that possess ____ as principal components of their structure
HETEROCYCLIC NITROGENOUS BASES
contain several million nucleotides
DNA
contain only a few thousand nucleotides
RNA
DNA is contained in the ____ of the nucleus
CHROMOSOMES
humans have how many chromosomes
46 chromosomes (23 pairs)
- basic unit of heredity
- responsible for synthesis of single protein
GENES
the portion of the DNA molecule responsible for the synthesis of a single protein
GENE
The nucleotide monomers that compose DNA and RNA consist of
monosaccharide (sugar)
Nitrogenous base
phosphate group
In RNA the monosaccharide is the aldopentose
D-ribose
In DNA the monosaccharide is the aldopentose
D-2-deoxyribose
PYRIMIDINE BASES
Cytosine
Uracil
Thymine
PYCUT
naming of pyrimidine
counterclockwise
PURINE bases
Guanine
Adenine
PUGA
naming of PURINE bases
start sa ring that has 2 nitrogen
DNA bases
A, G, C, T
RNA bases
A, G, C, U
nucleoside is a ____
GLYCOSDIE
To name a nucleoside derived from a pyrimidine base, use the suffix
-idine
For deoxyribonucleosides, add the prefix
deoxy-
To name a nucleoside derived from a purine base, use the suffix
-osine
A nucleoside is formed by joining 1’carbon of the monosaccharide in which N atom of PYRIMIDINES
N1
A nucleoside is formed by joining 1’ carbon of the monosaccharide in which N atom of PURINES
N9
are formed by adding a phosphate group to the 5′-OH of a nucleoside.
NUCLEOTIDE
2 important bonds formed in a NUCLEOTIDE
glycosidic bond (N-type)
phosphodiester bond
Nucleotides are formed by adding a phosphate group to the ____ of a nucleoside.
5′-OH
Nucleic acids are composed of ____
nucleotide
NUCLEOSIDE contains
Nitrogenous base
Sugar (monosaccharide)
nucleotide is synonymous to
nucleoside phosphate
Nucleic acids (DNA and RNA) are polymers of nucleotides joined by
phosphodiester linkages
The ____ and ____ of the bases distinguish one polynucleotide from another (primary structure)
identity & order
In DNA, the ____ carries the genetic information of the organism
sequence of the bases
A polynucleotide has one free ____ group at the 3’ end
OH
found on the backbone of nucleic acids
phosphodiester linkages
A polynucleotide has one free ____ group at the 5’ end
phosphate
Serves as genetic material in most organisms
DNA
contains a backbone consisting of alternating sugar and phosphate groups
POLYNUCLEOTIDE
Double-stranded helix arrangement
DNA
DNA
It is also present in ____ and in the ____ of plants.
MITOCHONDRIA
CHLOROPLAST
DNA
Prokaryotic cells may also contain nonchromosomal DNA in the form of ____
PLASMID
Single stranded
RNA
- Serves as genetic material for some viruses;
- Carrier of genetic information to the site of protein synthesis
RNA
small, circular DNA structures that are found in prokaryotes
PLASMID
DNA
In eukaryotic cells, it is present in chromosomes in the ____
NUCLEUS
DNA
Prokaryotic cells, which lack nuclei, have a ____ chromosome
SINGLE
The DNA model was initially proposed by ____ and ____ in 1953
WATSON & CRICK
DNA consists of two polynucleotide strands that wind into a
RIGHT-HANDED DOUBLE HELIX
DNA DOUBLE HELIX
The sugar-phosphate groups lie on the ____
OUTSIDE OF THE HELIX
DNA DOUBLE HELIX
The bases lie on the
INSIDE OF THE HELIX
Hydrogen bonds present in:
ADENINE-THYMINE
2
Hydrogen bonds present in:
CYTOSINE-GUANINE
3
The two strands of DNA are arranged ____ to one another
ANTIPARALLEL
WATSON’S & CRICK PROPOSED…
DNA was made of 2 long stands of nucleotides arranged in a specific way called the
COMPLEMENTARY RULE
WATSON & CRICK
in the structure, Nitrogenous bases are called
RUNGS OF LADDER
WATSON & CRICK
in the structure, Phosphate & sugar backbone are called
LEGS OF LADDER
spaces between 1 turn
groove
diamter of one turn
20 A
Length of one complete turn
34 A
Major / Large groove
22 A
Minor / Small groove
- The number of adenosine residues equals the number of thymidine residues** (A = T)**
- The number of guanosine residues is equal to the number of cytidine residues (G = C)
- Therefore: A + G = T + C
CHARGAFF’S RULE
responsible for the formation of the unique double helical structure of DNA
FORCES OF ATTRACTION
FOCES OF ATTRACTION (DNA)
- The force responsible for the complementarity between base pairs
- However, it does not contribute significantly to the stability of the structure
- easily denatured, melt easily
- a weak type of force
H BOND
FOCES OF ATTRACTION (DNA)
shield the negative charges of backbone phosphates
METAL CATIONS
FOCES OF ATTRACTION (DNA)
- hydrophobic interactions
- responsible for the ring portions of DNA bases
BASE-STACKING INTERACTIONS
FOCES OF ATTRACTION (DNA)
interactions between the stacked adjacent base pairs
HYDROPHOBIC
Levels of DNA Structure
Covalent structure and nucleotide sequence
PRIMARY
Levels of DNA Structure
Any regular, stable structure taken up by some or all of nucleotides in a nucleic acid
SECONDARY
Levels of DNA Structure
Complex folding of large chromosomes in the chromatin
TERTIARY
Levels of DNA Structure
- The arrangement (or order) of specific nucleotides along the chain is called the sequence.
- The sequence is genetic information
PRIMARY STRUCTURE
the arrangement (or order) of specific nucleotides along the chain is called the ____
SEQUENCE
Levels of DNA Structure | SECONDARY STRUCTURE
- most common double helical structure
- right-handed helix with 10 base pairs per 360°turn of the helix.
- Mostly found in DNA chromosomes
B-DNA
Levels of DNA Structure | SECONDARY STRUCTURE
- temporary
- produced by moderately dehydrating B-DNA, right-handed helix with 11 base pairs per turn and are not perpendicular to the helix axis (but lie 20° to the perpendicular)
A-DNA
Levels of DNA Structure | SECONDARY STRUCTURE
left handed helix with 12 residues per turn (zigzag look of phosphodiester backbone)
Z-DNA
Unusual Secondary Structures
Regions of DNA with inverted repeats, such that an inverted, self-complementary sequence in one strand is repeated in the opposite orientation in the paired strand
(opposite sides, magkabilaan)
PALINDROMES
Unusual Secondary Structures
forms of palindromic DNA
hairpin
cruciform
Unusual Secondary Structures
Forms when the inverted repeat occurs within each individual strand of the DNA
SAME SIDE
MIRROR REPEAT
Higher (Tertiary) Structure
- Intrinsic property of DNA tertiary structure
- Coiling of a coil
- Results when DNA is subject to some form of **structural strain **
- Importance:
To facilitate compaction through supercoiling
§ Common - underwinding
Important to enzymes of DNA metabolism that must bring about strand separation
§ During DNA replication
SUPERCOILING
DNA structure in the form of double helix
COIL
further coiling of DNA upon itself
SUPERCOILING
- right-handed supercoiling (underwinding)
- Fewer than number of turns
NEGATIVE SUPERCOIL
- left-handed supercoiling (overwinding)
- Greater than number of turns
- During DNA replication
POSITIVE SUPERCOIL
DNA is continuously ____
INTERTWINED
is either restricted or forbidden altogether
FREE END ROTATION
Two circular strands are linked ____
ONLY ONCE
____ is impossible, unless one of them is broken
UNTANGLING
DNA strands are unaffected by continuous deformation (conformational changes, protein interactions) as long as no breaks are introduced.
DNA TOPOLOGY
refers to a DNA segment constrained so that the free rotation of its ends is impossible
TOPOLOGICAL DOMAIN
Maintained only if the DNA is a closed circle or if it is bound and stabilized by proteins so that the strands are not free to rotate about each other
TOPOLOGICAL DOMAIN
- enzymes responsible for altering the superhelicity/supercoiling of the cellular DNA
- important in the process of replication
TOPOISOMERASES
cuts one strand of DNA and reseals after
TOP I
cut both strands of DNA
TOP II
- found in eukaryotes only
- Formed by electrostatic attraction between the negatively charged phosphate group of DNA and the positively charged group of histones
DNA + HISTONE =
CHROMATIN
DNA is complexed with a number of proteins (basic proteins):
HISTONES
will stabilize histone
ELECTROSTATIC INTERACTION
DNA + HISTONE
NUCLEOSOME
- the major class of proteins associated with DNA which exists in approximately equal to DNA in the chromatin.
- Small, basic proteins that bind to DNA by noncovalent interactions to form nucleosomes
HELPER PROTEINS
HISTONES
Histones bind to DNA by noncovalent interactions to form ____
NUCLEOSOMES
linker histone
H1
In many eukaryotes there are amino acid sequence variants of all the histones except
H4
All histones are ____ modified at various stages of cell cycle
POST-TRANSLATIONALLY
- Single-stranded; most carry out functions as single strands
- Acts as an intermediary by carrying information encoded in DNA to specify the amino acid sequence of a functional protein
- Found both in the nucleus and cytoplasm
- Roles
¨ Storage and transmission of information
¨ Catalysis
RNA
RNA is produced during
TRANSCRIPTION
- Encode the amino acid sequence of one or more polypeptides specified by a gene or set of genes
- Once mRNAs reach the ribosomes, the messengers provide the templates that specify amino acid sequences in polypeptide chains
CONTAINS THE MESSAGE
MESSENGER RNA
mRNA
One mRNA codes for only one polypeptide
MONOCISTRONIC
One mRNA codes for 2 or more polypeptide:
POLYCISTRONIC
- Adapter molecules that act in protein synthesis
- Read the information encoded in the mRNA and transfer the appropriate amino acid to a growing polypeptide chain during protein synthesis
TRANSFER RNA
tRNA
Components of ribosomes
RIBOSOMAL RNA
rRNA