(L2) DNA Structure Flashcards
DNA and RNA are _________ (they are made up
of repeating units of nucleotides)
polynucleotides
The sugar component of the genetic material is a fivecarbon molecule, known as _________
pentose
Sugar name for DNA:
Deoxyribose
Sugar name for RNA:
ribose
- monomer units or building blocks of nucleic acids.
- It is a compound consisting of a nucleoside linked to a
phosphate group.
Nucleotides
_______ form the basic structural unit of
nucleic acids such as deoxyribonucleic acid or
DNA and the ribonucleic acid/RNA
Nucleotides
The universal currency of energy, namely __, is a
nucleotide derivative.
ATP
___________ serve as donors of phosphoryl groups (e.g. ATP or GTP), of sugars (e.g. UDP- or GDP sugars), or of lipids (e.g. CDP-acyglycerol)
Nucleotide
For the coding regions in the DNA, they are for
_________
genes such as proteins.
For non-coding regions, they are either for _______.
DNA junk or to help regulate protein synthesis
________ are ring structures or aromatics that contain nitrogen and carbon in their rings. Thus, referred to as ________.
Nitrogenous Bases; heterocyclic
The nitrogen bases can be either:
Purines: Adenine, Guanine
Pyramidines: Uracil, Thymine, Cytosine
Purines and Pyrimidines are ______ whose
rings contain both carbon and other elements. (hetero
atoms)
cyclic compounds
Chemical Formula for Purines:
C5 H4 N4
Chemical Formula for Pyramidines:
C4 H4 N2
A Nitrogen base that has a double ring structure – (the
_____ ring and five membered imidazole ring)
Purine
A Nitrogen base that has a Single Ring Structure
Pyramidine
The DNA molecule has A, G, C, and T, while RNA ____________.
also has A, G, and C but T was replaced with U.
_________ are nitrogen bases that hold DNA strands together through hydrogen bonds.
Purines & Pyrimidines
A \_\_\_\_\_\_\_ contains a pyrimidine ring fused with an imidazole ring (a five-member ring with two nonadjacent nitrogen atoms).
purine
Purine is a two-ringed structure that has nine atoms forming the ring:
5 carbon atoms and 4 nitrogen atoms.
Different purines are distinguished by the _____________
atoms of functional groups attach to the rings
Purines serve much the same function as pyrimidines in
organisms:
- cell signaling
- energy storage
- enzyme regulation.
The molecules in Purines are used to make __________. Purines are abundant in meat, fish, beans, peas, and grains.
starch and proteins
A pyrimidine is an organic ring consisting of six atoms:
4 carbon atoms and 2 nitrogen atoms
Pyrimidines function in DNA & RNA:
- Cell signaling
- Energy storage
- Enzyme regulation
- Make protein & starch
Derive the nucleotide:
Nitrogenous base + Sugar + Phosphate = Nucleotide
_____ are heterocyclic, aromatic organic compounds
consisting of a pyrimidine ring fused to an imidazole
ring. (2 rings)
Purines
______ are heterocyclic, aromatic organic
compounds similar to purine containing 2 nitrogen
atoms at positions 1 & 3 of the membered ring.
Pyrimidines
__________ contains the information that determines inherited characteristics.
DNA (Deoxyribonucleic acid)
It has the code for making proteins.
DNA
It has the code for making proteins.
DNA
DNA is found in the ________ of the eukaryotic cells and in the _____ of prokaryotes if we take a closer look at
the chromatin inside the nucleus.
nucleus; cytosol
All cells require some form of instructions to be able to function properly. They need guidelines, rules, codes for making materials in the cell – and that code is ___.
DNA
A nitrogen base covalently binds with a sugar to form a
nucleoside. The bond formed is _______.
N-glycosidic bond
One of the [-PO4] groups in DNA is bound to carbon number 5 of one sugar molecule and the other to carbon number 3 of the adjacent sugar molecule. This is known as the _______.
phosphodiester linkages or bridges
The DNA has repeating subunits called _________, specifically.
monomers or nucleotides
A purine is always in pair with a pyrimidine and the slanted shape of DNA molecule causes it to form a __________
spiral or a helix
In the structure of DNA, along the sides of the molecule, it is a backbone made of alternating _________molecules while on the inside are the ________
sugar and phosphate ; nitrogen bases.
Adenine and Thymine form ___ hydrogen bonds together while Cytosine and Guanine form ___ hydrogen bonds together.
2 ; 3 (AT2 bonds / CG3 bonds)
Adenine and Thymine form ___ hydrogen bonds together while
Cytosine and Guanine form ___ hydrogen bonds together.
2 ; 3 (AT2 bonds / CG3 bonds)
letters A & T both use _____ lines; having 2 bonds
C & G uses _____ lines; having 3 bonds
straight; curved
pentagon shapes on the sides (sugar)
Deoxyribose
circles in between the deoxyribose (backbone shape)
Phosphate
How many hydrogen bonds for A & T?
2; straight line
How many hydrogen bonds for G & C?
3; curved line
have 2 rings (A & G)
Purines
have 1 ring (C & T)
Pyramidines
DNA is found in the ________
nucleus
RNA is found in the ________
nucleus and cytoplasm
Nitogen bases for DNA:
A-T-G-C
Nitogen bases for RNA:
A-U-G-C
Bases for DNA:
DNA is a long polymer with a deoxyribose & phosphate backbone
Bases for RNA:
RNA is a polymer with a ribose & phosphate backbone
Job/ Roles of DNA:
storage and transmission of genetic info.
Job/ Roles of RNA:
Transfer the genetic code needed for the creation of proteins from the nucleus to the ribosome.
This process prevents the DNA from having to leave the nucleus.
Single-stranded chain of alternating phosphate & ribose units with the bases A/G/C/U bonded to the ribose
RNA
A nucleic acid that contains the genetic instructions used in the development & functioning of all known living organisms
DNA
Predominant structure: A single-stranded molecule in most of its biological roles
RNA
Predominant Structure: Typically, a double-stranded molecule with a long chain of nucleotides
DNA
_______ molecules are involved in protein synthesis and in the transmission of genetic information.
RNA
Stability of DNA:
less reactive; stable in alkaline solution
Stability of RNA:
more reactive; not stable in alkaline solutions
The helix geometry of DNA is of _______
B-form
The helix geometry of RNA is of ______
A-form
_______ strands are continually made, broken down, and reused.
RNA
_____ is completely protected by the body.
DNA
____ can be damaged by exposure to ultra-violet rays
DNA
___ more resistant to damage by ultra-violet rays
RNA
Who founded in 1940 that DNA differ in different species. Each specie has different ratio of bases?
Erwin Chargaff
________ of molar equivalence between the purines and pyrimidines in DNA structure. DNA has equal number of Adenine and Thymine residues and an equal number of Guanine & Cytosine residues.
Chargaff’s rule
The double helical structure of DNA derives its strength from ________
Chargaff’s rule
Chargaff, in 1950, observed using current language that in any doublestranded DNA segment, the Adenine and Thymine frequencies are equal, and so are the frequencies of Cytosine and Guanine (Chargaff 1950).
Chargaff’s first parity rule
Chargaff also perceived that the parity rule approximately holds in the single-stranded DNA segment. Although it is not well understood, it has been confirmed in several organisms (Mitchell & Bride, 2006)
Chargaff’s second parity rule.
Who defended the double helix structure of DNA?
Watson & Crick (DNA double-helix structure
model)
Who defended the double helix structure of DNA?
Watson & Crick (DNA double-helix structure
model)
describes the flow of genetic information in all of life (plants, animals, humans)
CENTRAL DOGMA OF BIOLOGY
CENTRAL DOGMA OF BIOLOGY Process by which the instructions in DNA are converted into a functional product. It was first proposed in 1958
by ________, discoverer of the ______.
Francis Crick; structure of DNA
The __________ explains the flow of genetic information from DNA to RNA to make a functional product called the protein.
central dogma of molecular biology
The _______
is the basic unit of all living tissue.
cell
Each chromosome contains a long strand of DNA, tightly packaged around proteins called _________.
histones
Summary for Central Dogma:
Cell - Nucleus - Genome - Split between 23 pairs of chromosomes - DNA packaged histones - Genes contain protein-making instructions
RNA polymerase attaches to DNA and splits it → Matches mRNA at the free bases → Sections in the mRNA are added and removed.
Transcription
Ribosomes bind to mRNA in the cytoplasm → tRNA carries pre-made/pre-attached amino acids and matches to the corresponding mRNA section → the chain folds into a complex 3D shape to form a protein
Translation
- Genetic information travels from the DNA to the RNA (and
all species contain DNA that contains genetic information). - DNA is capable of replication using DNA polymerase.
- DNA contains genetic info that is transferred to RNA
through transcription
Replication
- RNA polymerases use DNA as template to make RNA.
Transcription
contains all DNA information.
(messenger) mRNA:
complexes with proteins that make up the cellular organelle called the ribosome.
(ribosomal) rRNA:
carries amino acids which works with rRNA to enable the process of translation.
(transfer) tRNA:
- mRNA is read as a template by the rRNA and proteins in
ribosome which also uses tRNA to make protein out of
amino acids. x proteins go on to perform cellular functions:
replicating, phosphorylating, signaling aspect of the cell.
Translation
Aside from the three general transfers, there are what we call special transfers or extensions of the central dogma:
- Retroviruses
2. RNA Replicase
Are viruses with RNA as the genetic material. Contain a unique enzyme Reverse Transcriptase.
Retrovirus
This enzyme can catalyze the enzymatic synthesis of a DNA complimentary to the viral RNA
Retrovirus
Example for Retrovirus or Reverse Transcriptase:
Human Immunodeficiency virus (HIV-AIDS)
RNA-containing viruses when present in their host cell (E. coli) bring about the synthesis of a set of enzymes
Because of the presence of these enzymes, the duplication of the virus RNA is made possible.
RNA Replicase
Four basic requirements for a biomolecule to quality as a genetic material:
- Ability to store large amounts of genetic information.
- Ability to transfer the information to daughter cells.
- Physical and chemical stability
- Mutability
The DNA is a very stable biomolecule mainly due to the three factors inherent in its structure:
- Sugar-phophate backbone
- Base-stacking
- H-bonding
extremely stable under all conditions like extreme temperature and pH
Sugar-phosphate backbone
which prefers to the tendency of the hydrophobic N-bases to pile on top of the other, also contributes to stability of the gene.
Base-stacking
are weak themselves, they can add tremendous stability when found between millions
between base pairs of a whole DNA structure.
H-bonds
Who termed Genetic code?
George Gamow
The collection of codons is called ________
genetic code
For 20 amino acids there should be ________
20 codons
__________ is a dictionary that corresponds with sequence of nucleotides and sequence of amino acids.
Genetic code
______ is a set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins by living cells.
Genetic code
Each codon should have 3 nucleotides to impart specificity to each of the amino acid for a specific codon.
o 1 nucleotide – __ combinations
o 2 nucleotide – __ combinations
o 3 nucleotide – __ combinations (most suited for 20
amino acids)
4; 16; 64
The _________ is a particular sequence of nucleotide that tells which amino acid are to be linked together to form a protein.
genetic code
The genetic code consists of ___ Triplets of Nucleotides that code for ___ amino acids. Each of these triplets are known as codons.
64; 20
As there are 64 codons and only 24 amino acids, a single amino acid can be coded by more than one codon. This property of genetic code is known as ___________
degeneracy
For example: Proline (CCU, CCC, CCA, CCG)
Degeneracy
However, a single codon will all be scored for a single amino acid. This property of genetic code is called __________ nature. One codon cannot specify more than one amino acid.
Non-ambiguity/Non-ambiguous nature
for example, CCU will always encode Proline and AUG always codes for Methionine.
Non-ambiguity/Non ambiguous nature
The genetic code is ______ which means, after reading one triplet the reading frame shift over the other three nucleotides. One base cannot participate in the formation of more than one codon.
Non overlapping
The genetic code is of __________. It is coma-less which means that there is no extra nucleotide between the codons. The gene is transcribed and translated continuously from a fixed starting point to the fixed stop point.
Continuous Translation
The genetic code has a start and stop codon. ____ is usually a start codon that codes for Methionine
AUG; Methionine
the stop codons are _________.
UAA, UAG, UGA.
A stop codon is also known as _____ as they do not code for any amino acid
nonsense codon
The genetic code is nearly _______ which means it is the same in human, bacteria, plants, amphibians, and viruses. However, there are some exceptions in mitochondrial genome,
Exception of a few minor variations in mitochondria,
some bacteria, and some single-celled eukaryotes.
universal
The genetic code is also _____ in a way that AUG is a codon for methionine in the mitochondria. The same code which is AUG codes for Isoleucine in the
cytoplasm.
universal
Lastly, the code has a definite direction for reading of messages which is referred to as ______. Reading of messages from left to right and right to left will specify for different amino acid.
Polarity
For example, UUG Leucine | GUU Valine
Polarity
Types of Codons:
Sense Codon and Signal Codons
code for amino acids
Sense Codons
code for signal during protein synthesis.
Signal Codons
(AUG is the initiation codon.) Its codes for
the first amino acids in all protein. At the starting point, it codes for Methionine in eukaryotes and Formyl Methionine in prokaryotes.
Start Codons
(UAA, UAG, UGA are the termination codons.) Often referred to as amber, ochre, and opal
codon
Stop Codons
The base sequence of tRNA which pairs with
codon of mRNA during translation is called ______
Anticodon
- could be present in both DNA & RNA
- written in 5 to 3 direction
- are sequentially arranged in nucleic acid strand
- defines which anticodon should come next with an amino acid to create the protein strand
Codon
- always present in RNA & never in DNA
- usually written in 3 to 5 direction.
- discretely present in cells with amino acids attached or not
- helps in bringing a particular amino acid at its proper position during translation
- of some tRNA molecules have to pair with more than one codon.
Anticodon
Mutations can be well explained using the ________
genetic code.
Point Mutations
- Silent Mutations
- Missense Mutations
- Nonsense Mutations
- Frame Shift Mutations
- Mutations in DNA that do not have an observable
effect on the organism’s phenotype. - Single nucleotide change (GAA-Glutamate to GAGGlutamate), same amino acid is incorporated.
Mutation goes unnoticed
Silent Mutations
- is a point mutation in which a single nucleotide change result in a codon that codes for a different amino acid.
- The single nucleotide change (CAT-Histidine to CCTProline) different amino acid incorporated. Loss of functional capacity of protein.
Missense Mutations
- A single nucleotide change (CAG-Glutamine to
TAG-stop), a stop codon is generated (in mRNA
represented by UAG), - The premature termination of chain may be
incompatible with life. - This type of mutation results in a shortened
protein that may function improperly or not at all
Nonsense Mutations
genetic manipulation of microorganisms for the production of antibiotics,
hormones, etc.)
Biotechnology
tests are used in detection of a crime
Forensics
→ ____ is the blueprint for life
→ ____ isolation is one of the most basic and essential
techniques in the study of ____.
→ The extraction of ____ from cells and its purification are
of primary importance to the field of biotechnology
and forensics
DNA
