Chapter 3: Nucleotides, Nucleic Acids, and Genetic Information Flashcards
What are nucleic acids?
Nucleic Acids are biopolymers and polynucleotides—that is, long chainlike molecules composed of a series of nearly identical building blocks called nucleotides.
Nucleic Acids function?
Store genetic info and a variety of other functions
Nucleic acids are made up of monomers called?
Nucleotides
The two kinds of nucleic acids?
DNA and RNA
What is the general structure of a nucleotide?
Ribose or Deoxyribose sugar (5 carbon sugar), Phosphate, and Nitrogenous base
What are the two types of nitrogenous bases and what are the difference between them?
Purine- has double ring
Pyrimidine- single ring
What are the common purines? Pyrimidines?
Purine- Adenine and Guanine
Pyrimidine- Cytosine, Uracil, and Thymine
What is a nitrogenous base?
molecules that contain nitrogen and act as a base. nitrogen combines with C,H, and O to form ring like structure. Called bases because they donate electrons to other molecules and form new molecules.
Where do Purines bond to the sugar?
purines form bonds to the sugar via their N9 atoms to C1 of sugar
Where do Pyrimidines bond to the sugar?
Pyrimidines form bonds with sugar via their N1 atom to sugar’s C1
Bond that links carbs with other structures
glycolic bond
Draw the structure of a nucleotide
what are the two pentoses?
-In ribonucleotides the pentose is Ribose –In deoxyribonucleotides the pentose is deoxyribose
Difference between ribose and deoxyribose?
At C2,
-ribose has hydroxide atom, less stable
-deoxyribose has hydrogen atom, more stable cause one less functional group
What is a phosphate?
Has 4 oxygen atoms bonded to a phosphorous atom.
Has a negative charge
holds atp
Phosphate is present in?
ATP
(triphosphate)
energy carrying molecule of the body
How does phosphate attach to Sugar?
-In ribonucleotide, Phosphate bonds to C5 of sugar
-In deoxyribonucleotide, Phosphate bonds to C3 of sugar
nucleoside means
no phosphate present
chain of nucleotides
polynucleotides which are either DNA or RNA
How do polynucleotides form?
Hydrogen bond between bases
and
Sugar phosphate backbone. C5 of sugar on bottom bonds to C3 of sugar above it. repeated.
When bases bond what does it create?
DNA,
bonds through hydrogen bond
What is Chargaff’s Rule?
Complimentary base pairing?
A=T
G=C
Common nucleotides? Where do bases occur?
-A,G, & C occur in RNA & DNA
-U occurs in only RNA
-T occurs in only DNA
the best known free nucleotide?
ATP
(adenosine triphosphate)
What is ATP
energy carrier or energy transfer agent
Describe the hydrolysis of ATP to ADP
When ATP transfers one or two of its phosphate groups to another molecule creating ADP
What does ADP stand for
Adenosine Diphosphate
The type of bond that holds the phosphate group to the sugar in DNA’s backbone is called a ?
phosphodiester bond
What is Chargaff’s Rule? what does it exclude
A=T
G=C
composition analysis of DNA
complimentary base pairing
base composition of DNA
it excludes RNA
Describe DNA structure
The Watson–Crick model of DNA has the following major features
1. Two polynucleotide chains wind around a common axis to form a double helix.
- The two strands of DNA are antiparallel (run in opposite directions), but each forms a right-handed helix. (
Why does RNA form a stem loop?
because base pairing occurs intramolecularly and since RNA has a single stranded structure, it loops and interacts with each other
Why does DNA replication occur?
because when cells divide, the new cells need DNA info, DNA has to replicate before dividing.
What is the central dogma of molecular biology? describe steps
DNA is converted into protein.
The DNA of a gene is transcribed to produce an RNA molecule that is complementary to the DNA. The RNA sequence is then translated into the corresponding sequence of amino acids to form a protein
What role do mRNA, tRNA, and rRNA have in the central dogma?
The RNA that corresponds to a protein-coding gene (called messenger RNA, or mRNA) makes its way to a ribosome, an organelle that is itself composed largely of RNA (ribosomal RNA, or rRNA). At the ribosome, each set of three nucleotides in the mRNA pairs with three complementary nucleotides in a small RNA molecule called a transfer RNA, or tRNA (Fig. 3-13). Attached to each tRNA molecule is its corresponding amino acid.
DNA is transcribed into? and the RNA is translated into?
RNA
proteins
The overall strategy for sequencing any polymer of nonidentical units is?
- Cleave/Split the polymer into fragments that are small enough to be fully sequenced.
- Determine the sequence of residues in each fragment.
- Determine the order of the fragments in the original polymer by aligning fragments that contain overlapping sequences.
1.Restriction Endonucleases Cleave DNA at Specific Sequences
2.Electrophoresis Separates Nucleic Acids According to Size
Treating a DNA molecule with a restriction endonuclease produces a series of precisely defined fragments that can be separated according to size.
3.Traditional DNA Sequencing Uses the Chain-Terminator Method
What are restriction enzymes?
restriction enzymes are the enzymes that cleaves the dna in small fragments.
protect the dna of prokaryotes against the invading bacteriophages
Where only can restriction enzymes cleave in the DNA?
the restriction enzyme can fragment only non-methylated dna hence the host dna remains protected.
This system destroys foreign (phage) DNA containing a recognition site that has not been modified by methylation. The host DNA is always at least half methylated,
How are restriction enzymes named?
A restriction enzyme is named by the first letter of the genus and the first two letters of the species of the bacterium that produced it, followed by its serotype or strain designation, if any, and a roman numeral if the bacterium contains more than one type of restriction enzyme. For example, EcoRI is produced by E. coli strain RY13.
isoschizomers
Restriction enzymes with the same recognition sequence isolated from different organisms
neoschizomers
Restriction enzymes with the same recognition sequence but with a different cutting pattern
purpose of gel electrophesis?
separates nucleic acids according to size
describe gel electrophoresis and how it works
Uses agarose gel
Relies on dna molecules having a negative charge
dna goes into wells
Longer DNA pieces tend to have a higher molecular weight and they take more time to make it across the gel when you compare it to shorter DNA pieces which move at a faster rate.
Longest closest to wells
What is the chain-terminator method?
DIDEOXYNUCLEOTIDE
The DNA to be sequenced must be converted from double stranded to single strand. This is done using heat. Use single strand as template strand.
Primer is added to template strand to allow for addition of nucleotides
4 reaction mixers are set up, add template strand with primer to each mixer. Add dna polymerase , free nucleotides (dNTPS’), and ddNTP. Chain terminator begins because theres no OH,
Take sample of each of the 4 reaction mixers put in Gel electrophoresis.
in vivo meaning
living system
in vitro meaning
in test tube
recombinant DNA is also known as?
molecular cloning
makes it possible to isolate, amplify, and modify specific DNA sequences.
how to clone dna?
- A fragment of DNA of the appropriate size is generated by a restriction enzyme, by PCR (Section 3-5C), or by chemical synthesis.
- The fragment is incorporated into another DNA molecule known as a vector, which contains the sequences necessary to direct DNA replication.
- The vector—with the DNA of interest—is introduced into cells, in which it is replicated.
-THAN PLACE PLASMID IT INTO AN ORGANISM/SOLUTION THAT CAN MAKE THE COPIES
-ORGANISM THAT IS TYPICALLY USED IS THE BACTERIA KNOWN AS E COLI, it uses heat shock to take in the plasmid
-PLACE A GENE for ANTIBIOTIC RESISTANCE IN PLASMID so only bacteria that have taken plasmid will aoear
-THEN put bacteria/plasmid on plate to grow bacteria - Cells containing the desired DNA are identified, or selected.
Transformed cells can be identified by selectable markers.
list some vectors
E. coli plasmid designated pUC18,Bacteriophage λ,bacterial artificial chromosomes (BACs) or yeast artificial chromosomes (YACs)
Genomic libraries contain ?
all the DNA of an organism. Clones harboring particular DNA sequences are identified by screening procedures.
A DNA library is a collection of cloned DNA segments that can be screened to find a particular gene.
The polymerase chain reaction
amplifies/multiplies selected sequences of DNA by repeatedly synthesizing complementary strands.
