Nucleotides And Nucleic Acids Flashcards
What are the two types of nucleic acids
DNA
RNA
What are the monomer and polymer of a nucleic acid
Monomer- nucleotide
Polymer-nucleic acid
What are the 3 components of a nucleotide
Phosphate
Pentose (5C) sugar
Organic nitrogenous base
Name the elements found in dna and rna nucleotides
Carbon Hydrogen Nitrogen Phosphorus Oxygen
What reactions take place to make a nucleotide
What does this mean
Two condensation reactions
2 water molecules are released
Name the bases present in dna and rna
DNA-ATGC
RNA-AUGC
What happens during the formation of nucleic acids
The phosphate group at the 5th carbon of pentose sugar of one nucleotide forms a covalent bond with the OH group at the third carbon of pentose sugar of an adjacent nucleotide
What is another name for the covalent bond formed between nucleotides
A phoshodiester bonds
Describe the strands in DNA
It’s double stranded
They run antiparallel
Each strand has a phosphate group at one end and a hydroxyl group at other
How are dna strands attached together
By hydrogen bonds
What happens to the strands of dna
They coil into a helix called a double helix
Name two purines
Adenine
Guanine
What is a purine
2 rings of carbon atoms
Name the two Pyrimidines
Thymine
Cytosine
What is a pyrimidine
Has 1 ring of carbon
Which bases form two hydrogen bonds
Adenine
Thymine
Which bases form 3 hydrogen bonds
Guanine
Cytosine
What is chargraffs rule
Adenine must pair with thymine
Guanine must pair with cytosine
There are equal amounts of A and T
There are equal amounts of G and C
What is the job of RNA
DNA stores all genetic info but is too big to fit out the nucleus
Short sections of dna molecule corresponding to a single gene are transcribed into a short messenger RNA molecule (single stranded)
This can leave the nucleus and go to the ribosome for protein synthesis
What is mRNA
A polymer composed of many nucleotide monomers - it’s a polynucleotide
Three similarities between RNA and DNA
5 carbon sugar
Bases of CGA
Has a phosphate group
Three differences between RNA & DNA
rna single stranded dna double stranded
Rna has uracil instead of thymine in dna
Rna has ribose sugar and dna has deoxyribose sugar
Explain the dna precipitation (peas) experiment
Peas mashed up
Washing liquid added
Add protease enzyme
Add ethanol on top -causes dna to precipitate out of the solution
White strands of dna form between the same and layer of alcohol
Where does dna replication occur
In the nucleus
Explain the stages of semiconservative DNA replication
1) the DNA helix unwinds by action of gyrase enzyme
2) Strands separate by action of helicase enzyme which breaks the hydrogen bonds between complimentary bases
3) Free DNA nucleotides are attracted and with the complimentary bases and hydrogen bonds form
4) DNA polymerase forms the sugar phosphate backbone by forming phosphodiester bond
What enzyme unwinds the dna helix
Gyrase
What enzyme separate strands in DNA replication
Helicase
What bonds form in the sugar phosphate backbone
Phosphodiester bond
Why do we call semiconservative DNA replication that
Because two identical copies of DNA are made and each DNA molecule has one original strand and one new strand each original strand acts as a template
Describe nitrogen 15
Heavy - dense- bottom of test tube
Describe nitrogen 14
Light- less dense- forms at top of test tube
Why is the sequence of organic bases in DNA important
The sequence of bases determines the sequence of amino acid’s in the primary structure
What is an advantage of the double helix structure
It gives the molecule stability
What is a codon
Three bases that code for an amino acid
What does it mean by non-overlapping
Each nucleotide is only part of one triplet of bases
What is the de-generative code
There are a lot more codons than amino acids
What is the universal code
The same specific base triplets code for the same amino acids in all living organisms
What is Protein synthesis used for and where does it occur
Used for making proteins it happens in the nucleus and at the ribosomes
Define Gene
The sequence of nucleotide bases in DNA which determine the sequence of amino acid in the polypeptide chain
What is the purpose of transcription
Where does it occur
Makes mRNA from DNA
Occurs in the nucleus
Explain the process of transcription
1) The enzyme DNA helicase unwinds and unzips the DNA helix
2) Hydrogen bonds are broken the DNA helix unwinds in the region of the chromosome that codes for the gene
3) Complimentary RNA nucleotides come into position to form a complimentary copy of the gene known as mRNA
4) RNA polymerase joins RNA nucleotides to make the mRNA this is a condensation reaction
5) Phosphodiester bonds formed between the RNA nucleotides this forms the sugar phosphate backbone
What is the strand of DNA that contains coded information called
The sense strand
What does the antisense strand to do during transcription
It acts as a template which means the RNA strand carries the same base sequence as the Sense strand
What does DNA helicase do
Breaks hydrogen bonds between base pairs so that the section of DNA containing the gene unzips
What does RNA polymerase do in transcription
Forms phosphodiester bonds between RNA nucleotides to make messenger RNA
forms of sugar phosphate backbone
What is the purpose of translation and where does it occur
At the ribosome and it makes a protein from messenger RNA
What is the purpose of ribosomal RNA
How old is the messenger RNA in position while it is translated into a specific sequence of amino acid
What is the ribosome composed of
Two subunits one large and one small and these are composed of proteins and ribosomal RNA
What happens during translation
2) Transfer RNA with the complimentary anticodon to start the code on comes into the ribosome and binds to the mRNA start codon
4) the Next transfer RNA with the anti codon complimentary to the next codon it brought in to the ribosome
5) The peptide bond forms between the two amino acid’s
6) This is catalysed by an enzyme called peptidyl transferase
7) The stages are repeated with another amino acid being added each time to the polymer
What is the overall job of the codon
Codons on a mRNA determine the specific transfer RNA that comes into position
What is the role of transfer RNA
To bring in specific amino acid’s to the ribosome in the correct order
What are the amino acid’s then join together bye
Peptide bonds
Name the enzyme that catalyse is translation
Peptidyl transferase
What does ATP stand for
Adenosine Triphosphate
Describe the structure of adenosine
There are three phosphate’s, a pentose sugar and a nitrogenous base which is Adenine
What is ATP used for
Energy transfer in all cells of living organisms
In ATP what is not stable
The phosphate bonds are not stable this means ATP is not a good long-term store of energy
What is ADP
Where ATP loses a phosphate, bond is broken as this is the hydrolysis reaction and water is used
Name 4 properties of ATP
It is small so it’s easily to move into and out of cells
It is soluble in water
Releases energy in small quantities
Energy is contained in the bonds between phosphate is large enough for cell reactions
