Module 2: section 3 - Nucleotides And Nucleic Acids Flashcards
What is a nucleotide?
Monomer from which nucleic acids ,like DNA and RNA are formed
What is the basic structure of a nucleotide
Pentose sugar(made of 5 carbons)
A phosphate group
A nitrogenous base
What is a polynucleotide
Polymer of nucleotides
How do nucleotides join and what bond do they form
Via a condensation reaction between a phosphate group of one nucleotide and the sugar of another
and they form a phosphodiester bond
What are the bonds between bases
Hydrogen
What is anti parallel orientation
Helix’s two strands run in opposite directions
What is complementary base pairing
Each base can only join with one particular partner
What bases pair with each-other in DNA
Adenine and thymine
Guanine and cytosine
How many hydrogen bonds form between A and T and G and C
A and T= 2
G and C =3
Why is the hydrogen bonds being weak so important
It allows the DNA to separate so replication and transcription can occur
What does DNA being semi conservative mean
One strand from the original polynucleotide and the other is a new complementary strand
What is helicase and what does it do
It’s and enzyme
It breaks the hydrogen bonds between the base pairs on the two polynucleotide DNA strands
What is polymerase and
what does it do
It’s an enzyme
It forms phosphodiester bonds between the nucleotides
What is the process of DNA replication
1) DNA helicase breaks hydrogen bonds between base pairs, unwinding the helix to form two single strands
2) free floating nucleotides form hydrogen bonds with complementary bases
3) condensation reaction join the nucleotides of the new strands together using DNA polymerase
What does it mean when it states a code is degenerate
Multiple codons can encode a single amino acid
Is DNA or RNA a nucleic acid
Both
What are the two categories nitrogenous bases can be categorised into
purines and pyrimidines
How many carbon-nitrogen rings do purines have and what are the examples
Have 2 carbon-nitrogen rings
adenine and guanine
How many carbon-nitrogen rings do pyrimidines have and what are the examples
Has 1 carbon-nitrogen ring
thymine, uracil and cytosine
What are the sugars in RNA and DNA called
RNA-ribose (sugar)
DNA- deoxyribose(sugar)
*in exam refer to the type of sugar or you don’t get a mark
What is ATP’s structure
a pentose sugar (ribose)
a nitrogenous base (always adenine)
three phosphate groups
How is ATP made
ADP+ Pi –>ATP+ H2O
Made during both types of respiration via a condensation reaction and using the enzyme ATP synthase
How does ATP release energy
-It is hydrolysed using the enzyme ATP hydrolase
- Breaking one of the Phosphoanhydride bonds between the phosphate group releases a small amount of energy
What is phosphorylation
when the inorganic phosphate released can bond onto a completely different compound to make them more reactive
How does DNA structure relate to its function
-stable structure due to the sugar phosphate backbone (covalent bonds) and the double helix
-double stranded so replication can occur using both strands as a template
-weak hydrogen bonds between bases for easy separation of the two strands in a double helix during replication
-complementary base pairing allows identical copies to be made
what are the three types of RNA
-mRNA
-tRNA
-rRNA
What is mRNA
a copy of one gene from DNA
what is a codon
three bases on mRNA that codes for a specific amino acid
what does the 5’(prime) end or 3’ (prime) end mean
these numbers refer to what which carbon in the deoxyribose sugar is closest to the top/bottom
What are the special features of the genetic code
degenerate, universal and non overlapping
what does the term universal mean
the same triplet of bases codes for the same amino acid in all organisms
what does the term non overlapping mean
each base in a gene is only part of one triplet of bases that codes for one amino acid
What happens in transcription
mRNA is created from a copy of one gene on DNA
What happens in translation
where mRNA joins with a ribosome and a corresponding tRNA molecule brings the specific amino acid the codon codes for
what is a nucleic acid
A nucleic acid is a chain of nucleotides which stores genetic information in biological systems
describe the process of transcription
1) DNA helicase breaks the hydrogen bonds between the bases
2) this causes the DNA helix to unwind and one strand acts as a template
3) Free mRNA nucleotides align opposite exposed complementary
DNA bases
4)The enzyme RNA polymerase joins together the adjacent RNA nucleotides, forming phosphodiester bonds to create a new mRNA polymer chain
describe the process of translation
1)once the modified mRNA has left the nucleus it attaches to the small subunit of the ribosome at the start codon
2) The tRNA molecule with the complementary anticodon to the start codon aligns opposite the mRNA held in place by the ribosome. The ribosome can hold 2 tRNA molecules at one time.
3) The two amino acid that have been delivered together are joined together via a peptide bond
4)The ribosome will move along the mRNA molecule to the next codon and another complementary tRNA will attach to the next codon
5)This continues until the ribosome reaches the stop codon at the end of the mRNA molecule causing the ribosome to detach and end translation
compare DNA transcription and replication
Similarities · DNA unwinds and unzips · Helicase enzymes · Template DNA · Complementary base pairing · Hydrogen bonds · Free, activated nucleotides · Polymerase enzymes
Differences · Only a small section of DNA (where the gene is located) unzips during transcription · Both strands act as templates in replication · RNA vs DNA free nucleotides · RNA vs DNA polymerase · Different helicase enzymes · Products are two new daughter strands of DNA in replication and one mRNA strand in transcription · mRNA leaves nucleus whereas the new DNA strand remains bound to the template strand
what elements do all nucleotides contain
carbon
hydrogen
oxygen
nitrogen
phosphorus
What are the steps involved in purifying DNA using ethanol precipitation?
1)Cell Lysis: Break open the cells using a detergent solution (e.g., sodium dodecyl sulphate, SDS) to release DNA.
2)Remove Contaminants: Add a salt solution (e.g., sodium chloride) to neutralize DNA and help remove proteins and lipids.
Precipitate DNA: Add ice-cold ethanol to the mixture. DNA will precipitate out of the solution.
3)Collect DNA: Centrifuge the solution to form a DNA pellet at the bottom of the tube.
Wash and Dry: Wash the DNA pellet with cold ethanol to remove impurities and air-dry the DNA.
