Unit 2.3- Nucleotides and nucleic acids Flashcards
Nucleotide definition:
Molecule consisting of a five-carbon sugar, a phosphate group and a nitrogenous group.
Polynucleotide definition:
Large molecule containing many nucleotides.
What are the 4 DNA bases called?
- Adenine
- Guanine
- Cytosine
- Thymine
Which DNA are purine?
Adenine and Guanine
Which DNA are pyrimidine?
Cytosine and Thymine
How many carbon nitrogen base rings do purine DNA bases have?
2
How many carbon nitrogen base rings do pyrimidine DNA bases have?
1
What type of bonds make up the backbone of DNA ?
Phosphodiester bonds
What types of bonds are there between the bases of DNA?
Hydrogen
What type of nucleotide is DNA?
Polynucleotide (made of 2 polynucleotide chains)
Whats is the structure of RNA like?
-Single stranded polymer Each RNA nucleotide consists of: -A pentose sugar -A phosphate group -A base (Uracil instead of Thymine)
What is difference between the structure of deoxyribose and the structure of ribose?
On deoxyribose there is a H connected under C2, but on ribose it is an OH
How many hydrogen bonds are there between A and T?
2
How many hydrogen bonds are there between C and G?
3
What is the structure of AMP, ADP and ATP like?
- Adenine connected to the right of a ribose molecule
- 1, 2 or 3 phosphate groups connected on the left side of the ribose molecule.
What do ATP, ADP and AMP all do?
Help to regulate many metabolic pathways.
What is different about the two sides of the DNA ladder?
They’re antiparrallel (running in different directions)
What does it mean by the 2 sides of the DNA ladder being antiparrallel?
5prime_______3prime
3prime_______5prime
This is because when one strand is upside down, it is going in the other direction compared to the first strand
Why does a purine have to bond with a pyrimidine?
Purines have 2 rings and pyrimidines have 1 so when they bond there are 3 so all the rungs of the ladder are the same size.
Where is RNA found?
The nucleus and cytoplasm
What are the types of RNA?
mRNA (messenger)
tRNA (transfer)
rRNA (ribosomal)
How do the sizes of DNA and RNA compare?
RNA is generally shorter
Why does DNA need to replicate?
To get an exact copy of DNA when cells divide through mitosis or meiosis
What stage of mitosis and meiosis does DNA replicate in?
The interphase
Why is DNA replication called Semi-conservative replication?
Because half of it stays the same and the other half is created.
How does DNA replication happen?
- DNA helicase unzips and unwinds the DNA, breaking the hydrogen bonds
- This results in 2 single strands of DNA with exposed nucelotide bases which free floating nucleotide bases in the nucleoplasm can bond to
- DNA polymerase causes the addition of the new nucleotide bases in the 5 prime 3 prime direction
- The leading strand is synthesised continuously whereas the lagging strand is in fragments that are later joined
- Hydrolysis of the activated nucleotides to release the extra phosphate groups supplies energy to make phosphodiester bonds for the backbone.
What is the job of DNA polymerise?
Joins up the backbone in the 5 prime 3 prime direction by creating phosphodiester bonds
What is the job of DNA helicase?
Unzips the DNA by breaking hydrogen bonds between the nucleotide bases.
What is DNA replication?
Copying of DNA
What is DNA transcription?
Turning DNA into RNA
What is DNA translation?
Turns mRNA into proteins
How do DNA and RNA monomers compare?
Both P-S-B (phosphate-sugar-base)
How do the sugars in DNA and RNA compare?
DNA= deoxyribose RNA= ribose
How does the location of DNA and RNA compare?
DNA= nucleus only RNA= nucleus and cytoplasm
How does the function of DNA and RNA compare?
DNA= carries/transfers genetic information RNA= same as DNA and protein synthesis
How does the structure of DNA and RNA compare?
DNA= double strand RNA= single strand
How does DNA transcription happen?
- DNA helicase causes DNA to unwind and unzip, breaking the hydrogen bonds between the bases
- RNA polymerase causes free floating RNA nucleotide bases form hydrogen bonds with the complementary DNA base pairs and creates a backbone for the RNA
- RNA helicase breaks the hydrogen bonds between the DNA and RNA bases
- The RNA leaves through the nuclear pore
- The DNA joins back together
How does DNA translation happen?
- mRNA leaves the nucleus through the nuclear pore
- A ribosome attaches to the mRNA and reads the bases in codons (triplets)
- Each codon codes for an amino acid, which are building blocks for proteins
- tRNA codons have specific anticodons for each of the 20 amino acids
- The complementary anticodon is attracted to the complementary codon on the mRNA and forms a weak hydrogen bond
- The second codon on the mRNA attracts the second anti codon of tRNA and a peptide bond forms between the adjacent amino acids
- The tRNA starts to leave as amino acids are bonded
- The polypeptide chain has then been formed and is released into the cytoplasm
- The tRNA molecules are activated after use by recombining with their specific amino acids
- The protein then goes to the RER which packages the protein into a vesicle
- The vesicle then fuses with the golgi body
How is DNA organised in eukaryotic cells?
- The majority of the DNA is in the nucleus
- Each large molecule of DNA is tightly wound around histone proteins into the chromosomes. Each chromosome is therefore one molecule of DNA
- There is also a loop of DNA without the histone proteins inside mitochondria and chloroplasts
How is DNA organised in prokaryotic cells?
- DNA is in a loop in the cytoplasm
- Not wound around histone proteins
- ‘Naked DNA’
How is DNA organised in viruses
It is a loop of naked DNA
What kind of bonds are formed between amino acids?
Peptide bonds
What is the genetic code described as?
- Near universal
- Degenerate
- Non-overlapping
What does it mean by the genetic code being near universal?
In nearly all organisms, the same triplet of DNA bases codes for the same amino acids
How many different amino acids are there that can be found in proteins?
20
Proteinogenic definition:
Amino acids are proteinogenic if they are found in proteins
What does it mean by the genetic code being degenerate?
For every amino acid apart from two there is more than one DNA triplet that codes for it
Frame shift definition:
When a mutation occurs causing a base to be deleted, causing other bases to move down and different amino acids to be made
Point mutation definition:
One bases changes
Where is rRNA found?
Ribosomes
What are ribosomes made of?
A combination of RNA and a bunch of proteins all working together
What does the RNA in the large sub unit of a ribosome function as?
A ribosome and catalyses the formation of new peptide bonds during photosynthesis
