Polymers of Life 8: DNA & RNA Flashcards
Does DNA stand for
Deoxyribose Nucleic Acid
Definition of ribose
Sugar like glucose but with only five carbon atoms and it’s molecule
Definition of deoxyribose
Almost the same as ribose but lacks 1 alcohol group
Describe the basic building blocks of DNA
- Deoxyribose for DNA or ribose
for RNA - phosphate groups ( H3 PO4 )
- 4 different bases ( A, G, C, T )
How do you join a deoxyribose molecule and a phosphate group together
-be able to draw
- condensation reaction ( water formed)
- 2 alcohol groups from the deoxyribose drawing to the phosphate group
- 2 Alcohol groups from the phosphate group join to the deoxyribose molecule
Look at sheet on how to draw
What does the joining of many phosphate groups and deoxyribose
- Starting polymer structure for different kinds of DNA nucleotide formation
- exposed OH on deoxyribose will bond to the bases
- non exposed chain = phosphate backbone = remain the same ( where as different bases will be attached to exposed OHs)
What is a DNA nucleotide
deoxyribose + phosphate + one of the bases
3 things have to be present for it to be a DNA nucleotide
Name the 4 most common organic bases
- Adenine, A
- Thymine, T
- Cytosine, C
- Guanine, G
Which part of the bases joins with the alcohol on the deoxyribose
Amine group = hydrogen bonding
Be able to draw a full DNA nucleotide
Look at sheet
How is the DNA molecule formed
- By millions of nucleotides joined together in a long chain
- alternating sugar-phosphate groups ( backbone ) + bases
Why is DNA double stranded
Each of the nucleotides has 2 base & the complimentary base has to pair with it
Give the bearings of the bases
baes always pair up in the same way
- Adenine & Thymine = A-T
- Cytosine & Guanine = C-G
What kind of bonding is there between the base pairing
Hydrogen bonding between the base pairs holds DNA strands together
Describe the difference in hydrogen bonding between GC & AT
- GC contains 3 hydrogen bonds
- AT contains 2 hydrogen bonds
Describe the structure of DNA
- double helix
- Base paired strands = coiled into a spiral = double helix
Describe the steps of protein synthesis ( 3 )
- Transcription = copy DNA into mRNA
- mRNA leaves the neucleus & goes to the ribosomes ( protein synthesis takes place in ribosomes )
- Ribosomes read mRNA & hook on the correct amino acid = Translation
What happens in transcription ( 2 )
- Part of the DNA double helix unwinds & unzips
2. One strand acts as a template for the synthesis of a single-stranded mRNA copy of the gene
What are the key differences between DNA and RNA
- DNA = deoxyribose
RNA = ribose - DNA = A T C G
RNA = A U C G ( uracil not Thymine ) - DNA = double stranded
RNA = single stranded
How does mRNA carry the code
- In a sequence of bases that - corresponds to a particular amino acid
- Code = triplet code = 3 bars coding for each amino acid = codon
What is the rule for each triplet code or codon
- Each triplet codes for a specific amino acid
- amino acids = joined together in the correct sequence to make part of a protein
What happens once the DNA strand is transcripted into mRNA
- Code carried by mRNA is translated with the aid of a transfer RNA (tRNA ) and particles in the cell called ribosomes
What does mRNA and tRNA stand for
- Messenger RNA and transfer RNA
What does tRNA have
Contains anti codon for binding to a codon on mRNA from the nucleus
How does tRNA work
- tRNA molecules bind to the mRNA molecule in the ribosome and a bond forms between the two amino acids that they carry away
- having delivered it’s amino acid the tRNA molecule separates from the mRNA and leaves the ribosome
- The ribosome moves further along the mRNA chain & continues to put different amino acids together
What happens when a complete proteins is synthesised
Certain mRNA codons ( UAA, UGA, UAG ) code for a stop, signalling the release of the completed protein
How does an amino acid link to a tRNA molecule
Forms an ester bonds with the carboxylic acid present on the amino acid
