Nucleic Acids Flashcards
What does DNA stand for
Deoxyribosenucleic acid
Describe the structure of a nucleotide
Pentose sugar (deoxyribose in DNA)
A phosphate group attached to the sugar
A nitrogenous base (A,T,C or G)
What is the difference between ATP and a RNA nucleotide
ATP has become phophorylated (gained 2 extra phosphates)
What term describes the direction the 2 DNA strands run in
Antiparallel
What is the name of the covalent bond between the pentose sugar and the phosphate
Phosphodiester bond
What is a purine and what are the 2 examples
A purine is a nitrogenous base with 2 rings
Adenine and Guanine
What is a pyramidine and what are the 2 examples
A pyramidine is a nitrogenous base with only 1 ring
Thymine and Cytosine
How many hydrogen bonds form between A and T
2
How many hydrogen bonds form between C and G
3
What is the name of the shape of a DNA molecule
Double Helix
How is DNA stored in Eukaryotes
The majority is stored in the nucleus
wrapped around protiens called histones to form chromosomes
there is a loop of DNA without a histone in mitochondria and chloroplasts
How is DNA stored in Prokaryotes
DNA is in a loop within the Cytoplasm (no nucleus)
DNA is described as naked as it has no histone
What stage of the cell cycle does DNA replication take place
Interphase
S
What is the name of the enzyme that catalyses the ‘unzipping’ process
DNA Helicase
What enzyme catalyses the unwinding process
Gyrase
What is the name of the type of replication DNA performes
Semi-conservative Replication
What is Semi-conservative Replication
DNA replication where 1 strand in the new molecule is from the origional molecule and 1 strand is newly formed
What is the name for a different variation of a gene
an Allele
What are the 5 structural differences between RNA and DNA
Sugar is different (Ribose in RNA)
Uracil replaces Thymine
Single stranded
Shorter chain
3 forms of RNA (mRNA, tRNA and rRNA)
What specifically does DNA code for
the Amino acid sequence (primary structure)
Why is it importand that the amino acid sequence (primary structure) is correct
because then it allows the chain to flod and be held in its tertiary structure giving it its specific 3D shape
Having a specific 3D shape is vital to a protiens function
What process allows the genetic code to be able to be moved out the nucleus, and what molecule does this form
Transcription
forms mRNA
Describe the process of Transcription
Gyrase and DNA helicase unwind and unzip the DNA
Hydrogen bonds break between bases
RNA polymerase catalyses the formation of tempory hydrogen bonds between RNA nucleotides and the DNA bases
The RNA strand is now complementary to the ‘template strand’
mRNA moves out the nucleus and joins a ribosome
Where are tRNA molecules made
the Nucleolus
What is the name of the 3 bases at the top of the loop on a tRNA molecule
the Anticodon
What joins to the 3 bases at the straight tip of a tRNA molecule
Amino acid
What causes the ribosome to stop moving along the mRNA chain
the Stop Codon
What happens to the mRNA chain after translation
it breaks down into free nucleotides again
