Nucleic Acids Flashcards
What is ATP made up of?
Adenine
Ribose
3 phosphates
What does ATP stand for?
Adenosine triphosphate
Why is ATP known as the universal energy currency of the cell?
Used as a source of energy in all cells in all organisms
Active transport of molecules across membranes
Transport molecules within a cell
What does ADP stand for?
Adenosine diphosphate
How does ATP become ADP?
ATP is hydrolysed by ATPase
How does ADP become ATP?
By phosphorylation
Condensation reaction by ATP synthase
How much energy is released when ATP is hydrolysed into ADP?
30.6 kJ/mol ATP
What type of reaction is it when ATP is hydrolysed into ADP?
Exergonic (catabolic)
What type of reaction is it when ADP is combined with Pi into ATP?
Endergonic (anabolic)
Why is ATP a good energy currency?
Energy in small amounts, when and where needed
Single step reaction so energy is released immediately
Only requires one enzyme - ATPase
What are the six roles of ATP
Active transport
Metabolic processes
Nerve transmission
Secretion
Protein synthesis
Cellular division
Muscle contraction
What are the sub units of DNA called?
Nucleotides
What are the nucleotides of DNA called?
Deoxyribose sugar
Phosphate group
Nitrogenous base
What are the nitrogenous bases in DNA?
Cytosine
Guanine
Thymine
Adenine
What are the nitrogenous bases in RNA?
Cytosine
Uracil
Guanine
Adenine
What are pyrimidines?
Single ring structure nitrogenous bases
Why are purines?
Double ring structure nitrogenous bases
Which nitrogenous bases are pyrimidines?
Cytosine
Thymine
Uracil
Which nitrogenous bases are purines?
Adenine
Guanine
What is the backbone of DNA made up of?
Deoxyribose and phosphate
What are the bonds that hold together the backbone of DNA?
Phosphodiesta bonds
What is the structure of messenger RNA (mRNA)?
Long single stranded helix
What is the function of mRNA?
Manufactured in nucleus and carries genetic code from DNA in the nucleus to the ribosome
What is the structure of ribosomal RNA (rRNA)?
Long, large, complex molecule, both double and single helixes
What is the function of rRNA?
Ribosomes are made up of protein and rRNA
What is the structure of transfer RNA (tRNA)?
Small, single-stranded clover leaf shape. Amino acids attach at one end. Anticodon of 3 based on the other end
What is the function of tRNA?
Bring amino acids to ribosomes so proteins can be synthesized
What are the differences between a DNA nucleotide with an RNA nucleotide?
DNA: deoxyribose, A C T G bases
RNA: ribose, A C U G bases
What are the differences between a DNA polymer and an RNA polymer?
DNA polymer: double stranded, only 1 type, stays in nucleus (in eukaryotes)
RNA polymer: single stranded, 3 types (mRNA, rRNA, tRNA), made in nucleus, leaves and then goes into cytoplasm
Which enzyme unwinds and separates the base pairs in the double helix?
DNA helicase
Which enzyme links the nucleotides covalently allowing H bonds to form?
DNA polymerase
What is the correct term for the replica DNA helix?
Semi-conservative replication (one new strand, and one old strand)
What is the function of DNA ligase?
To join together fragments of newly synthesized DNA to form a seamless strand
What is the function of DNA primase?
Synthesizes short RNA primers that are essential for initiating DNA replication
What is the difference between the lagging and leading strands in DNA replication?
The lagging strand is put together discontinuously, using Okazaki fragments
The leading strand is put together continuously
Which bonds hold together the sugar-phosphate backbone of DNA?
Phosphodiester bonds
What was the goal of Meselson and Stahl’s experiment?
To prove that DNA was semi-conservative
How did Meselson and Stahl carry out the first stage of their experiment?
Cultured E.coli in a medium containing amino acids with the heavy isotope 15N
The 15N was incorporated into the DNA of the E.coli
Bacterial DNA was extracted via lysis (breaking open the cells) and put into an ultra centrifuge
Banding in the test tube was observed
How did Meselson and Stahl carry out the second stage of their experiment?
The 15N bacteria were washed and transferred to a medium containing 14N and divided once (one generation)
DNA was extracted via lysis and put into an ultra centrifuge
Banding in the test tube was observed
How did Meselson and Stahl carry out the third stage of their experiment?
The bacteria were allowed to replicate again (2nd generation)
DNA extracted via lysis and put into an ultra centrifuge
Banding in the test tube was observed
How does transcription happen in protein synthesis?
DNA copied into a complementary strand of mRNA
Gene to be transcribed unzips and the H bonds break
Activated RNA nucleotides bind (H bonds) to their exposed complementary base - catalysed by DNA polymerase
Produces a copy of the coding strand in mRNA form
mRNA released from DNA and passes through the nuclear envelope
What happens during translation?
mRNA binds to small subunit of ribosome
tRNA binds to large subunit of ribosome
Peptide bonds form between the amino acids on the anticodon
Form a polypeptide chain
What is the structure of a ribosome?
Made up of a large subunit and a small subunit
Large subunit contains an amino acid binding site, a peptidyl-tRNA binding site and an exit site
What are exons?
Regions of DNA that code for proteins
What are introns?
Regions of noncoding DNA inbetween exons
What happens during RNA splicing?
Ribozymes used to remove the introns and splice together the exon-derived RNA into mRNA
What are STR’s?
Short tandem repeats - length of the STR (how many repeats) e.g. GATAGATAGATA has 3 repeats- inherited from parents.
When are STR’s used?
In genetic fingerprinting in order to show differences between individuals
What are three main mutation types?
Deletion
Insertion
Substitution
Which mutations cause a frameshift in the amino acid sequence?
Deletion
Insertion
What are the different types of a substitution mutation?
Missense
Silent
Nonsense
What is a missense mutation?
If the substitution changes the amino acid
What is a silent mutation?
If the substitution does not change the amino acid
What is a nonsense mutation?
If the amino acid is changed to a stop
What is the one gene one polypeptide hypothesis?
Every gene synthesises for one polypeptide
