Nucelic acids Flashcards
(32 cards)
Strcuture of DNA to its functions
-sugar phosphate backbone and many H bonds to provide stability
-long molecule stores lots of infomation
-helix is compact for storage in nucleus
-base sequence of triplets code for amino acids
-double stranded for semi-conservative replication
-complementary base pairing for accurate replication
-weak H bonds breaj si strands seperate for replication
Meleson-stahl experimnt
- Bacteria grown in medium containing heavy 15N for many generations
- Some bacteria moved to medium containing light isotope 14N. Samples extracted after 1 and 2 cycles of DNA replication
- Centifrugion formed a pellet, heavier DNA settled closer to bottom of the tube
Structure of mRNA
-long ribose polynucleotide
-contains uracil instead of thymine
-single stranded and linear
-codon sequence is complementary to exons of 1 gene from 1 DNA strand
Pentose sugar of DNA
Deoxyribose
Why is DNA replication known as semi-conservative
Strands from original DNA molecule act as a template
New DNA molecule contains 1 old strand and 1 new strand
Complementary basis pairs in RNA
2 h bonds between Adenine and uracil
3 h bonds between guanine and cytosine
Whhy did scientists initially doubt that DNA carried the genetic code
Chemically simple molecule with few components
Role of iron ions in the body
fe 2+ bonds to porphyin ring to form haem group in haemoglobin
Haem group has binding site to transport 1 moecul of o” around body in the blood stream
4 haem groups per haemoglobin molecule
What are inorganic ions and where are they found
-ions that do not contain carbon atoms
-found in cytoplasm and extracellular fluid
-high or low concerntrations
Role of phosphate ions in the body
Component of:
DNA
ATP
NADP
cAMP
Why is ATP suitable as the energy currency of cells
-high energy bonds between phosphate groups
-small amounts of energy released at a time=less energy wasted as heat
-single step hydrolysis=energy abaliable quickly
Readily resynthesised
Process of semiconservative replication
-DNA helicase breaks H bonds between base pairs
-Each strand acts as a template
-Free nucelotidde from nuclear sap attach to exposed bases by complementary base pairing
-DNA polymerase catalyses condensation reactions that join adjacent nucleotides on a new strand
-H bonds reform
What does ATP hydrolase catalyse
ATP- ADP + Pi
role of mRNA in living cells
Complementary sequence to 1 gene from DNA with introns spiliced out. Codons can be translated into a polypeptide by risomes
Structure of DNA
Double helix of 2 polynucleotide strands
H bonds between complementary purine and pyrimidine basis on opposite strands
Order DNA mRNA and tRNA according to increasing length
tRNA
mRNA
DNA
Pentose sugar of RNA
Ribose
Structure of mRNA to its functions
-Breaks down quickly so no excess polypeptides form
-ribosome can move alow strand and tRNA can ond to expose bases
-can be translated into specefic polypeptide ribosomes
Role of sodium ions in the body
involved in co-transport for absorption of glucose and amino acids in lumen of gut
Involved in propagation of ction potentials in the neurons
Role of hydrogen ions in the body
-high conc of H+ low pH
-H+ ions interact with H bonds and ionic bonds in tertiary structure of proteins, which can cause them to denature
role of rRNA in living cells
component of ribosomes
How is ATP resynthesised in cells
ATP synthase catalyses condensation reaction between ADP and Pi
during photosynthesis and respiration
Role of DNA in living cells
Base sequence of genes codes for fuctional RNA and amino acid sequence of polypeptides
Genetic information determines inherited characters= influences structure and function of organisms
Which bases are purine and which are prymidine
A & G= 2 ring purine basis
T & C & U= 1 ring pyrimidine bases
