Nucleic acids Flashcards
2.1 Nucleotide structure
Three components
1.phosphate group
2.pentose sugar
3.Nitrogenous base
cytosine - guanine
adenine - thymine
uracil
three components are joined through condensation reactions to from a mononucleotide
two monnucleotides are joined together through condensation- Sugar & Phosphate) to form a dinucleotide
continued linking of monomer create a polynucleotide
RNA structure
polynucleotide
pentose suger-ribose
N BASES- A,G,U,C
DNA structure
pentose sugar- deoxyribose
N Bases- A,G,T,C
Base pairing
bases on two strand of DNA attach together by H bonds
Adenine-Thymine
Guanine-Cytosine
complementory
nA=nT
nC=nG
Double helix
ladder like arrangement of two polynucleotide chains being twisted.
phosphate and sugar form a backborn
The stability of DNA
Stable bcz
-phosphodiester back bone protects the more reactive organic bases inside
-H bonds link the bases forming bridges
*3H bonds in C-G(more cg means more stable
*2H bonds in A-T
Function of DNA
Adapted to carry out its function
Heredity material responsible for passing genetic info from cell to cell and gen to gen
3.2 billion base pairs
-Very stable structure which passes from gen to gen. rarely mutates.
-two strands are joined by H bonds
can be seperated for DNA replication
-large molecule,∴large amount of genetic mat.
-Genetic material is protected from chemicals by the helical cylinder of DNA
-base paring enable replication and info passing to mRNA
+function depends on the sequence of base pairs
2.2 DNA replication
Two stages of cell division
1.nuclear division-process by which the nucleus divides(mitosis & meiosis)
2.cytokinesis-cell divides after nuclear division
Semi-conservative replication
+ REQUIREMENTS
Four requirements
1.four bases of DNA must be present
2.both strands of DNA act as templates for attachment of nucleotides
3.the enzyme polymerase
4.a source of chemical energy
process
*DNA helicase breaks the H bonds between bases
*Double helix separates
*Each exposed polynucleotide acts as a template for complementary free bases to bind with
*Nucleotides join by condensation reactions by the enzyme polymerase and form the missing polynucleotide
* each new DNA molecule has 1 original strand (50%)
2.3 Energy and ATP
Structure of ATP
three components
1.adenine-nitrogen-containing base
2.ribose-sugar molecule-a sugar molecule with 5-carbon ring structure which acts as the backbone for the molecule
3.phosphates-a chain of three phosphate molecules
How ATP store energy
A nucleotide and has three phosphate groups. Bonds between them are unstable and have a low Ea
when they break they release a considerable amount of energy
usually only the terminal molecule is removed
ATP+H2O—–>ADP+P1+E
hydrolysis reaction
Catalysed by ATP hydrolase
(ATPase)
Synthesis of ATP
ATP to ADP is a reversible reaction
∴ energy can be used to add an inorganic phosphate to ADP to reform ATP
Enzyme ATP synthase
condensation reaction
addition of a phosphate molecule to ADP occurs in 3 ways
1.in chlorophyll-containing plant cells during photosynthesis (photophosphorylation)
2.in plant and animal cells during respiration(oxidative phospholyration)
3.in plant and animal cells when phosphate groups are transferred from donor molecules to ADP(substrate level phospholyration)
Roles of ATP
+A good energy donor as it has vey unstable phosphate bonds. ∴, it is the immediate energy source of the cell.
+Less energy is released from the reactions. ∴ it is more manageable than the release of energy for glucose molecules.
Metabolic processes
-ATP provides the energy needed to build up macro-molecules
Movement
-Provides energy for muscle contraction
Active transport
-ATP provides energy for carrier proteins to change shape.
Secretion
-ATP is needed to form lysosomes
Activation of molecules
-The phosphate released during the hydrolysis can be used to phosphorylate compounds
