Flashcards in Chapter 2 Nucleic Acids Deck (26):
What is the structure of a nucleotide?
Nitrogen containing base (CGATU).
What reaction joins the pentose sugar, phosphate group and organic base in a nucleotide?
What is the bond between two mononucleotides?
Complementary base pairs in DNA
DNA strands are arranged into a...
What is the structure of RNA?
-Pentose sugar is ribose
-Organic bases are C G A U
What are the three types of RNA?
(1) Transfers genetic information from DNA to ribosomes.
(2) Ribosomes are made up of proteins and another type of RNA.
(3) Involved in protein synthesis.
What is the structure of DNA?
-Pentose sugar is deoxyribose.
-Two strands of nucleotides.
-Strands joined by hydrogen bonds.
Why is DNA a stable molecule?
-Phosphodiester backbone protects more chemically relative organic bases inside the double helix.
-Hydrogen bonds link base pairs. As there as three hydrogen bonds C and G, the greater the C-G pairings, the more stable DNA.
How is DNA adapted to carry out its functions?
-Stable so passes from generation to generation without changing. Rarely mutates.
-Extremely large and so it carries a lot of genetic information.
-Base paring leads to DNA being able to replicate and to transfer information as mRNA.
-Hydrogen bonds allow strands to separate during DNA replication.
-Genetic material is protected by backbone.
Describe semi-conservative replication.
(1) DNA helicase breaks hydrogen bonds between strands.
(2) Double helix unwinds.
(3) Exposed nucleotides on the template strand pair with free nucleotides by specific base pairing.
(4) Nucleotides are joined by a condensation reaction by DNA polymerase.
What is the structure of ATP?
Why are the bonds between ATP easily broken?
They are unstable so have a low activation energy.
How much energy is released when bonds between ATP are broken?
Equation for ATP + H2O ->
ADP + Pi + E
Catalysed by ATP hydrolase.
What processes is ATP used in?
Activation of molecules.
Tendency of molecules to stick together.
Why does water have large cohesive forces?
It has hydrogen bonding so it can be pulled through a tube such as xylem.
Describe the surface tension of water.
When water molecules meet the air, they tend to be pulled back into the body of water rather than escaping from it.
Water as a solvent.
Water readily dissolves in other substances:
-Wastes such as ammonia and urea.
-Gases such as oxygen and carbon dioxide.
-Enzymes, whose reactions take place in solution.
Give important features of water.
-Not easily compressed and so provides support.
-Transparent and so aquatic plants can photosynthesise.
-Its evaporation cools organisms and helps with temperature control.
Water in metabolism.
-Used to break down complex molecules by hydrolysis.
-Chemical reactions take place in aqueous environment.
-Raw material in photosynthesis.
Define latent heat of vaporisation.
Amount of heat to evaporate 1 gram of water.
Specific heat capacity of water.
Water has a high specific heat capacity due to hydrogen bonds.
Why does water act as a buffer against sudden temperature change?
Due to its high specific heat capacity.