nucleic acids Flashcards
What is a phosphodiester bond?
A covalent bond between the phosphate group of a nucleotide with the sugar of another.
What are the base pairs in DNA and how many hydrogen bonds between them?
Adenine & Thymine - 2
Cytosine & Guanine - 3
What does DNA stand for?
Deoxyribose nucleic acid
How is DNA being a long molecule and coiled related to its function?
Stores a large amount of genetic information & compact shape
How is DNA having a sugar-phosphate backbone related to its function?
Bound by relatively strong phosphodiester bonds so does not denature easily.
How is DNA having bases in sequence related to its function?
Base sequence is the genetic code, sequence determines the mRNA molecule transcribed from it, which in turn determines the primary structure of a protein.
How is DNA having complimentary base pairs related to its function?
Holds polynucleotide strands together when not being replicated. Allows info to be replicated as view DNA.
How is DNA having a helical structure related to its function?
Protects weak hydrogen bonds & helps make molecule stable.
Describe the first stage of semi-conservative replication of DNA.
DNA helicase breaks hydrogen bonds between base pairs of DNA so 2 strands are separated and each can act as a template.
Describe the second stage of semi-conservative replication of DNA.
Free DNA nucleotides are attracted to complimentary bases on the separated strands. Can base pair by hydrogen bonds (no enzymes required)
Describe the third stage of semi-conservative replication of DNA.
A second enzyme ( DNA Polymerase) joins the adjacent nucleotides together so forms sugar-phosphate backbone.
Why is DNA replication described as semi-conservative?
Each new DNA molecule formed contains 1 original polynucleotide strand and 1 new one. Each original nucleotide strand acts as a template.
What are 3 ways ATP is made?
-Formed as a biproduct of other reactions
-By oxidative phosphorylation
-By photophosphorylation (adding a phosphate group)
list the properties of ATP
- Broken down in one step, energy released quickly.
- Rapidly re synthesised, readily available
- Bonds between phosphate group are unstable so easily break, low activation energy.
- soluble, easily transported
Why is water a polar molecule?
partial negative charge on oxygen and partial positive charge on hydrogens.
Why is water a good solvent?
Many substances are ionic. When added to water positive ions are attracted to the slightly negative hydrogen. Each ion ends up surrounded by water and dissolves.
Why is water a good habitat?
Has a high SHC and LHV it doesn’t change temp or evaporate easily. Provides a stable environment. Water freezes to form ice which acts as an insulting layer so organisms survive.
Why is water a good temperature buffer?
Has a high SHC. The hydrogen bonds can absorb a lot of energy before being broken. High SHC means its resistant to rapid temperature changes so allows body to remain a constant temperature.
Why is water good for transport?
Has strong cohesion and adhesion which helps water flow through organisms.
Why is water good at cooling?
A high LHV so lots of energy required to change state. Can use evaporation of water without loosing too much heat energy. When water evaporates the water takes heat away from the body.
List the roles of water.
Solvent
Temperature control
cooling mechanism
transport
metabolite
habitat
