Nucleic Acids Flashcards
What is DNA
DNA is made out of deoxyribonucleic acid and it contains genetic material
What is the structure of DNA
Has 2 phosphate backbones held together by bases in a double helix structure with a deoxyribose sugar
What are the DNA bases
Thymine, adenine, guanine, cytosine
How are the DNA bases paired
Adenine has a double hydrogen bond to thymine
ctyosine has a triple hydrogen bond to guanine
What is RNA
sugar is ribose not deoxyribose, it is single strand not double stranded. 2 types of RNA, mRNA and tRNA
What is the RNA base pairings
Thymine is replaced by uracil, all of the other bases are the same
What type of replication do does DNA go through
Semi conservative- one parent strand, one new daughter strand
Steps of DNA replication
- DNA helicase unwinds by breaking thr hydrogen bonds between the nucleotides to separate the 2 strands
- Each original strands acts as a template for new strand. Free DNA nucleotides are attracted to the exposed bases through complementary base pairing.
- The free nucleotides are joined by a condensation reaction and is catalysed by DNA polymerase which form hydrogen bonds between the 2 bases.
How does DNA polymerase work
Each DNA strand has a dstructures structure due to the end of each strand being either sugar that’s attached to the 5th carbon 5’ end or a hydroxyl group attached the 3’ end. DNA polymerase is only complimentary to the 3’ end of the template strand so it can only move along the template strand and add nucleotides in the 3’ and 5’ direction. The strand is build in a 5’ 3’ direction as it is antiparallel. Leading strand is continuously built and lagging is built in sections.
Evidence for semi-conservative replication
Meselson and Stahl- two isotopes of nitrogen, 14N(light) and 15N(heavy). Bacteria grown in 15N is transferred into a broth of 14N. If replication was semi conservative the line on the test tube would be in between the line of heavy nd light nitrogen. This is what they found in the first generation.
What is ATP
ATP provides energy
What is the structure of ATP
It contains a ribose sugar, an adenine base and 3 phosphate groups.
How is energy stored
Energy is stored in the phosphate bonds and when they are hydrolysed, the energy is released
What is the phosphate separated from the ATP used for
It can be used to phosphorylate other molecules in cells to make them more reactive
What is ATP that goes through a condensation reaction called
It is called ADP (adenine diphosphate) and a Pi group (an inorganic phosphate group) is catalysed by bt the enzyme ATP hydrolase.
Why is water considered a polar molecule
Water is considered a polar molecule as the hydrogen molecules have a slight positive charge and the oxygen has a slight negative charge. Slight negative oxygen is attracted to the slight positive hydrogen molecules.
What happens when water molecules get close together
When the water molecules get close together, the opposite charged parts of the molecules attract each other, forming hydrogen bonds, called cohesion. At room temperature water forms a lattice.
What are the properties of water dependent on
The properties depend on the polar nature of the water molecule and on the hydrogen binding between water molecules
What is water useful for
.It is a good solvent
.Attracted to other substances that are also polar
.Water molecules cluster around charged parts of the solute molecule or ions and help to stay apart dissolved and solution can be formed
.hydrogen bonds pull water molecules towards each other causing cohesion
.high surface tension as hydrogen bonds pull the molecules inwards at the surface
.high heat capacity
.strong cohesion between water molecules so supports tube like transport cells of plants
Role of hydrogen ions and ph
A high concentration of hydrogen ions yield a low pH, whereas a low level of hydrogen ions result in a high pH.
Iron ions and haemoglobin
Iron ions are the central part of the haem group in haemoglobin allowing red blood cells to transport O² and CO²
Role of Sodium ions in the co-transport of glucose
Sodium binds to co-transported proteins to allow glucose and amino acids to be transport as it binds to the other molecule that needs transporting
The roles of phosphate ions as components of DNA
It creates the phosphate backbone to provide structure to the DNA
