3.1.5/6 DNA + RNA/ ATP Flashcards
What is DNA?
Codes for the sequence of amino acids in the primary structure of a protein, which determines the final 3D structure and function of a protein
DNA is a polymer and is a double helix
Why is DNA important?
It’s essential as it contains the genetic code and has to be passed on to new cells without being damaged
What monomer makes up DNA?
A nucleotide
What is the structure of a DNA nucleotide?
Deoxyribose (pentose sugar)
A nitrogenous base (guanine, cytosine, thymine and adenine)
One phosphate group
How is a polynucleotide made?
It’s created through condensation reactions between the deoxyribose sugar and the phosphate group where water is removed, creating a phosphodiester bond (strong covalent bond)
How is the double helix created?
The DNA polymer occurs in pairs joined by hydrogen bonds between bases
Where do hydrogen bonds form?
Between complementary base pairs e.g. cytosine and guanine & adenine and thymine
What is RNA
A polymer of a nucleotide formed of a ribose, a nitrogenous base and a phosphate group
What are the bases in RNA?
Adenine
Cytosine
Guanine
Uracil
Difference between DNA and RNA?
The RNA polymer is a relatively short polynucleotide chain and it’s single stranded.
In structure, RNA is ribose and DNA is deoxyribose
Function of RNA?
To transfer the genetic code from DNA in the nucleus to the ribosomes. Some RNA (rRNA) is also combined with proteins to create ribosomes.
What is the process of DNA replication called?
Semi-conservative replication
(In the daughter DNA one strand is from the parental DNA and one strand is newly synthesised)
What is the 1st step of DNA replication?
DNA helicase breaks down the hydrogen bonds between the complementary base pairs which causes the DNA double helix to unwind and separate.
What is the 2nd step to DNA replication?
The separated strands will act as a template. Free floating DNA nucleotides within the nucleus will then align opposite the complementary base pairs.
What is the 3rd step of DNA replication?
DNA polymerase joins the nucleotides together to make phosphodiester bonds
What is the 4th step in DNA replication
Now we have our newly synthesised DNA combined with the template strand and that is the new molecule of DNA.
Evidence for DNA replication
Watson and Crick- discovered structure of DNA (double helix) in ‘53 helped by Rosalind Franklin’s research on x-ray diffraction
Meselson and Stahl- conducted an experiment which proved DNA replication must be semi-conservative
What is ATP?
Adenosine TriPhosphate is an immediate source of energy for biological processes.
Metabolic reactions in cells must have a constant, steady supply of ATP.
Structure of ATP
A nitrogen-containing base (adenine)
A pentose sugar (ribose)
3 phosphate groups
How is ATP made?
During respiration
Made from ADP + Pi (inorganic phosphate) by a condensation reaction using the enzyme ATP synthase
When does ATP release energy
ATP releases energy when it’s hydrolysed into ADP + Pi using enzyme ATP hydrolase
