2.1.3 Nucleotides and nucleic acids Flashcards
What is the structure of a nucleotide?
phosphate, pentose sugar and nitrogenous base
How many carbon rings do purines have?
two
How many carbon rings do pyrimidines have?
one
What is the sugar in a DNA nucleotide?
deoxyribose
2 OH
What is the sugar for a RNA nucleotide?
ribose
1OH
What bases does ribose bind to?
guanine
cytosine
uracil
adenine
What bases does DNA bind to?
adenine
thymine
guanine
cytosine
What are the purine bases?
adenine
guanine
What are the pyrimidine bases?
thymine
cytosine
uracil
How are polynucleotides formed?
the OH of the phosphate and the H from the sugar bind to form a phosphodiester bond = condensation reaction water is released
= 3’ to 5’ phosphodiester bond = sugar phosphate backbone
How are polynucleotides broken down?
add water = hydrolysis reaction
What is the structure of ATP?
3 phosphate groups
ribose sugar
adenine base
When water is added to ATP what happens?
the hydrolysis reaction causes ADP to be produced and energy; inorganic phosphate is released
What is the structure of DNA?
anti-parallel = double helix
3’ to 5’
How many hydrogen bonds are formed between C and G?
three hydrogen bonds
How many hydrogen bonds are formed between A and T?
two hydrogen bonds
PAG 9; Why do you have to crush the piece of fruit using a pestle and mortar?
this helps break down the cellulose cell wall
PAG 9; Why is detergent added?
this dissolves the cell surface membrane
PAG 9; Why is a protease enzyme/pineapple juice?
breaks down the histones/proteins associated with DNA
PAG 9; Why is cold ethanol added for observe DNA?
DNA insoluble in alcohols = float to the top
What is the process of semi-conservative DNA replication?
1) the enzyme DNA helicase breaks down hydrogen bonds between bases = the double helix unwinds = each strand acts as a template
2) free DNA nucleotides from cytoplasm of cell and assemble on the template of the DNA in complementary base pairs
3) hydrogen bonds reform between the bases - the enzyme DNA polymerase joins the nucleotides forming a new sugar phosphate back bone by new phosphodiester bonds formed
= two identical DNA molecules are produced
What is meant by semi-conservative DNA?
the new DNA molecules contains one new and one old strand of DNA
What is the nature of the genetic code?
1) non-overlapping = coded by triplets once
2) degenerate = some amino acids have more than one triplet code
3) universal = used across all organisms/languages
What is a gene?
a gene is a section of DNA that codes for the sequence of amino acids in a polypeptide
Describe the process of transcription? (nucleus)
1) DNA helicase breaks hydrogen bonds between bases
2) Free RNA nucleotides attach forming a complementary mRNA strand (no thymine = uracil)
3)RNA polymerase helps forms the phosphodiester bonds in between the RNA nucleotides = mRNA is formed
4) mRNA leaves nucleus through the nuclear pores and the DNA helix reforms
Describe the process of translation?
1) mRNA attaches to ribosome = made of two subunits of rRNA (one large one small)
2) the anti-codon on the tRNA will find the complementary codon on the mRNA, bringing a specific amino acid that corresponds with that codon
3) amino acids are joined by a peptide bond to give a protein with a specific primary structure
