2.1.3 Flashcards
What is the structure of a nucleotide?
phosphate group
pentose sugar
nitrogenous base
What is DNA?
a polymer / polynucleotide
made of many nucleotides joined together
How are 2 nucleotides joined together?
condensation reaction
between sugar of 1 nucleotide and phosphate group of another
What is the difference in the pentose sugars in DNA and RNA?
RNA has ribose sugar
DNA has deoxyribose
What are the purine bases?
Adenine
Guanine
What are the pyrimidine bases?
Cytosine
Uracil
Guanine
How is the phosphodiester bond formed between 2 nucleotides?
condensation reaction
carbon 3 on sugar and carbon 5 on another sugar
What is the structure of ATP?
pentose sugar
nitrogenous base
at least 1 phosphate group
What is the base called in ATP?
Adenine
Atp and water
ADP and inorganic phosphate and energy
What reaction is ATP and water?
hydrolysis
What is the reaction to make ATP from ADP
condensation
What are antiparallel DNA strands
2 polynucleotide strands running in opposite directions
starnds are held by hydrogen bonds between bases
how many hydrogen bonds between C and G?
3
How many hydrogen bonds between A and T?
2
What does a purine always bind to?
pyrimidine
What is a double helix?
2 strands of DNA twist around eachover to form a double helix
When does DNA replication happen?
during interphase
Outline semi-conservative DNA replication?
1)DNA helicase breaks the hydrogen bonds between the bases
Dpouble helix unwinds
each strand acts as a template
2) Free nucleotides from the cytoplasm assemble on the template DNA in complimentary base pairs
3) Hydrogen bonds reform between bases
DNA polymerase joins nucleotides forming a new sugar-phosphate backbone
2 identical DNA molecules have been produced
What does semi-conservative DNA replication mean>?
each new DNA molecule contains 1 new strand and 1 old strand
What happened in the Mesleon and Stahl experiment?
the more replications, the darker the band of nitrogen-14 formed in the testtube
What is a gene?
Section of DNA that codes for a sequence of amino acids in a polypeptide
What are alleles?
different versions of a gene
What is non-overlapping code?
each sequence of 3 bases determines 1 amino acid
triplet code
What is the degenerate nature of DNA?
some amino acids have more than 1 triplet code
What is the universal nature of genetic code?
universal and used across all organisms
Outline the practical to extract DNA from fruit?
1) Crush piece of fruity using pestle and mortar
2) Add detergent
3) Add protease enzyme
4) Filter to remove any solids
5) Add salt
6)Pour ice-cold alcohol into mixture
Why do we crush the piece of fruit?
to help break down celluose cell wall
Why do we add detergent?>
dissolve the cell surface / plasma membrane
Why do we add protease?
break down the histones / proteins associated with DNA
Why do we add salt?
to clump the DNA together
Why do we add ice-cold alcohol?
DNA is insoluble in alcohol and should float on top
Outline transcription?
1) split the hydrogen bonds that hold the double helix together with DNA helicase
2)Free nucleotides in the nucleoplasm form a complimentary mRNA strand. mRNA is a copy of the DNA sense coding strand
3) RNA helps form phosphodiester bonds in between RNA nucleotides
4) mRNA peels away from DNA and leaves through a nuclear pore and DNA helix reforms
Outline translation
5) mRNA attaches to the ribosome and this is made of 2 subunits of rRNA
6) anti-codon on tRNA will find the complimentary codon on mRNA bringing a specific amino acid with it
7) amino acids are joined together by peptide bonds , primary structure -> secondary -> tertiary
