nucleotides Flashcards
(20 cards)
What is a nucleotide?
The monomer of a nucleic acid.
What does a nucleotide consist of?
- A pentose sugar
- A nitrogenous base
- A phosphate group
What are the 4 bases DNA contains?
- Adenine
- Guanine
- Cytosine
- Thymine
Which of the 4 bases are purines and which are pyrimidines?
- Adenine and guanine - purine
- Cytosine and thymine - pyrimidine
Remember : PURE as gold
purine
What 4 bases does RNA contain?
Adenine and Guanine - purine
Cytosine and Uracil - Pyrimidine
What bases are paired together during replication?
Adenine - Thymine / uracil
Cytosine - Guanine
What does ATP and ADP contain?
ADP - adenine base, ribose sugar, 2 phosphate groups
ATP - adenine base, ribose sugar, 3 phosphate groups
What is ATP synthesised from?
- Synthesised from ADP and inorganic phosphate, using the energy from an energy releasing reaction e.g breakdown of glucose in respiration.
How is ATP created?
- ADP is phosphorylated to from ATP and a phosphate bond is formed.
What bond is formed when the nucleotides join up between the phosphate group of one nucleotide and the sugar of another?
Phosphodiester bond
What is the bond that joined two DNA polynucleotide strands together?
Hydrogen bond
What are the stages of DNA semi- Conservative replication?
1- DNA helicase unzips DNA, separating two strands by breaking hydrogen bonds between complementary bases.
2- Free DNA nucleotides are attracted to their exposed bases by complementary base pairing.
3 -Free nucleotides joined together through phosphodiester bonds by DNA polymerase - Forms sugar- phosphate backbone and new DNA strand.
4- Two DNA molecules produced from 1 new and 1 old strand.
What is a genetic code?
When DNA must code for a sequence of amino acids.
What is a triplet code?
A sequence of three bases called a codon.
What is a gene?
A section of DNA that contains the complete sequence of bases to code for an entire protein.
What does it mean by the genetic code is universal?
All organisms use the same code, although the sequences of the bases coding for each individual protein will be different.
How many different base triplets or codons are possible?
64
What signals the start and end of the sequence and how many of each?
start codon: 1
stop codon: 3
What does it mean by the code is degenerate?
Many amino acids can be coded for more than one codon.
What the sense and antisense strand?
Sense strand - The strand of DNA that contains the code for the protein to be synthesised runs from 5’ to 3’.
Antisense strand - Complementary copy of sense strand and does not code for protein runs from 3’ to 5’.
