Nucleotides Flashcards
What are the four nitrogenous bases?
Adenine, Thymine, Cytosine, Guanine
What does DNA stand for?
Deoxyribonucleic acid
What type of nucleotide is ATP?
Phosphorylated nucleotide
Which nucleotides are purines?
Adenine and guanine
What are purines?
nucleotides with a double ring structure
Which nucleotides are pyrimidines?
Cytosine and thymine and uracil
How many polynucleotides is DNA made of? And what direction do they run?
2 antiparallel strands.
What bonds hold the nucleotides together horizontally?
Phosphodiester bonds. between phosphate groups and and the third carbon on the pentose sugar
What 3D shape does DNA make?
Double helix
What is the backbone of the DNA called?
sugar-phosphate backbone
When does DNA replication occur?
S phase (interphase)
What kind of nucleotides are found in the nucleus?
Inactive nucleotides: Nucleoside triphosphate
What is the role of DNA Polymerase? And how do they do it? (explain)
Catalyses condensation reaction between the deoxyribose and the adjacent and phosphate groups by removing the two extra phosphate groups from the nucleosides and using the energy to create the phosphodiester bonds
How are Okazaki fragments created?
DNA polymerase can only build strands from the 5’ to 3’ direction. When RNA primase places the primers (starting places) in the lagging strand (the strand that runs from the 3’ to the 5’ direction), the polymerase builds from 5’ to 3’, and when another primer is placed near the unwinding site, the polymerase goes back and starts building from there. Creating fragments
What is the name of the enzyme that unzips DNA?
Helicase
Which enzyme joins the fragments together?
DNA ligase
What is the difference between ribose sugar and the deoxyribose sugar?
Ribose sugar has a hydroxyl (OH) group attached to the 2nd carbon. Deoxyribose only has a hydrogen
What is a gene?
A sequence of nucleotides that forms part of a DNA molecule
What is the function of telomeres?
Prevention of loss of genes, permits continuous replication. Their length determines cell life span
What is the function of ribosomes in protein synthesis?
Translation of polypeptides. It provides a binding site for mRNA, and a binding site for tRNA. This is where two amino acids are held close together and they form peptide bonds.
What’s the name of the enzyme that catalyses the formation of peptide bond during protein translation?
Peptidyl transferase
Which enzyme forms the mRNA in transcription?
RNA polymerase
What does tRNA look like?
Hairpin loops in the shape of a three leafed clover. With an anticodon loop at the bottom and an amino acid attached to the top.
How many tRNA molecules can fit into the ribosome at any given time?
2
What are the three main types of mutations?
Insertion, deletion, substitution
What is frameshift mutation?
Insertion or deletion of a nucleotide in the genetic code resulting in a base sequence that is not divisible by three
What are the three different types of substitution mutations?
Silent and missense and nonsense
What is a nonsense mutation?
A substitution mutation that creates a premature stop codon
