Nucleotides & Nucleic Acids Flashcards
What 3 things compose Nucleotides?
- Phosphate group
- Nitrogenous base
- Pentose sugar
How many polynucleotide chains are in DNA?
Two
Both strands in DNA consist of what structure?
A Sugar-Phosphate backbone
What type of bonds join nucleotides?
Phosphodiester bonds
What bond forms to join two complementary bases?
Hydrogen bonds
What must happen to the DNA in the nucleus?
It must be packaged
DNA winds around what, allowing it to become condensed?
Histone Proteins
How is DNA found in Mitochondria?
In naked loops.
Give two functions of DNA
- Acts as information store
- Needs to be replicable
Why are Hydrogen bonds used to hold the two strands together in DNA?
- Strong enough to maintain DNA structure
- Weak enough to overcome during DNA replication
In what phase of the cell cycle does DNA replication occur?
The ‘S’ phase
Which enzyme unwinds/unzips the DNA strands?
DNA Helicase
Which enzyme bind nucleotides together with covalent bonds?
DNA Polymerase
Outline the process of DNA replication
- DNA helicase breaks hydrogen bond between base pairs, and unzips the helix
- Exposed bases act as a template for new strand
- Free nucleotides move towards exposed bases
- DNA polymerase binds nucleotides together with covalent bonds.
- Forming sug/phos backbone
- This process happens to both strands
What is the name given to a sequence of 3 bases codes for one amino acids?
A triplet code
What is Transcription?
The process of copying RNA from DNA
Outline the process of Transcription
- DNA strand unzips from DNA Helicase
- RNA nucleotide bases pair up with exposed DNA bases
- RNA Synthase forms covalent bonds between the nucleotide bases
- RNA is SINGLE stranded
- mRNA strand formed and breaks away from DNA
- DNA zips itself up due to natural formation of ‘H’ bonds
- mRNA now free to leave nucleus through pores.
Outline the process of Translation
- RNA leaves nucleus and
attaches to ribosome - tRNA carries
corresponding amino acid to each on the mRNA - Anti-codon is a triplet of bases that from part of a tRNA molecule + ensure correct amino acid is joined onto polypeptide chain
- Its active, so needs ATP
- Amino acid transported by tRNA attaches to ribo.
- Adjacent amino acids join by peptide bonds creating polypeptide chain
- Process continues until ribosome reaches stop codon on the mRNA
(Polypeptide chain breaks loose from the ribosome)
What is Translation?
The second step of protein synthesis — the process of creating polypeptides based off mRNA
