Biochem - Nucleic Acids Flashcards
What bond forms when nucleotides are polymerised?
Phosphodiester bonds
tRNA anticodon sequence is the same as….
The template strand (With thymine switched to uracil)
Helicase…
Helicase unzips and unwinds the DNA
The template DNA is…
The DNA complimentary to the coding strand; it is the strand which complimentary nucleotides bond to the recreate the sequence of the coding strand
Purine bases pair with…
Pyrimidine bases
Phosphodiester bonds link…
adjacent nucleotides.
Explain how nitrogenous bases allow identical copies of DNA to be made.
Adenine pairs with Thymine because of hydrogen bonding; Purine can only bond with pyrimidine because of their different sizes and-so bases can only pair with their one complimentary base.
Outline protein synthesis:
mRNA transported out of nucleus.
mRNA transported to ribosome, where translation occurs.
tRNA brings specific amino acids, based on the complimentary anticodon on the tRNA.
Amino acids form peptide bonds - form polypeptide.
Polypeptide processed by golgi apparatus.
What substance can be used to release DNA from nuclear envelope?
Detergent, because it works as an emulsifier (Attracts phospholipid molecules) and breaks open the nuclear membranes.
True or False: Genetic code overlaps
True
Helicase….
Unwinds the DNA molecule and breaks hydrogen bonds between base pairs.
DNA polymerase…
Links new nucleotides together in DNA replication.
RNA polymerase…
Links mRNA nucleotides in transcription
How many nucleotide bases that code for a single amino acid.
3
There is a maximum of….. different base combinations.
64
Why are not all base combinations used to code for amino acids?
Some amino acids can be made from multiple base combinations.
Some amino acids are stop/start codons.
What nucleotide bases are in both DNA and RNA
Adenine, Cyrosil and guanine
What nitrogenous base changes between DNA and RNA?
Thymine is replaces with Uracil.
Protease digests what proteins.
Histone proteins.
DNA is wrapped around what protein?
Histone proteins.
Nucleic acids are made from…
nucleotide monomers.
Nucleotides consist of…
A phosphate group between pentose molecules. (forms ‘backbone’) and a nitrogenous base
What causes the helix shape of DNA?
hydrogen bonding between the two antiparallel strands.
Cytoplasmic ribosomes produce proteins for…
intra-cellular use
RER ribosomes produce proteins for…
to export elsewhere.
What do ribosomes consist of?
Large and small subunits.
What are the subunits of ribosomes made from?
Proteins and ribosomal DNA.
Where are ribosomes made?
The nucleolus
Peptidyl transferase…
Catalyses formation of peptide bonds between amino acids in ribosome.
Translation is dependant on…
Complimentary base pairing between codons on mRNA and anticodons on tRNA.
Ribosome moves in a…. along the mRNA
5’ to 3’ direction
What codon is the start codon?
Methionine (AUG)
Which codons contain sulphur?
Methionine and Cysteine
What 2 types of RNA bind to the ribosome?
mRNA and tRNA
What form of RNA aids the accuracy of translation?
rRNA
What phosphorylated nucleotide provides energy?
ATP - Adenosine triphosphate
Why is the amino acid sequence important?
Form secondary and tertiary structure.
What is the role of the nuclear envelope?
To prevent the DNA form being damaged by the cytoplasm.
mRNA is complimentary to the …
template strand, making it a copy of the coding strand.
What is the role of mRNA?
TO carry information outside of the nucleus.
Where is the amino acid on tRNA
The amino acid is attached to the 3’ end on the ‘attachment site’
Initiation of transcription:
RNA polymerase binds to DNA at a promoter.
What direction is DNA in trancription?
3’ to 5’ and the RNA ploymerase moves in a 5’ to 3’
Protein synthesis Outline:
mRNA formed by transcription of nuclear DNA passes through the pores of the nuclear envelope and attaches to ribosomes fixed to the RER. Specific amino acids are brought the the mRNA by molecules of tRNA which attach to the codons of the mRNA. Adjacent amino acids form peptide bonds, which are catalysed by peptidyl transferase. These assemble into polypeptides in spaces of vesicles of RER or transported to the Golgi Complex for processing
Role of rRNA?
Provide structural stability to the protein synthesis sequence and helps to catalyze the reaction.
Properties of ATP
small,
water-soluble
easily regenerated
releases energy in small quantities - from bonds between phosphates
