chapter 2b Flashcards
anti parallel meaning
Running in an opposite direction to the other (still parallel)
whats complementary base pairing
describes which nucleotides can form hydrogen bonds with each other C/G and A/T (U in RNA).
whats messenger RNA (mRNA)
RNA molecules that are produced during transcription and carry genetic information from the nucleus to the ribosomes.
whats transfer RNA (tRNA)
RNA that recognises specific codons on the mRNA strand and adds the corresponding amino acid to the polypeptide chain during protein synthesis.
whats ribosomal RNA (rRNA)
RNA that is a key structural component of ribosomes, which assembles proteins.
whats transcription
The process whereby a sequence of DNA is used as a template to produce a complementary sequence of mRNA
whats translation
The process where an mRNA sequence is read to produce a corresponding amino acid sequence to build a polypeptide
whats a triplet
The sequence of three nucleotides in DNA coding for one amino acid.
whats a codon
The sequence of three nucleotides in mRNA coding for one amino acid.
whats a promoter
The sequence of DNA to which RNA polymerase binds. (e.g. TATA box – promoter region)
whats an RNA polymerase
The enzyme responsible for constructing a pre-mRNA sequence from a DNA sequence during transcription.
whats an intron
Non-coding regions of DNA that do not code for proteins. They are spliced out during RNA processing
whats an exon
Regions of DNA that code from proteins and are not spliced out during RNA processing
whats a termination sequence
A sequence of DNA that signals the end of transcription.
whats an operator
A short region of DNA that interacts with repressor proteins to alter the transcription of an operon.
whats an operon
The gene/genes that get transcribed when the operator is bound.
whats a repressor protein
a protein coded for by a regulatory gene that prevents gene expression by binding to its operator
what makes up the DNA structure
DNA is made up of two polynucleotide chains which run antiparallel to each other. We call the first strand as running from 5’ to 3’ (phosphate and O pointing up) and the other is running 3’ to 5’ (phosphate and O pointing down).
The nucleotides from each chain forms a hydrogen bond with one another. Cytosine (C) forms three hydrogen bonds with Guanine (G), and Adenine (A) forms two hydrogen bonds with Thymine (T) in DNA and Uracil (U) in RNA. This forms a complementary base pairing as they can only bond with their complementary base pair.
Due to this, we can predict the number of nucleotides as there will always be an equal amount of A to T/U and C to G.
DNA forms a double helix which coils around histone proteins. These histone proteins condense even further to form chromosomes.
three types of RNA structures
mRNA: Carries genetic information from nucleus to protein for protein synthesis.
tRNA: delivers specific amino acids to the ribosomes.
rRNA: serves as the structural component of ribosomes within cells.
why is Uracil used in RNA instead of Thymine
Thymine is used with DNA, but Uracil is used with RNA.
This is due to T reacting with oxygen outside of the nucleus, causing it to degenerate faster than normal. Therefore, we replace T with U to ensure longevity of the DNA sequence as it travels outside of the nucleus to the ribosomes.
