DNA, RNA and Protein Synthesis. Flashcards
what is a gene?
a section o coding on a chrimisine coding for one or more polypeptides
what is a gene?
a section o coding on a chrimisine coding for one or more polypeptides
what is an allele?
one of an alternative forms of a gene
what is a locus?
the position of a gene on a chromosome
what is a histone?
proteins which together with DNA make up chromosomes of a eukaryotic cell
what is meant by homologous?
a pair of chromosomes one maternal and one paternal both with gene loci
what is meant by degenerate?
most amino acids are coded by more than one triplet
what is an intron?
introns are non coding sequences of DNA in a gene
what is an exon?
sequences of DNA that code for amino acids in a gene
what is a genome?
the complete set of genes in a cell
what is a cells protege?
the full range of proteins that the cell is able to produce.
what is functional RNA?
RNA other than mRNA which perform special tasks during protein synthesis. some senses don’t code for polypeptides at all and instead they code for polypeptides instead
what are the different types of RNA?
mRNA and tRNA
what does mRNA do?
made during transcription it carries the genetic code from the DNA to the ribosomes
what does tRNA do?
it is involved in translation. it carries amino acids that are used to make proteins to the ribosomes. it is a single polynucleotide strand. has a specific sequence of three bases at one end called an anticodon they also have an amino acid binding site at the the other
describe the stages of protein synthesis
1) transcription starts when RNA polymerase attaches to the DNA double helix at the beginning of a gene.
2) the hydrogen bonds between the strands break, separating them an then the DNA molecule uncoils at some of the points revealing the bases
3) one of the strands is them used as a template for mRNA
4) RNA polymerase lines up free RNA nucleotides (specific complementary base pairing)
5) once they have paired up they are joined together by the RNA polymerase
6) moves along the DNA operating the stands and assembling the mRNA strand.
7) when the RNA polymerase reaches a stop signal it stops making the mRNA detach from the DNA which then moves out of the nucleus through a pore.
what is pre-mRNA?
a sequence that contains both introns and exons
describe the second stage of protein synthesis
1) the mRNA attaches too a ribosome and transfer RNA molecules carry amino acid molecules to it. ATP provides the energy needed for the bond between the amino acid and the tRNA to form.
2) the tRNA molecule with an anticodon that i complimentary to the first codon on the mRNA attaches itself by specific base pairing.
3) then a second
3) the two amino acids are joined by a peptide bond and then the first tRNA moves away leaving its amino acid behind. this continues until a polypeptide chain has formed (stop signal)
what is genetic code/
Non-overlapping, degenerate and universal.
what is meant by degenerate?
there are more triplet combination stain there are amino acids
what is meant by universal?
the same specific base triplets code for the same amino acids in all living things.
what is an allele?
one of an alternative forms of a gene
what is a locus?
the position of a gene on a chromosome
what is a histone?
proteins which together with DNA make up chromosomes of a eukaryotic cell