Y12 MW - Protein Synthesis and Mutations (Complete) Flashcards
What is the genome?
All of the coding and non-coding genetic material of an organism
What is the proteome?
The entire set of proteins that can be produced by a cell at a certain time
What is transcription?
The process of mRNA being produced from DNA
What is an expressed protein?
One that can be made
Splicing only occurs in ——— cells
Eukaryotic
What is a gene?
a base sequence of DNA that codes for a protein
What is a gene loci?
The fixed position of a gene on a particular DNA molecule / chromosome
What is a triplet?
A sequence of 3 nitrogenous bases which code for a specific amino acid
What is a codon?
A sequence of 3 RNA bases
What is an anticodon?
A sequence of 3 nucleotide bases at one end of a tRNA molecule which is complementary to the mRNA codon
What is an exon?
The sequences within a gene which code for the polypeptide
What is an intron?
The non-coding sequence of bases in a gene that do not code for the amino acid sequence. They are removed during splicing
What are the properties of the genetic code?
Non-overlapping
Degenerate
Universal
What does it mean that the genetic code is universal?
A particular triplet codes for the same amino acid in all living organisms
What does it mean that the genetic code is non-overlapping?
The triplets are read sequentially
What does it mean that the genetic code is degenerate?
More than one DNA triplet codes for the same amino acid
What is the structure of tRNA?
tRNA is made up of linear RNA nucleotides which are folded into a “cloverleaf” shape. This is held together by hydrogen bonds between the complementary base pairs
What is the structure of mRNA?
mRNA is made up of short, linear RNA nucleotide sequences that carry the genetic code for the construction of a polypeptide
Does splicing take place inside or outside of the nucleus?
Inside of the nucleus
What is the structure of a chromosome?
A chromosome is made up of two identical chromatids which are joined at the centromere
What are homologous chromosomes?
A pair of chromosomes which have identical genes
True or false? Only one DNA strand acts as a template to code for proteins
True
How many different amino acids are there?
20
What is the process of transcription?
DNA helicase unwinds the DNA strands in a section of the DNA molecule by breaking the hydrogen bonds between the bases
One DNA strand acts as a template
Free RNA nucleotides diffuse into position with their complementary base pair (A with U and C with G)
RNA polymerase joins the RNA nucleotides by forming phosphodiester bonds
This forms a mRNA molecule
The pre-mRNA is then spliced to remove the introns
The nature mRNA now only contains exons
What does it mean that mRNA is unstable?
It is broken down and destroyed rapidly (meaning continuous production of proteins e.g hormones and enzymes does occur)
Does splicing occur in prokaryotic cells?
No as prokaryotic mRNA does not contain introns
What is translation?
Where mRNA is translated and an amino acid sequence is produced
What is the process of translation?
mRNA leaves the nucleus through the nuclear pores to the ribosome in the cytoplasm
Codon on the mRNA is complementary to the anti-codon on tRNA so the tRNA pairs with the mRNA and hydrogen bonds form between the codon and anti-codon
tRNA carries a specific amino acid so the sequence of codons on the mRNA determines the order of amino acids
Peptide bonds form between the amino acids held close on the ribosome
The tRNA detaches and collects another amino acid from the cytoplasm
The ribosome moves along the mRNA molecule
What is a mutation?
A change in the nucleotide base sequence of DNA
How does a mutation occur?
Spontaneously as DNA is being replicated when a cell divides by mitosis or meiosis
By mutagenic agents
What is a base substitution?
Where one nucleotide is replaced with another, containing a different base
What is a deletion mutation?
This is where there is a loss of a nucleotide, causing the frame to shift
What is an inversion mutation?
Where two nucleotides are swapped around
What is a duplication mutation?
Where an addition of the same nucleotide occurs again in the sequence, causing a frame shift
What is a translocation mutation
Where a part of the DNA sequence is removed and placed in a different area of the DNA
Many mutations affect the ————— of a protein molecule
Tertiary structure
What is a mutagen? Give examples of this
A mutagen is anything which causes a mutation
These include ionising radiation, UV radiation and certain chemicals e.g benzene in crude oil
