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Genes and Protein Synthesis; - Coggle Diagram
Genes and Protein Synthesis;
Genes;
DNA contains genes.
A gene is a sequence of DNA nucleotides that codes for a polypeptide.
The sequences of DNA nucleotides that code for a polypeptide.
Different proteins have a different number and order of amino acids.
It's the order of nucleotide bases in a gene that determines the order of amino acids in a particular protein.
Each amino acid is coded for by a sequence of three bases (called a triplet) in a gene.
Different sequences of bases code for different amino acids.
This is the genetic code.
The sequence of bases in a section of DNA is a template that is used to make proteins during protein synthesis.
DNA;
DNA molecules are formed in the nucleus of the cell, but the organelles that make proteins (ribosomes) are found in the cytoplasm.
DNA is too large to move out of the nucleus, so a section is copied into mRNA.
This process is called transcription.
The mRNA leaves the nucleus and joins with a ribosome in the cytoplasm, where it can be used to synthesis a protein.
This process is called translation.
RNA;
RNA is a single polynucleotide strand and it contains uracil (U) as a base instead of thymine.
Uracil always pairs with adenine during protein synthesis.
RNA isn't all the same. You need to know about;
Messenger RNA (mRNA).
Transfer RNA (tRNA).
Ribosomal RNA (rRNA).
mRNA;
mRNA is a single polynucleotide strand.
It is made up in the nucleus during transcription.
mRNA carries the genetic code from the DNA in the nucleus to the cytoplasm, where it is used to make a protein during translation.
In mRNA, groups of three adjacent bases are usually called codons.
tRNA;
tRNA is a single polynucleotide strand that is folded into a clover shape.
Hydrogen bonds between specific base pairs hold the molecule in this shape.
Every tRNA molecule has a specific sequence of three bases at one end called an anti codon.
They also have an amino binding site at the other end.
tRNA is found in the cytoplasm where it's involved in translation.
It carries the amino acids that are used to make proteins to the ribosomes.
rRNA;
rRNA forms the two sub units in a ribosome, along with proteins.
The ribosome moves along the mRNA strand during protein synthesis.
the rRNA in the ribosomes helps to catalyse the formation of peptide bonds between the amino acids.
The genetic code;
The genetic code is the sequence of base triplets (codons) in the DNA or mRNA, which codes for specific amino acids.
In the genetic code, each base triplet is read in sequence, separate fro the triplet before it and after it.
Base triplets don't share their bases - the code is non-overlapping.
The genetic code is degenerate - there are more possible combinations of triplets than there are amino acids (20 amino acids but 64 possible triplets).
This means some amino acids are coded for by more than one base triplet.
Not all triplets code for amino acids thought. For example, some triplets are used to tell the cell when to stop production of a protein - these are called stop signals. They are found at the end of the mRNA.
The genetic code is also universal - the same specific base triplets code for the same amino acids in all living things.