Amino Acids are linked together by condensation to form polypeptides.
➧Polypeptides are made by linking amino acids together through condensation reactions producing water.
➧The bonds between different amino acids are peptide bonds. Some are made with a single polypeptide, and some are made with multiple.
Skill: Drawing molecular diagrams to show the formation of peptide bonds.
There are twenty different Amino Acids in polypeptides synthesized on ribosomes.
➧There are twenty different amino acids that are made in the ribosomes to make polypeptides.
➧These twenty different amino acids have different R-Groups. The R-Groups are what makes the amino acids different from one another.
Looking for patterns, trends, and discrepancies - most but not all organisms assemble the same proteins from the same amino acids.
➧Most organisms use the same twenty amino acids to make proteins.
➧Several hypotheses have been proposed on why this is the case:
1. These are the twenty amino acids that were available to be used.
2. They are the best twenty, so they were chosen through natural selection.
3. Life has developed from a common ancestor that used those twenty amino acids.
Amino acids can be linked together in any sequence, giving a huge range of possible polypeptides.
➧Since any of the twenty amino acids can be linked together to make a polypeptide, it allows any sequence to be created.
The amino acid sequence of polypeptides is coded for by genes.
➧ All of the information for the thousands of different polypeptides must be present in the genes of the organism. The role of most genes is to store the amino acid sequences for polypeptides.
➧Each three bases of a gene make a codon which codes for an amino acid. There are some genes that do not do this.
A protein may consist of a single polypeptide or more than one polypeptide linked together.
➧Some examples: lysozyme has one polypeptide, integrin has two, collagen has three, and hemoglobin has four.
➧Some proteins need the multiple parts and some do not.
The amino acid sequence determines the three dimensional conformation of a protein.
Elongated with repeated structures
Glob. Literally. It’s a glob. It’s that simple.
The amino acid sequence prevents folding.
Folds which are stabilized by bonds between the R-Groups.
Application: Denaturation of proteins by heat or by deviation of pH from the optimum.
➧The three-dimensional structure of proteins is held together by weak bonds and interactions between the R-Groups that can be disrupted or broken.
➧ Denaturation is when this three-dimensional structure is disrupted. This is hormonally permanent.
➧Heat can cause denaturation because the vibrations break the bonds.
➧Extreme high or low pH can also denature a protein.
Living organism synthesize many different proteins with a wide range of