Proteins & Protein Synthesis Flashcards
What are proteins?
Proteins are giant molecules (polymers) that are made up of amino acids (monomers) that form polypeptide chains.
Proteins are…
the link between genes and they body they build as they are produced from the intructions of genes.
What do polypeptide chains do in Fibrous Proteins
In Fibrous proteins, polypeptide chains form tough rope-like bundles. (like Collagen and Keratin)
What function does a Fibrous protein obtain?
Typically, Fibrous proteins contain a mechanical function such as support and protection. Others are contractile for movement.
What function does a Globular protein obtain?
Typically, Globular proteins have a chemical function (eg. hemoglobin for oxygen transport) or a regulatory function (such as enzymes as catalysts)
What do polypeptide chains do in Globular Proteins?
In Globular proteins, the polypeptide chains are folded irregularly into a globe-shaped molecule (eg. in enzymes and some hormones)
What is the Primary Structure?
The primary structure is the amino acid sequence which is different for each protein.
Where is the Info for the sequence of amino acids?
The information for the sequence of amino acids in a polypeptide is stored in a gene.
What happens when a mutation occurs?
When a mutation occurs it usually results in an altered protein. This can either be ineffective towards the proteins function or it can cause a non functioning protein altogether.
What is secondary structure and how is it held in place?
Secondary structure is where the primary structure is bent or twisted regularly to form a helix or pleated sheet (in which the polypeptide chains run side by side) It is held in place by hydrogen bonding between certain amino acids.
What is Tertiary Structure and how is it held in place?
The tertiary structure is where globular proteins are further irregularly bent to form a complex globular shape. The shape is maintained by hydrogen and disulfur bonding between certain amino acids
What is the Quaternary structure?
The quaternary structure is where some globular proteins are made up of 2 or more polypeptide chains that are held loosely together. (eg. the oxygen transporter, hemoglobin, has 4 polypeptide chains)
Where does chemical activity occur in globular proteins?
Although Globular proteins are large molecules, the chemical activity usually resides in a small part of the molecule which is in the active sight of an enzyme.
What are Enzymes?
Enzymes are biological catalysts that are used for the chemical reactions of life.
How do Enzymes work?
Enzymes take part in catalysing reactions by temporarily combining with the substrate(s) they act on (the substrate) forming an enzyme-substrate complex. Which occurs at the active sight.
What is the Induced Fit Mechanism and how is it possible?
The induced fit mechanism is where the active sight will slightly change to fit the substrate. This is possible because the bonds holding the protein in shape are weak enough to allow for some movement.
What is a triplet?
A triplet is a sequence of 3 bases in the DNA, A triplet codes for an amino acid.
What does the base sequence of DNA code for?
The base sequence of DNA codes for the amino acids that make up a protein (one gene codes for one polypeptide chain)
Every gene has 3 regions, What are they and what do they do?
The promotor turns the gene off and on and signals the sight of transcription. The coding region which has the base sequence for the protein and the terminator which signals the end point of transcription.
What are introns
Introns are regions of the DNA that isn’t needed for the formation of a protein
What are Introns and Exons
Introns are regions of DNA that aren’t needed for the formation of a protein and Exons are regions of DNA that are needed for the formation of proteins
Describe the process of transcription.
Transcription is where the enzyme RNA polymerase binds with the promoter causing the DNA to unwind and unzip. Only 1 of the two DNA strands are copied to make mRNA, this strand is called the template strand.
The other strand is called the coding strand because it has the same base sequence as the mRNA transcribed except U replaces T in the mRNA strand. When RNA polymerase reaches the terminator sequence, transcription is completed; mRNA detaches and the two DNA strands anneal and the helix reforms.
The mRNA is the primary transcript and is ‘edited’. There are some regions in the DNA that are needed for the formation of proteins and others that aren’t needed. These two regions are called introns and exons. Introns are the regions of DNA that aren’t important (therefore not used) in the formation of a protein and Exons are regions of DNA that are important and used in the formation of DNA. These exons are spliced together creating the final transcript of mRNA. (depending on the amount of exons spliced together, more than one of the final version can be made)
Why is it important to know that exons can be spliced together?
It is important to know that exons can be spliced together in different combinations to create different versions of a final transcript because it provides evolutionary flexibility. The double-edged nature of this process allows for the creation of new proteins (generating diversity) but it also poses risks when mutations or dysregulation occur.
When does translation start?
Translation occurs when the edited mRNA exits the nucleus and travels to the ribosomes in the cytoplasm
What are ribosomes built of?
Proteins and rRNA (ribosomal RNA)
