Topic 2.4: Proteins Flashcards
Amino acids are joined together on the ribosome to form long chains called
polypeptides
The covalent bond between the amino acids is called
a peptide bond
Define primary structure of protein
The order of the amino acid sequence is called the primary structure and determines the way the chain will fold
Define secondary structure of protein
Amino acid sequences will commonly fold into two stable configurations, called secondary structures
Define tertiary structure of protein
The overall three-dimensional configuration of the protein is referred to as the tertiary structure of the protein
Define quaternary structure of protein
Certain proteins possess a fourth level of structural organisation called a quaternary structure
Quaternary structures are found in proteins that consist of more than one polypeptide chain linked together
When do alpha helices occur?
Alpha helices occur when the amino acid sequence folds into a coil / spiral arrangement
When do beta-pleated sheets occur?
Beta-pleated sheets occur when the amino acid sequence adopts a directionally-oriented staggered strand conformation
Define denaturation
a structural change in a protein that results in the loss (usually permanent) of its biological properties
What two conditions can cause denaturation of proteins?
temperature and pH
Define proteome
the totality of proteins expressed within a cell, tissue or organism at a certain time
collagen and spider silk are examples of what type of protein function?
structure
insulin and glucagon are examples of what type of protein function?
hormones
immunoglobins are examples of what type of protein function?
immunity
hemoglobin and cytochrome are examples of what type of protein function?
transport
rhodospin are examples of what type of protein function?
sensation
actin and myosin are examples of what type of protein function?
movement
rubisco are examples of what type of protein function?
enzymes
What are the two main classes of protein tertiary structure?
fibrous proteins and globular proteins
Define fibrous proteins
Fibrous proteins are generally composed of long and narrow strands and have a structural role (they are something)
Define globular proteins
Globular proteins generally have a more compact and rounded shape and have functional roles (they do something)
What is the difference between fibrous proteins and globular proteins in terms of shape?
Fibrous: long and narrow
Globular: round/spherical
What is the difference between fibrous proteins and globular proteins in terms of purpose?
Fibrous: structural
Globular: functional
What is the difference between fibrous proteins and globular proteins in terms of acid sequence?
Fibrous: repetitive amino acid sequence
Globular: irregular amino acid sequence
What is the difference between fibrous proteins and globular proteins in terms of durability?
Fibrous: less sensitive to changes in pH, temperature
Globular: more sensitive to changes in pH, temperature
What is the difference between fibrous proteins and globular proteins in terms of solubility?
Fibrous: generally insoluble in water
Globular: generally soluble in water
Collagen is an example of what type of protein (globular or fibrous)?
Fibrous protein
Myosin is an example of what type of protein (globular or fibrous)?
Fibrous protein
Fibrin is an example of what type of protein (globular or fibrous)?
Fibrous protein
Actin is an example of what type of protein (globular or fibrous)?
Fibrous protein
Keratin is an example of what type of protein (globular or fibrous)?
Fibrous protein
Elastin is an example of what type of protein (globular or fibrous)?
Fibrous protein
Enzymes is an example of what type of protein (globular or fibrous)?
Globular protein
Hemaglobin is an example of what type of protein (globular or fibrous)?
Globular protein
Insulin is an example of what type of protein (globular or fibrous)?
Globular protein
Immunoglobulin is an example of what type of protein (globular or fibrous)?
Globular protein
