2.4 proteins Flashcards
what is a monomer of a protein?
amino acid
draw an amino acid
see p. 155
polypeptide
long chains of covalently bonded amino acids joined together on the ribosome
how many amino acids are there?
20
peptide bond
a covalent bond that joins amino acids, at the carboxyl group of one amino acid to the amino group of the other amino acid, with the release of a molecule of water.
how can amino acids can be covalently joined together?
via condensation reaction, forming a dipeptide and water
how can polypeptide chains be broken?
via hydrolysis reactions
draw the formation of a peptide bond
see p. 155
primary structure
- determines the way the chain will fold
- Different amino acid sequences will fold into different configurations due to the chemical properties of the variable side chains
secondary structures (2 configurations)
- folding into repeat patterns (alpha-helix or beta-pleated sheet)
- By hydrogen bonds between amine and carboxyl groups
what happens if there is no secondary structure?
the polypeptide chain will form a random coil
tertiary structure
- Overall three-dimensional arrangement of a polypeptide
- Determined by interactions between variable side chains
quaternary structure
found in proteins that consist of more than one polypeptide chain linked together OR if they include inorganic prosthetic groups as part of their structure
An example of a protein with a quaternary structure
haemoglobin
- composed of four polypeptide chains (two alpha chains and two beta chains)
- It is also composed of iron-containing haeme groups (prosthetic groups responsible for binding oxygen)
SHITS ME
structure, hormones, immunity, transport, sensation, movement, enzymes
what is SHITS ME
acronym for protein functions
collagen
A component of the connective tissue of animals (most abundant protein in mammals)
spider silk (fibroin)
A fiber spun by spiders and used to make webs (by weight, is stronger than kevlar and steel)
insulin
Protein produced by the pancreas and triggers a reduction in blood glucose levels. is a hormone.
glucagon
Protein produced by the pancreas that triggers an increase in blood glucose levels
immunoglobulins
Antibodies produced by plasma cells that are capable of targeting specific antigens
haemoglobin
A protein found in red blood cells that is responsible for the transport of oxygen
cytochrome
A group of proteins located in the mitochondria and involved in the electron transport chain
rhodopsin
A pigment in the photoreceptor cells of the retina that is responsible for the detection of light
actin
Thin filaments involved in the contraction of muscle fibres
myosin
Thick filaments involved in the contraction of muscle fibres
rubisco
(ribulose carboxylase)
the enzyme that catalyses the first step of photosynthesis (probably the most abundant protein on Earth). involved in carbon fixation during photosynthesis.
proteome
The totality of all proteins that are expressed within a cell,
tissue or organism at a certain time
why are proteome unique?
protein expression patterns are influenced by a unique genome
denaturation
structural change in a protein that results in the loss (usually permanent) of its biological properties
conditions that cause denaturation
temperature and pH
how does temperature cause denaturation
High levels of thermal energy may disrupt the hydrogen bonds that hold the protein together
As these bonds are broken, the protein will begin to unfold and lose its capacity to function as intended
Temperatures at which proteins denature may vary, but most human proteins function optimally at body temperature (~37ºC)
how does pH cause denaturation
alters protein charge ➡ changes solubility & shape
albumin
the main protein of human plasma. Its main function is to regulate the osmotic pressure of blood.
amino group
NH2
carboxylic group
COOH
gene
a heritable section of DNA that controls a specific trait.
ribosome
cell organelle functioning as the site of protein synthesis.
