B1.2: Proteins Flashcards
Monomers of proteins?
Amino acids.
How many amino acids are there?
20 amino acids only
Which organelle produces proteins
Ribosomes
Why do we still need to consume meat/soya for protein if we have a lot of them due to ribosomes?
We don’t have all types of amino acids, therefore, they need to be supplemented via meat or soya, etc.
Define muscle wasting (DOUBLE CHECK)
the wasting (thinning) or loss of muscle tissue
- when proteins as a source of energy when carbs and lipids aren’t there
Outline the two types of amino acids
Essential and non-essential
Define essential proteins
Protein from other organism
Define non-essential proteins
Come from our body (thus it’s not essential to consume from external sources)
What are a 2 amino acids tgt called?
Dipeptide
Outline the sequence of complexity
amino acid (monomer) -> dipeptide -> polypeptide -> proteins
Define denatured on terms of proteins
The (natural quality which is specifically:) functional shape of protein is disrupted
Outline the different structures found in an amino acid
Amine grp (NH2)
Carboxyl grp (COOH)
Hydrogen atom (H)
Variable side chain (R)
What is the chemical composition of proteins?
CHON/S
(Carbon, Hydrogen, Oxygen, Nitrogen and with or without?? Sulfur)
Draw the structure of a generalised amino acid
(no need to draw a box)
What is the bond between protein?
Peptide bond
What makes an amino acid different from eachother
Their R (variable side chain)
- determines type of protein (polar or non-polar)
What determines the charge of the amino acid/protein?
The R
Describe the folding of long amino acid chains
The R’s can be attracted to each other and thus “fold” the chain which affects the structure and function
Most natural polypeptide chains contain between how many amino acid residues?
50 - 2000
Describe peptide bonds
- covalent bond
- condensation to dipeptide and water
- broken by hydrolysis (?)
(between C and N — the one in green. btw they bind at one’s carboxylic group and amine group)
amino acid + amino acid —> ?
dipeptide + water
Outline the types of structure in proteins
1.) Primary
2.) Secondary
3.) Tertiary
4.) Quaternary
Describe the primary structure of amino acid
Purely the sequence/arrangement
e.g.: Amino acid 1 - amino acid 2 - amino acid 3 - …
Describe the secondary structure
Folding (depends on R)
- Two stable forms:
1.) B (beta)-pleated
2.) A (Alpha)-helices (helical)
- both result from hydrogen bonds (and peptide) between amino acids
- Bonding of amino acids not to the neighbor - non-adjacent
Describe the B-pleated secondary structure (CONT.)
It consists of various beta strands linked by hydrogen bonds between adjacent strands.
- Unique folding (zigzag)
Define helical bond in the secondary structure
Circular
Describe the tertiary structure of the protein
Determined by the interactions between the R chains
- 3D configuration
- hydrophobic inside; hydrophilic outside
Describe quarternary structure
Made up of different polypeptides folded to one another with diff. prosthetic grps
e.g.: tertiary and tertiary, tert and secondary, quarternary and..
Define denaturation
a structural change that results in the loss of its biological properties
- additionally, can also break bonds
What is the denaturation of proteins caused by?
Temp and pH
Describe tertiary structure
R side groups bond tgt, 3D Configuration/Arrangement
- (relation to the R groups and 3D-ness): Polar amino acids stick outside whereas non-polar amino acids hide inside
Where do peptide bonds form?
Carboxyl group and Amine group by condensation
(removal of the OH from the carboxyl group and the H atom from the amine group of another amino acid -> water byproduct -> allows one more bond for the carbon and nitrogen to create a peptide bond!)
Why are prosthetic groups not the same as the R group
Prosthetic groups are not part of the amino acid
- R group is pat of the amino acid, therefore, not part of the amino acid
- But prosthetic groups, despite not being an amino acid, are bonded to the polypeptides in quaternary structures
Outline the two types of proteins according to structure and function
1.) Globular, functional (reactions) — round
- e.g. enzymes
2.) Fibrous, on structure — long and thin
Outline the two causes of denaturation of proteins
1.) Temperature
2.) PH level
Why is protein sensitive to temperature?
High thermal energy can disrupt the hydrogen bonds that hold the protein together (2nd structure)
- Also note: peptide bond within amino acid, hydrogen bond between amino acid (like covalent bonds and hydrogen bonds in water)
- will cause protein to unfold and therefore not function
Why is protein sensitive to pH
amine grp and carboxyl grp not bonding tgt, attracted to other atoms (H if more acidic and OH if more alkaline)
- thus, it’ll alter the shape of the protein (primary structure?) -> protein shape and protein solubility (-> function?)
What determines the type of protein?
By the sequence of genes (Translation)
- usually 1 gene 1 protein type??, e,g, 1 gene -> hair color (DOUBLE CHECK)
- But the grouping of genes to proteins is different due to translation (ADD PHOTO)
e.g.: The reason why some people are lactose-intolerant is that their genes have “turned off” the lactose-tolerating proteins (? DB)
The genes determine the hair-color
Define proteome
total proteins expressed with a cell, tissue, organism at a certain time
Which do we have more of? Proteins or genes?
Proteins > genes
Explain the 1 gene to 1 protein type ratio
1 gene -> 1 type/purpose (e.g. hair color) -> different variations of proteins (e.g. brown blue and green in one person
- The proteome depends on the expression of proteins (dom vs recess.)
Describe fibrous proteins
- Long, narrow
- Structural
-Repetitive amino acid sequence
- Less sensitive to changes in pH and temp, etc.
- Generally insoluble in water
e.g.: collagen, myosin, fibrin. actin and keratin, etc.
Describe globular proteins
- Round/spherical
- Functional
- Irregular amino acid sequence
- More sensitive to changes in pH, temp. etc. (they have optimum pH level and temp for chem reactions — enzymes)
- Generally soluble in water (ig related to the chemical reaction function??)
e,g, enzymes
Give the function of the enzyme Rubisco
Catalyzes photosynthesis — carbon-fixation
- fixes carbon dioxide from the atmosphere — provides carbon needed by living organisms
Give the function of the hormone Insulin
Lowers blood glucose levels
Give the function of the structural protein, Collagen
To prevent skin tearing by wounding three polypeptides in a rope-like way.
- (which is why you oft see collagen in shampoo ads)
Give the function of the antibody, immunoglobulin
bind to antigens (substances that illicit a bodily reaction) in pathogens
Give the function of the pigment Rhodopsin
makes the rod cells of the retina light-sensitive
Which atom makes a bond covalent?
Oxygen — has electrons for electron sharing (covalent bond)
