Mrs Williamson Flashcards
Proteins are made of:
Long chains of amino acids
What is the monomer of a protein
Amino acids
Polypeptide =
Two or more amino acids
Proteins =
One of more polypeptides
Protein structure 4 stages:
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
What is the primary structure
String of amino acids
Type
Number
Sequence
Secondary structure
Coil into alpha helix
OR
fold into beta pleated sheet
Tertiary protein structure
Held together by:
- disulphide bridges
- ionic bonds
- hydrogen bonds
Quaternary protein structure
Several polypeptide chains joint together
4 examples of proteins
Enzymes
Antibodies
Transport proteins
Structural proteins
Role of enzymes
- Synthesise to make large molecules
2. Digestive enzymes
Role of antibodies
Immune response
Function of transport protein
In cell membrane
Transport molecules across membrane
Function of structural protein
Strong
Found in hair and nails
What is the test for protein called?
Biuret test
What is the biuret test
- Add drops of sodium hydroxide solution to make it alkaline
- Add copper sulfate solution
If protein is present, it turns lilac
In the biuret test why do you add hydroxide solution
To make it a alkaline
Enzymes are…
Biological catalysts that speed up a chemical reaction without being used up
What makes enzymes so unique
They have an active site which is determined by the tertiary structure
What is the lock and key model
Enzymes have an active site which exactly fits the substrate.
This forms an enzyme-substrate complex
What is the induced fit theory
Enzyme active site is similar to substrate
Active site changes slightly to fit substrate exact
Four factors effecting enzyme activity:
Temperature
pH
Enzyme concentration
Substrate concentration
How does temperature effect enzyme activity
More heat, more kinetic energy, more collisions
If to hot, enzyme may denature
How does pH effect enzyme activity
Enzymes work best at optimum pH but can get denatured if too high
How does enzyme concentration effect enzyme activity
More enzymes, more likely to collide
Until substrate runs out
How does substrate concentration effect enzyme activity
More substrate, more collisions, faster rate
Until substrate runs out
What are the two types of inhibitors
Competitive
Non competitive
What is a competitive inhibitor
- similar shape to substrate molecules
- bind to active site, so substrate can’t
- no reaction takes place
What is a non competitive inhibitor
- bind to enzyme away from active site
- cause active are to change shape
- substrate no longer fits
Why does digestion occur
Large molecules are too big to cross cell membranes, therefore can’t be absorbed from gut into blood
Polymers and broken down into molymers through…
Hydrolysis reaction (+ H2O)
During hydrolysis carbohydrates are broken down into…
Disaccharides and then monosaccharides
Amylase is a
Digestive enzyme
Amylase is producers in the
Salivary glands and pancreas
Starch (polysaccharide) turns into
Maltose (disaccharide) when broken down
Lipids are broken down by
Lipase with the help of bile salts
Lipids break down into
Monoglycerides and fatty acids
Lipase is made in the
Small intestine
Example of Endopeptides
Trypsin
Example of exopeptidases
Dipeptidases
Endopeptidases break down
Middle bonds
Exopeptidases break down
End bonds
Difference between diffusion and active transport
Active transport requires energy
Diffusion does not require energy
What is the ileum
Bottom of the small intestine
What is the lumen
Middle of the ileum
What happens during active transport
Conc of glucose is too low to diffuse into the blood
Sodium diffuses into epithelial cell
Sodium then actively pumped out cell with glucose attached
How are monosaccharides absorbed across cell membranes (2)
Glucose + Galactose absorbed by active transport proteins via co transport
How are monosaccharides absorbed across cell membranes (1)
Fructose absorbed via facilitated diffusion through transport protein
How are monoglycerides and fatty acids absorbed across cell membranes
Lipid soluble therefore diffuse directly across epithelial cell membrane
How are Amino acids absorbed across cell membranes
Sodium diffuses into cell carrying amino acids
Sodium actively transports back out the cell
How are carbs digested
Hydrolysis:
Break down into disaccharides then monosaccharides
How are lipids digested?
Emulsification:
Lipid + bile salts —>
Lipase digestion —> monoglycerides + fatty acids
How are proteins digested
Large molecules broken down into smaller molecules by digestive enzymes
