Bio Molecules Proteins

Question 1

Why can R groups determine tertiary structure

Answer 1

As some r groups attract and repel
Disulfide bonds form between cysteine
Hydrogen bonds form
Ionic bonds form between oppositely charged R groups

Question 2

Similarity of collagen and hemoglobin

Answer 2

Both have amino acids chain
Peptide bonds
Both have ionic hydrogen and disulfide bonds
More than one polypeptide

Question 3

Structure of haemoglobin

Answer 3

P: sequence of amino acids joined by peptide bonds
S:Amino acid chain begins to fold into alpha helix which is held together by hydrogen bonds
T: secondary structure undergoes further coiling. Disulfide ionic hydrophobic and hydrophilic interactions form
Q: contains 2 alpha and 2B subunits and 1 heam group per polypeptide. Prosthetic group is haem which contains iron ion

Question 4

Structure of collagen

Answer 4

Peptide bonds form between amino acids.
Every 3rd amino acid is the same
This twists and forms a left handed helix
Glycine allows twisting of polymer chains and forms 3 polypeptide chains.
No hydrophilic R groups are on the outside of the molecule.
Adjacent molecules are joined by cross links forming fibrils

Question 5

Fibrous and globular protein differences

Answer 5

F:insoluble,strong,unreactive
G:soluble,round/compact,reactive

Question 6

How would a second amino acid bond to cysteine in forming the primary structure

Answer 6

A peptide bond would form between the carboxyl group of one amino acid and the amine of another amino acid. H from amine combines with OH from carbonyl in a condensation reaction.

Question 7

Describe globular proteins with the help of hemoglobin

Answer 7

Gp:spherical,hydrophobic r groups are on the inside hydrophilic r group on the outside, forms H bonds with water and is soluble eg amylase.HAEMOGLOBIN: Carrie’s oxygen and contains prosthetic group F2+ which allows o2 to be carried.polypeptide chains inside hawmoglobin have tertiary structure

Question 8

Describe fibrous proteins with the help of collagen

Answer 8

Are linear. Chains can form hydrogen bonds with adjacent molecules. They are insoluble as they have a few hydrophilic groups.they are strong and gave structural support. COLLAGEN: has high proportion of glycine so chains lie close together. It forms cross links between molecules. These cross links are staggered to avoid weak points. Collagen forms parts of tendons

Question 9

cholesterol

Answer 9

makes vitamin D and regulates fluidity of phospholipid bilayer

Question 10

what molecules bind with cholesterol to make ldls

Answer 10

lipids and proteins

Question 11

describe how concentration of a reducing sugar can be measured using a calorimeter

Answer 11

use standard concentrations of reducing sugar
heat with benedicts solution use the same volume of solution each time
use excess benedicts
colour change to green yellow or brick red
remove precipitate
calibrate colorimeter to 0 using distilled water
use a red filter
read transmission/absorbance
obtain callibration curve and plot transmission against absorbance.

Question 12

what are triglycerudes used for

Answer 12

used for storage for energy as theyre insoluble

Question 13

why does an emulsion form if lipid present

Answer 13

as lipids cannot dissolve in water so if present they form an emulsion