Chemistry of Life

Question 1

Polymer

Answer 1

A substance made of many similar units bonded together

Question 2

Monomer

Answer 2

A single molecule that can be bonded to others to form a polymer

Question 3

Nucleic Acid

Answer 3

Long-chain of nucleotides present in living cells ie.DNA and RNA

Question 4

Nucleoside

Answer 4

base + sugar

Question 5

Bases and H-bonding

Answer 5

Purines (2 rings) – pyrimidines (1 ring)
Adenine – Thymine/Uracil (2 H-bonds, weaker)
Guanine – Cytosine (3 H-bonds, stronger)
Hydrogen Bonding
(H with N, O or F)
-Slightly ionic (opposite charges)
-Slightly covalent ( H gets full shell, O/F/N does not)
-Strong because molecules are polar and H valence e- in closest shell so very strong attraction
-Very different electronegativities

Question 6

nucleic bases descriptions

Answer 6

Purines (2-rings):
Adenine (no Oxygen, NH2 at top)
Guanine (1 Oxygen at top + NH2 on lower right)

Pyrimidines (1 ring):
Thymine (Oxygen at top and lower right, CH3 top right)
Uracil (Oxygen at top and lower right, smaller than T)
Cytosine (NH2 on top, Oxygen lower right only)

Question 7

Van Der Waals Interactions

Answer 7

Dipole-dipole attraction
temp, perm (polar), H-bonding (perm + H-O/F/N)
-Weak between 2 atoms, accumulatively large within DNA structure
-Stronger when closer together
-Result of uneven e- distribution within molecules
-H-bonding within the base pair (A-T/U, G-C)

Question 8

pH of bases

Answer 8

Phosphoric acid ion: H3PO4

• Phosphate charge -1 (1 negative O2 atom because only 3H+ but 4O-)
• DNA is a weak acid
• Bases are weak base, acidic phosphates protect them
• Attraction between nucleic acid and cation cloud
  
  • Strong electrostatic bond
  • Form strong ionic bond - donate e-
  • Stronger with larger difference in charges

Question 9

Organic Compound

Answer 9

Contains Carbon

Question 10

Functional Groups

Answer 10

-INPUT FROM CHEM FLASHCARDS-

Phosphate H3PO4 -> H2PO4- (acidic)
Phosphodiester is phosphate with 2 ester bonds
amide is basic normally
amide is acid when in peptide bond

Question 11

Amino acids

Answer 11

polarity:
H-bonding:
Hydrophilic/phobic

Question 12

H-bonding
Donor
Acceptor

Answer 12

NH or OH functional group - H covalently bonded, high electronegativity
O or N functional groups - lone e- pair, dipole attraction to H nucleus (whose e- is more attracted to other covalent molecules as more electronegativity)
donate - loose H+
accepts - gains H+

Question 13

Acid-base

Answer 13

Brønsted–Lowry
Acid - donates H+ NOTE: NH in Amide is not basic as donates H+
Base - accepts H+

Question 14

stereochemistry

Answer 14

3D arrangement of molecules

double bonds cause fixed rotation

Question 15

Chiral center

Answer 15

4 different sections off the center

Question 16

Peptide bond

Answer 16

hydroxyl + amine forms amide and excess water
large chain of repeating structure
amide is acidic due to loosing H

Question 17

Fat Structure

Answer 17

Fatty acids linked to glycerol
Fatty acid - ester followed by long C chain (including double bonds at times)
Glycerol - 3-carbon unit connecting fatty acids
Try-glyceride - glycerol + 3 fatty acids

Question 18

Fat Properties

Answer 18

Hydrophobic
Even though ester groups present at one side
Long carbon chains unable to H-bond
Repels water and other H-bonding substances
Reduced interaction with H20
Increases entropy as things push apart
So clumps together separate to water
Polar head
Nonpolar tail

Question 19

Lipid Bilayer

Answer 19

Thin polar membrane of 2 layers of molecules
Prevents unintentional diffusion
Choline - hydrophilic polar head to create bilayer, hydrophobic fatty acid points inwards
Cholesterol - inserts itself within the layer to maintain rigidity under changing temperatures

Question 20

Glycogen

Answer 20

The storage form of glucose
Organised in 8-12 rings bonded together due to insulin
Stored in muscle and liver cells - closest to where it is needed, high blood supply present due to the activity of areas allowing for quick transport to other areas as needed
Lots of H-bonds so Hydrophilic so attracts water - need much more water to store glycogen than fat
Glycogen:water 1:3 or 1:4 ratio
Less energy efficient in storing energy than fat, as a result, more energy-efficient in releasing energy than fat
Benefits - quickly converted into energy, stores 6-8h at a time
Limitations - takes a while to restore stocks, takes a while to make glycogen

Question 21

Polysaccharide molecules

Answer 21

Polysaccharide – carbohydrate made of multiple sugar molecules bonded
Features:
Store energy from food
Cell structure

Question 22

Fats as energy

Answer 22

Mammals - fat slow-release energy store, difficult as fat hydrophobic
Migrating birds - more fatty acid transport protein to cope with this to allow easier conversion of fat to energy

Question 23

Enzyme Proteins

Answer 23

The catalyst for biochemical reaction, substrates -> products
specific to given reaction

Question 24

Defensive Proteins

Answer 24

Antibodies, found in the immune system

Question 25

Storage Proteins

Answer 25

Store metal ions and amino acids, found in plant seeds, eggs, milk

Question 26

Structural Proteins

Answer 26

Fibrous proteins keep physical structure ie. Keratin in hair, nails etc.

Question 27

Transport Proteins

Answer 27

Move molecules across the plasma membrane (passive, active) | Specific protein for each molecule transported

Question 28

Receptor Proteins

Answer 28

Receives chemical signals outside of the cell, cause cellular response ie. electrical transmits instructions from outside cell into it

Question 29

Motor proteins

Answer 29

Motor - hydrolyse ATP to convert chemical energy into mechanical, move along cytoplasm of animal cells

Question 30

Contractile Proteins

Answer 30

Contractile - used in muscle contractions myofibrils (myosin and actin)

Question 31

Signalling Proteins

Answer 31

Signal endocrine system about hormone balance | regulates metabolism and cell function as a result

Question 32

Physical Structure

Answer 32

Primary – 2D wiggly line, determined by dna sequence Secondary – 3D fold Ɑ-helix – h-donation to below molecule, coiled structure Β-strand – lateral h-donation, pleated snake structure Tertiary – comprehensive 3D structure (over and under) Hydrophobic Interactions – repel/attract H-bonding – hold the structure in a given place Ionic Bonding – opposite charged R groups come in close contact Van der Wall or Covalent – stabilise Quaternary – interaction between multiple chains (subunits)

Question 33

Similarity between structures

Answer 33

Proteins of similar sequence often fold in similar ways Similar sequence means related strands of DNA However, this does not necessarily mean they have a similar function Similar structure: Chicken Ovalbumin - egg white - main difference: V in code in place of R Human Antithrombin - blood plasma - R in code in place of V V = valine (C5H11NO2) - smaller, less H-bonding, molecules easier to separate Donates and accepts Hydrophobic Charge: R = arginine (C6H14N4O2) - larger, more H-bonding Length width Donates and accepts H+ Hydrophilic Charge: positive