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Karan - MBBS Year 1: Principles Week 1 > Biomolecules > Flashcards

Biomolecules Flashcards

1
Q

Define cell.

A

Building block of all living things

Made up of biomolecules

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2
Q

Outline the composition of cells

A

Water - 60%
Proteins - 16%
Triglycerides - 13%
Membrane lipids - 2.5%
Nucleic acids - 0.2%

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3
Q

What are the four main types of biomolecule?

A
  • Lipids
  • Carbohydrates
  • Nucleic acids
  • Proteins
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4
Q

What is a polymer?

A
  • Large macromolecules made up of repeating units - monomers
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5
Q

How do biomolecules form?

A
  • Carbon is the central atom
  • Share 4 valence electrons with partner atoms C, H, O , S, P and N to form functional groups
  • Functional groups on monomers join to form bonds and link, forming polymers.
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6
Q

What is the difference between condensation and hydrolysis?

A
  • CONDENSATION - Endergonic (energy requiring)
  • HYDROLYSIS - Exergonic - energy releasing
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7
Q

What do inorganic molecules not contain? Give examples.

A
  • Don’t have carbon
  • EXAMPLE: water
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8
Q

Describe covalent bonds.

A
  • Interaction between atoms based on the sharing of electron pairs
  • Strong with high energy so hard to break
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9
Q

Describe non-covalent bonds.

A
  • May or may not involve the exchanging of electrons
  • Weak with low energy so bonds are reversible - break and form constantly
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10
Q

Outline the order of strength of bonds.

A

COVALENT > IONIC > HYDROGEN > HYDROPHOBIC > VAN DER WAALS

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11
Q

RECAP TO A-LEVEL: What are valence electrons?

A

Electrons found in outermost electron shell

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12
Q

What are the main rules followed in covalent bonding?

A
  • Only valence electrons used
  • Outer orbitals filled to 2 or 8 electrons depending on energy level
  • One covalent bond involves sharing of 2 electrons
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13
Q

Define electronegativity.

A

Power of an atom in a molecule to attract electrons towards itself

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14
Q

Describe non polar covalent bonds with an example.

A
  • Equal sharing of electrons
  • Atoms have similar electronegativity
  • No net charge e.g C-C, C-H
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15
Q

Describe polar covalent bonds with an example.

A
  • Electrons unevenly shared
  • Atoms - different electronegativities
  • Form dipoles e.g O-H, N-H
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16
Q

Define ionic bond.

A

Electrostatic attraction between oppositely charged ions.

16
Q

Describe hydrogen bonds.

A
  • Occur in water and in proteins and DNA
  • Dipole-dipole interaction between a H and an electronegative O, N and F in another molecule
17
Q

Describe van der Waals forces.

A
  • Two types: Dipole-dipole (between polar molecules) and London dispersion (between induced polar)
  • When molecules come close, electrostatic repulsion between electron shells overcomes attractive force
18
Q

How do nucleotides form DNA?

A
  • Phosphodiester bond between 5’ phosphate and 3’ OH of
    sugar. Pyrophosphate released and sugar-phosphate backbone forms
  • Bases of 2 separate strands hydrogen bond by base pairing to form double stranded DNA. Winds to form double helix.
19
Q

What determines activity of a protein?

A

Specific 3D structures determined by specific amino acid sequence

20
Q

Give examples of proteins found in the body.

A
  • Enzymes
  • Antibodies
  • Transport proteins
  • Amino acid storage e.g casein
  • Hormones e.g insulin
  • Receptors for cell signalling
  • Motile proteins e.g actin, myosin
21
Q

Describe lipid solubility.

A
  • Insoluble in polar solvents e.g water
  • Soluble in non polar solvents e.g benzene
22
Q

Describe the hydrocarbon chains in lipids.

A
  • Hydrophobic
  • Nonpolar
23
Q

What are the three types of lipids?

A
  • Triglycerides
  • Membrane lipids
  • Steroids
24
Q

Where are triglycerides stored and what are they used for?

A
  • Adipose tissue
  • Energy storage
25
Q

Describe the components of triglycerides.

A
  • 1 glycerol and 3 fatty acid molecules
  • Glycerol - alcohol with 3 hydroxyls
  • Fatty acids - made up of carboxyl group and hydrocarbon chain that is saturated or unsaturated
26
Q

Why do humans need fats?

A

Absorption of fat-soluble vitamins e.g Vitamins A, D, E and K

27
Q

What are the differences between saturated and unsaturated fatty acids?

A

SATURATED - contain C-C bonds but unsaturated have C=C double bonds (causing kinks)

28
Q

Describe phospholipids.

A
  • Hydrophilic heads and hydrophobic tails
  • Tails are 2 fatty acid chains
  • Heads contain 1 glycerol, phosphate group and choline group
29
Q

What are the functions of phospholipids?

A
  • Structural component of cell membranes
  • Regulate fluidity and permeability
30
Q

What are steroids characterised by?

A

4 fused carbon rings

31
Q

What are the functions of steroids?

A
  • Hormones/signaling molecules
  • EXAMPLE: Cholesterol - found in cell membranes
32
Q

What are the functions of carbohydrates?

A
  • Energy source for cell
  • Structural roles
33
Q

Describe monosaccharides.

A
  • Chain of carbons with a -OH at each carbon except one, which forms a carbonyl group
  • Classified based on location of carbonyl/number of carbons
  • Form ring structures - aldehyde/keto group forms bond with one of the -OH
34
Q

How do monosaccharides form polysaccharides?

A
  • Combine in condensation reaction by forming glycosidic bonds
35
Q

Describe glycogen.

A
  • Stored in liver and muscle cells
  • Energy store
  • Branched - containing α-1,4 glycosidic bonds
36
Q

Describe cellulose.

A
  • Constituent of cell wall in plants
  • Linear polymer
  • Contains β-1,4 glycosidic bonds

Karan - MBBS Year 1: Principles Week 1 (14 decks)

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