Life Chemistry

Question 1

Describe the structure of an atom

Answer 1

Atoms have a nucleus of protons(+) and neutrons, with electrons(-) orbiting the nucleus.

Question 2

List the four macromolecules that form the chemical composition of a cell

Answer 2

• Proteins
• Carbohydrates (polar - hydrophilic - charged)
• Lipids (non-polar - hydrophobic - neutral)
• Nucleic Acids (DNA & RNA)

Question 3

List the four elements that form the bulk of body matter

Answer 3

Oxygen
Carbon
Hydrogen
Nitrogen

Question 4

List the 6 important IONS in the human body

Answer 4

Ca calcium
Cl chloride
K potassium
Mg magnesium
Na sodium
P phospherous

Question 5

Explain how the properties of elements determine molecule characteristics

Answer 5

The extra electron on the outer shell of the atom (valence electron) determines which other atom it might be happy to bind with. The arrangement of electrons in an atom, and chemical bond determines the properties of the molecule. One of the key properties of a molecule is whether it is polar or non-polar, which dictates if it will dissolve in water or not, and what other atoms it might bond with.

Question 6

Name the four types of chemical bonds

Answer 6

Ionic
Covalent
Hydrogen
Polar covalent

Question 7

Name four features of ionic bonds

Answer 7

1. Structures are still, strong bond & frequently crystalline eg salt
2. High melting point
3. Dissolves in water
4. Polar (charged, hydrophilic)

Electron is transferred from one atom to another, joining them together

Question 8

Name the 3 features of covalent bonds

Answer 8

1. 2 molecules share electrons to join together
2. Quite strong
3. Can be polar or non-polar

Sharing of electrons between two atoms

Question 9

Provide an example of molecules created with a non-polar covalent bond

Answer 9

O2
CO2

Question 10

Provide an example of molecules created with a polar covalent bond

Answer 10

H2O (O is negative, 2 x H are +)

Question 11

What is the main limitation of a hydrogen bond? Give an example of a hydrogen bond

Answer 11

It is weak!
Water molecules are an example - the negative of one molecule is attracted by the positive part of another water molecule

Question 12

Name the three main classes of macromolecule

Answer 12

Proteins
Carbohydrates
Lipids

Question 13

Describe the atomic composition of proteins

Answer 13

Made from polymers/chains of amino acids
1 x amino group, central carbon, 1 x carboxyl group, 1 x R group (variable side chain)

Question 14

Describe the properties of proteins

Question 15

Describe the atomic composition of carbohydrates

Answer 15

Made from polymers of saccharides
eg monosaccharides (1 x saccharide)
disaccharides (2 x saccharides)
oligosaccharides (up to 9 x saccharides)
polysaccharides (thousands of saccharides)

Question 16

Describe the properties of carbohydrates

Question 17

Describe the atomic composition of lipids

Answer 17

Most commonly made from polymers of carbon called fatty acids. part of molecule (head) has charge (polar), part (tail) does not (non-polar)

Question 18

Describe the properties of lipids

Answer 18

Very limited water solubility, due to non-polar tail

Question 19

Define the terms ‘polar’ and ‘non-polar’.

Answer 19

Polar = water soluble, has charge
Non Polar= water insoluble, neutral/no charge

Question 20

Define the properties of molecules which determine their polarity and which class the macromolecules fall into

Question 21

Define the term ‘ion’

Answer 21

An ion is an atom or molecule with a net electrical charge. They have gained or lost electrons, so have a charge on them.

Question 22

What is an ion called, with a positive charge?

Answer 22

Cation

Question 23

What is an ion called, with a negative charge?

Answer 23

Anion

Question 24

9. Discuss concentrations and molarity

Answer 24

• Concentration is based on the number of particular types of molecules within an area.
• Avogadro’s number allows concentration to be calculated
• The unit of measurement is moles or millimoles
• Molarity is ……….

Question 25

Discuss how concentration gradients drive ion movements

Answer 25

• A high concentration will naturally want to flow to a low-density state, to reach a point of balance.
• Like pouring water down a slide, molecules flow in a natural movement, down a concentration gradient.
• The process is passive
• Called diffusion

Question 26

Define the basic transport process of diffusion, where ions move through cell membranes

Answer 26

The natural movement of molecules down a concentration gradient, as seen where lipid-soluble molecules flow directly through the phospholipid bilayer of a cell membrane

Question 27

Define concentration gradient

Answer 27

Difference in concentration of a substance across a space

Question 28

Discuss the basic transport processes of the two types of membrane proteins that facilitate diffusion, and rely on concentration difference

Answer 28

1. Channel-mediated facilitated diffusion - ions fall through if the opening is big enough
2. Carrier-mediated facilitation diffusion - via carriers specific for one chemical (carriers bind molecules and transfer them across)

Question 29

What in the world is osmosis, when discussing basic transport processes to move ions and other molecules through a cell membrane

Answer 29

The diffusion of a solvent such as water through a specific channel protein (aquaporin) or through the semipermeable lipid bilayer, regulated by osmoregulation

Question 30

Discuss active transport of ions against gradients

Answer 30

This refers to the movement of substances across a membrane using energy from the cell (ATP). The energy is generated in the mitochondria. Proteins can then push molecules against the concentration gradient. An example is the Na+ K+ pump.

Question 31

Draw elements from the periodic table