life at the cellular level (2) - molecules

Question 1

which elements is 99% of our body made up of

Answer 1

Hydrogen (H)
Oxygen (O)
Nitrogen (N)
Carbon (C)

Question 2

where do H,O,N,C lie on the periodic table and what does that mean

Answer 2

they lie early in the periodic table meaning they are relatively light atoms
generally speaking, light atoms form the strongest bonds

Question 3

how many bonds do H,O,N,C make

Answer 3

1,2,3,4 respectively

Question 4

which of the four atoms (H,O,N,C) is the most versatile

Answer 4

carbon

Question 5

what is a molecule

Answer 5

two or more elements bonded together

Question 6

what does the bonding versatility of C explain

Answer 6

why it forms the basis of almost all biomolecules

Question 7

why is C particularly versatile

Answer 7

it can form stable:
single bonds (with H)
single and double bonds (with O and N)
single, double and sometimes triple binds with other C atoms

Question 8

what does the variety of C’s bonding capability underlie

Answer 8

the evolution of all the different combinations of H,O,N, and C into biological molecules

Question 9

what defines biomolecular functions

Answer 9

functional groups

Question 10

what are functional groups

Answer 10

groups of elements (e.g. -OH) bonded to C

Question 11

name 3 important functional groups

Answer 11

hydroxyl groups
aldehyde groups
keto groups

Question 12

what is critical in determining functionality

Answer 12

the polarity in a molecule

Question 13

what is polarity

Answer 13

distribution of electrons

Question 14

give examples of stable bonds

Answer 14

C-C and C-H bonds are relatively stable as they share e-‘s equally

Question 15

give examples of highly polar bonds

Answer 15

C-O and C-N or C-functional group bonds are highly polar, which alters the bond reactivity

Question 16

what does the function of biomolecules depend on

Answer 16

the configuration of groups on the molecule

Question 17

what does configuration mean

Answer 17

the fixed arrangement of atoms in a molecule

Question 18

lots of biomolecules contains a double bond between carbon atoms (C=C), what is this called

Answer 18

a rigid conformation

Question 19

what are the two distinct configurations

Answer 19

trans and cis

Question 20

how can you interconvert between the two configurations

Answer 20

by breaking and re-forming bonds

Question 21

give an example of when configuration can be important biologically

Answer 21

Rhodopsin is a protein embedded in the (rods of the) retina of the eye. On exposure to light the configuration of rhodopsin alters and this alteration stimulates nerves cells in the optic nerve to send messages to the brain where we “see”.

Question 22

what can carbon mades molecules be

Answer 22

symmetrical (achiral)

asymmetric (chiral)

Question 23

what are the 2 forms of asymmetric (chiral) carbon molecules

Answer 23

L- (Laevo)
D- (Dectro)
each exert different biological effects

Question 24

what are all proteins made from

Answer 24

L-amino acids only

Question 25

what does conformation mean

Answer 25

the precise arrangement of atoms in a molecule

Question 26

what are the 5 chemical reactions of life

Answer 26

- redox reactions - making and breaking C-C bonds - internal rearrangements - group transfers - condensation and hydrolysis reactions

Question 27

what happens in many biological reactions

Answer 27

two e-'s (and two protons) are gained or lost

Question 28

what is often transferred from one molecule to another

Answer 28

2 hydrogen atoms (protons) are transferred in dehydrogenation reactions

Question 29

what does oil rig mean in redox reactions

Answer 29

oxidation is loss (of electrons) | reduction is gain (ofelectrons)

Question 30

what is a reducing agent

Answer 30

it becomes oxidised itself as it reduces another compount

Question 31

what is an oxidation agent

Answer 31

it becomes reduced itself as it oxidises another compound

Question 32

why are NAD+ and NADH very important agents

Answer 32

they allow biochemical reactions to take place in cells

Question 33

what type of agent is NADH

Answer 33

a reducing agent

Question 34

what type of agent is NAD+

Answer 34

an oxidising agent

Question 35

give an example of making/breaking C-C bonds

Answer 35

cleavage of glucose in the glycolysis pathway

Question 36

give an example of internal rearrangements

Answer 36

in glycolysis, a rearrangement of the conformation of G6P occurs before the sugar is split

Question 37

give an example of group teransfers

Answer 37

in glycolysis, in an enzyme catalysed reaction, a phosphoryl group (PO32-) is transferred from ATP to F6P ATP provides energy for cellular reactions

Question 38

what is a condensation reaction

Answer 38

occurs where two smaller molecules combine to form a larger molecule and in doing so release water (or other small molecules e.g. methanol)

Question 39

what is a hydrolysis reaction

Answer 39

involve adding water to a molecule, and most commonly simultaneously breaking down a large molecule into smaller units

Question 40

what is joined by condensation and broken by hydrolysis reactions

Answer 40

the sub-units of protein, polysaccharides and nucleic acids

Question 41

what reactions are condensation and hydrolysis reactions important in

Answer 41

carbohydrate metabolism

Question 42

what are complex carbohydrates composed of

Answer 42

``` Complex carbohydrates (polysaccharides) such as starch or glycogen are composed of many individual monosaccharide molecules e.g. glucose. A disaccharide e.g. sucrose, is simply two monosaccharides joined together. ```

Question 43

 give examples of glucose polymers

Answer 43

glycogen | starch

Question 44

how are glucose polymers formed

Answer 44

by condensation reactions between two glucose monomers

Question 45

how are the glucose monomers in glycogen and starch linked together

Answer 45

one glucose monomer is liked to another which locks the additional glucose in a cyclic form

Question 46

how are lots of monomers liked together

Answer 46

all monomers of the chain are locked in the cyclic form except the end monomer, which can remain linear this end monomer then forms a 'reducing end'

Question 47

give an example of a reduced sugar

Answer 47

D-glucose

Question 48

what functional group does the linear form of D-glucose have attached

Answer 48

an aldehyde group which can be oxidised | If this is oxidised then the other reactant would be reduced, so glucose is termed a ‘reducing sugar’

Question 49

what is the difference between proteins and polypeptided

Answer 49

Proteins are (sometimes multiple) long chains of amino acids. Polypeptides on the other hand are shorter (but not necessarily short!) chains of amino acids.

Question 50

what do nucleic acids form

Answer 50

the core structure of DNA and RNA

Question 51

what are nucleic acids

Answer 51

polymers of nucleotide monomers linked by 3’,5’-phosphodiester bonds

Question 52

what makes up a nucleotide monomer

Answer 52

a bade a sugar molecule a phosphate group

Question 53

what are the 2 kinds of base in nucleic acids

Answer 53

pyrimidines | purines

Question 54

what are pyrimidines

Answer 54

cytosine (C) thymine (T) (DNA only) uracil (U) (RNA only)

Question 55

what are purines

Answer 55

adenine (A) | guanine (G)

Question 56

what is RNA made from

Answer 56

"normal" ribose sugars

Question 57

what is DNA made from

Answer 57

deoxyribose sugars, which lack an oxygen atom

Question 58

what is DNA

Answer 58

a double stranded nucleic acid. In other words, it is two independent chains of nucleic acids, linked together by their bases, which wrap around themselves to form the characteristic double helix of DNA

Question 59

what is RNA

Answer 59

a single stranded nucleic acidAlthough it can wrap itself up in such a way that double stranded sections may form.

Question 60

how does base pairing occur in DNA and RNA

Answer 60

a pyrimidine always pairs with a purine

Question 61

how does base pairing occur in DNA

Answer 61

purines - pyrimidines adenine - thymine guanine - cytosine

Question 62

how does base pairing occur in RNA

Answer 62

purines - pyrimidines adenine - uracil guanine - cytosine

Question 63

how are fatty acids formed

Answer 63

long chains of carbon and hydrogen atoms

Question 64

what type of bonds can be within the fatty acid between the carbon atoms

Answer 64

single or double

Question 65

what does it mean if the fatty acid is saturated

Answer 65

all of the bonds in the fatty acid are single

Question 66

what does it mean if the fatty acid is mono-unsaturated

Answer 66

there is one double bond in the fatty acid

Question 67

what does it mean if the fatty acid id polyunsaturated

Answer 67

there are more than one double bond in the fatty acid

Question 68

what happens to a fatty acid molecule the more double bonds present

Answer 68

it becomes more "bendy"

Question 69

what effect does desaturation have on the fluidity of the fatty acid

Answer 69

The more unsaturated the fatty acid (the more double bonds in the chain) the more fluid the fatty acid. This has important implications for cell membranes, which are largely composed of fatty acids, and health generally.

Question 70

what are lipids

Answer 70

a family of molecules made up of fatty acids

Question 71

what are the 3 classes of lipids

Answer 71

triacylglycerides phospholipids sterols

Question 72

what are triacylglycerides

Answer 72

they are also called triglycerides storage lipids non-polar 3 fatty acid chains lined to glycerol

Question 73

what are phospholipids

Answer 73

Similar to triacylglycerides, But they have only two fatty acids chains and a phosphate group attached to the ‘head’ of these chains This makes them polar They form biological cell membranes – very important!

Question 74

what are sterols

Answer 74

Produced in plants, animals and some micro-organisms Most important one in humans is cholesterol -Another essential component of cell membranes -Precursor to steroid hormones and fat soluble vitamins (A, D, E)