2.1-2.5 Flashcards
(104 cards)
1
Q
Properties of lipids
A
- source of energy
- waterproofing- insoluble in water
- insulation - slow conductor of heat
- protection- stored around delicate organs
- fats are solid at from temperature, oil is sorted
2
Q
Properties of triglycerides
A
- 3 fatty acids, each forms ester bonds with glycerol in a condensation reaction
- excellent source of energy
- low mass- to- energy ratio
- insoluble in water
- important source of water ( release it when oxidised)
3
Q
Properties of phospholipids
A
- 2 fatty acids and one phosphate head
- hydrophilic phosphate head
- hydrophobic fatty acid tail
- polar molecule
- can make glycolipids by joining carbohydrates
4
Q
What are amino acids?
A
Monomer units used to make polymers called peptides
5
Q
What is used to text for starch?
A
Iodine solution
6
Q
What colour does iodine turn in the presence of starch?
A
From brown to black
7
Q
What do you use to test for protein?
A
Bieruts ( copper sulfate and sodium hydroxide)
8
Q
What do you use to test for lipids?
A
Ethanoic solution
9
Q
What colour does bieruts turn in the presence of protein?
A
From clear blue to light purple
10
Q
What colour does ethanoic solution turn in the presence of lipids?
A
Colourless to white emulsion
11
Q
What is used to show reducing sugars?
A
Copper sulfate in Benedicts solution
12
Q
What sugars with reduce ( add hydrogen to) another substance?
A
glucose, fructose, other monosaccharides and maltose ( disaccharide)
13
Q
How do you test for non reducing sugars?
A
Add substance with HCl- shake- neutralise with sodium hydroxide- then repeat test for reducing sugars
14
Q
Which food groups must be in aqueous solution for the tests?
A
Protein, sugars
15
Q
What is an organic molecule?
A
Living organisms with carbon
16
Q
Where is urea formed and why?
A
In the kidney as a waste product
17
Q
What is the theory of vitalism?
A
That all organic compounds could only be made using a vital principle and didn’t conform to the laws of physics or chemistry, so couldn’t be made in labs.
18
Q
How was the vitalism principle proved wrong
A
Friedrich Wöhler made urea artificially when trying to make ammonium cyanate
19
Q
Why haven’t we been able to make all organic compounds yet?
A
Due to complex protein structures and chaperone proteins
20
Q
What are examples of carbon molecules in the body?
A
Carbohydrates
Lipids
Proteins
Nucleic acids
21
Q
Give some examples of lipids
A
Steroids, waxed, fatty acids and triglycerides
22
Q
What are carbohydrates composed of?
A
Carbon, hydrogen and oxygen. 2 H: 1 O
23
Q
What are proteins composed of?
A
One or more chain of amino acids. All of these contain carbon, hydrogen, oxygen and nitrogen, but 2 of the 20 amino acids contain sulphur too.
24
Q
What are nucleic acids composed of?
A
Subunits called nucleotides, which contain carbon, hydrogen, oxygen, nitrogen and phosphorus.
25
What are the 2 types of nucleic acid?
RNA and DNA
26
Describe the structure of ribose and it's formula
- C5H10O5
| - molecule is a 5 membered ring with a side chain
27
What is the formula and structure of glucose?
- C6H12O6
| - molecule is a 6 membered ring with a side change
28
What is the structure of a hydroxyl, OH?
-O-H
29
What is the structure for amine, NH2?
/H
-N
\H
30
What is the structure of Carboxyl, COOH?
```
O
//
-C
\
O-H
```
31
What is the structure of Methyl, CH3?
```
H
|
-C-H
|
H
```
32
Describe the structure of saturated fatty acids
- carbon atoms form an unbranched chain
- bonded by single bonds
- carbon atoms between 14-29
- at one end the carbon is part of a carboxyl group
- at the other end, the Carbon is bonded to 4 Hydrogens
- all other Cs are bonded to 2 Hs
33
Within an amino acid, what is the carbon in the centre bonded to?
- an amine group
- a carboxyl griuo
- hydrogen atom
- R group, variable part
34
Draw a simple version of a saturated fatty acid
```
O OH
\\ /
C
|
H-C-H
|
H-C-H
|
H
```
35
Draw the simple structure of an amino acid
```
H R O
\ | //
N-C-C
/ | \
H H O- H
```
36
What is metabolism?
The sum of all the chemical reactions that happen in a cell
37
What is catabolism?
The breakdown of complex molecules into simpler molecules, including the hydrolysis of macromonomers into monomers
38
What are some examples of catabolism?
- digestion of food
| - respiration ( glucose or lipids are oxidised to CO2 and H2O)
39
What is anabolism?
The joining together of molecules to make a larger molecule
40
What are examples of anabolism?
- protein synthesis using ribosomes
| - DNA synthesis during replication
41
What does metabolism consist of?
Catabolism and anabolism
42
Why is oxygen more positive than hydrogen?
It has a bigger nucleus and thus more protons
43
What does electronegative mean?
More electrons are attracted to the element
44
Why is oxygen electro negative?
Because the negative electrons will be mote attracted by the positive oxygen nucleus, so they are pulled closer to the oxygen
45
Why is the bond between hydrogen and oxygen in water a polar covalent bond?
Because the nucleus of the oxygen atom is more attractive to the electrons than the nuclei of the hydrogen atoms
46
How does the unequal sharing of electrons in water molecules affect the charge of the elements?
Hydrogen atoms will have a partial positive charge and oxygen will have a partial negative charge
47
What type of bond do negative ions and positive ions create?
An ionic bond
48
What is a hydrogen bond?
The force that forms when a hydrogen atom in one polar molecule is attracted to a slightly negative atom of another polar covalent molecule
49
Why does water have cohesive properties and how is this helpful?
It's hydrogen bonds mean the molecules stick together and are able to be pulled up the xylem for long distances due to this strength.
50
How is water adhesive?
Hydrogen bonds can form between water and other polar molecules, causing water to stick to them
51
How does waters adhesive properties help keep plants moist?
If water evaporates from the cell walls and is lost from the leaf, adhesive forced cause water to be drawn out of the nearest xylem vessel- this keeps the walls most so they can absorb carbon dioxide for photosynthesis
52
Why does water have a high specific heat capacity?
Hydrogen bonds restrict the motion of water molecules, increasing the temperature of water required to break them. A high amount of energy is needed to raise the temperature of water, making is a thermally stable habitat for aquatic animals
53
Why does water have a high latent heat of vaporisation?
Water is a good evaporative coolant due to the amount of heat needed to evaporate it, as the hydrogen bonds have to be broken, removing heat from the body.
54
What heat properties does water have?
- high specific heat capacity
- High latent heat of vaporisation
- High boiling point
55
Why does water have solvent properties?
The polar nature of water means that it forms shells around charges and polar molecules, preventing them from clumping together and keeping them in solution. It's partially negative oxygen pole is attracted to positively charged ions and it's partially positive hydrogen pole to negatively charged ions, so both dissolve.
56
Give a biological example of water as a good solvent.
Cytoplasm is a complex mixture of dissolved substances, allowing the chemical reactions of metabolism to occur
57
What are the properties of water?
- cohesive
- adhesive
- high specific heat capacity
- high latent heat of vaporisation
- high boiling point
- solvent
58
Why is oil less dense than water?
It has less hydrogen in it and can't form hydrogen bonds
59
How is methane produced biologically?
It is a waste product of anaerobic respiration in certain prokaryotes that live in habitats where oxygen is lacking
60
What is the specific heat capacity of methane?
2.2
61
How is NaCl transported in the blood?
It dissolved because of ionic bonds in the blood plasma
62
How are amino acids transported in the blood?
They are charged, solubility depends on R groups, and can be carried dissolved in blood plasma
63
How is glucose transported in the blood?
Polar so dissolved in blood plasma
64
How is oxygen transported in the blood?
Non polar, can dissolve due to small size but sparingly/ held by haemoglobin in red blood cells
65
How are fats transported in the blood?
Non polar so require lipo protein complexes
66
How is cholesterol transported through the blood?
Hydrophobic so requires lipoprotein complexes
67
What is the use of carbohydrates?
To supply and store energy
68
What is a monosaccharide?
A single sugar unit, the monomers of polysaccharides
69
What is the difference between monosaccharides?
The arrangement of atoms
70
Glucose + glucose --->
Maltose + water
71
What is a condensation reaction?
The joining of two monosaccharides, whilst forming a water molecule
72
What is a pentose?
A sugar with 5 carbons
73
What is a hexose?
A sugar with 5 carbons
74
What is a use for glucose?
Being an energy source for respiration
75
What is lactose made of?
Glucose and galactose
76
What is sucrose made of?
Glucose and fructose
77
What is the ending of a lipid?
```
O
//
-C
\
O- H
```
78
How are saturated and unsaturated fatty acids different?
Saturated fatty acids have all single bonds between carbons.
Unsaturated have one or more double carbon bonds
79
What are the properties and structure of a cis-fatty acid?
- hydrogens are on the same side of the double bond
- bend in the chain at the double bond
- less good at packing together
- low melting point
80
What are the properties and structure of a trans- fatty acid?
- hydrogens are on opposite sides of the double bond
81
What do triglycerides consist of?
3 fatty acids + glycerol ( with a by product of 3H2O)
82
How are triglycerides formed?
By a condensation reaction
83
What are the functions of lipids?
- used for energy storage ( human fats, oil in plants)
- used as heat insulation ( under skin)
- allows buoyancy ( less dense than water)
84
Properties of lipids
- long term energy storage
- transported in lipoprotein complex
- slower energy release
- energy released is double that of carbs
85
Properties of carbohydrates
- used as short term energy storage
- easily dissolved in blood plasma
- easily soluble
- quick energy release
- dissolves so has osmotic effect ( effects rate of water movement)
86
How many different amino acids are there and why?
20 different amino acids synthesised on ribosomes due to 20 different T groups
87
How would you justify the complexity of peptides?
The number of amino acids in them raises the number of possibly sequences- ie 2 amino acids= 20^2= 400
88
How does the transcription of DNA to mRNA affect its bases?
T is replaced with U- single stranded
89
What are coding sections of DNA called?
Open reading
90
How are globular proteins formed?
Bonds between R groups stabilise the amino acids, making them 3D- spherical
91
How are soluble proteins formed?
Hydrophilic R groups on the outside of the protein
92
How are membrane proteins formed?
Hydrophilic R groups on the outside of the protein
93
How are fibrous proteins formed?
Their amino acid sequence prevents folding
94
What happens when proteins denature?
Bonds between R groups break, changing the structure
95
What are functions of proteins ( with examples)?
- catalysis ( enzymes)
- cyto skeletons ( micro tubules)
- blood clots ( fibrin)
- transport of nutrients ( haemoglobin)
- cell adhesion
- membrane transport ( pump proteins)
- hormones ( oestrogen)
- receptors
- packing of DNA ( histoine)
- immunity ( antibodies)
96
What is the function of immunoglobulin?
Creates antigens that act as a marker to white blood cells to engulf pathogens
97
What is rhodopsin?
A pigment that absorbs light
98
What are the differences between methane and water?
Boiling point: methane- -160, water - 100
Specific heat capacity: methane- 2.2, water- 4.2
Latent head of vaporisation: methane- 760, water- 2257
98
What is hydrolysis?
The splitting of a substance into 2 subunits, with water added
99
What are enzymes ?
Biological catalysts that control and sped up reactions
100
How do enzymes work?
They have an active site to which substrates bind, forming an enzyme- substrate complex, and the substrate becomes a product. They lower the activation energy of a reaction.
101
What are immobilised enzymes?
Enzymes attached to insolubles, permitting reuse of enzyme and ensuring that the product is enzyme free
102
What is lactose intolerance?
People unable to produce lactase in pancreatic juice or on villi, so cannot digest sugar. Lactose passed to the large intestine without being hydrolysed to monosaccharides, so bacteria feed on it, releasing fatty acids and methane
103
How is lactose free milk made?
Obtained by passing milk through a column with immobilised lactase, breaks down lactate in milk to glucose and galactose
