3 - Biological Molecules Flashcards
1
Q
What is a polar molecule? Give an example.
A
A molecule with a slight positive charge at one end (𝛿+) and a slight negative at the other (𝛿-). eg. water
2
Q
What bond is formed between 2 monosaccharides in a condensation reaction?
A
glycosidic
3
Q
Name the bond holding amino acid monomers together
A
peptide
4
Q
What reaction breaks polysaccharides into their constituent parts? (What are the additional reactants/products)
A
Hydrolysis reaction
you must add water
5
Q
Give 3 examples of globular proteins
A
- enzymes
- antibodies
- hormones
6
Q
Water is a solvent. How does water affect reactions?
A
increases the rate of reaction (more particles to collide with and change direction)
7
Q
Glucose, fructose and galactose are all what type of sugars?
A
Hexose monosaccharides
8
Q
Water helps control the temperature in our cells. What 2 properties help it do this?
A
High specific heat capacity (a buffer for temperature change)
High latent heat of vaporisation (cooling effect through evaporation)
9
Q
α-glucose + α-glucose –>
A
maltose
10
Q
Are polar molecules hydrophilic or hydrophobic? How can we tell?
A
Hydrophilic, they dissolve in water
11
Q
What is the molecular formula of galactose?
A
C₆H₁₂O₆
12
Q
What happens to polar molecules in water? Why is this important?
A
- All polar molecules dissolve in water
- Water can therefore be used as a solvent to transport polar molecules in and out of cells
13
Q
Describe the structure of amylopectin
A
- polymer of glucose (1,4 glycosidic bonds)
- branched (1,6) glycosidic bonds
14
Q
A chain of β-glucose molecules makes what?
A
cellulose
15
Q
A chain of α-glucose molecules makes what?
A
starch
16
Q
What are the 2 types of starch?
A
Amylopectin and amylose
17
Q
Disaccharides are made through what type of chemical reaction? (what additional products/reactants are needed?)
A
condensation (also makes water)
18
Q
What type of protein (shape) is insulin? Why does it do this and what bonds are formed?
A
- globular
- hydrophobic components protected from aqueous environments of the blood or the cell
- hydrophilic and hydrophobic interactions
19
Q
Define isomer
A
compounds with the same moleclar formulae but different arrangements (structural formulae) and therefore different properties
20
Q
Which type of starch hydrolyses more quickly? Why?
A
Amylopectin
-branched, therefore, more accessible bonds to hydrolysed at one time
21
Q
Describe the structure of amylose
A
- polymer of glucose
- helical
- unbranched
22
Q
Water’s polarity means it has _____ properties
A
cohesive
23
Q
glucose + fructose –>
A
sucrose
24
Q
glucose + galactose –>
A
lactose
25
Describe the structure of an amino acid
- Central carbon atom
- H atom
- Amine group (NH3)
- Carboxylic acid functional group (COOH)
- R group
26
What are the 4 types of bonds between proteins monomers? (tertiary structure)
- hydrogen
- ionic
- disulfide bridges
- hydrophillic and hydrophobic interactions
27
What type of sugar is maltose and how is it made (reactants and type of reaction)?
disaccharide
α-glucose + α-glucose
condensation reaction
28
What makes a protein have a quarternary structure?
2 or more seperate polypeptide chains
29
What elements do nucleic acids contain?
CHONP
30
What elements do carbohydrates contain?
CHO
31
What elements do proteins contain?
CHONS
32
What elements do lipids contain?
CHO
33
What is the structure of a triglyceride?
Glycerol backbone with 3 fatty acid groups coming off
34
Suggest why a specific fatty acid may be liquid at room temperature.
It is unsaturated (C=C) casuing kinks, unable to pack as tightly together
35
What is a fatty acid?
Long polymers of carbon and hydrogen
| with a carboxyl group at the end (-COOH)
36
What bond is present between each glycerol and fatty acid in a triglyceride?
An ester bond
37
How many ester bonds are present in a triglyceride
3
38
Lipids are short-term/long-term energy stores
Lipids are long-term energy stores
39
What is the structure of a phospholipid?
Phosphate ion with 2 fatty acid branches
40
Which enzyme catalyses the addition of amino acids in the ribosomes?
Peptidyl transferase
41
What are the 2 types of secondary protein structure?
alpha helix or a beta pleasted sheet
42
What bonds determine the secondary protein structure?
Hydrogen
43
What is a conjugated protein?
a protein that contains a non-protein component or a prothestic group (eg. haem in haemoglobin)
44
State the properties of collagen
strong
flexible
inelastic
45
State the properties of keratin
inelastic
insoluble
fibrous
strong
46
Describe the quarternary structure of collagen
3 polypeptide chains twisted and held together by cross-linkages
47
Why is collagen inelastic
Cross-linkages
| stabilised by twisted polypeptide chains
48
What 5 things should you mention when you compare proteins
```
SPADES
S-shape
P-purpose (funtional/structural)
A-acid sequence (repetitive/irregular)
D-durability (to pH and temp)
E-examples
S-solubility
```
49
Compare the acid sequence in globular and fibrous proteins
globular=irregular
| fibrous=repetitive
50
Compare the durability (pH and temp) in globular and fibrous proteins
globular=more sensitive
| fibrous=less sensitive
51
Compare the functionality in globular and fibrous proteins
globular=functional
| fibrous=structral
52
What is the name of the test for reducing sugars?
Benedicts test
53
What does a positive test for reducing sugar look like?
```
Coloured precipitate will form
Blue=none
Green/yellow
orange/red
brick red=large amounts
```
54
Is Benedicts test quanitative?
Semi-quanititative and subjective
55
How does Benedicts test for reducing sugars work?
Reagent blue from Cu2+ ions
Reducing sugars are able to donate electrons
coloured precipitate formed
more sugar more Cu2+ ions reduced
56
Which sugars are reducing sugars
```
All monosaccharides
Some disaccharides (maltose and lactose)
```
57
How do you test for non-reducing sugars?
if reducing sugar test does not work
boil sugar solution with dilute HCl (this hydrolyses into monosaccharides)
neutralise with sodium hydrocarbonate
repeat benedicts
58
What is the test for starch?
Iodine, goes from yellow to blue/black
59
What is the structure of a nucleotide?
Pentose sugar (deoxyribose or ribose)
1' - nitrogenous base
3' - OH
4' to 5' to phosphate group (PO4 3-)
oxygen at top
60
How do nucleotides join together
Condensation reaction OH on one joins with phosphate group on the next
61
What are the 4 bases in DNA
Adenine
Thyamine
Guanine
Cytosine
62
What are the 4 bases in RNA
Adenine
Uracil
Guanine
Cytosine
63
What is the difference between a pyramidine and a purine?
```
Pyramidine = single ring
purine = dounle ring
```
64
Which nucleotides are pyramidines?
C and T and U
65
Which nucleotides are purine?
A and G
66
How many hydrogens bonds can T and A bases form between each other?
2
67
How many hydrogens bonds can C and G bases form between each other?
3
68
State 3 differences between DNA and RNA
- DNA has thyamine RNA has uracil
- DNA deoxyribose, RNA ribose
- DNA double stranded, RNA single stranded
69
What is the sense strand?
Strand of protein used to code for proteins, 5' to 3'
70
What is the Anti-sense strand?
Template for mRNA, 3' to 5'
71
What is the backbone of DNA made of
Alternating phosphate sugar backbone
72
What bond is formed between 2 nucleotide bases in a polynucleotide?
Phosphodiester bond
73
What reaction adds a nucleotide base of to DNA?
condensation
74
What is important about the backbone of DNA?
shields base pairs and protects them from damage
75
Define triplet code
3 bases (1 codon) code for an amino acid
76
Define degenerate
Different codons can code for the same amino acid
77
What can mutations result in, in regard to proteins
- protein not functional
- protein not as effective
- no protein is made
78
Where does Transcription occur?
nucleus
79
Where does translation occur?
ribosomes
80
What is transcription?
The formation of a complementary molecule of mRNA from the DNA template (anti-sense strand)
81
What enzymes catalase transcription
DNA helicase- unzips
| DNA polymerase- joins to make one backbone from free nucleotides
82
What is an exon
A region fo DNA that codes for proteins
83
What is an intron
A region of DNA that does not code for proteins
84
How does transcription work?
DNA unzips, free nucleotides pair up with anti-sense strand and form mRNA, leaves through nuclear pores
85
What has to happen to the mRNA before it leaves the nucleus
introns removed by enzymes
86
What is tRNA
transfer RNA
| a single-stranded ribonucleotide chain folded into a cloverleaf shape, carries a specific amino acid
87
What happens in translation?
- mRNA enters ribosome
- tRNA molecule with complementary bases joins mRNA
- next tRNA molecule joins next codon
- bonds form between amino acids they carry
- first tRNA released and next one joins
- repeated until stop codon
88
Name the long term store fo energy for plants
starch
89
Name the long term store fo energy for animals
glycogen
90
What is the structure of an ATP molecule
Ribose (pentose sugar) bonded to
1'---3x phosphate groups
5'---adenine (base)
91
What does ATP stand for?
Adenosine triphosphate
92
ATP + H2O-->
ADP +Pᵢ (inorganic phosphate) +energy
93
What enzyme catalyses the breakdown of ATP
ATP hydrolase (ATPase)
94
Can ATP be stored?
No
95
What feature of ATP makes it an efficient source of energy
It releases small and discrete quantities of energy
96
Name 5 uses of ATP
```
synthesis of macromolecules
movement
active transport
secretion
Activiation of molecules
```
97
Suggest, with reasons, why water is such an important component of the blood (5 marks)
- polar solvent - can transport things as:
- many biological molecules are polar
- and ions are charged
- liquid so transport medium
- coolant to resistant to temp change
98
Describe why water is such an important component of stroma in the chloroplasts and the matrix in the mitochondria. (5 marks)
(these are places where chemical reactions take place)
- liquid
- therefore allows movement of enzymes and substrates
- that need to move in order for the reaction to occur
- polar solvent
- substrate, enzyme, products are polar
99
What makes fats solid at r.t and oils liquid at r.t.
oils- unsaturated fatty acids
kinks therefore can't pack tightly together
fats - saturated fatty acids
100
Describe the formation of an ester bond in triglycerides
hydroxyl group from glycerol and hydroxyl group from fatty acid (actually -cooh) in condensation reaction
101
describe how the emulsion test for lipids works
dissolve lipids in ethanol
mix water in
water is more soluble in ethanol than lipids so it displaces the lipids
lipids are not soluble in water so forms a suspension
