Topic 1 Biological Molecules Flashcards
carbs, lipids, proteins, enzymes, inorganic ions, water
1
Q
What kind of molecule is water?
A
Polar
Meaning electrons aren’t shared equally
2
Q
Dipole property of water
A
2 poles, oxygen is electronegative (slightly negative) , hydrogen is slightly positive
3
Q
What atoms are electronegative?
A
Usually
Oxygen nitrogen or fluorine
4
Q
Why is water a good solvent?
A
Weak hydrogen bonds so water easily disassociates into OH- and H+ to form other bonds
Because it is DIPOLE
pH
5
Q
Why does water have a high specific heat capacity?
A
Takes a lot of energy to break down a lot of hydrogen bond
Stronger together
6
Q
What are hydrophobic molecules and their properties
A
Water fearing molecules
Insoluble
Molar is not polar, so cannot form H bonds hence cannot dissolve
7
Q
What are Hydrophilic molecules and their properties?
A
Water loving
Soluble because molecules are polar, so can form hydrogen bonds with water
8
Q
Give 3 properties of water
A
-ice floats
-tension, cohesion and adhesion
-water in reactions (pH, solvent, hydrolysis)
-transparency (predators can spot prey)
-water as transport medium
-high SHC, thermal stability
-incompressible
9
Q
Give 3 properties of water
A
-ice floats
-tension, cohesion and adhesion
-water in reactions (pH, solvent, hydrolysis)
-transparency (predators can spot prey)
-water as transport medium
-high SHC, thermal stability
-incompressible
10
Q
What are some macromolecules?
A
Proteins, lipids, starch, nucleic acid
11
Q
Role of nitrate ions in plants?
A
- supply of nitrogen to synthesize protein, nucleic acids, chlorophyll etc
12
Q
Nitrate ion deficiency symptoms in plants?
A
Reduced chlorophyll
Leaves turn pale / yellow
13
Q
Role of Magnesium ions in plants?
A
Make chlorophyll
14
Q
Symptom of magnesium ion deficiency in plants?
A
- failure to synthesis chlorophyll
therefore: Stunt growth, yellowing leaves
(Since less magnesium = less p/s = less glucose for respiration = less ATP)
15
Q
Role of calcium ions in plants?
A
Build new cell walls - Form calcium pectate for the middle lamellae
16
Q
Symptom of calcium ion deficiency in plants?
A
stunted growth bcs of poor cell wall development
17
Q
Role of phosphate ions in plants?
A
Make DNA, RNA, ATP
18
Q
What does ATP stand for?
A
Adenosine Triphosphate
19
Q
Give 3 differences between starch and cellulose
A
Starch / cellulose
Alpha glucose / beta
Is branched / not
Has 1,4-glycosidic bonds and 1,6-glycosidic bonds / 1,4 only
Same orientation / flipped glucose molecules
20
Q
What is the structure and function of glycogen?
A
Made up of alpha glucose
1,4 and 1,6 - glycosidic bonds
In animal cells
Insoluble so doesn’t affect water potential
Compact and branched, allows quick hydrolysis to supply for respiration in muscles
21
Q
What are the structures and functions of cellulose. (3 marks)
A
Made up of beta glucose
Straight chains, only 1,4 glycosidic bonds. Alternate Beta glucose flipped 180°
Fibres held together by HYDROGEN bonds
High tensile strength , give plants structure
Polar so allows water to diffuse through
22
Q
How do triglycerides form
A
Condensation reaction by ester bonds between a glycerol and three fatty acids
23
Q
Relate structures of triglycerides to their functions
A
• High energy:mass ratio = high calorific value from oxidation (energy storage).
• Insoluble hydrocarbon chain = no effect on water potential of cells & used for waterproofing.
• Slow conductor of heat = thermal insulation e.g.
adipose tissue.
• Less dense than water = buoyancy of aquatic animals.
24
Q
Functions of phospholipids relate to their structure
A
Barrier to Protect cells from external
glycerol backbone attached to 2 hydrophobic fatty acid tails & 1 hydrophilic polar phosphate head
• forms phospholipid bilayer in water = component of membranes
• tails can splay outwards = waterproofing
25
what are the 3 monosaccharides?
fructose, glucose, galactose
26
what is maltose made up of?
2 alpha glucose
27
what is sucrose made up of?
gluocse + fructose
28
what is lactose made up of?
glucose + galactose
29
what is a polysaccharide?
chain of many monosaccharides
30
what is starch made up of?
chain(polymer) of ALPHA glucose
(Amylose and amylopectin)
31
what is starch used for?
chloroplast stroma
energy storage in plants
32
what is glycogen made up of?
chain(polymer) of alpha glucose
(Very branched)
33
what is glycogen used for?
muscle cells
main energy storage
34
what is cellulose made up of?
chain (polymer) of **beta** glucose
35
what is cellulose used for?
plant cell wall
36
Name the reaction involved when a disaccharide is formed
condensation reaction
37
name the type of bond formed when disaccharides are formed
glycosidic bonds
38
what is starch made up of?
80% amylopectin
20% amylose
v compact
39
what is amylopectin's structure?
branched
having both α-1,4-glycosidic and α-1,6-glycosidic
40
what is amylose's structure?
helix structure
only α-1,4-glycosidic bonds
41
is starch soluble in water?
no, it is insoluble
42
why is amylopectin hydrolysed easier?
because it is highly branched with protruding ends, so more SA for enzymes to work on
43
how to test for starch?
iodine test
turns blue black precipitate
44
how to test for reducing sugars? (e.g. glucose fructose maltose)
Benedict's test
water bath
turns brick red ppt
45
how to test for non-reducing sugars? (e.g. sucrose)
benedict's reagent + dilute HCl
boil
dnf
46
what is a triglyceride made up of?
1 glycerol + 3 fatty acids
47
what bond is formed between glycerol and fatty acids?
ester bonds
48
give 3 main functions of lipids
- energy storage
- thermal insulation
- waterproofing
- buoyancy (less dense than water)
- major component of cell membranes
- cushion and protection of internal organs
49
what are some lipid examples?
triglycerides
phospholipids
cholesterol
50
what is the structure of phospholipids?
1 phosphate group + 2 fatty acids
Hydrophilic head, hydrophobic tail
51
is phospholipid soluble in water
the head is soluble (bcs can ionise)
but tail is insoluble (non-polar, hydrophobic)
52
what are 5 structures of the fluid mosaic model
- fluid phospholipid bilayer, movable
- internal/integral protein
- external/surface protein
- cholesterol
- channel protein
53
what are saturated fatty acids?
only single bonds between carbon atoms
(it is a -COOH carboxylic acid)
54
what bond is formed between 2 amino acids?
peptide bond via condensation
55
what are two secondary structures of polypeptides?
alpha-helix
beta pleated sheet
56
what are two tertiary structures of protein molecules?
globular and fibrous
57
which 4 bonds are used for peptide folding?
- hydrogen
- ionic
- disulfide
- hydrophilic/phobic
58
compare globular vs fibrous proteins
- circular vs strands
- irregular amino acid sequence vs regular
- functional vs structural
- generally soluble vs insoluble
59
what are some examples of globular proteins?
haemoglobin, enzymes, insulin
60
what are some examples of fibrous proteins?
collagen, fibrin, actin
61
protein synthesis vs dna replication - what is the diff?
Protein synthesis makes proteins, while DNA replication makes DNA
62
what does a nucleotide consist of?
phosphate, deoxyribose sugar and nitrogenous base
63
name 4 DNA bases and number of carbon rings they have
Adenine
Guanine - Purine - 2
(A-G-POO-TWO)
Cytosine
Thymine - Pyrimidine - 1
64
what bonds are formed between phosphate and deoxyribose sugar ( in DNA )
phosphodiester bond
65
How many H bonds between Adenine and Thymine?
2
66
How many H bonds between Cytosine and Guanine?
3
67
whats the relationship between A-T and C-G
complementary
68
what are the steps (+enzymes) used in DNA replication?
- DNA helicase unwinds & breaks H bonds between complementary bases
- free nucleotides match complementary bases into Okazaki fragments
- DNA polymerase adds adjacent nucleotides tgt (5' to 3' direction?? CHECK NOTES)
- DNA ligase seals the gaps between nucleotides
69
what method is used for DNA replication?
semi conservative
bcs new DNA consist of 1 new + 1 old strand
70
What is the evidence for the semi-conservative replication?
Meselson and Stahl
Replication of Nitrogen using 'heavy' isotope 15 N and 'light' 14N
1st Gen - each DNA made up of 1 parent + 1 new strand
after replication in 2nd Gen there were 2 layers, one lighter one heavier
71
what structure is DNA?
double helix
72
what are the stages of a cell cycle?
G1 - cellular contents replicated
S - replication of DNA
G2 - check for errors
M - mitosis
C - cytokinesis
73
what are enzymes?
protein that changes rate of chemical reaction without changing itself
74
4 major factors that influence enzyme RoR
temp
pH
enzyme conc
substrate conc
75
What is the induced fit hypothesis?
shape of active site changes to fit precisely around the substrate
76
What are cofactors? + examples?
Helper to enzymes, required to function properly
e.g. coenzymes, inorganic ions and prosthetic groups
77
What is an inhibitor?
substance that slows RoR
78
What is a competitive inhibitor?
competes with the substrate for the active site of the enzyme
79
is competitive inhibitor reversible or no?
reversible
80
what is a non-competitive inhibitor?
they bind to allosteric sites of enzymes, changing the active site of enzymes, so fewer/no ES complexes formed
81
what is the change of graph if there are competitive inhibitors?
RoR decreases but plateaus at about the same time
82
is non-competitive inhibitor reversible or no?
irreversible, permanent change
83
what is the change of graph if there are non-competitive inhibitors?
RoR slows
plateaus earlier
84
what is catabolism?
breaking large molecules into smaller ones
e.g. digestion
85
what is anabolism?
building up smaller molecules to larger ones
e.g. muscle growth
86
why are carbohydrates vital in humans?
energy source
87
why are fibres vital in humans?
helps w digestion
88
why are proteins vital in humans?
muscle growth and repair
found in DNA
89
why are lipids vital in humans?
energy storage
thermal insulation
used for plasma membrane
90
why are vitamins and minerals vital in humans?
help w immunity, chemical reactions
91
why is water vital in humans?
- temp control
- transport substances
- chemical reactions (metabolism)
92
what does DNA polymerase do?
line up nucleotides and join them via phosphodiester bonds (condensation reaction)
93
what is the only direction DNA polymerase can travel in?
5' to 3'
94
What breaks hydrogen bonds between complementary bases?
DNA helicase
95
in where is Uracil used instead of Thymine?
(t)RNA
96
What bond is formed to bind nucleotides together?
phosphodiester bond
97
What do ribosomes do in protein synthesis?
bind to mRNA, read code 3 bases at a time aka codon
98
what is the shape of tRNA?
clover leaf shape
99
what are exons and introns?
exons - coding part of gene
introns - non-coding part of gene
100
Why do mutations occur?
mutagen exposure in our environment eg UV light
randomly occurs
101
How does one get sickle cell anaemia?
base substitution (A replaces T) in beta haemoglobin chain
changing shape of haemo.
102
what is the issue of sickle cell anaemia?
haemoglobin stop carrying oxygen so efficiently, causing blockages in small blood vessels
103
why are mutations sometimes good?
advantageous mutations allows positive evolution
104
what are monomers?
single small molecule that can join together and form a polymer
e.g. nucleic acids
105
What are buffers?
they resist changes to pH
106
how to test for proteins?
Biuret's reagent
blue to purple
107
how to test for fat/lipids?
dissolve in ethanol
emulsion test
there will be emulsion/greasy patch produced in comparison to water
108
are lipids polar?
NO! generally hydrophobic
109
what are the 2 types of fatty acids?
saturated and unsaturated
110
How do 2 monosaccharides join together to form a disaccharide?
Glycosidic bond forming condensation reaction
111
Compare phospholipids and triglycerides…
Phospholipids are polar
Triglycerides are non-polar
112
What bonding is present in both secondary and tertiary structures of proteins?
Hydrogen only
113
Give the meaning of a tertiary structure of a protein (2 marks)
3D shape of protein
Held together by bonds between R groups
114
What are the steps of translation? (4 marks)
- mRNA attaches to ribosomes
- tRNA attached to **specific** amino acids
- tRNA anticodon binds to mRNA codon
- peptide bonds form between amino acids
- process involves start/stop codons
115
What is it meant by secondary structure of protein? 2 marks
Folding of primary structure
Into alpha helix or beta pleated sheet
From formation of hydrogen bonds
116
Explain how a primary structure of a hormone determines its’ properties. 4 marks
- sequence of amino acids determining tertiary structure
- because determines position of R group bonds
- eg hydrogen, ionic, disulfide
- final structure has to be specific, complementary to receptor molecules
117
Why are globular proteins soluble in water? (3 marks)
- folded so hydrophilic groups are facing the outside
- exposed R groups are polar
- so can form H bonds with water
- because water is a polar solvent
118
Which enzyme in DNA replication forms phosphodiester bonds?
DNA polymerase AND ligase
P-P
119
What are 2 things about calcium pectate?
Found in middle lamallae
Hold Cell walls together
120
What ions are needed to make amino acids?
Nitrate
121
What ions are needed to make amino acids?
Nitrate
122
What ions are needed to make amino acid and DNA?
Nitrate and phosphate ions
123
how does the dipole nature of water enable muscle layers of worm to push against cavity and change the shape of earthworm? 3 marks
- water is tightly bonded together
- via H bonds
- so they are incompressible
- change body shape since pressure increases, but volume stays the same
124
what components are found in phospholipids?
glycerol and phosphate in the head
fatty acid in tail
125
what properties of water result in surface tension? 3 marks
- polar molecules
- can form H bonds
- therefore cohesive
126
Why does respiration of lipid generate more energy than carbs?
More C-H bonds and H bonds
127
Does amylose or amylopectin hydrolyse quicker? Why?
Amylopectin because it is branched with 1,4 and 1,6-glycosidic bonds!
128
What is the relationship between sweating (heat loss) and dipole nature of water?
Dipole is H is positively charged, forming weak H bonds between molecules
Lots of energy needed to break this bond
Water evaporate, taking heat w it )(high latent heat evaporation)
129
What happens when you freeze water?
Expands
Lots of H bonds
130
Explain how a structure of cellulose is adapted for its function in cell walls. (3 marks)
- straight chain of molecules
- held tgt by H bonds
- prevent cell bursting
- polar, so allows water to diffuse through
131
what are the steps of translation
(+ release)
- mRNA leaves via nuclear pores
- attach to ribosomes (on rER)
- codon pair with anticodons on tRNA + brings amino acid
- peptide bonds formed between amino acids
(- enter Golgi to modify
- travel in vesicles
- exocytosis)
132
what are ribosomes made of?
ribosomal RNA and protein
133
what is the role of tRNA in protein synthesis?
during translation, it brings a specific amino acid to the ribosome by binding its anticodon to mRNA codon
134
What is the role of a ribosome in protein synthesis?
holds mRNA-tRNA complexes tgt
- so condensation reactions can form between amino acids
- peptide bonds can form between carboxylic acid and amine groups
135
what is the difference in structures of mRNA and tRNA?
mRNA / tRNA
carry info from genes to produce polypeptides/ transport amino acids to ribosomes
linear / clover shape
larger + size varies / smaller, same size
no amino acid binding site / yes
has codons / has anticodon
136
what are the differences between DNA replication and transcription? (there are 5)
DNA rep / transcription
involves DNA polymerase / RNA polymerase
DNA nucleotides / RNA nucleotides
semi conservative / is not
2 template strands / 1
uses double stranded molecule / single
137
Describe the structure of globular proteins. (3 marks)
- 3D spherical shape
- hydrophilic R groups on the outside
- hydrophobic on the inside
- ionic / hydrogen / disulfide
138
Name the covalent bond formed between two polypeptide chains.
Disulfide
139
Describe how a molecule of mRNA is formed during transcription. (4 marks)
- DNA unwinds
- RNA mononucleotides line up and attach to template
- between complementary bases
- form phosphodiester bonds
- condensation reaction
- using RNA polymerase, DNA helicase, DNA ligase
- mRNA detaches from DNA
140
Explain how a poly protein molecule is converted into ten separate molecules. (2 marks)
- hydrolysis of peptide bonds
- by protease
141
Explain why the non-competitive inhibitor has decreased the maximum rate of reaction. (2 marks)
- due to fewer enzyme substrate complexes formed
- as some active sites are no longer complementary
142
Give 3 differences between the structure of collagen and haemoglobin. (3 marks)
collagen / haemoglobin
fibrous / globular
3 polypeptides / 4
little to no 3° structure / has 4°
doesn't / has haem group
hydrophobic R group on surface / opposite, hydrophilic
143
What is the role of mRNA in protein synthesis? (2 marks)
- is a copy of antisense
- made up of codons
- used in translation
- binds to ribosomes
144
What is the role of tRNA in protein synthesis? (2 marks)
- transports specific amino acid
- binds to mRNA
145
Act D inhibits transcription.
Explain why pollen tubes could still grow in the presence of act D. (2 marks)
- some mRNA in pollen grain
- so some translation / protein synthesis can take place
146
Describe how monomers are bonded to a polypeptide chain during the synthesis of actin. (2 marks)
Peptide bonds formed
Between amino and carboxyl group
By condensation reaction
147
What happens in the rough endoplasmic reticulum?
Protein synthesis
148
Explain how the properties of starch make it suitable as an energy store in cell. (2 marks)
- branched
- so easily hydrolysed to release ATP for respiration
Or
- tightly packed
- a lot can be stored in a small space
Or
- insoluble
- so does not have osmotic effect
149
Describe the structure of an enzyme. (3 marks)
- globular / 3D / tertiary
- held tgt by H / disulfide / ionic bonds
- between R groups
- has an active site
150
Name and describe the 3 enzymes involved in DNA replication. (3 marks)
- DNA polymerase forms phosphodiester bonds between nucleotides
- DNA helicase breaks H bonds between complementary bases
- DNA ligase joins Okazaki fragments together
151
What is the benefit of having (at times) different DNA base combinations coding for the same amino acids?
Help prevent mutation from changing the structure of a protein!
152
What does ‘degenerate’ mean in terms of genetic code?
Some amino acids have more than one codon
153
How is cellulose bonded together?
Hydrogen bonds and 1,4-glycosidic bond only
154
Explain how a poly protein molecule is converted into ten separate protein molecules. (2 marks)
- by hydrolysis of protein
- using protease
155
Explain the importance of DNA replication during the development of a zygote into a blastocyst. (3 marks)
- lots of genetically identical DNA produced
- zygote divides by mitosis
- so all cells in blastocyst will be diploid
