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Ocr A Level Biology > biological molecules > Flashcards

biological molecules Flashcards

1
Q

21What are elements?

A

Elements are different types of atoms and they are distinguished by the number of protons that they hold.

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2
Q

What are ions?

A

An atom with a charge. It must have gained or lost an electron.

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3
Q

What is a cation?

A

A positive ion (loses electron(s))

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4
Q

What is an anion?

A

A negative ion(gains electron(s))

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5
Q

what happens in covalent bonds?

A

The electrons will be closer to one atom than the other. Atom with a greater share of the electron(s) will be slightly negative. S^-. Atoms with a lower share of the electron(s) will be slightly positive. S^+

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6
Q

What does delta mean and provide example

A

Delta means slightly. For example, slightly negative or slightly positive

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7
Q

What does polar mean?

A

Uneven distribution of charge

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8
Q

What is water?

A

Water is a polar molecule. It is apart of the hydroxyl group (OH)

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9
Q

How are hydrogen bonds formed?

A

Polar molecules interact with each other so the positive and negative regions of the molecule attract each other and form the bond.

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10
Q

Hydrogen bonds are..

A

individually weak but collectively strong

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11
Q

What are isomers?

A

same molecular formula but different structure.

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12
Q

Importance’s of water

A

-Aquatic habitats
-solvent
-main component of blood
-in cytoplasm
-hydrolysis
-thermoregulation
-osmoregulation

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13
Q

Water as a solvent

A

-many ions will dissolve in it
-positive ions will be attracted to the slightly negative oxygen ion
-negative ions will be attracted to the slightly positive hydrogen ion.
-allows chemical reactions to occur within cells since dissolved solutes are more chemically reactive when they are free to move about
-metabolites can be transported efficiently(except non-polar molecules which are hydrophobic)

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14
Q

Water and high specific capacity

A

-Water has a high specific heat capacity of around 4200 J/Kg degrees
-high specific heat capacity is due to the many hydrogen bonds present in water
- a lot of thermal energy is required to break the bonds so temp of water does not fluctuate greatly

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15
Q

Advantages of high SHC in water

A

-provides suitable habitats
-maintain constant temperature as water is able to absorb a lot of heat without big temperature fluctuations
-vital in maintaining temperatures that are optimal for enzyme activity
-water in blood plasma is also vital in transferring heat around the body helping to maintain a fairly constant temperature

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16
Q

Water and latent heat of vaporisation

A

-A large amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate.
-advantage for living organisms as little water has to evaporate for a great mount of heat loss
-provides cooling effect for living organisms (transpiration from leaves or evaporation of water in sweat on the skin)

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17
Q

Water/ Cohesion

A

-hydrogen bonds between water molecules allows for strong cohesion between water molecules (allowing columns of water to move through the xylem of plants and blood vessels in animals)
-enables surface tension where body of water meets air(hydrogen bonds occur between the top layer of water molecules to create a film on the body of water)

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18
Q

Water/Adhesion

A

water is able to hydrogen bond to other molecules such as cellulose

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19
Q

Why is oxygen slightly negative?

A

Oxygen has more protons than hydrogen so it is a more positive atom thus attracts the negative electron with stronger force making it slightly negative.

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20
Q

What is the general formula of the monomer glucose?

A

Cn(H2O)n

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21
Q

What is a monomer?

A

-smaller units that can join together to form a polymer
- 2 monomers join to make a dimer by a single bond

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22
Q

What is a polymer?

A

made from lots of monomers joined together

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23
Q

Name 3 monomers

A

glucose, amino acids and nucleotide

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24
Q

name 3 polymers

A

starch, protein and DNA and RNA

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25
Carbohydrate is a biological molecule. What is it made from?
Carbon, hydrogen and oxygen
26
Lipid is a biological molecule. What is it made from?
carbon, hydrogen and oxygen
27
Protein is a biological molecule. What is it made from?
carbon, hydrogen, oxygen, nitrogen and sulphur
28
Nucleic acids is a biological molecule. What is it made from?
Carbon, hydrogen, oxygen, nitrogen and phosphorus
29
The 3 monosaccharides(monomers for carbohydrates)
glucose, fructose and galactose
30
The 3 disaccharides(dimers for carbohydrates)
sucrose, maltose and galactose
31
the 3 polysaccharides(polymers for carbohydrates)
starch, cellulose and glycogen
32
What forms maltose?
glucose + glucose(water is also formed)
33
What forms sucrose?
glucose + fructose(water is also formed)
34
What forms lactose
glucose + galactose(water is also formed)
35
Difference between alpha glucose and beta glucose?
in the alpha glucose the hydroxyl group is beneath hydrogen whereas in the beta glucose the hydroxyl group is above hydrogen.
36
Why is water formed when the monosaccharides make disaccharides
because the glucose is joined via glycosidic bond which is due to condensation which eliminates water as a by product
37
What is a condensation reaction?
joining 2 molecules together by removing water
38
what is a hydrolysis reaction?
splitting apart molecules via the addition of water(water is added and they return to their monosaccharides)
39
Alpha glucose details
-hexose -molecular formula is C6H12O6 -produces energy. is absorbed in small intestine via bloodstream and transported into mitochondria -monomer in starch -monomer in glycogen
40
Beta glucose details
-hexose -molecular formula is C6H12O6 -used to build cellulose
41
Ribose details
-pentose -molecular formula is C5H10O5 -monosaccharide found in cells-essential in energy production
42
Deoxyribose details
-pentose -molecular formula is C5H10O5 -assists in the formation of the phosphate backbone of DNA molecules
43
Give details of starch, a polymer of glucose
Made of amylose-made from alpha glucose joined together by 1-4 glycosidic bond. long straight chain and it is unbranched. it is coiled into a helix Made of amylopectin-branched polysaccharide and there are 1-4 and 1-6 glycosidic bonds. also made from alpha glucose. There are hydrogen bonds between.
44
How does the structure of starch lead to its function?
-helix is compact to fit lots of glucose in small space -branched structure of amylopectin allows for rapid hydrolysis back to glucose because of increased surface area -insoluble-won't affect water potential
45
where is starch located?
In plant cells in the cytoplasm in the amyloplasts
46
Glycogen details
monomer: alpha glucose bond between monomers:1-4 and 1-6 glycosidic bonds -branched molecule -spiralled -contains hydrogen bonds function: store of glucose location: muscle and liver cells How does structure lead to its function? branched structure increases surface area for rapid hydrolysis back to glucose insoluble-won't affect water potential
47
Cellulose details
monomer: Beta glucose bond between monomers:1-4 glycosidic bonds function: structure for cell walls location: plant cell structure: polymer forms long straight chains. chains are held in parallel by hydrogen bonds to form fibrils -non branched, regular arrangement and compact
48
explanation of how structure leads to function(cellulose)
-many hydrogen bonds provide collective strength -insoluble so it won't affect water potential
49
Cellulose in plant cell walls
-60 to 70 cellulose molecules bind together to form a microfibril(10-30nm in diameter) -they bundle to form microfibrils(fibres) -they form plant cell walls by running in all directions creating a criss-cross surrounding the cell
50
Lipid key points
-macromolecules not polymers -non polar molecules -insoluble in water -dissolve in organic solvents such as ethanol -hydrophobic -lipids are made from 2 molecules which are fatty acids and glycerol's and they do not form polymers
51
What are the 3 lipids?
Triglycerides , phospholipids and cholesterol
52
triglyceride key points:
-formed via the condensation between one molecule of glycerol and 3 molecules of fatty acid(esterification which is the formation of ester bonds) -glycerol is apart of the alcohol group
53
Mono-unsaturated definition
one double bond between carbon atoms(liquid at room temp)
54
polyunsaturated definition
more than one double bond between carbon atoms(liquid at room temp)
55
saturated
no double bonds between carbon atoms(solid state at room temperature)
56
What are the differences between triglycerides and polysaccharides?
-less oxygen bonds in triglycerides than in polysaccharides -more carbon and hydrogen bonds in triglycerides than polysaccharides -no hydrogen bonds
57
Roles of lipid
store fat, insulate heat, make up the cell membrane, chemical messengers and store enzyme use
58
Properties of triglycerides#1
can transfer energy-large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms, a lot of energy can be transferred when it is broken down
59
Properties of triglycerides#2
can act as a metabolic water source-high ratio of hydrogen to oxygen atoms. triglycerides can release water is they are oxidised
60
Properties of triglycerides#3
Large and hydrophobic so they are insoluble in water-will not affect water potential and osmosis
61
Properties of triglycerides#4
lipids are low in mass so a lot can be stored in an animal without it increasing the mass and preventing movement
62
Phospholipids
-made of 1 glycerol attached to 2 fatty acid chains and an organic phosphate group attached to the glycerol -2 fatty acids also bond to the glycerol via 2 condensation reactions, resulting in 2 ester bonds -one chain is saturated(no double bond between carbon atoms) and one chain is monounsaturated(1 double bond between carbon atoms)
63
How does the structure of a phospholipid differ from the structure of a triglyceride?
-lacks a 3rd fatty acid chain -has an organic phosphate group -it has double bond between carbon atoms
64
phospholipids description
-hydrophilic head and it is polar. hydrogen bonds can form with the oxygen and the hydrogen in water -hydrophobic tails (2 fatty acid tails) since it is non polar(will mix with fats though)
65
the entire phospholipid is considered amphipathic. What does amphipathic mean?
polar and non polar regions
66
What is the difference between a saturated fatty acid and an unsaturated fatty acid?
In a saturated fatty acid, there are no double bonds between carbon atoms. In an unsaturated fatty acid, there are double bonds between carbon atoms.
67
Another property of phospholipid
-forms a phospholipid bilayer membrane structure which makes up the plasma membrane around cells
68
Structure and properties of cholesterol
-manufactured in liver and intestines -it is amphipathic-both polar and non polar parts -cholesterol is really small and embeds within the cell membrane -controls fluidity of the membrane and impacts permeability of the membrane -different temp=different role
69
Cholesterol in the fluid mosaic model:
-regulates fluidity of plasma membrane -impacts permeability
70
cholesterol's role in warmer temp
-keeps the hydrophobic tails together
71
cholesterol's role in lower temp
cholesterol keeps them away from each other to stop it becoming rigid in cold temp(prevent it from becoming a solid)
72
What is a steroid?
-lipid macromolecule -made of 4 carbon rings -not made of fatty acids and glycerol -sterols are a subgroup of steroids and are alcohols
73
What would happen without cholesterol
in the heat, membrane would be too fluid/flexible and won't hold shape in the cold, membrane would ne rigid and could break
74
Amino acids
-The polar/non polar group refers to the R group
75
Why are some amino acids referred to as essential and others non-essential?
-9 essential amino acids cannot be synthesised by our bodies so they need to be consumed in diet non amino acids can be synthesised so they do not need to be consumed in a diet
76
Proteins
-Contain carbon, hydrogen and oxygen (some have sulphur) -they are large polymers which are composed of amino acids found in enzymes, antibodies and hormones/
77
Amino acids in solution can ionise to..
help regulate the PH which is a process called buffering
78
Describe the structure of proteins
They all have primary, secondary and tertiary structure. Only some have a quaternary structure.
79
Primary structure
-Order of amino acids in a polypeptide chain -order of amino acids is determined by the order of nucleotides in a gene -there are peptide bonds
80
Secondary structure
-formation of alpha helices and Beta pleated sheets -polypeptide chain starts to fold -there are peptide bonds -there are hydrogen bonds between carboxyl group of one amino acid and the amine group of another amino acid.
81
Tertiary structure
-specific 3D shape -non polar R groups form weak hydrophobic interactions -Disulphide bonds between 2 R groups of amino acids that contain sulphur -ionic bonds between the oppositely charged R groups -hydrogen bonds
82
Quaternary structure
-more than 1 polypeptide chain -only some proteins have this structure -has non covalent bonds like hydrogen bonds and vande waaals forces to hold the polypeptide chain together.
83
Haemoglobin
-oxygen carrying molecule -have all the bonds except hydrogen -non covalent bonds such as ionic bonds -has 4x polypeptide chains -has a haem group which is not a protein -haem group made of Fe^2+(iron)
84
Conjugated protein
-some proteins are conjugated -they have a prosthetic group which is a non protein group -attached via hydrogen/ionic/covalent bonds
85
Examples of conjugated proteins
-glycoprotein(plasma membrane)-role in immune system and cell recognition(polypeptide is bound to polysaccharide) -haemoglobin-haem group(an iron ion) -lipoprotein(lipid and protein) -hemocyanin-has carbon to deliver blood -myoglobin-transport protein in muscle
86
Globular proteins(functional)
-usually have a compact and spherical shape(a lot of amino acids in an area) -hydrophobic groups are on the inside and hydrophilic groups are on the outside which makes globular proteins soluble in water. -whether it is hydrophobic or hydrophilic depends on the R group -hydrophobic=non-polar R group -hydrophilic=polar R group
87
Examples of globular proteins
-transport proteins(haemoglobin, carrier proteins and channel proteins) -enzymes(all in cytoplasm) -protein hormones(insulin) -antigens
88
fibrous proteins(structural)
-formed from parallel cross-linked polypeptide chains -form rope-like fibres, with high tensile strength -primary structure consists of a limited number of repeating A As with small, hydrophobic R groups leading to organised structures which are insoluble in water
89
Fibrous proteins #2
-insoluble in water, strong and unreactive -can withstand a high level of mechanical force/pressure -compact because of the small AAs. -all have a quaternary level of structure because there is more than one polypeptide chain
90
Examples of fibrous proteins
-collagen(found in connective tissue(cartilage, tendons and ligaments) -keratin(found in hair, nails, horns , tusks and scales) -elastin-layer of skin.(can stretch/flexible. Has elasticity and recoils after being deformed)
91
connective tissue stuff
ligaments(bone-bone) tendons(bone-muscle) cartilage(joints-bones)
92
What is a denatured protein?
-loss of 3D shape due to loss of chemical bonds and it is irreversible due to temp and PH
93
weakest to strongest bonds
-weak hydrophobic interactions -hydrogen bonds -ionic bonds -disulphide bonds -peptide bonds
94
Calcium ion
-neuronal-synapses-gap between neurones -cell signalling -muscle contraction
95
Sodium ion
-transmission of nerve impulses -sodium potassium pump -propagation of an action potential
96
potassium ion
-propagation of an action potential
97
hydrogen ion
-makes ATP -PH regulation -chemiosmosis in respiration
98
ammonium ion
-deamination of protein -plants use it to make proteins -makes DNA and RNA
99
nitrate ion
-proteins and DNA and rna
100
hydrogencarbonate ion
-transportation of carbon dioxide in the blood
101
chloride ion
-chloride shift in blood-maintains PH
102
phosphate ion
-formation of nucleotides -ATP, DNA, RNA and phospholipids
103
hydroxide ion
-formation of hydrogen-hydrogen bonds -sterol synthesis -involved in PH regulation

Ocr A Level Biology (6 decks)

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