Biological molecules Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

what is a covalent bond

A

atoms consist of a nucleus surrounded by shells of electrons. most atoms tend to be stable when their outermost shells have a full 8 electrons. atoms of different elements have different numbers of electrons in their outermost shells. for example, carbon has 4. by sharing electrons with other atoms, the atoms outer shells can be filled which forms a strong bond, called a covalent bond.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is a condensation reaction

A

a condensation reaction occurs when two molecules are joined together with the removal of water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is a hydrolysis reaction

A

when two molecules are split apart with the addition of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what elements (monomers) are in the molecules carbohydrates, proteins, and nucleic acids

A

carbohydrates= carbon hydrogen and oxygen
proteins= carbon hydrogen oxygen nitrogen and sulfur
nucleic acids= carbon hydrogen oxygen nitrogen and phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe the molecular structure of water molecules

A

water consists of two hydrogen atoms, each covalently bonded to an oxygen atom. oxygen, however, has a greater number of positive protons within its nucleus. so therefore it exerts a stronger attraction for the shared electrons. so oxygen becomes slightly negative and hydrogen becomes slightly positive. when this happens we call the molecule polar.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the liquid properties of water

A

as in any liquid, water molecules are consistently moving. however unlike other liquids, as they move they continually make and break hydrogen bonds. the bonds between water molecules make it difficult for molecules to escape and become a gas. so water is liquid at room temperature with a low viscosity. So water can now:
-provide habitats for living things in rivers, lakes, and seas.
- form a major component of tissues in living organisms
-provides a reaction medium for chemical reactions as well as a transport medium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the density properties of water

A

as water becomes colder it starts to lose its density as ice begins to form which creates a lattice of bonds that leaves gaps for air. because ice is less dense than water it floats atop which allows for species to have a liquid environment throughout the winter.
ponds and other bodies of water are insulated against extreme colds, this reduces heat loss from the rest of the pond allowing for an animal habitat to be maintained underneath.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe waters properties as a solvent

A

water is a good solvent for many substances found in living things. this includes ionic solutes such as sodium chloride and covalent solutes such as glucose. because water is polar, the positive and negative parts of the water molecules are attracted to the charged parts of solutes. the water molecules cluster around these charged parts and will help keep them separate. and at this point they dissolve and a solution is formed. Because of its good solvent properties molecules and ions can be transported around living things whilst dissolved in water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what properties does water have in terms of cohesion and surface tension

A

water molecules at the surface are all hydrogen bonded to molecules beneath them and hence the surface of the water contracts and gives it the ability to resist the force applied to it. this is known as surface tension and cohesion. this allows for insects to walk on water and water to be pulled up xylem tissues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the properties of water with its high specific heat capacity

A

water temperature is a measure of the kinetic energy of the water molecules. water molecules are held together tightly by hydrogen bonds. therefore you have to put in a lot of energy to increase the kinetic energy and temperature. this means that living things can have a stable environment for enzyme-controlled reactions to take place. as well as this aquatic organisms need a stable environment in which to live.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are carbohydrates for?

A

carbohydrates contain carbon hydrogen and oxygen. they are hydrated carbons, meaning that for every carbon atom, there are two hydrogen atoms. the act as a source of energy(glucose), as a store of energy (starch and glycogen) and as structural units (cellulose in plants and chitin in fungi)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is a monosaccharide

A

a monosaccharide is the simplest of carbohydrate. they are improtanr in living things as a source of energy, and are well suited to this role because of their high amounts of carbon and hydrogen. they are sugars meaning they are soluble in water and are insoluble in nonpolar solvents. they can exist in rings or in straight chains and often have a carbon-bonded backbone, and a double bond to oxygen to form a carboxyl group. different sugars have different numbers of carbon atoms. pentose has 5 and hexose sugars have 6.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the two isomers of the carbohydrate glucose

A

-Alpha glucose
-Beta glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what disaccharide is formed with the condensation of two alpha glucose molecules

A

maltose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what disaccharide is formed with the condensation of an beta glucose molecule and a beta glucose molecule

A

cellobiose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what disaccharide is formed with the condensation reaction of a beta galactose and alpha glucose molecule

A

lactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what disaccharide is formed with the condensation reaction of an alpha glucose molecule and a fructose molecule

A

sucrose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what type of bond is formed when two hydroxyl groups lone up next to each other, from which a water molecule is removed which leaves an oxygen atom acting as a link between two monosaccharide units

A

glycosidic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the process called when a disaccharide is broken to make two monosaccharides units

A

hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what type of sugar is alpha and beta glucose

A

hexose sugars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what type of sugar is ribose or deoxyribose

A

pentose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the difference between alpha and beta glucose

A

alpha glucose has the hydrogen molecule above the plane of the ring of carbon 1 while beta glucose has the hydrogen molecule below the plane of the ring of carbon 1 ( meaning that the OH group sits above the plane in beta glucose, but below in alpha glucose)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the molecular formula of maltose

A

C6,H22,O11

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what s the difference between ribose and deoxyribose

A

ribose molecular formula has one more oxygen atom than deoxyribose. making deoxyribose’s formula- C5,H10,O4 while ribose’s is C5,H10,O5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is a polysaccharide

A

a polysaccharide is a polymer of monosaccharide. they are made of thousands of monosaccharide monomers bonded together. if they are made entirely out of one monomer they are called homopolysaccharides, while those that have more than one monomer are known as heteropolysaccharides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what makes polysaccharides good energy stores

A

-glycogen and starch are compact, which means they do not occupy large amounts of space.
-polysaccharides hold glucose molecules in chains so they can easily be snipped off from the chain in hydrolysis during respiration
-some chains are branched (amylopectin and glycogen)
these branches allow for more glucose to be snipped off at one time as well as the fact that they are more compact in their structure.
As well as this the polysaccharides are less soluble in water than monosaccharides. meaning that they do not disrupt the water potential within cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

describe the polysaccharides found within plants

A
  • amylose, this molecule is a long chain of alpha glucose molecules, like maltose it has glycosidic bonds between carbons 1 and 4.
    coiled structure with no branches.

-amylopectin, is like amylose, with glycosidic bonds between 1 and 4 but also carbon 1 and 6 . Itdes coils into a spiral shape but with branches emerging

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

describe the polysaccharides found within animals

A

glycogen. this molecule is like amylopectin with glycosidic bonds 1 and 4 and with branches formed by glycosidic bonds between carbon 1 and 6. This has more branches than amylopectin making it more efficient and compact.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is cellulose

A

cellulose is found within plants’ cell walls. it is tough, insoluble, and fibrous. it is a homopolysaccharide of up to 15000 Beta glucose molecules bonded by glycosidic bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

why does the bonding of cellulose prevent the molecules spiraling

A

-hydrogen and hydroxyl groups on carbon 1 are inverted in beta glucose. this means that every other beta glucose molecule in the chain is rotated 180 degrees, this bondage prevents spiraling. As well as this there are hydrogen bonds between each rotated beta glucose molecule which helps support the chain and stop it from spiralling. and finally, the hydroxyl group on carbon 2 sticks out enabling hydrogen bonds to be formed between chains which adds additional strength in spiral prevention.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is the term used to describe 60 to 70 cellulose chains bound together

A

microfibrils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is the term used to describe a bundle of 400 microfibrils bonded together.

A

macrofibrils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what are pectins

A

pectins are what microfibrils are embedded within to form the cellulose cell wall in plant cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

why is cellulose a good material for plant cell walls

A

microfibrils and macrofibrils have very high tensile strength, both because of the strength of the glycosidic bonds but also the hydrogen bonds between the chains.
-macrofibrils also run in all directions along the cell wall for extra strength.
As well as strength there is space between macrofibrils for water and mineral ions to pass in and out of the cell making it fully permeable.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

why is the cellulose cell wall waterproof

A

the macrofibril structure can be reinforced with other substances for extra support or make the walls waterproof. for example, cutin and suberin are waxes that block the spaces in the cell wall and make it waterproof. and lignin strengthens the cell walls of xylem vessels by forming a woody substance.

35
Q

what are the properties of lipids

A

lipids contain large amounts of carbon and hydrogen and smaller amounts of oxygen. they are insoluble in water because they are not polar, and so do not attract water molecules, but do dissolve in alcohol.

36
Q

what is the structure of a triglyceride

A

triglycerides are made up of glycerol and 3 fatty acids. glycerol has three carbon atoms. it is an alcohol which means it has free -oh groups. there are three -OH groups, which are important to the structure of triglycerides.
fatty acids have a carboxyl group (-COOH) on one end, attached to a hydrocarbon tail.

37
Q

what is the difference between a saturated and unsaturated fatty acid

A

if a fatty acid is saturated this means that there are no C=C bonds in the molecule. if the fatty acid is unsaturated, there is a double bond between two of the carbon atoms instead, which means fewer hydrogen atoms can be bonded to the molecule.

38
Q

what do we call an unsaturated fatty acid if it has more than one double carbon bond

A

poly-unsaturated

if there is only one double carbon bond we refer to it as mono-unsaturated

39
Q

what happens to the melting point there are more unsaturated fatty acids

A

having one or more double carbon bonds changes the shape of the hydrocarbon chain, giving it a kink where the double bond is. because these kinks push the molecules apart slightly it makes them more fluid. animal lipids contain lots of saturated fatty acids, which are often solid at 20 degrees. if there are more unsaturated fatty acids, the melting point is lower.

40
Q

what is the bond that joins the glycerol to 3 fatty acids within a triglyceride

A

an ester bond

41
Q

how is an ester bond formed

A

a condensation reaction happens between the -cooh group of the fatty acid and the -oh group of the glycerol. because there are 3 oh groups, three fatty acids will bond, hence the name Triglyceride. water is produced in formation as well as an ester bond.

42
Q

how can triglycerides be used as an energy source

A

triglycerides can be broken down in respiration to release energy and generate ATP. the first step is to hydrolyze the ester bonds, and then both glycerol and the fatty acids can be broken down completely to carbon dioxide and water. respiration of a lipid produces more water than respiration of a sugar

43
Q

how can triglycerides be used as an energy store

A

because triglycerides are insoluble in water, they can be stored without affecting the water potential of the cell. mammals store fat in adipose cells under the skin. one gram of fat releases twice as much energy as one gram of glucose. this is because lipids have a higher proportion of hydrogen atoms than carbohydrates, and almost no oxygen atoms.

44
Q

how can triglycerides be used as insulation

A

adipose tissue is a storage location for lipids in whales (blubber) acting as a heat insulator. lipid in nerve cells acts as an electrical insulator. and finally animals preparing for hibernation store extra fat.

45
Q

how can triglycerides be used as buoyancy

A

because fat is less dense than water, it is used by aquatic mammals to help them stay afloat

46
Q

how can triglycerides be used in protection

A

Humans have fat around delicate organs, such as their kidneys, to act as shock absorbers.

47
Q

what is the structure of a phospholipid

A

phospholipids have a similar structure to triglycerides, except that one of the fatty acids is replaced by a phosphate group. a condensation reaction between an OH group on a phosphoric acid molecule and one of the three -OH groups on glycerol forms an ester bond. most fatty acids found in phospholipids have an even number of carbon atoms. commonly one of these chains is also saturated and one is unsaturated.

48
Q

what is the behaviour of phospholipids in water

A

when surrounded by water, the phosphate group has a negative charge, making it polar (attracted to water). however, the fatty acid tails are non-polar and so are repelled by water. we call the head, hydrophilic and the tail hydrophobic.

49
Q

what are Micelles

A

Micelles are tiny balls with the phospholipid hydrophobic tails tucked away inside, and hydrophilic heads pointing out toward the water.

50
Q

what is the phospholipid bilayer

A

a phospholipid bilayer is a membrane with two rows of phospholipids, tails pointing inwards and heads pointing outwards into the solution. around 80 percent of membranes of animal and plant cells are made of phospholipids. bacterial membranes however tend to contain a greater proportion of protein.

51
Q

what is the other molecule found embedded within the phospholipid bilayer that is not a protein

A

cholesterol

52
Q

what is the function of cholesterol within membranes

A

cholesterol is a steroid alcohol- a type of lipid which is not made from glycerol or fatty acids. it consists of four carbon-based rings. its small and hydrophobic, which means that it can sit in the hydrophobic area of the Bilayer. it regulates the membrane fluidity, preventing it from becoming to fluid or stiff.

53
Q

where is cholesterol mainly made within animals

A

within the liver

54
Q

what steroid hormones are made from cholesterol

A

-testosterone
-oestrogen
-vitamin D

55
Q

what are the monomers that make up proteins

A

amino acids

56
Q

what are some uses of proteins

A
  • structural components of animals in particular. for example, muscles are made of proteins
    -they have a tendency to adopt specific shapes which makes enzymes, antibodies and hormones
    -they can act as carriers and channels across membranes in facilitated diffusion.
57
Q

what is the structure of an amino acid

A

each amino acid contains the elements, carbon, hydrogen, oxygen and nitrogen. and some amino acids contain sulfur. there are over 500 amino acids but only 20 are proteinogenic, which means they are found in proteins. each protein chain of amino acids has an amino group (-NH2) at one end, and a carboxyl group at the other (-COOH). as well as a Hydrogen atom and an R group.

58
Q

what are the bonds that combine amino acids to make poly-peptides

A

amino acids are joined together by covalent bonds called peptide bonds. just like the glycosidic bond and ester bond, making this bond requires a condensation reaction. however, enzymes catalyse the hydrolysis reaction. protease enzymes in the intestines break peptide bonds during digestion. they also break down hormones so that their effects are not as permanent.

59
Q

describe what is meant by the primary structure of a polypeptide chain/ protein chain.

A

the sequence of amino acids in a protein chain is called its primary structure. the number and order of amino acids in a protein chain is important, as changing just one amino acid can alter the function of the protein. there are 20 to the power of 100 ways of ordering amino acids.

60
Q

describe what is meant by the secondary structure of a polypeptide chain/ protein chain

A

the chain of amino acids is not straight, but twists into as shape called the secondary structure. some chains coil into an Alpha helix, with 36 amino acids per 10 turns of the helix. this helix is held together by hydrogen bonds between the -NH group of one of the amino acids and the -CO group of another 4 places ahead of it in the chain.
other chains fold very slightly into a zig-zag structure. when one such chain folds over on itself, this produces a beta-pleated sheet. hydrogen bonds between the -NH group of one amino acid and the -CO group hold the sheet together. although hydrogen bonds are very weak, many are formed, which makes both the alpha helix and the beta pleated sheet stable structures at optimal temperatures and PH.

61
Q

describe what is meant by the tertiary structure of a polypeptide chain / protein chain

A

when these coils and pleats themselfs start to fold, along with areas of straight chains of amino acids, this forms the tertiary structure. the tertiary structure is a ver precise shape that is held firmly in place by bonds between amino acids that lie close to each other. the tertiary structure may adopt a supercoiled shape ( fibrous proteins) or a more spherical shape (globular proteins). the bonds involved with the tertiary structure are hydrogen bonds, ionic bonds, disulfide links, and hydrophobic and phillic interactions. these bonds are introduced through amino acids R groups.

62
Q

describe what is meant by the quaternary structure of a polypeptide chain or protein chain.

A

many proteins are made up of more than one polypeptide chain. the quaternary structure describes how multiple polypeptide chains are arranged to make a complete protein molecule. this may be held together with the same bonds used within the tertiary structure.

63
Q

where do hydrogen bonds form in polypeptide chains

A

form between hydroxyl, carboxyl, and amino groups.

64
Q

where can ionic bonds form in a polypeptide chain

A

ionic bonds can form between carboxyl and amino groups that are part of R groups.

65
Q

where do disulphide bridges form on a polypeptide chain

A

formed between two R groups of two cysteines.

66
Q

how do hydrophobic and hydrophilic interactions distort protein shape

A

hydrophobic interactions avoid water and therefore fold to the inside of the protein while hydrophilic interactions do the opposite and expose themselves to the outside. this means that the protein folds in shapes to support these interactions.

67
Q

what is a fibrous protein

A

fibrous proteins have regular, repetitive sequences of amino acids, and are usually insoluble in water. these features enable them to form fibres, which tend to have a structural function. examples include collagen and elastin.

68
Q

what is a globular protein

A

globular proteins tend to roll up into an almost spherical shape. any hydrophobic interactions are turned inward and hydrophilic groups are exposed on the outside. this makes the proteins water soluble, they then have very specific shapes which helps them take up roles as enzymes, hormones and haemoglobin

69
Q

what are the functions and properties of the fibrous protein collagen

A

the function of collagen is to provide mechanical strength
- in artery walls, a layer of collagen prevents the artery from bursting when withstanding high pressures from blood being pumped by the heart.
-tendons are made of collagen and connect muscles to bones. allowing them to pull on bones
-bones are made from collagen, and then reinforced with calcium phosphate, which makes bones hard
-cartilage and connective tissue are made from collagen

70
Q

what are the functions and properties of the fibrous protein keratin

A

keratin is rich in cystine so lots of disulfide bridges form between its polypeptide chains. alongside hydrogen bonding, this makes the molecule very strong.

keratin is found wherever the body needs to be hard and strong. It’s found in fingernails, hair, claws, hooves, scales and fur. it provides mechanical protection, but also an impermeable barrier to infection and is waterproof to block water-borne pollutants

71
Q

what are the functions and properties of the fibrous protein elastin

A

cross-linking and coiling make the structure of elastin strong and extensible. it is found where things need to stretch and adapt shape as a part of life processes.
for example:
skin can stretch around bones and muscles
in the lungs, it allows inflation and deflation and helps the stomach and bladder expand to hold food and urine.
-helps blood vessels stretch as blood is pumped through them, helping maintain pressure.

72
Q

what are the functions and properties of the globular protein Haemoglobin

A

the quaternary structure of hemoglobin is made up of four polypeptides: two alpha globin chains and two Beta globin chains. each has its very own tertiary structure, but when fitted together they form a hemoglobin molecule. the shape of the interactions between the polypeptides gives the molecule a very specific shape. at one position on the outside of each chain, there is a haem group. groups like this are called prosthetic groups. they are an essential part to the proteins functioning, but they are not made of amino acids. the haem group contains an iron ion. we call this type of protein a conjugated protein (meaning a protein with a prosthetic group) the function of hemoglobin is to carry oxygen from the lungs to the tissues. the oxygen binds to the iron of each haem group and hemoglobin turns from purple to a bright red. when tissues are reached, oxygen is then released.

73
Q

what are the functions and properties of the globular protein Insulin

A

insulin is made up of two polypeptide chains. the A chain begins with a section of the alpha helix, and the b chain ends with a section of the beta pleat. both chains fold into a tertiary structure and then are joined together by disulfide links. is soluble in water as hydrophilic R groups are found on the outside of the molecule. insulin binds to glycoprotein receptors on the outside of the muscle and fat cells to increase their uptake of glucose from the blood, and increase rate of glucose consumption when blood sugars are high.

74
Q

what are the functions and properties of the globular protein Pepsin

A

pepsin is an enzyme that digests protein in the stomach. the enzyme is made up of a single polypeptide chain of 327 amino acids, but it folds into a symmetrical tertiary structure. pepsin has very few amino acids with basic R groups, whereas it has 43 amino acids with acidic R groups. which explains why it’s so stable in its acidic environment of the stomach. the tertiary structure is also held together by hydrogen bonds and two disulfide bridges.

75
Q

describe how Ab initio protein modelling works

A

in this approach, a model is built based on the physical and electrical properties of the atoms in each amino acid in the sequence. with this technique, there can be multiple solutions to the same amino acid sequence, and other methods sometimes need applying to reduce the number of solutions.

76
Q

describe how comparative protein modelling works

A

one approach is protein threading, which scans the amino acid sequence against a data base of solved structures and produces as set of possible models which would match that sequence.

77
Q

describe what biological processes the cation calcium is in.

A

calcium (Ca2+)
-increases the rigidity of bone, teeth, and cartilage
-regulates permeability of cell membranes
-stimulates muscle contraction and regulates the transmission of nerve impulses.

78
Q

describe what biological processes the cation sodium is in

A

sodium (Na+)
-involved in the regulation of osmotic pressure
-maintenance of PH
-contributes to nervous transmission and muscle contraction
-component of vacuoles in plants which helps maintain turgidity

79
Q

describe what biological processes the cation potassium is in

A

potassium (K+)
-involved in maintenance of PH
-assists active transport of materials of the cell membrane
-contributes to nervous transmission and muscle contraction
-component of plant cell vacuoles, helping maintain turgidity
-generates healthy leaves and flowers in flowering plants

80
Q

describe what biological processes the cation hydrogen is in

A

hydrogen (H+)
-involved in photosynthesis and respiration
-involved in the regulation of blood PH
-involved in transport of oxygen and carbon dioxide in the blood

81
Q

describe what biological processes the cation ammonium is in

A

ammonium (NH4+)
-Component of amino acids, proteins, vitamins and chlorophyll
- an essential component of nucleic acids
-involved of the maintenance of bodily PH
-a component of the nitrogen cycle

82
Q

describe what biological processes the anion nitrate is in

A

nitrate (NO3-)
- a component of amino acids, proteins, vitamins and chlorophyll
-essential component of nucleic acids
-component of the nitrogen cycle

83
Q

describe what biological processes the anion hydrogen carbonate is in

A

hydrogen carbonate (HCO3-)
-regulation of blood PH
-involved in transport of carbon dioxide in and out of the blood

84
Q

describe what biological processes the anion chloride is in

A

chloride (Cl-)
-helps in the production of urine in the kidney, and maintains water balence
-involved of carbon dioxide in and out of the blood
-regulation of blood PH
-used to produce HCL in the stomach

85
Q

describe what biological processes the anion phosphate is in

A

phosphate (PO4,3-)
-increases rigidity of bone, teeth and cartilage
-component of phospholipids, ATP, nucleic acids and several important enzymes
-regulation of blood ph
-helps roots grow in plants

86
Q

describe what biological processes the anion hydroxide is in

A

hydroxide (OH-)
-regulation of blood ph