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biology unit 1 > chemical elements and biological compounds > Flashcards

chemical elements and biological compounds Flashcards

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1
Q

what elements do organic compounds always contain

A

carbon , hydrogen, oxygen and/or nitrogen

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2
Q

what do inorganic compounds contain and why are they inorganic

A

carbon, hydrogen, oxygen and nitrogen but made without the involvement of living organisms

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3
Q

properties of water

A

-ice less dense and water
- liquid at most temperatures found on earth
- water is colourless/ transparent
-water has a high surface tension
- water has high specific heath capacity- can absorb alot of energy and only small rise in temp
-water has a high latent heat of vapourisation
- strong cohesive and adhesive properties

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4
Q

what is the significance of ice being less dense than water for life

A

forms an insulating layer over the surface of aquatic habitats; ponds and other aquatic habitats do not freeze so animals can still swim

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5
Q

what is the significance that water is found mostly at liquid due to temperature for life

A

it can be used as a transport medium(blood, mammals, water transporting ions up xylem)

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6
Q

whats the significance that water is transparent for life

A

light can pass through so plants can still photosynthesise

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7
Q

what is the significance that water has a high surface tension for life

A

support the mass of many organsisms and can become a habitat for them (pond skaters)

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8
Q

what is the significance that water has a high specific heat capacity for life

A

temperature of cells and aquatic habitat dont change quickly. helps conditions maintain thermally stable. helps enzymes not denature

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9
Q

what is the significance that water has a high latent heat of vapourisation for life

A

a lot of energy is needed to evaporate water so organisms use water evaporation to cool down (sweating and transpiration)

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10
Q

what is the significance that water has strong cohesive and adhesive bonds for life

A

due to hydrogen bonds, water molecules stick together and stick to eachother non-polar or charged substances. water molecules can be placed under high tensile forces and pulled through plants during transpiration

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11
Q

what are saccharides

A

single sugars named according to the number of carbon atoms in the molecule. the amount of carbon atoms change the start of the name

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12
Q

what is the general formula for monosaccharides

A

(CH2O)n n= number of atoms

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13
Q

what is the difference between an alpha isomerism or beta isomerism

A

ABBA alpha OH on the bottom beta OH on the top

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14
Q

what is a disaccharides

A

sugars made from 2 monosaccharide units

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15
Q

how are disaccharides formed

A

condensation reaction(loss of water) from OH groups on two monosaccharides

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16
Q

what type of bond holds disaccharides

A

glycosidic bonds

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17
Q

how do you name the bond

A

(alpha/ beta) (the number carbons that reacted) glycosidic bond

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18
Q

name of lactose

A

beta 1-4 glycosidic bond

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19
Q

name of sucrose

A

alpha 1-2 glycosidic bond

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20
Q

what are polysaccharides

A

complex carbohydrates. large molecules or polymers consisting of chains of monosaccharides linked by glycosidic bonds

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21
Q

the functions of polysaccharides

A

some have metabolic functions and others have structural functions in a cell

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22
Q

functions of starch and glycogen

A

these are involved in the metabolism. these both storage polysaccharides that can store and release when necessary. starch in plants and glycogen in animals

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23
Q

starch is mixture of which two polysaccharides

A

amylose and amylopectin

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24
Q

in amylopectin, where are the bonds between glucose molecules and the brantches branch;

A

alpha-1,4 glycosidic bonds but at branching points, bonds are alpha-1,6 glycosidic bonds

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25
Q

why is amylose coiled

A

glucose is polar, hydrogen bonds can form between the Odelta- on C2 of one glucose molecule and C3delta+ of the next glucose molecule in the chain, this causes amylose to coil up into a helix

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26
Q

effects of glucose being a polar molecule on starch

A
  • less soluble in water(ideal for storage)
    because starch is insoluble it doesnt affect water potential of the cell so its osmotically stable
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27
Q

where is glycogen branched

A

glycosidic bonds forming between OH groups on c1 and c4 but also c1 and c6. this makes is even more branched than amylopectin

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28
Q

use for glycogen

A

can form granules in cells and act as a carbohydrate/energy store

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29
Q

why do the branches in amylopectin and glycogen make them a better release for glucose

A

there are more ends where glycosidic bonds can be hydrolysed and glucose released, which can be used in respiration to produce ATP

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30
Q

what is cellulose

A

complex carbohydrates made of a polymer beta-glucose molecules. the beta-1,4 glycosidic linkages result in -CH2OH groups being on opposite sides of the chains of adjacent glucose molecules

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31
Q

structure of cellulose chain

A

adjacent glucose molecules are rotated 190 degrees relative to each other. this means that OH groups are aligned and a water molecule can be removed to form a glycosidic bond.

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32
Q

how the structure of cellulose effect the hydrogen bonds

A

hydrogen bonds do not form between glucose molecules in different chains. this means hydrogen bonds form cross-linkages which holds the chains together. this makes cellulose into long threads called microfibrils

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33
Q

function of cellulose

A

completely insoluble and microfibrils are laid down in overlapping layers in plant cell walls

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34
Q

why is cellulose very difficult to digest

A

very high numbers of hydrogen bonds between chains of beta glucose

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35
Q

what property does the hydrogen bonds give cellulose and explanation

A

high tensile strength. cells with cellulose in their cell wall are more resistant to osmotic lysis (not likely to burst because cellulose stops to much water entering cell

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36
Q

where is chitin found

A

cell walls of fungi and exoskeletons of insects

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37
Q

what does chitin contain to make it a hetropolysaccharide

A

nitrogen

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38
Q

why does chiltin microfibrils have a higher tensile strength than cellulose microfibrils

A

it contains side groups containing N, more hydrogen bonds can form making it stronger

39
Q

chemicals to test for reducing sugars, non-reducing sugars, proteins, starch, fats and oils

A

-reducing sugars-benedicts reagent and 80 degree got water bath
-non-reducing sugars- HCl and 80 degree hot water bath
-proteins- biuret reagent- shake gently
- starch- iodine-Kl reagent- shake gently
-add ethanol- add water to a boiling tube and and add to boiling tube

40
Q

positive tests for reducing sugars

A

green, yellow, orange , brown, brick red depending on quantity of reducing sugar present

41
Q

positive test of non-reducing sugars

A

Colour change from green to yellow to orange to brown to brick
red depending on the quantity of non-reducing sugar present

42
Q

positive test for protein

A

Colour change from pale blue to purple

43
Q

positive test for starch

A

Colour change from yellow-brown to blue-black (amylose) or
red-purple (amylopectin)

44
Q

positive test for lipids

A

White, cloudy emulsion forms

45
Q

what are lipids

A

organic compounds made from carbon, hydrogen, and oxygen. all lipids have high proportion of CH2 groups

46
Q

lipids solubility in water

A

lipids have a low solubility in water but high solubility in organic solvents

47
Q

what are triglycerides

A

triglycerides are molecules that form fats or oils depending on the size of the molecule.

48
Q

what is triglyceride made of

A

made from glycerol combined with three fatty acids through a condensation reaction—– releases three water molecules

49
Q

what bonds bind fatty acids to the glycerol

A

ester bonds

50
Q

what breaks down a triglyceride

A

hydrolysis reaction – insertion of three water molecules

51
Q

how is the carbon chain in fatty acids represented

A

with an R, a variable group containing a chain of between 4 and 24 carbon atoms

52
Q

what are fats

A

lipids with longer hydrocarbons that are solid at room temperature

53
Q

what are oils

A

with short hydrocarbons which are liquid at room temperature

54
Q

why are oils liquid at room temp and fats solid

A

week forces of attraction between the fatty acid chains- the longer the carbon chain, the greater the force of attraction, so the higher the melting points

55
Q

functions of triglyceride and why

A

-efficient energy storage molecules.(more efficient than carbohydrates 1g fat=38kj 1g carb=17kj)
- good thermal insulators and provide mechanical protection for delicate organs
- provide buoyancy for many aquatic animals
-fur and feathers to make them waterproof(hydrophobic)

56
Q

what are saturated fatty acids

A

not only the length fatty acids can change
they can also be saturated, with only single bonds between carbon atoms. they contain max number of hydrogen atoms

57
Q

why do lipids containing only saturated fatty acids generally form fats at room temperature

A

because the fatty acid tails are straight and can pack closely together. stronger forces of attraction can form which means more energy is needed to break the bonds and melt the fat - mp is higher

58
Q

what are unsaturated fatty acids

A

fatty acids can also be unsaturated, with one of more double bonds between carbon atoms
they do not contain max H atoms. for each carbon-carbon double bond, the fatty acid will contain two fewer H atoms

59
Q

why are lipids containing unsaturated fatty acids usually oils at room temperature

A

the double bonds make the tail less straight (kink) so cannot pact closely together
the forces of attraction between the fatty acids are weaker, so less energy is needed to break the bonds and melt the fat - they have lower mp

60
Q

what are phospholipids

A

essential components of cell membranes

61
Q

what do phospholipid molecules include

A
  • a molecule of glycerol
  • a phospholipid head (phosphate ion) hydrophilic
  • two fatty acid side chains - hydrophobic
62
Q

what happens when phospholipids are poured into water

A

the molecules arrange themselves in a single layer. but in cell membranes form a bilayer

63
Q

what is a bilayer with phospholipids

A
  • the hydrophilic phosphate groups are attracted to water molecules in the cytoplasm and outside the cell
  • the hydrophobic tails are repelled by water molecules and hide form water in the cytoplasm and outside the cell
64
Q

how does having saturated/ unsaturated fatty acid in a phospholipids affect fluidity of the membranes

A

-those where only saturated fatty acids are present are the least fluid
-those where only unsaturated fatty acids are present are the most fluid

65
Q

how does fluidity effect cell membrane

A

affects how easy it is for the cell membrane to move

66
Q

effects of eating polyunsaturated fat

A

an essential fat we must get as we cannot produce it. it lowers LDL (bad cholesterol)
found in- most cooking oils, fatty fish and pumpkin seeds
known as- omega-3 and omega-6 fatty acids

67
Q

effects of eating monosaturated fat

A

considered healthy fat- lowers LDL(bad cholesterol) maintains HDL(good cholesterol) found in - olive oil, avocado and most nut and nut butters

68
Q

effects of eating saturated fats

A

increase total cholesterol and LDL (bad cholesterol) best to consume in moderation
found in- red meat, whole milk, cheese, deep fried foods.

69
Q

effects of eating trans fat

A

a by-product of processing healthier fats to give them a longer shelf life. raises your LDL(bad cholesterol) and lowers HDL(good cholesterol). intake should be limited
known as- partially hydrogenated oil

70
Q

what are proteins

A

polymers made up of about 20 naturally occuring subunits called amino acids

71
Q

each amino acid has a central carbon atom with four functional groups attached which are:

A
  • amino/-NH2 which has basic properties and can gain H+ in acidic conditions making -NH3+
  • carboxylic acid/-COOH group which has acidic properties and can lose a H+ in alkaline conditions to form a COO- group
  • an atom of hydrogen
  • a variable group, R
72
Q

in the amino acid cysteine, what is R and properties of the group its in

A

R = -CH2-SH2
the -SH group of one cyteine can form a covalent bond with the -SH group of another cyteine. this bond is called disulfide bridge and is important in maintaining the 3D protein structure

73
Q

how do you get polypeptides and dipeptides from amino acids

A

they can polymerise through a condensation reaction

74
Q

what bonds do amino acids have and between which group

A

peptide bond that forms bonds between the carboxyl group of one amino acid and the amino group of the other

75
Q

two different dipeptides can be formed from two different amino acids meaning

A

the dipeptides can have different properties because the arrangements of the amino acids on either side of the peptide bond

76
Q

what effects the charges of the amino acid and therefore the properties of the dipeptide

A

the NH2 end- the N terminal- will have a basic group at the end however the COOH end - the C terminal- will have an acidic group

77
Q

what is a polypeptide

A

a chain of amino acids held together by a series of peptide bonds

78
Q

what does the sequence or order of amino acids effect

A

organisation of a molecule as its processed to form a functional protein

79
Q

what is a chain with five amino acids called

A

a pent peptide. if the order of the amino acids changed, it would produce different pentapeptides, each with different properties

80
Q

how many levels of protein structure and organisation are there

A

four

81
Q

each protein and polypeptide has a specific primary structure which is based on:

A
  • which amino acids are present
    -the number of each type of amino acids that are present
    -the sequence of amino acids in a polypeptide chain
82
Q

define the primary structure

A

the sequence of amino acids that contain many polar groups

83
Q

in the secondary structure, each chain of amino acids contain many polar groups:

A

-the amino group -N-H delta+
-the carboxylic group -C=Odelta-

84
Q

what happens between the amino group and carboxylic group

A

because opposites attract, they are attracted to each other and form hydrogen bonds. These make the amino acid chain fold and twist into a new shape. this new shape is called the secondary structure of the protein.

85
Q

the two most common types of secondary structure are:

A
  • alpha helix
  • beta pleated sheet
86
Q

protiens with a secondary structure play important structural roles in organsisms, why is this.

A

the alpha helix gives rise to fibrous proteins where several strands of alpha helices can be coiled together to give a rope-like arrangement. these are insoluble in water and have a structural function in organisms
- alpha-keratin in wool
collagen in skin and blood vessels
- beta pleated sheets form layers of protein E.g fibroin in silk

87
Q

what is the tertiary structure in protein

A

the tertiary structure of a protein depends on the properties of the R group

88
Q

the different chemical natures of the variable groups make them interact with each other (in tertiary structure) and form several types of bond

A

-ionic bonds(charged variables can interact with water to help dissolve)
- covalent bonds(variable groups containing sulfur which can form disulfide bridge. strong and hard to break)
-additional H bonds can form between polar variable groups
- hydrophobic interactions (non-polar. repelled by water and found inside protein far away form water .)if rich in non polar side groups will be less soluble in water.

89
Q

what functions does a tertiary structured protein shape give them

A

the additional folding of the protein gives rise to a compact, globular, three dimensional shape that makes the protein soluble in water- charged groups on the outside and hydrophobic groups on the inside. the tertiary structure gives globular proteins a specific 3D shape which gives the protein its function

90
Q

many globular proteins have a metabolic function in organisms:

A

-enzymes- active sites bind to a substrate
-antibodies - site for binding to antigens
- hormones- sites for binding to specific receptors

91
Q

what is a quaternary structure

A

proteins that are made of two or more polypeptide chains, combined to form the fully functional protein. each of the polypeptide chains has a primary, secondary and sometimes tertiary structure. the arrangement of several polypeptides is the quaternary structure of protein

92
Q

what bonds the polypeptide chains together

A

disulfide bridges bond the polypeptide chains together in metabolic function, for example:
- insulin
- haemoglobin
- immunoglobulins
in other proteins, hydrogen bonds bind the polypeptides together e.g
-collagen
-silk

93
Q

collagen is a fibrous protein, what happens due to the hydrogen bonds

A

the high number of hydrogen bonds between the polypeptide chain in collagen stops the chains sliding past each other and makes collagen strong

biology unit 1 (3 decks)

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