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Biology topic 1 (biological molecules) > proteins > Flashcards

proteins Flashcards

1
Q

how do amino acids join together

A

by a reaction between the amino group of one amino acid and the carboxyl group of another

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2
Q

what reaction do amino acids join in

A

a condensation reaction and a molecule of water is lost

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3
Q

what bond is formed when to amino acids join

A

peptide bond

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4
Q

whats the result of a peptide bond

A

a dipeptide molecule

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5
Q

polypeptide chains

A

lots of amino acids joined in chains

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6
Q

how are proteins formed

A

when the polypeptide coils or folds or associates with other polypeptide chains it forms a protein

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7
Q

what are proteins needed for

A

nails
hair
metabolism
enzymes
enable blood clot
transport oxygen in from haemoglobin

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8
Q

what group are proteins

A

macromolecules

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9
Q

how many naturally occuring amino acids are there

A

about 20

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10
Q

formula for amino group

A

NH2

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11
Q

formula for carboxyl group

A

COOH

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12
Q

basic structure of all amino acids

A

basic amino group with carboxyl group attached to carbon atom

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13
Q

what is the bond between amino acids

A

a strong peptide bond

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14
Q

what other bonds can amino acids form

A

hydrogen bonds
disulfide bonds
ionic bonds

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15
Q

how do amino acids form hydrogen bonds

A

tiny negative charges are present on oxygen of carboxyl groups and tiny positive charges present on hydrogen atoms of amino groups.
when these charges groups are close together they attract and form a hydrogen bond

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16
Q

how can hydrogen bonds be broken

A

if PH levels change of temp conditions change

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17
Q

why are hydrogen bonds important in amino acids

A

because they help on the folding and coiling of the polypeptide chain

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18
Q

when do disulfide bonds form

A

when two cysteine molecules are close together in the structure of a polypeptide.
an oxidation reaction takes place between the two sulfur groups which makes strong covalent bonds that are disulfide bonds

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19
Q

what are disulfide bonds important for

A

for holding the folded polypeptide chains in place

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20
Q

beta pleated sheet

A

square up and down

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21
Q

alpha helix sheets

A

coiled sheets folds

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22
Q

when do ionic bonds occur in amino acids

A

can form between some of strongly positive and negative amino acid side chains found buried deep in protein molecules
links are salt bridges

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23
Q

primary structure of proteins

A

primary is sequence of amino acids that make up the polypeptide chain held together by peptide bonds

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24
Q

secondary structure of proteins

A

arrangement of polypeptide chain into a regular repeating structure held together by hydrogen bonds

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25
Q

example of secondary structure of proteins

A

right handed alpha helix and r groups sticking out sides
another is beta pleated sheets held together by hydrogen bonds between amino and carboxyl at ends of amino acids

26
Q

what structure do most fibrous proteins have

A

beta pleated sheet structure

27
Q

tertiary structure of amino acids

A

level of 3D organisation on top of many secondary structures
amino acid is folded further into complicated shapes
hydrogen disulfide and ionic bonds hold it in place

28
Q

example of a secondary structure protein

A

fibrous protein

29
Q

example of tertiary structure protein

A

globular protein

30
Q

quaternary structure of proteins

A

only seen in proteins that have lots of polypeptide chains
it describes the way seperate polypeptide chains fit together in 3D

31
Q

examples of quaternary proteins

A

enzymes and haemoglobin

32
Q

fibrous proteins

A

-have little or no tertiary structure
long parallel polypeptide chain with occasional cross linkages that form into fibres

33
Q

physical properties of fibrous proteins

A

they are insoluble in water and very tough
ideally suited to their structural functions within organisms

34
Q

where do fibrous proteins appear

A

they appear in structure of connective tissue in tendons and matrix of bones in muscles and silk of spiders webs and keratin that makes hair and many more

35
Q

what type of protein is collagen

A

fibrous protein

36
Q

use of collagen

A

gives strength to tendons ligaments bones and skin

37
Q

physical features of collagen

A

very strong fibres compared to steel
due to chemical structure

38
Q

chemical structure of collagen

A

its made up of three polypeptide chains which are 100 amino acids long
-primary structure of these are glycerine
-

39
Q

collagen fibres

A

found in bone tissue
high tensile strength
-genetic disease osteogenesis imperfecta the collagen triple helix doesnt form properly
bone lacks high tensile strength

40
Q

globular proteins

A

have complex tertiary and quaternary structures and fold into spherical shapes

41
Q

how do globular proteins behave in water

A

they are large
-because their carboxyl and amino ends gives them ionic properties
they dont dissolve and form a colloid

42
Q

role of globular proteins

A

important in holding molecules in position in cytoplasm
for immune system
form enzymes and hormones involved in maintaning the structure of the cytoplasm

43
Q

example of a globular protein

A

haemoglobin

44
Q

chemical structure of haemoglobin

A

large molecule made of 574 amino acids arranged into four polypeptide chains held together by disulfide bonds.

45
Q

whats special about haemoglobin

A

its a globular protein and its conjugated

46
Q

what does it mean that haemoglobin is conjugated

A

the iron enables the haemoglobin to bond and release oxygen molecules and its arrangement of the polypeptide chains that determine how easily the oxygen binds or is released

47
Q

prosthetic group

A

some protein molecules are joined or conjugated to another molecule and are a prosthetic group

48
Q

why is chlorphyll conjugated

A

because it has the magnesium prosthetic group

49
Q

what are glycoproteins

A

proteins with a carbohydrate prosthetic group

50
Q

chemical structure of a glycoprotein

A

carb part of the molecule helps then to hold on to lots of water and makes protein digesting enzymes to break them down

51
Q

examples of glycoproteins

A

mucus
synovial fluid
because of their water holding properties make them lubricants which reduces friction
explains mucus in stomach protects protein walls from digestion

52
Q

lipoprotein

A

protein conjugated with liquid prosthetic groups

53
Q

importance of lipoproteins

A

important in transport of cholesterol in the blood
the lipid part of the molecule allows it to combine with cholesterol

54
Q

what are the 2 main forms of lipoproteins

A

low and high density lipoproteins

55
Q

low density lipoproteins

A

LDLs around 22nn in diameter

56
Q

high density lipoproteins

A

HDLs around 8-11 nn in diameter

57
Q

why are HDLs more dense than LDLs

A

because they contain more protein and proteins are more compact molecules than lipids

58
Q

determine primary structure of proteins

A

sequence
number and type of amino acids in polypeptide
determined by types of codons in mRNA

59
Q

define secondary structure of proteins

A

hydrogen bonds form between slightly negative oxygen attached to -C=O and H slightly positive attached to -NH

60
Q
A

Biology topic 1 (biological molecules) (11 decks)

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