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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
example of secondary structure of proteins
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
what structure do most fibrous proteins have
beta pleated sheet structure
27
tertiary structure of amino acids
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
example of a secondary structure protein
fibrous protein
29
example of tertiary structure protein
globular protein
30
quaternary structure of proteins
only seen in proteins that have lots of polypeptide chains it describes the way seperate polypeptide chains fit together in 3D
31
examples of quaternary proteins
enzymes and haemoglobin
32
fibrous proteins
-have little or no tertiary structure long parallel polypeptide chain with occasional cross linkages that form into fibres
33
physical properties of fibrous proteins
they are insoluble in water and very tough ideally suited to their structural functions within organisms
34
where do fibrous proteins appear
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
what type of protein is collagen
fibrous protein
36
use of collagen
gives strength to tendons ligaments bones and skin
37
physical features of collagen
very strong fibres compared to steel due to chemical structure
38
chemical structure of collagen
its made up of three polypeptide chains which are 100 amino acids long -primary structure of these are glycerine -
39
collagen fibres
found in bone tissue high tensile strength -genetic disease osteogenesis imperfecta the collagen triple helix doesnt form properly bone lacks high tensile strength
40
globular proteins
have complex tertiary and quaternary structures and fold into spherical shapes
41
how do globular proteins behave in water
they are large -because their carboxyl and amino ends gives them ionic properties they dont dissolve and form a colloid
42
role of globular proteins
important in holding molecules in position in cytoplasm for immune system form enzymes and hormones involved in maintaning the structure of the cytoplasm
43
example of a globular protein
haemoglobin
44
chemical structure of haemoglobin
large molecule made of 574 amino acids arranged into four polypeptide chains held together by disulfide bonds.
45
whats special about haemoglobin
its a globular protein and its conjugated
46
what does it mean that haemoglobin is conjugated
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
prosthetic group
some protein molecules are joined or conjugated to another molecule and are a prosthetic group
48
why is chlorphyll conjugated
because it has the magnesium prosthetic group
49
what are glycoproteins
proteins with a carbohydrate prosthetic group
50
chemical structure of a glycoprotein
carb part of the molecule helps then to hold on to lots of water and makes protein digesting enzymes to break them down
51
examples of glycoproteins
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
lipoprotein
protein conjugated with liquid prosthetic groups
53
importance of lipoproteins
important in transport of cholesterol in the blood the lipid part of the molecule allows it to combine with cholesterol
54
what are the 2 main forms of lipoproteins
low and high density lipoproteins
55
low density lipoproteins
LDLs around 22nn in diameter
56
high density lipoproteins
HDLs around 8-11 nn in diameter
57
why are HDLs more dense than LDLs
because they contain more protein and proteins are more compact molecules than lipids
58
determine primary structure of proteins
sequence number and type of amino acids in polypeptide determined by types of codons in mRNA
59
define secondary structure of proteins
hydrogen bonds form between slightly negative oxygen attached to -C=O and H slightly positive attached to -NH
60

Biology topic 1 (biological molecules) (11 decks)

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