proteins Flashcards

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1
Q

what chemical elements are proteins made of

A

C,H,O,N and sometimes S

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2
Q

are proteins polymers

A

yes

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3
Q

whats the name of the monomers that make up proteins

A

amino acids

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4
Q

what is the name of polymers of proteins

A

polypeptides

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4
Q

what determines the function of a protein

A

its shape

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5
Q

what determines the shape of a protein

A

the sequence,type and number of amino acids within a protein/the amino acid sequence of a protein

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6
Q

name everything that proteins form

A

-enzymes
-cell membrane proteins
-transport proteins e.g haemoglobin
-immunoglobulins
-structural proteins like collagen, keratin
-hormones
-contractile proteins

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7
Q

state some functions of proteins

A

-cell growth
-repair of tissues and cell
-acts as carrier molecules r in cell membranes e.g hormones,antibodies,enzymes
-structurally important like collagen

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8
Q

what happens if a mutation occurs and the sequence of amino acids changes

A

the shape of the protein,its tertiary structure which will alter the function of the protein

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9
Q

how many amino acids exist in living organisms

A

20

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10
Q

draw the structure of an amino acid

A
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11
Q

what is the R group detrmine in an amino acid

A

-determines the chemical properties of an amino acids,it gives it its unique characteristics

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12
Q

what distinguishes one amino acid from another

A

the R group contained within each amino acid

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13
Q

what can the R group within an amino acid by

A

-polar/non-polar
-basic/acidic
-have sulfur
-have rings
-hydrophilic/hydrophobic
-positively charged/negatively charged

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14
Q

what determines whether an amino acid is polar or non-polar

A

the R group contained in the amino acid’s basic structure

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15
Q

what is the peptide bond

A

-a type of covalent bond that occurs between adjacent amino acids
-it forms in a condensation reaction

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16
Q

describe how a peptide bond forms

A

In a condensation reaction,a hydroxyl group within the carboxylic group of one amino acid interacts with the hydrogen atom of the amino group of another amino acid to release a molecule of water and form a peptide bond.

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16
Q

hoe does a dipeptide form

A

forms from the condensation reaction between 2 amino acids

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17
Q

draw the structure of a dipeptide

A
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18
Q

how does a polypeptide form

A

from the condensation reaction between more than 3 amino acids

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18
Q

how many polypeptide chains can a protein have

A

one or multiple polypeptide chains interacting with each other

19
Q

describe how a peptide bond is broken

A

in a hydrolysis reaction a water molecule is added to break the peptide bond between amino acids resulting in the dipeptide/polypeptide being broken down into two separate amino acids

20
Q

describe the primary structure of a protein

A

its the specific sequence of amino acids .bonded together by peptide bonds to form a polypeptide chain

20
Q

what determines the primary sequence of a protein

A

dna determines the sequence of amino acids,carries information which codes for the primary structure of a protein

-instructs a cell to add certain amino acids in specific quantities,and sequence

21
Q

what happens to the shape and function of a protein if the primary structure of the protein undergoes changes-What if a mutation occurs ?

A

the primary structure of a protein influences how a polypeptide folds into its tertiary structure which determines the shape of the protein.Thus any changes to the primary structure will result in a change in the shape of the protein and so will alter its function

22
Q

describe the secondary structure of a protein

A

ist when hydrogen bonds occur between nearby amino acids in a polypeptide chain, making the polypeptide either coil into an alpha helix shape or fold into a beta-pleated sheet

22
Q

where do the hydrogen bonds occur to form an alpha helix

A

-hydrogen bonds occur between amino acids within a polypeptide chain

-this pulls the polypeptide chain in,forcing it to coil into an alpha helix

22
Q

where do the hydrogen bonds occur to form a beta-pleated sheet

A

-hydrogen bonds occur between the amino acids of parallel polypeptide chains, joining them together

-they then fold to form a beta-pleated sheet

23
Q

describe the tertiary structure of a protein

A

its the folding of a protein into its final shape

-the tertiary structure determines the function of a protein

-The folding/coiling of the polypeptide chain into its secondary structure brings the R groups of different amino acids closer together

-Various bonds form between the R groups of different amino acids which stabilise and hold the tertiary structure of a protein together.

-The bonds that form cause the polypeptide chain to fold into its final shape

23
Q

what do ionic bonds form between

A

-form between positively and negatively charged R groups-

-between oppositely charged R groups

24
Q

what do hydrogen bonds form between

A

they form between slightly positive charges and slightly negatively charged R groups

25
Q

what to disulphide bonds form between

A

-occur between R groups which contain sulfur
-strongest

26
Q

what to weak hydrophobic/hydrophilic interactions form between

A

-occur between polar and non-polar R groups

26
Q

which bonds holding the tertiary strcuture of a protein together are the strongest and which the weakest

A

disulphide bonds are the strongest, hydrogen bonds are the weakest

27
Q

which is stronger ionic or hydrogen bonds

A

ionic

28
Q

what is the most common bonds that form in a tertiary structure of a protein and which are rare

A

hydrogen bonds as can occur between wide range of R groups

-ionic,disulphide and hydrophobic, hydrophilic are not common

29
Q

what breaks disulphide bonds

A

oxidation

30
Q

what breaks ionic bonds

A

ph changes

31
Q

describe the quaternary structure of a protein

A

its the 3d structure of protein,only present in proteins that have more than 1 polypeptide chain

-Multiple bonds interact with one another, and various of bonds form between the polypeptide chains -

the same as the bonds that form in tertiary structure but form between different polypeptide chains

-This causes a protein to fold into its final £D structure

32
Q

what can subunits be

A

both identical or different

32
Q

how many subunits does haemoglobin have

A

4 ,2 alpha and 2 beta subunits

33
Q

what are different polypetide chains known as in quartenary structure

A

subunits

34
Q

how many levels of structure does a protein with 1 polypeptide chain have

A

3

35
Q

what is a negative result in the test

A

solution remains blue

35
Q

describe the test for proteins

A

-use the biuret test to test for proteins
-first add sodium hydroxide to the sample to make the conditions slightly alkaline
-then add copper II sulfate to the sample which is blue

36
Q

how many levels of structure does a protein with
more than 1 polypeptide chain have

A

4

37
Q

what is a positive result in the test

A

colour change from blue to purple,might nee dto use a white tile as the colour change is very subtle

37
Q

state limitation of the test

A
  • if the sample contains amino acids or dipeptide the result will be negative as there must be at least 2 peptide bonds present to be detected

-test is qualitative and doesn’t give a quantitative value of how much protein is present in the sample

37
Q

what is the name of the test used to test for proteins

A

biuret test

38
Q

what detrmines how proteins fold into their teriatury structure

A

-hydrophobic and hydrophilic interaction

-proteins are assembled in an aqueous environment,in the cytoplasm

hydrophobic R groups clump together on the inside of the protein,away from the aqueous environment,while the hydrophilic R groups are pushed on the outside surface of the protein.

39
Q
A