2.4 Proteins Flashcards

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1
Q

How am a are assembled into proteins

A

Am a linked by peptide bonds in condensation reactions (H2O forms) to form polypeptides - in translation

Amino and carboxyl ends - terminals

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2
Q

Define: dipeptide, polypeptide, oligopeptide

A

Dipeptide: a molecule consisting of two ami a linked by peptide bond

Polypeptide: a molecule consisting of many am a linked by peptide bonds

Oligopeptide: chains of polypeptides of fewer than 20 am a linked by peptide bonds

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3
Q
A
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4
Q

Diversity of am a

A

Different R groups lead to diversity of am a -> 20 different -> if x am a in polypep - 20x variations

Diverse properties of am a:

  • hydrophilic/hydropohobic
  • polarity/non-polarity
  • rings
  • charged/non-charged
  • basic/acidic
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5
Q

Am a and origins of life

A
  1. Not all organisms share the same am a
  2. Am a were produced by chemical processes before origin of life - some organisms used
  3. Ideal 20 am a for making wide range of proteins - natural selection favoured organisms which used am a
  4. All life evolved from single ancestor which used all 20 am a - polyppetides are made by ribosomes in all species
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6
Q

How genes and polypeptides are linked

A
  1. Am a sequence of a polypeptide is coded by a gene
  2. Genes store instructions fro making the sequence
  3. Three bases code for one am a - but genes always longer, so if 20 am a in sequence - 20x3+x = >60 bases
  4. Gene transcribed into mRNA - to ribosomes
  5. mRNA translated to am a sequence by tRNA and anticodons
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7
Q

Importance fo protein conformation

A

Conformation determines function of protein

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8
Q

Shapes of proteins

A
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9
Q

Protein structures

A
  1. Primary (ribosomes): only sequence, non-functional
  2. Secondary (cytoplasm): alpha helices and beta pleated sheets (H bonds), functional
  3. Tertiary (Golgi, rER): bonds bwteen adjacent chains (H bonds, dipole, disulfide bridges, ionic), become globular - 3D
  4. Quaternary (Golgi): many polypeptides come together
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10
Q

Denaturation of proteins

A

Denaturation: loss of 3D conformation, bonds between R broken

  1. pH: reversible, charges of R hroups changed, soluble proteins can become insoluble
  2. Temperature: irreversible, vibrations - bond breaking, proteins differ in heat tolerance
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11
Q

Protein functions in organisms

A
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12
Q

Industrial uses of proteins

A
  1. Detergents: removing stains
  2. Monoclonal antibodies: pregnancy tets, HIV test, COVID test
  3. Treatment: insulin, vaccines
  4. Lactose catalysis - lactose intolerence
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13
Q

Rubisco

A
  • enzyme in plant leaves
  • fixes CO2 form atmosphere - plant photosynthesis
  • most abundant protein on Earth
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14
Q

Insulin

A
  • hormone
  • receptors for insulin - bind reversibly
  • signals cells to absorb glucose from blood
  • diabetes I - insufficinet production
  • diabetes II - disruption of receptors
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15
Q

Immunoglobulins

A
  • antibodies
  • bind to antigens - immune response - phagocytosis of pathogen
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16
Q

Rhodopsin

A
  • pigment
  • absorbs light in rod cell membranes in retina
  • absorbs light - changes shape - nerve impulse
17
Q

Collagen

A
  • fibrous protein
  • gives strength, prevents from tearing
  • in skin, blood vessels, teeth, bones
18
Q

Spider silk

A
  • proetins produced by spiders
  • parallel arrays formed from polpeptides
  • very strong - stretchy
19
Q

Define proteome:

A

PROTEOME: the totlaity of proteins produced by a cell, tissue or ogranism

Every individual has a unique proteome

Proteomes vary in different cells in organism - unlike genome

20
Q

Research techniques in proteins

A
  1. Gel electrophoresis - separation + identification
  2. Fluorescant antibody tagging - identify transport + if protein is present