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1. Foundations of Medicine PoNF > Proteins > Flashcards

Proteins Flashcards

1
Q

Define Protein

A

Macromolecule of AA subunits arranged in a particular structure which enables it to carry out a specific function in a particular context

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2
Q

What can proteins be in terms of their role in the body/biological processes

A

Structural (actin within cell or keratin in skin) or functional (catalytic function of enzymes or antibodies in immune defence)

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3
Q

What is DNA

A

Blueprint for proteins:
* tells cells how to make messenger RNA (mRNA) transcription
* mRNA used by cell as code to make AA chains translation
* Chains form protiens

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4
Q

What can combinations of 3 bases do?

A

code for AA or stop instruction

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5
Q

Outline the basic structure of an AA

A

Amine group (NH2), Carboxylic acid group (COOH), R group (vairable side chain), H on centre carbon

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6
Q

What are AA

A

Chiral - 4 diff groups on central Carbon (except glycine)

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7
Q

How does the acid-base environment affect AA?

A

Changes in pH affect Protien structure.
* Acid = proton donor
* Base = proton acceptor

Low pH: COOH, NH3+
Neutral pH: NH3+ COO-
High pH: NH2, COO-

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8
Q

Name and describe all the major AA classes

A
  1. Aliphatic: R group of hydrocarbon chains - hydrophobic and non-polar
  2. Aromatic: hydrocarbon ring
  3. Sulphur-containing: S allows for di-sulphide brides to occur between AA
  4. Basic
  5. Acidic
  6. Polar - carry charge at end of R-group (e.g. hydroxly group)
  7. Other: proline (hard to break so in tissues requiring strength)
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9
Q

Define primary AA structure

A

Sequence in which AA monomers are bonded together to form a polypeptide chain - massive variability in protein structure

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10
Q

What reaction occurs in the formation of primary structure

A

Dehydration reaction: 2 AA combine forming a peptide/amide bond and release water

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11
Q

What are 2 AA monomers called

A

dipeptide - more and more = polypeptide

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12
Q

What is secondary structure

A

3D spatial arrangement of AA located near each other in polypeptide chain. Relies on H-bonding between amino hyrdogen of one AA and carboxyl oxygen of another AA in same chain.
Depending on primary structure, protien can configure as an alpha helix or beta pleated sheet

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13
Q

What is tertiary structure

A

Functional groups of R chains of AA in the polypeptide chain interact with one another

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14
Q

What forces are all involved in tertiary structure

A

Van der Waals, ionic, hydrogen, disulphide and hydrophobic interactions

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15
Q

What level can functional proteins exist at?

A

A tertiary structure

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16
Q

How does hydrophobicity/or polar R groups influence protein function

A

Confers fucntion to some protiens (e.g. membrane proteins or surface proteins)

17
Q

Explain quaternary protien structure

A

Several polypeptides intercat with one another to form the quaternary structure (e.g. heamoglobin)

18
Q

How can denaturation occur?

A

protein’s chemical bonds are disrupted or destroyed) within secondary or tertiary structure - temp/permanent loss of biological functionality
Rarely stong enough to break primary structure which remains same after denaturation

19
Q

What is protein structure dependent upon

A

DNA sequence that codes for AA monomers

20
Q

What does the way AA monomers interact with each other dictate?

A

The final structure and function of the protein

21
Q

What is lost when proteins become denatured

A

Structure and function is lost

22
Q

Give the 8 main functions of proteins

A
  1. Structural - support for connecting tissues
  2. Enzymatic proteins - e.g. digestion
  3. Receptor proteins - G-proteins coupled receptors
  4. Hormonl protiens - coordinate metabolic function
  5. Transport protiens - heamoglobin or Na/K pump
  6. Storage proteins
  7. Defensive protiens - protection (immunoglobulin)
  8. Contractile proteins - movement (actin/myosin)
23
Q

What can post-translational modification/co-translational modification give?

A

Conjugated proteins

24
Q

Give 3 examples of conjugated proteins

A
  1. Glycoprotiens
  2. Lipoprotiens
  3. Metalloprotiens
25
Q

What are glycoprotiens and how are they formed

A
  • Proteins with more than 1 carbohydrate molecule(s) covalently attached
  • Co-translational or post-translational modification where oligosaccharide chains are attached to a protein
26
Q

WHat are the effects of glycosylation

A

Alters physical properties:
1. Inc stability
2. Altered solubility
3. Cell signalling
4. Orientation

27
Q

What are lipoproteins

A

Proteins combined with lipids

28
Q

Where can lipoproteins be found and what do they do?

A

Found in cell membranes and transport hydrophoibic (lipid) molecules (e.g. cholestrolal transport in blood)

29
Q

What are metalloprotiens and what are their function

A
  • Protien with a metal ion within its structure (co-factors)
  • Various functions (e.g. enxymatic, signal transduction, storage and transport) - heamoglobin
30
Q

What are globular proteins (structure)

A

tprotiens wih 3D molecular structure

31
Q

Give some examples of glubular protien functionn

A
  • Storage
  • Enzymes
  • Hormones
  • Transporters
  • Structural
32
Q

What are fibrous protiens (structure)

A

Elongated protiens with a sheet-like structure

33
Q

Give some functions of fibrous protiens

A
  • Muscle fibres
  • Connective tissue
34
Q

What can mutations in the DNA sequence coding for a protien lead to?

A

Disease

35
Q

What properties may the possetion of quaternary structure confer upon a protein

A

Post-t modification can give conjugated proteins
* Glycoprotiens
* Lipoprotiens
* Metalloproteines

36
Q

renaturation

A

the process in which the complementary strands are reformed by the formation of hydrogen bonds

37
Q

Heamoglobin

A

iron-containing oxygen-transport metalloprotein in red blood cells. Quaternary protein. Hemoglobin in blood carries oxygen from the respiratory organs to the rest of the body.

38
Q

name some other proteins

A

elastins, collagens, keratins

1. Foundations of Medicine PoNF (22 decks)

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