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Grade 12 Biology Biochemistry > Proteins > Flashcards

Proteins Flashcards

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1
Q

What are the seven (7) important functions of proteins?

A
  • structural support
  • storage
  • transport of substances (facilitated diffusion, active transport)
  • intercellular signals
  • movement (muscles)
  • Defense against foreign substances
  • act as Enzymes
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2
Q

What is hemoglobin?

A

A protein in blood cells that carries oxygen from one place to another in mammals

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3
Q

What is keratin?

A

The most common protein found in vertebrates, in hair and fingernails.

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4
Q

What is Fibrin?

A

Protein that assists with blood clotting, and collagen (protein component in bones, skin, ligaments and tendons)

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5
Q

What determines a protein’s function?

A

The structural characteristics of each amino acid that makes up a polypeptide chain

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6
Q

What groups make up an amino acid?

A
  • Carboxyl group
  • A hydrogen group
  • An amino group
  • A side (R) group
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7
Q

How many different amino acids can be found in animals?

A

20 different amino acids

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8
Q

Why are amino acids considered amphiprotic?

A

They posses both carboxyl (acidic) and amino (basic) functional groups.

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9
Q

What are the three (3) different electrostatic characteristics of amino acids?

A
  • Hydrophilic (polar)
  • Hydrophobic (non polar)
  • Charged (acidic [negative charge] or basic [positive charge])
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10
Q

What is the name of the amino acid whose side chain forms a covalent bond with its own amino group

A

Proline (pro)

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11
Q

What functional group do acidic amino acids have as their side chain?

A

Carboxyl group

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12
Q

What functional group do basic amino acids have as their side chain?

A

Amino group

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13
Q

Jeopardy:

The three dimensional shape of a protein that is determined by the sequence of amino acids it contains

A

What is conformation?

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14
Q

Jeopardy:

An amino acid polymer

A

What is a polypeptide?

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15
Q

What is the process of protein synthesis?

A

When polypeptides are constructed in the cytoplasm of cells

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16
Q

What are the 8 essential amino acids?

A
  • Tryptophan
  • Methionine
  • Valine
  • Threonine
  • Phenylalanine
  • Leucine
  • Isoleucine
  • Lysine
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17
Q

What process involves the joining of amino acids together using what three organelles?

A

The process of protein synthesis directs ribosomes, RNA and enzymes to join amino acids together

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18
Q

The bond between amino acids is called _____

A

peptide bonds (amide linkage)

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19
Q

How are peptide bonds formed?

A

They are formed by the condensation reaction between an amino group in one amino acid and the carboxyl group of an adjacent amino acid

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20
Q

Name of bond between an amino group in one amino acid and the carboxyl group of an adjacent amino acid.

A

Amide bond

21
Q

A polypeptide chain will always have a(n) __________ at one end and a(n) __________ at the other. These are called ________ and _________

A

an amino group (A-terminus) at one end and a carboxyl group (C-terminus) at the other end

22
Q

Jeopardy:

Round, spherical polypeptide chains

A

What are globular proteins?

23
Q

Each of the amino acids in a polypeptide is referred to as _______

A

A residue

24
Q

Why is the final conformation of protein sensitive to its primary structure? How does this apply to sickle cell anemia?

A

When the sequence of one amino acid is changed, the 3D structure of the polypeptide chain will also be changed making the protein (overall polypeptide chain(s)) lose its function. For ex: sickle cell anemia: the red blood cells become deformed and block the blood vessels impeding blood flow in the body.

25
Q

During protein synthesis, amino acids are added to the chain ___ ___ _ ______

A

one at a time

26
Q

True/False:

A primary structure has folds and coils.

A

False:

Secondary structures are characterized by their folds and coils

27
Q

In a secondary structure, what causes the polypeptide chains to form folds and coils?

A

Hydrogen bonds between the electropositive hydrogen of the amino group (N-H) four peptide bonds away and the electronegative oxygen atom of the carboxyl group (C=O) of one peptide bond

28
Q

What is an a-helix?

A

Hydrogen bonds, repeated over a specific length of a polypeptide chain, causing structures to bend and form coiled structures.

29
Q

Give two (2) examples of a-helix

A

a-keratin a fibrous protein found in hair is almost completely shaped into an a-helix.

An enzyme called lysozyme, a globular protein, acts as a disinfectant in sweat, saliva, and tears. It has areas of a-helix that are separated by B-pleated sheets.

30
Q

How are B-pleated sheets formed?

A

This type of secondary structure is formed by polypeptide chains situated parallel to each other

31
Q

How are hydrogen bonds formed in B-pleated sheets?

A

In this case, the oxygen atom from the carboxyl group at one strand bonds with the hydrogen atom from the amino groups on an adjacent strand

32
Q

Give an example of B-pleated sheets

A

The silk in spider web, a type of fibrous proteins, has many B-pleated sheets with hydrogen bonds. These bonds make the silk in spider webs stronger than steel. Spider webs can stretch farther than steel before breaking.

33
Q

What type of proteins are characterized by their levels of structure? Name these levels of structure.

A

Globular proteins are characterized by their four levels of structure:

  • Primary structure
  • Secondary structure
  • Tertiary structure
  • Quaternary structure
34
Q

How are tertiary structures formed?

A

Attraction and repulsion between the polypeptide and its environment causes the structure to be supercoiled

35
Q

How are tertiary structures made stable?

A

They are stabilized by a number of different R-group interactions

36
Q

How are two cysteine residues stabilizers of tertiary structures?

A

The sulfur in the R-groups of two cysteine residues will attract each other and form a disulfide bridge (covalent bond of two sulfurs) which are strong stabilizers of tertiary structures.

37
Q

How does proline (pro) contribute to the shape of tertiary structures?

A

Proline’s R group bonds with its amino group. This bond creates a kink in proline’s structure which helps with shaping tertiary structures

38
Q

Jeopardy:

Two or more polypeptide subunits forming a functional protein

A

Quaternary structure

39
Q

Give four (4) examples of proteins that are in a quaternary structure

A
  • Collagen
  • Keratin
  • Hemoglobin (globular proteins)
40
Q

Give three (3) examples of proteins that are in a quaternary structure

A
  • Collagen
  • Keratin
  • Hemoglobin (globular proteins)
41
Q

What may cause proteins to unravel?

A

Proteins may unravel due to higher or lower than normal temperatures, pH levels, ionic concentration and other factors in their surroundings.

42
Q

What is the effect of the unravelling of proteins called?

A

Denaturation

43
Q

Under what circumstances are denatured proteins able to regain their shapes?

A

When the denaturing agents such as heat or chemicals are removed from the protein, the denatured protein is able to regain its shape as long as its primary structure is still intact

44
Q

What will cause a protein to be destroyed?

A

If the denaturing agent destroys the peptide bonds between the amino acids, then the protein will be destroyed.

45
Q

Give 2 examples of when protein denaturation becomes useful.

A

Curing meats by applying high concentrations of salt or sugar preserves the food by killing or denaturing the enzymes in the bacteria that would spoil the food quickly.

Blanching fruits and/or vegetables by quickly dropping and removing them from hot water denatures the enzymes that would cause them to turn brown in the atmosphere.

46
Q

Jeopardy:

Proteins that help the growing polypeptide to fold into a tertiary structure

A

What are chaperone proteins?

47
Q

What is the primary purpose of cooking?

A

To denature the fibrous proteins in muscle cells of meat that make them hard to chew

48
Q

What is used to determine a protein sequence, why is it used?

A

PITC - phenylisothiocyanate - is used to determine protein sequences because it attaches to a residue without destroying the rest of the peptide bonds, and so scientists are able to identify each of the amino acids and the order in which they are organized in the polypeptide chain.

49
Q

Why do egg whites turn white and solid when heated?

A

Heat denatures the protein, albumin, in the egg white and causes the protein structures to uncoil, which then gets tangled with each other and block light rays or become opaque.

Grade 12 Biology Biochemistry (7 decks)

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