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Biology HL > 2.4 Proteins > Flashcards

2.4 Proteins Flashcards

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1
Q

What is one of the central ideas in biology?

A

Structure dictates function

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2
Q

Polypeptides vary hugely in:

A

the # and combination of amino acids that they are composed of

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3
Q

How are amino acids linked together? What do they form?

A

Amino acids are linked together by condensation to form polypeptides

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4
Q

What is a protein?

A

Polymer made of amino acid sequence

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5
Q

What are polypeptides?

A

molecule consisting of (>20) amino acids

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6
Q

How many polypeptides do proteins contain

A

some proteins contain one polypeptide other contain 2+ polypeptides

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7
Q

What does a condensation reaction involve?

A

Amine group of one amino acid and the carboxyl group of another

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8
Q

Two amino acids can create

A

a peptide bond, forming a dipeptide

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9
Q

What is released as a byproduct of condensation?

A

Water

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10
Q

What is a Dipeptide

A

2 amino acids joined together

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11
Q

what is an oligopeptide

A

chains of 3-20 amino acids

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12
Q

What is a polypeptide

A

chains of >20 amino acids

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13
Q

describe structure of insulin

A

a small protein the contains two polypeptides (one with 21 amino acids and the other with 30 amino acids)

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14
Q

Hemoglobin is made up of

A

is made up of 4 polypeptides (2 alpha- 2 beta)

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15
Q

Titin

A
  • Largest polypeptide discovered
  • contains 34,350 amino acids in humans
  • Part of muscle structure
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16
Q

What are ribosomes and what do they do?

A

Ribosomes are the molecules within cells that facilitate the formation of peptide bonds and hence where polypeptides are synthesized

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17
Q

How many amino acids are used by ribosomes to make polypeptides?

A

20 different amino acids

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18
Q

what is Hydroxyproline an example of

A

An amino acid that is modified after the polypeptide is synthesized

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19
Q

Can amino acids be modified after a polypeptide is synthesized? (example)

A

yes, ex: hydroxyproline

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20
Q

Hydroxyproline is a modification of the amino acid

A

proline

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21
Q

What does this modification of proline do?

A

Increases the stability of the collagen triple helix

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22
Q

Collagen

A

A structural protein used to provide tensile strength in tendons, ligaments, skin, and blood vessels.

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23
Q

What is the amino acid sequence of polypeptides coded by?

A

genes

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24
Q

Living organisms-

A

only produce a small fraction of the possible polypeptides that could be produced

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25
Q

A typical cell produces polypeptides with

A

thousands of different sequences and stores the information to produce these within genes (DNA)

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26
Q

The DNA sequences is tr__

A

transcribed to messenger RNA which brings this genetic code to the ribosomes

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27
Q

Describe The central dogma of genetics

A

DNA is a gene
RNA is a message
Polypeptide is the product

DNA is transcribed in the nucleus to make RNA

RNA is translated in the cytoplasm t make the polypeptide

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28
Q

What does the amino acid sequence determine?

A

The dimensional conformation of a protein

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29
Q

What are polypeptides?

A

Chains of amino acids joined by peptide bonds

30
Q

Describe each amino acid group and its unique properties:

A
  • Some are hydrophilic (polar)
  • Some are hydrophobic (non-polar)
  • Some are + or - charged (acidic - , basic+)
  • Some contain sulfur (systene)
31
Q

What do the unique properties of amino acids determine?

A

They determine how a polypeptide folds into a protein

32
Q

What are proteins commonly described as in nature?

A

Fibrous or globular

33
Q

What are the possible properties of fibrous and globular proteins

A

Shape, role, solubility, sequence, stability, examples

34
Q

List all properties of fibrous proteins

A 
Long and narrow,
structural (strength and support)
Generally insoluble in water
Repetitive amino acid sequence
Less sensitive to heat and pH changes
Collagen, myosin, fibrin, actin, keratin, elastin
35
Q

List all the properties of globular proteins

A 
Rounded / spherical
functional (catalytic, transport)
Generally soluble in water
Irregular amino acid sequence
more sensitive to changes in heat, pH
Catalase, Haemoglobin, insulin, immunoglobin
36
Q

How are globular proteins soluble?

A

Hydrophobic R-groups are folded into the core of the molecule away from the surrounding water molecules

37
Q

Why are fibrous proteins insoluble?

A

Hydrophobic r-groups are exposed

38
Q

Name all the functions of proteins

A

Catalysis, cell adhesion, clotting, cytoskeleton, muscle contraction, tensile strengthening, transport of nutrients and gases (blood), membrane transport, hormones., receptors, packing DNA, immunity.

39
Q

Catalysis

A

There are thousands of different enzymes to catalyze specific chemical reactions within the cell or outside it (ex: rubisco)

40
Q

Muscle contraction

A

Actin and Myosin together cause the muscle contractions used in locomotion and transport around the body

41
Q

Cytoskeleton

A

Tubulin is the subunit of microtubules that give animals cells their shape and pull on chromosomes during mitosis.

42
Q

Tensile Strengthening

A

Fibrous proteins give tensile strength needed in skin, tendons, ligaments, and blood vessel walls (ex: collagen)

43
Q

Blood clotting

A

Plasma proteins act as clotting factors that cause blood to turn from a liquid to a gel in wounds

44
Q

Transport of nutrients and gases

A

Proteins in blood help transport oxygen, carbon dioxide, iron, and lipids

45
Q

Cell Adhesion

A

Membrane proteins cause adjacent animal cells to stick to each other within tissues

46
Q

membrane transport

A

Membrane proteins are used for facilitated diffusion and active transport, and also for electron transport during cell respiration and photosynthesis

47
Q

Hormones

A

Some such as insulin, FSH, and LH are proteins, but hormones are chemically diverse

48
Q

Receptors

A

Binding sites in membranes and cytoplasm for hormones neurotransmitters, tastes and smells, and also receptors for light in the ye and in plants (ex: Rhodopsin)

49
Q

Packing of DNA

A

Histones are associated with DNA in eukaryotes and help chromosomes to condense during mitosis.

50
Q

Immunity

A

This is the most diverse group of proteins, as cells can make huge numbers of different antibodies (ex: immunoglobulins)

51
Q

Examples of how biotechnology has allowed us to use proteins in industry:

A

Enzymes for removing stains in clothing detergent
Monoclonal antibodies for pregnancy tests
Insulin for treating diabetics
Disease treatments

52
Q

List examples of the range of protein functions

A

Rubisco, Insulin, Immunoglobulins, Rhodopsin, Collagen, Spider silk

53
Q

Rubisco

A

Used in cellular respiration, catalyzes the first reaction in carbon fixation

54
Q

Insulin

A
  • A hormone that is carried + dissolved in the blood and binds to insulin receptors in the membranes of body cells (lowers glucose levels)
  • The pancreas of type I diabetics don’t produce sufficient insulin therefore they must periodically inject synthetically produced insulin to correct their blood sugar concentration.
55
Q

Immunoglobulins

A

Also known as antibodies

binds to antigens

56
Q

Rhodopsin

A

A pigment in the retina of the eye

absorbs light in low-light conditions

57
Q

Collagen

A

Strucutural protien
3 polypeptides form rope like conformation
Gives strength to tendons, ligaments, skin, and blood vessel walls.
Forms part of teeth and bones, helps to prevent cracks and fractures to bones and teeth

58
Q

Spider Silk

A

Structural/fibrous protein
Dragline silk is stronger than steel and tougher than kevlar
Very high tensile strength and become stronger when stretched.

59
Q

What forms a Proteome

A

Genomes and environmental factors

60
Q

Describe a genome

A

All of the genes of a cell, tissue, or an organism. The genome determines what proteins an organism can possibly produce. A genome is unique to most individuals except identical twins and clones. (Variable)

61
Q

Describe environmental factors

A

The environment influences what proteins an organism needs to produce and in what quantity. Example factors would be temperature, nutrition, activity levels.

62
Q

Describe a Proteome

A

All of the proteins produced by a cell, tissue, or organism.

  • Because its a function of both the genome and the environment to which the organism is exposed, the proteome is both variable (over time) and unique to every individual (including identical twins and clones).
  • It reveals what is happening in an organism at a particular time. (FIXED)
63
Q

What stabilizes the 3-d conformation of proteins?

A

The 3-d conformation of proteins is stabilized by the bonds or interactions between R groups of amino acids within the molecule

64
Q

How are the bonds and interactions between R-groups of amino acids?

A

Most of the bonds/interactions are relatively weak and can be disrupted or broken.

65
Q

What is denaturation?

A

Change to the conformation of the protein

66
Q

Can a denatured protein return to its former structure?

A

Denaturation is permanent, so it can not return to its former structer.

67
Q

What happens to soluble proteins in denaturation?

A

Soluble proteins often become insoluble and form a precipitate

68
Q

Name and explain 2 things that cause denaturation

A

Heat can cause denaturation: vibrations within the molecule breaks the intermolecular bonds or interactions

Extremes of pH can cause denaturation: charges on R groups are changed, breaking ionic bonds within the protein or causing new ionic bonds to form.

69
Q

What is the optimum pH for Pepsin denaturation

A

1.5

70
Q

What are white smokers?

A

A particular kind of hydrothermal vent which produces very hot carbon dioxide gas. These vents can be found deep in oceans and produce tempratures in excess of 100 degrees C, but life can still be found around them

71
Q

What are thermophiles?

A

Organisms (often archea of eubacteria) that live in relatively hot conditions (45 to 122 degrees C)
-In order to survive, their proteins are stable at the higher than normal temperatures they experience

Biology HL (26 decks)

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