2.4 Proteins

Question 1

What are proteins comprised of?

Answer 1

Long chains of amino acids

Question 2

What do all amino acids share?

Answer 2

A common basic structure

Question 3

What is the basic structure of amino acids?

Answer 3

A central carbon atom attached to an amine group, a carboxylic acid group, a hydrogen atom and a variable side chain

Question 4

How many different amino acids are there?

Answer 4

20

Question 4

Where are amino acids joined together?

Answer 4

On the ribosome

Question 5

What are the long chains of amino acids called?

Answer 5

Polypeptides

Question 6

What do polypeptides make up?

Answer 6

Proteins

Question 7

How does each type of amino acid differ?

Answer 7

The composition of the variable side chain

Question 8

What causes each proteins fold and function differently?

Answer 8

Because they have a different distinct chemical properties

Question 9

Why do proteins fold and function differently?

Answer 9

To work in accordance to its specific position within the polypeptide chain

Question 10

Why are organisms capable of producing a huge range of possible polypeptides?

Answer 10

Because most polypeptide chains have 50 - 2000 amino acid residues

Question 11

What is the bonding between amino acids?

Answer 11

Covalent bonding

Question 12

What type of reaction is needed to join amino acids?

Answer 12

Condensation reaction

Question 13

What is the covalent bond between the amino acids called?

Answer 13

A peptide bond

Question 14

How can polypeptide chains be broken down?

Answer 14

Hydrolysis reactions

Question 14

What does amino acids joining together form?

Answer 14

A dipeptide and water

Question 15

What does the breakdown of polypeptide chains require and why?

Answer 15

Water to reverse the process

Question 16

Where do the peptide bonds form?

Answer 16

Between the amine and carboxylic acid groups of adjacent amino acids

Question 17

What forms water during the formation of a peptide bond?

Answer 17

The amine group losing a hydrogen atom and the carboxylic acid loses a hydroxyl (OH) creating water

Question 18

What is the order of amino acid sequence called?

Answer 18

Primary structure

Question 19

What does primary structure determine?

Answer 19

The way the chain will fold

Question 20

Why will different amino acid sequences fold into different configurations?

Answer 20

Due to the chemical properties of the variable side chains

Question 21

What will amino acids commonly fold into?

Answer 21

Secondary structures

Question 22

What is it called when the amino acids fold into two stable configurations?

Answer 22

Secondary structures

Question 23

When do alpha helices occur?

Answer 23

When the amino acid sequence folds into a coil/spiral arrangement

Question 24

When do beta pleated sheets occur?

Answer 24

When the amino acid sequence adopts a directionally oriented staggered strand conformation

Question 25

What causes both alpha helices and beta pleated sheets?

Answer 25

Hydrogen bonds forming between non adjacent amine and carboxyl groups

Question 26

What happens when no secondary structure exists?

Answer 26

The polypeptide chain will form a random coil

Question 27

What is the tertiary structure?

Answer 27

The overall three dimensional configuration of the protein

Question 28

What determines the tertiary structure of a polypeptide chain?

Answer 28

The interactions between the variable side chains

Question 29

What are four examples of interactions between the variable side chains?

Answer 29

Hydrogen bonds Disulphide bridges Ionic interactions Polar associations

Question 30

What affects the overall shape of the polypeptide chain?

Answer 30

The affinity or repulsion of side chains

Question 31

What determines all levels of protein folding?

Answer 31

Primary structure

Question 32

What determines the affinity or repulsion of side chains?

Answer 32

The position of specific amino acids within a sequence

Question 33

What is it called when certain proteins have a fourth level of structural organisation?

Answer 33

Quarternary structure

Question 34

Where do you find quaternary structures?

Answer 34

In proteins that have more than one polypeptide chain linked together

Question 35

What type of structure is it when a protein has an inorganic prosthetic group as part of their structure?

Answer 35

Quaternary structure

Question 36

Will all proteins have a quaternary structure and explain your answer?

Answer 36

No as many proteins only have a single polypeptide chain

Question 37

What is an example of a protein with a quaternary structure?

Answer 37

Haemoglobin

Question 38

How many and what polypeptide chains does haemoglobin have?

Answer 38

Four two alpha chains Two beta chains

Question 39

Apart from multiple polypeptide chains what does haemoglobin have to make it have a quaternary structure?

Answer 39

A prosthetic group

Question 40

What is denaturation?

Answer 40

Denaturation is a structural change in a protein that results in the loss of its biological properties

Question 41

What will cause the tertiary structure to alter its activity and why?

Answer 41

Any change or abrogation to the tertiary structure as the way a protein folds determines its function

Question 42

What are the two key conditions that can cause denaturation?

Answer 42

Temperature and pH

Question 43

What will high levels of thermal energy do to the proteins?

Answer 43

Break the hydrogen bonds that holds the protein together, causing them to unfold and lose its ability to function

Question 44

What does changing the pH of a protein do?

Answer 44

Alter the charge which alter the proteins solubility and overall shape

Question 45

What is the perfect temperature or pH called?

Answer 45

The optimum

Question 46

What is a gene?

Answer 46

A gene is a sequence of DNA which encodes a polypeptide sequence

Question 47

What is a gene sequence converted into?

Answer 47

A polypeptide sequence

Question 48

What are the two processes that convert gene sequence into a polypeptide sequence?

Answer 48

Transcription and translation

Question 49

What does transcription do?

Answer 49

Makes an mRNA transcription based on a DNA template

Question 50

What does translation do?

Answer 50

Uses the instructions of the mRNA transcript to link amino acids together

Question 51

Typically one gene will code for what?

Answer 51

One polypeptide

Question 52

What are the three exceptions to the fact that one gene will code for one polypeptide?

Answer 52

Genes may be alternatively spliced to generate multiple polypeptide variants Genes encoding tRNA sequences are transcribed but never translated Genes may be mutated and consequently produce an alternative polypeptide sequence

Question 53

What is the proteome?

Answer 53

All of the proteins expressed within a cell, tissue or organism at a certain time

Question 54

Why are proteomes of any given individual unique?

Answer 54

As protein expression patterns are determined by an individuals gene

Question 55

Is the proteome larger or smaller than the number of genes in an individual?

Answer 55

Larger

Question 56

What are the two reasons a proteome may be larger than the genes in a person?

Answer 56

Gene sequences may be alternatively spliced following transcription to generate multiple protein variants from a single gene Proteins may be modified following translation to promote more variations

Question 57

What are the different functions of proteins? (shits me)

Answer 57

Structure Hormones Immunity Transport Sensation Movement Enzymes

Question 58

What are two examples of the protein function structure?

Answer 58

Collagen Spider silk

Question 59

What is collagen?

Answer 59

Component of the connective tissue of animals

Question 60

What is spider silk?

Answer 60

A fibre spun by spiders to make webs

Question 61

What are two examples of the protein function hormones?

Answer 61

Insulin Glucagon

Question 62

What is insulin?

Answer 62

Protein produced by the pancreas and triggers a reduction in blood glucose levels

Question 63

What is glucagon?

Answer 63

Protein produced by the pancreas that triggers an increase in blood glucose levels

Question 64

What is an example of the protein function of immunity?

Answer 64

Immunoglobulins

Question 65

What are immunoglobulins?

Answer 65

Antibodies produced by plasma cells that are capable of targeting specific antigens

Question 66

What are two examples of the protein function transport?

Answer 66

Haemoglobin Cytochrome

Question 67

What is haemoglobin?

Answer 67

A protein found in red blood cells that is responsible for the transport of oxygen

Question 68

What is cytochrome?

Answer 68

A group of proteins located in the mitochondria and involved in the electron transport chain

Question 69

What is an example of the protein function sensation?

Answer 69

Rhosopsin

Question 70

What is rhodopsin?

Answer 70

A pigment in the photoreceptor cells of the retina that is responsible for the detection of light

Question 71

What are two examples of the protein function movement?

Answer 71

Actin Myosin

Question 72

What is actin?

Answer 72

Thin filaments involved in the contraction of muscle fibres

Question 73

What is myosin?

Answer 73

Thick filaments involved in the contraction of muscle fibres

Question 74

What is an example of the protein function enzymes?

Answer 74

Rubisco

Question 75

What is rubisco?

Answer 75

An enzyme involved in the light independent stage of photosynthesis