speciation

Question 1

what is speciation

Answer 1

establishment of species by origin by the use of analytical techniques

Question 2

how is speciation done

Answer 2

sampling of tissue, food, fluid or other organic matter

Question 3

what is the aim of speiciation

Answer 3

determine from a sample what species the sample came from

Question 4

why is speciation important

Answer 4

food fraud
medical testing
forensics
protection of rare spieces

Question 5

what types of approaches are used for speciation

Answer 5

utilise genetic differences between species via PCR or RT PCR - based on the gene

immunologic assays - ELISA, biosensors - Based on the gene product

Question 6

food production is a —— pound industry

Answer 6

multi billion

Question 7

what type of legislation is in place to protect the consumer

Answer 7

extensive

Question 8

when were food laws passed about food adulteration

Answer 8

recently

Question 9

how can we now detect and monitor food fraud

Answer 9

recent technological advancments

Question 10

what is adulterated foods

Answer 10

food containing poisons, colouring, other additives to disguise, inferior quality or where an important constituent has been substituted

Question 11

what is the most common for of adulteration

Answer 11

substitution of cheaper ingredient for a more expensive one

Question 12

when was food adulteration a main problem

Answer 12

19th century

Question 13

what was tea normally padded out with

Answer 13

gun powder

Question 14

what was the most adulterated staple

Answer 14

bread - add boiled potato, sawdust. chalk, clay, bone dust,

Question 15

cream thickened with what

Answer 15

calf brains

Question 16

name the methods of speciation

Answer 16

antibody based
DNA based
Infer-red spectroscopy
mass spectroscopy

Question 17

why use an ELISA for speciation

Answer 17

widely used in food 
compared to other methods it is highly sensitive
cheap
rapid
requires little training
antibodies readily available

Question 18

what is an ELISA

Answer 18

quantitative method used to measure antigens and antibodies
based on antigen/antibody interactions
antibodies produced in immune resoponce
antibodies are specific to a particular antigen

Question 19

what is an antibody

Answer 19

glycoprotein that recognise and bind to a particular antigen with very high specifity

Question 20

advantages of polyclonal antibodies

Answer 20

broad specify

cheap

Question 21

disadvantages of polyclonal

Answer 21

finate supply

Question 22

advantages of monoclonal antibodies

Answer 22

narrow specifity

continuous supply

Question 23

disadvantages of monoclonal antibodies

Answer 23

expensive

Question 24

advantages of recombinant antibodies

Answer 24

narrow specify

genetic manipulation

Question 25

disadvantages of recombinant antibodies

Answer 25

expensive | poor stability

Question 26

what is a recombinant antibody

Answer 26

bacteria fungi plants

Question 27

what is a monoclonal antibody

Answer 27

mouse rat hybridoma cells

Question 28

what is a polyclonal antibody

Answer 28

``` rabbit sheep goat house chicken ```

Question 29

advantages of ELISA

Answer 29

``` qualitative and quantitative detect antigen and how much is present can detect in serum, urine, saliva etc detect antibodies to indicate disease (HIV) can also use for environmental testing ```

Question 30

what will a specific assay only detect

Answer 30

desired analyse - won't give positive results with any other protein

Question 31

what is the limit of detection

Answer 31

lowest amount of antigen needed to be detected

Question 32

the lower the detection limit the ----

Answer 32

more sensitive the elisa

Question 33

describe reactants in an ELISA

Answer 33

once bound stay attached to the solid surface. washing steps- resulting in the removal of unbound reagents allow easy measurement of bound complex.

Question 34

what are ELISA normally carried out in

Answer 34

96 well micro titre plate allowing large analysis of large number samples

Question 35

what is the normal means of measurement in an ELISA

Answer 35

enzyme labelled component | normally peroxidase or phosphate conjugates

Question 36

simple ELISA is ----

Answer 36

direct detection

Question 37

Indirect ELISA is ---

Answer 37

indirect detection

Question 38

sandwich ELISA is ----

Answer 38

direct detection

Question 39

competitive ELISA is

Answer 39

both direct and indirect

Question 40

what are the disadvantages of an simple ELISA

Answer 40

primary antibody, must be labelled with enzyme or other label uses a lot of antibody, unsatisfactory when primary antibody is in short supply/ expensive

Question 41

describe advantages of simple ELISA

Answer 41

quick simple few steps avoids potential cross reactivity which may occur when using secondary antibodies

Question 42

advantages of indirect ELISA

Answer 42

labelled secondary antibody increases signal strength as several labelled secondary antibodies can bind to primary a single second antibody can be used with variety of primary antibodies made in same species secondary antibody is species specific

Question 43

disadvantages of indirect ELISA

Answer 43

more steps than direct | potential cross reactivity of secondary antibody

Question 44

describe direct sandwich ELISA

Answer 44

antibody imobilised into plate to capture antigen and extract from a sample antigen can be directly detected using labelled primary antibody or indirectly using primary antibody followed by labelled secondary antibody

Question 45

advantages of sandwich ELISA

Answer 45

highly specific used to extract minute amounts of antigen which is too small to be directly absorbed onto micro titre surface highly sensitive

Question 46

Disadvantages of sandwich ELISA

Answer 46

require 2 antigen specific antibodies | many steps involved

Question 47

common problems associated with ELISA include

Answer 47

non specific binding - can be due to other substance in sample, limited by blocking plate interference binding - due to other substance in sample problems with reagents - antibodies - many buffers used