V L4: Protein markers in Forensics Flashcards Preview

1st Year sem 2: Forensic Identification > V L4: Protein markers in Forensics > Flashcards

Flashcards in V L4: Protein markers in Forensics Deck (64)
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1
Q

what are polypeptide polymers?

A

proteins

2
Q

what are the building blocks for proteins?

A

amino acids

3
Q

what do amino acids contain?

A

chiral carbon with 4 groups attached

4
Q

How do amino acids differ?

A
  • size
  • charge
  • chemical properties
5
Q

what does an amino acid sequence determine?

A

determines protein conformation

6
Q

what are the four levels of structure?

A

primer
secondary
tertiary
quaternary

7
Q

The information contained in the genes in the DNA is transcribed into _____ and the _____ contained in the mRNA are translated into an _____ ______ _______.

A

mRNA
codons
amino acid sequence

8
Q

whats a codon?

A

3 consecutive nucleotides

9
Q

antibodies bind to?

A

antigens

10
Q

what are ANTIBODIES?

A

proteins that circulate in the blood, are made by the immune system in response to an invasion by antigens.

11
Q

what is an ANTIGEN?

A

substance (usually foreign) capable of reacting with an antibody. A foreign substance that can elicit antibody formation is known as an immunogen

12
Q

Binding of antigen-antibody is specific to the _____ of the antigen and the _____ site of the antibody. The complex formed is ______.

A

epitope
binding
reversible

13
Q

what shape is an antibody?

A

Y shaped protein

14
Q

How many chains does an antibody have?

A

4 amino acid residue chains

15
Q

what type of chains does an antibody have?

A

2 heavy

2 light

16
Q

what are the antigen binding sites on an antibody?

A

Complementarity determining regions

17
Q

what are the 5 classes of antibodies?

A

IgG, IgA, IgM, IgD, and IgE

18
Q

what are the 2 types of antibodies?

A

Polyclonal and monoclonal antibodies

19
Q

whats another word for a specific type of antigen ?

A

immunogen

20
Q

An immunogen contains a small portion known as an ______ which is recognised by an antibody.

A

epitope

21
Q

whats it called when theres more than one epitope on an immunogen ?

A

multivalent

22
Q

what can a epitope do?

A

elicit product of its own antibody

23
Q

who discovered the ABO system ?

A

Landsteiner 1901

24
Q

How many blood types are there, what are they?

A
4 
A
AB
B
O
25
Q

what sugar does O allele have?

A

no extra sugar

26
Q

what sugar does A allele have?

A

N-acetylgalactosamine

27
Q

what sugar does a B allele have?

A

galactose

28
Q

what antibodies does blood type A have?

A

A

29
Q

what antibodies does blood type B have?

A

B

30
Q

what antibodies does blood type AB have?

A

A and B

31
Q

what antibodies does blood type O have?

A

none

32
Q

The ABO gene is on what chromosome?

A

9

33
Q

A and B alleles are ______

A

codominant

34
Q

If you know the blood type of the parents, can you figure out the possible genotypes of the children?

A

yes

35
Q

How big is the ABO locus?

A

18kb in size with 7 exons

36
Q

The DNA sequence of A and B alleles differ by what?

A

7 single nucleotide substitutions

37
Q

___ of the ____ SNP’s translate into different amino acids

A

4

7

38
Q

what are the 4 SNPs that translate into different amino acids?

A

R176G
G235S
L266M
G268A

39
Q

what amino acid residue is most important in determining if it will be A-trsnferase or B-transferase?

A

266 and 268

40
Q

what are some ABO typing Advantages ?

A

Cheap and simple to perform

other markers increases accuracy

41
Q

what are some ABO typing limitations?

A

Highly sensitive and specific

relatively little individual discrimination

42
Q

whats a polymorphic gene?

A

A gene is said to be polymorphic if more than one allele occupies that gene’s locus within a population, leads to abnormal protein.

43
Q

Allele frequencies vary between ?

A

ethnic groups

44
Q

what are isoenzymes?

A

same enzyme reaction, different amino acid sequence

45
Q

Name 6 Isoenzymes?

A
Phosphoglucomutase (PGM)
Esterase D (EsD)
Adenosine deaminase (ADA)
Erythrocyte acid phosphatase (EAP)
Adenylate kinase (AK)
Glyoxalase (GLO)
46
Q

when was Phosphoglucomutase described?

A

1960s

47
Q

where is Phosphoglucomutase encoded?

A

Encoded at the PGM1 locus at chromosome 1

48
Q

whats the abbreviation for Phosphoglucomutase?

A

PGM

49
Q

Where can PGM be found?

A

PGM can also be found in semen

50
Q

what cases is PGM good for?

A

sexual assault cases

51
Q

PGM subgroups that can be detected by what?

A

isoelectric focusing

52
Q

what does Haemoglobin consist of?

A

consists of 2 α chains and 2 β chains

53
Q

when is feta Hb used?

A

cases of infantside and concealed birth

54
Q

Sickle cell Hb links too?

A

ethnic origin

55
Q

what 2 major isoenzymes are found in Human α-amylases?

A

Human salivary α-amylase (HSA).

Human pancreatic α-amylase (HPA)

56
Q

Identification of saliva is based on the detection of ?

A

HSA

57
Q

what is used for the detection of HSA?

A

primary binding assays
Immunochromatographic assays
enzyme linked immunosorbent assay (ELISA) techniques.

58
Q

what used when characterising proteins?

A
Centrifugation
(differential/rate-zonal)
SDS-PAGE 
Liquid Chromatography
Antibody assays
Mass spectrometry
59
Q

Sodium Dodecyl Sulphate (SDS)Polyacrylamide Gel Electrophoresis (PAGE)

A
  1. Β-MEOH breaks down the disulfide bridges
  2. SDS/heat unfolds the subunits of the protein
  3. Negatively charged linearised peptides are sieved through a gel mesh under an electric field
  4. Smaller peptides travel faster towards the + electrode than larger peptides.
  5. A size marker is run alongside samples
60
Q

what’s Liquid chromatography?

A

Protein fractionation through porous matrix within a column

61
Q

How does liquid chromatography work?

A

Proteins interact differently with different matrices and differ in time spent bound to the matrix

62
Q

what is Western blotting also knows as?

A

immunoblotting

63
Q

Specific proteins can be identified after SDS-PAGE separation using a labelled _____.

A

antibody

64
Q

How does western blotting work?

A
  1. blot proteins from the gel onto a sheet of nitrocellulose paper or nylon membrane using an electric field
  2. Soak membrane in solution with the labelled antibody.