cell bio lab quiz 3

What does ELISA stand for?

Enzyme linked immunosorbent assay

What does ELISA use to detect proteins?

antibodies

What type of samples can ELISA be performed on?

blood, urine

ELISA Step 1

binding of antigen to walls of microtiter plate

Role of polystyrene in microtome plate?

bind proteins by hydrophobic interactions

ELISA step 2

binding of antibody to the antigen, typically use two (indrect)

Primary antibody is specific for ___

antigen

Secondary antibody is linked to __

HRP (Horse Radish Peroxidase)

ELISA step 3

detection of antigen, HRP breaks colorless substrate into colored products

What are two big medical applications for ELISA?

pregnancy tests, disease detection

What protein does the antibody detect in a pregnancy test?

Human chorionic gonadotropin (HCG), found in urine

Pro to ELISA

Highly sensitive and specific

Cons to ELISA (2)

False positive/negative, negative results doesnt always mean theres no infection

Define cytoplasmic streaming

flow of cytoplasm in eukaryotic plant and animal cells

Cytoplasmic streaming is an _ or _ based process

actin, microtubule

Function of cytoplasmic streaming?

Cytoplasmic reorganization, delivery of nutrients and metabolites

Where do chloroplasts move in Elodea?

Along inner cell wall

Why would lower pH slow streaming?

Denature motor protein

Why would darkness followed by sudden light exposure increase streaming?

Chloroplasts position themselves for optimal light absorption

Why dont Janus and neutral red change streaming?

They’re vital stains

Why does cytochalasin D stop streaming?

Disrupts actin filaments

Why is streaming still present after taxol is added?

it prevents microtubule disassembly

Cytochalasin and taxol are made in DMSO solutions. Why is a DMSO alone control necessary?

To confirm that it doesnt stop streaming by itself

Define lectins

glycoproteins that cause cell agglutination

How does agglutination work?

The lectin ligand will bind to lectin receptors on surfaces of neighboring cells by interacting with the side chain

Con A

Coupled with HRP, reacts with peroxidase substrate to make a colored product

How does the sugar competition assay work?

Free sugar outcompetes

If less agglutination after adding sugar, then…

sugar forms the side chain on Con A receptor

If more agglutination after adding sugar, then…

sugar does NOT form side chain on Con A receptor

Define PCR

use extracted DNA to product DNA products of known size

Define gel electrophoresis

Separate DNA fragments by size (smaller = farther), move from negative to positive electrode

What is TBE buffer made of?

Tris, borate, EDTA

What composes the gel loading dye and what is the dye’s purpose?

bromophenol blue and xylene cyanol, visual tracking of DNA migration

Purpose of glycerol in electrophoresis?

Ensure that DNA in sample forms a layer at bottom of well

Purpose of gel red in agarose?

Visualize DNA