Cell Surfaces

Question 1

What major cell processes do cell surfaces (due to their many interactions) play a role in?

Answer 1

cell division

cell fusion

tissue organization

tissue growth

Question 2

What are agglutinins?

Answer 2

enzymes that bind to specific carbohydrates or glycoproteins on cell surfaces and cause an aggregation of cells = clumping tissues

Question 3

Describe the structure of agglutinins that allow them to clump cells together

Answer 3

they have 2+ identical binding sites which means they can bind to 2+ carbohydrates or glycoproteins on cell surfaces and cause clumps of cells

Question 4

What are agglutinins in mammals called?

Answer 4

antibodies

Question 5

what are agglutinins in plants called?

Answer 5

lectins

Question 6

What is an example of a lectin?

Answer 6

Concavalin A

Question 7

What is the purpose of antibodies causing agglutination?

Answer 7

antibodies bind to antigens (viruses/pathogens/infectious cells) and clump them which make it more difficult for the antigen to spread and easier for macrophages to engulf them

Question 8

What do antibodies bind to on antigens?

Answer 8

the proteins and/or polysaccharides on the surfaces of antigen cells

Question 9

How can agglutinins help us identify which carbohydrates exist on cell surfaces?

Answer 9

if a particular agglutinin is known to cause clumping in a particular cell type, that agglutinin can be used in a series of tests with different carbohydrates to observe clumping vs. not clumping to determine which carbohydrates exist on the cell surface

Question 10

What can be concluded if agglutination occurs in an experiment?

Answer 10

that the sugar used in the solution with the agglutinin is NOT present on the cell surface because nothing prevented the agglutinin from binding the cells together

Question 11

What can be concluded if agglutination does not occur in an experiment?

Answer 11

that the sugar used in the agglutinin solution IS present on the cell surface because it prevented the binding of the agglutinin to the cell surface

Question 12

Describe Concavalin A

Answer 12

A lectin (agglutinin) isolated from jack beans that can agglutinate a variety of cells including adipocytes, lympcytes, and cancerous cells

Question 13

Why is Con A an important agglutinin for research?

Answer 13

it is known to prevent tumour growth in some cells

Question 14

Describe the lab conducted

Answer 14

Baker’s yeast (S. cerevisiae) was exposed to a series of experimental solutions containing Con A lectin and different carbohydrates (glucose, fructose, galactose, lactose)

Question 15

What 4 sugars were used in this experiment?

Answer 15

glucose
fructose
galactose
lactose

Question 16

What were the 2 controls of this experiment?

Answer 16

negative control: yeast only

positive control: yeast + ConA

Question 17

What was the purpose of the negative control?

Answer 17

the yeast only solution provided no results to ensure that the yeast cells will not clump on their own

Question 18

What was the purpose of the positive control?

Answer 18

yeast + ConA was tested to make sure the ConA will clump the yeast cells in the absence of sugars

Question 19

What were the 4 treatments?

Answer 19

yeast/ConA/glucose

yeast/ConA/fructose

yeast/ConA/galactose

yeast/ConA/lactose

Question 20

Which 2 sugars resulted in no agglutination?

Answer 20

glucose and fructose

Question 21

Which 2 sugars resulted in agglutination?

Answer 21

galactose and lactose

Question 22

Which sugars are present on the yeast cell surfaces? explain

Answer 22

glucose and fructose

they prevented ConA from binding to the cell surfaces and agglutinating the cells

Question 23

Which sugars were not on the yeast cell surfaces? explain

Answer 23

galactose and lactose

they did not prevent ConA from binding to the yeast cells, so agglutination occurred