5.2: Phagocytosis

Question 1

Phagocytosis

Answer 1

Phagocytosis is the process in which invading microorganisms are:
1. Engulfed
2. Destroyed
by specific white blood cells known as phagocytes

Question 2

If a pathogen is to infect the body, it must first do what?

Answer 2

If a pathogen is to infect the body, it must first gain entry

Question 3

If a pathogen is to infect the body, it must first gain entry.
The body’s first line of defence is to form a physical or chemical barrier to entry.
Should this fail, the next line of defence is the white blood cells.
How many types of white blood cells are there?

Answer 3

There are 2 types of white blood cells:

1. Phagocytes
2. Lymphocytes

Question 4

If a pathogen is to infect the body, it must first gain entry.
The body’s first line of defence is to form a physical or chemical barrier to entry.
Should this fail, the next line of defence is the white blood cells.
There are 2 types of white blood cells phagocytes and lymphocytes
Phagocytes ingest and destroy the pathogen by a process called phagocytosis before it can cause harm.
What are lymphocytes involved in?

Answer 4

Lymphocytes are involved in immune responses

Question 5

Despite various barriers, pathogens still frequently gain entry and the next line of defence is then what?

Answer 5

Despite various barriers, pathogens still frequently gain entry and the next line of defence is then phagocytosis

Question 6

In the blood, the types of white blood cells that carry out phagocytosis are known as phagocytes.
They provide an important defence against the pathogens that manage to enter the body.
Some phagocytes travel in the blood, but can do what?

Answer 6

Some phagocytes travel in the blood, but can move out of blood vessels into other tissues

Question 7

The process of phagocytosis:

The phagocyte is attracted to the pathogen by what?

Answer 7

The phagocyte is attracted to the pathogen by chemical products of the pathogen

Question 8

The process of phagocytosis:

The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to do what?

Answer 8

The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient

Question 9

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along what?

Answer 9

The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient

Question 10

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
What does the phagocyte have on its cell-surface membrane?

Answer 10

The phagocyte has several receptors on its cell-surface membrane

Question 11

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
The phagocyte has several receptors on its cell-surface membrane that do what?

Answer 11

The phagocyte has several receptors on its cell-surface membrane that:
1. Recognise
2. Attach to
chemicals on the surface of the pathogen

Question 12

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
The phagocyte has several receptors on its cell-surface membrane that recognise and attach to chemicals on the surface of the pathogen.
What does the phagocyte do?

Answer 12

The phagocyte engulfs the pathogen to form a vesicle from the cell-surface membrane

Question 13

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
The phagocyte has several receptors on its cell-surface membrane that recognise and attach to chemicals on the surface of the pathogen.
The phagocyte engulfs the pathogen to form a vesicle from the cell-surface membrane, known as a what?

Answer 13

The phagocyte engulfs the pathogen to form a vesicle from the cell-surface membrane, known as a phagosome

Question 14

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
The phagocyte has several receptors on its cell-surface membrane that recognise and attach to chemicals on the surface of the pathogen.
The phagocyte engulfs the pathogen to form a vesicle from the cell-surface membrane, known as a phagosome.
What do lysosomes within the phagocyte do?

Answer 14

Lysosomes within the phagocyte:

1. Move towards the vesicle
2. Fuse with it

Question 15

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
The phagocyte has several receptors on its cell-surface membrane that recognise and attach to chemicals on the surface of the pathogen.
The phagocyte engulfs the pathogen to form a vesicle from the cell-surface membrane, known as a phagosome.
Lysosomes within the phagocyte move towards the vesicle and fuse with it.
What do the lysosomes do?

Answer 15

The lysosomes release their lysozymes into the phagosome

Question 16

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
The phagocyte has several receptors on its cell-surface membrane that recognise and attach to chemicals on the surface of the pathogen.
The phagocyte engulfs the pathogen to form a vesicle from the cell-surface membrane, known as a phagosome.
Lysosomes within the phagocyte move towards the vesicle and fuse with it.
The lysosomes release their lysozymes into the phagosome.
The lysozymes destroy ingested bacteria by what?

Answer 16

The lysozymes destroy ingested bacteria by hydrolysis of their cell walls

Question 17

The lysozymes destroy ingested bacteria by hydrolysis of their cell walls.
The process is the same as that for what?

Answer 17

The process is the same as that for the digestion of food in the intestines

Question 18

The lysozymes destroy ingested bacteria by hydrolysis of their cell walls.
The process is the same as that for the digestion of food in the intestines, namely what?

Answer 18

The process is the same as that for the digestion of food in the intestines, namely the hydrolysis of:
1. Larger, insoluble molecules
into
2. Smaller, soluble ones

Question 19

The process of phagocytosis:
The phagocyte is attracted to the pathogen by chemical products of the pathogen, causing the phagocyte to move towards the pathogen along a concentration gradient.
The phagocyte has several receptors on its cell-surface membrane that recognise and attach to chemicals on the surface of the pathogen.
The phagocyte engulfs the pathogen to form a vesicle from the cell-surface membrane, known as a phagosome.
Lysosomes within the phagocyte move towards the vesicle and fuse with it.
The lysosomes release their lysozymes into the phagosome.
The lysozymes destroy ingested bacteria by hydrolysis of their cell walls.
What happens to the what hydrolysis products from the breakdown of the pathogen?

Answer 19

The soluble hydrolysis products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte