6.2.1 - Structure Of Bacteria & Viruses

Question 1

What Are Bacteria?

Answer 1

Small, single-celled prokaryotes.

Question 2

What Features Do Bacterial Cells Have?
(9 Points)

Answer 2

~ Flagellum.

~ Ribosomes.

~ Cell wall.

~ Plasma / Cell membrane.

~ Capsule.

~ Plasmids.

~ Bacterial chromosome.

~ Pili.

~ Cytoplasm.

Question 3

What Are Viruses?
(2 Points)

Answer 3

~ Microorganisms, made of nucleic acids (DNA and RNA) surrounded by a protein.

~ Non-cellular infectious particles.

Question 4

What Is The Relative Size And Complexity Of Viruses Compared To Prokaryotic Cells?

Answer 4

Smaller and structurally simpler than prokaryotic cells.

Question 5

What Cellular Structures Do Viruses Lack?
(3 Points)

Answer 5

~ Plasma membrane.

~ Cytoplasm.

~ Ribosomes.

Question 6

What Components Make Up A Virus?
(5 Points)

Answer 6

~ Nucleic acid core.

~ Capsid.

~ Envelope.

~ Attachment proteins.

~ Proteins inside the capsid.

Question 7

Viruses Have A ‘Nucleic Acid Core’, What Is Meant By This?
(2 Points)

Answer 7

~ Contains either DNA or RNA.

~ Can be single or double stranded.

Question 8

Viruses Have A ‘Capsid’, What Is Meant By This?

Answer 8

Protein coat, protecting the genetic information of the virus.

Question 9

Viruses Have An ‘Envelope’, What Is Meant By This?
(2 Points)

Answer 9

~ Extra outer layer.

~ Made from membrane-phospholipids of the host cell.

Question 10

Viruses Have ‘Attachment Proteins’, What Is Meant By This?
(3 Points)

Answer 10

~ GP120.

~ Stick out from the edge of the capsid or envelope.

~ Allows the virus to attach to a host cells CD4 receptors.

Question 11

Viruses Have A ‘Proteins Inside The Capsid’, What Is An Examples Of This?

Answer 11

E.g. HIV has an enzyme called reverse transcriptase, that converts RNA -> DNA once it has infected a cell.

Question 12

What Can’t Viruses Survive Without?

Answer 12

Host cell.

Question 13

How Do Viruses Reproduce?

Answer 13

Infect living cells and use their components responsible for synthesising proteins to create new viral particles.

Question 14

What Is A Pathogen?

Answer 14

Any organism that causes disease.

Question 15

What Are Infectious Diseases?

Answer 15

Ones which are caused by pathogens.

Question 16

What Are Examples Of Pathogenic Microorganisms?
(3 Points)

Answer 16

~ Bacteria.

~ Fungi.

~ All viruses.

Question 17

What Does ‘HIV’ Stand For?

Answer 17

Human immunodeficiency virus.

Question 18

What Does HIV Do?

Answer 18

Infects and destroys T helper cells, which then acts as a host cell for the virus.

Question 19

What Type Of Virus Is HIV?

Answer 19

Retrovirus.

Question 20

How Is HIV Spread?

Answer 20

Through bodily fluids.

Question 21

Where Does HIV Replicate?

Answer 21

Inside the T helper cells.

Question 22

Describe The Process Of HIV Replication
(6 Points)

Answer 22

~ Attachment proteins (GP120) attaches to a receptor molecule (CD4) on the cell membrane of the host T helper cell.

~ Capsid is released into the cell, where it uncoats and releases RNA into the cells cytoplasm.

~ Inside the cell, reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template.

~ From this a double-stranded DNA molecule is made and inserted into the hosts DNA.

~ The hosts cell enzymes are used to make viral proteins from the viral DNA found within the human DNA

~ The viral proteins are assembled into new viruses, which bud from the cell and go on to infect T helper cells.

Question 23

What Will The Person With HIV Feel DURING The Initial Infection Period Of HIV?

Answer 23

Experience flu-like symptoms.

Question 24

What Happens AFTER The Initial Infection Period Of HIV?
(2 Points)

Answer 24

~ Replication drops.

~ Latency period occurs.

Question 25

What Happens During The Latency Period Of HIV?

Answer 25

The infected person won't experience any symptoms, often for years.

Question 26

What Does HIV Gradually Reduce?

Answer 26

The number of T helper cells in the immune system.

Question 27

If There Is A Low Number Of T Helper Cells In The Immune System What Is No Longer Activated Or Produced? (2 Points)

Answer 27

~ B cells are no longer activated. ~ No antibodies are therefore produced.

Question 28

What Does HIV Lead To?

Answer 28

AIDS.

Question 29

What Does 'AIDS' Stand For?

Answer 29

Acquired immune deficiency syndrome.

Question 30

What Is AIDS?

Answer 30

A condition where the immune system deteriorates and eventually fails.

Question 31

What Does AIDS Lead To?

Answer 31

Opportunistic infections.

Question 32

What Are Opportunistic Infections? (2 Points)

Answer 32

~ Diseases and infections that wouldn't cause serious problems in people with a healthy immune system. ~ E.g. TB.

Question 33

When Will A HIV Infection Progress To AIDS? (2 Points)

Answer 33

~ When an individual starts to suffer from constant opportunistic infections. ~ When the T helper cell count drops below a critical level.

Question 34

Describe How AIDS Progresses Through A Sequence Of Symptoms (4 Points)

Answer 34

~ The initial symptoms of AIDS include minor infections of mucous membranes and reoccurring respiratory infections, which is caused by a lower than normal number of T helper cells. ~ As AIDS progresses the number of T helper cells decreases further, patients become more susceptible to more serious infections. ~ During the final stages of AIDS a person will suffer from a range of more serious opportunistic infections, due to a very low number of T helper cells. ~ It is these opportunistic infections that kill AIDS patients.

Question 35

What Factors Affect How Quickly HIV Will Progress Into AIDS And How Long A Person With AIDS Will Survive? (4 Points)

Answer 35

~ Number of existing infections. ~ The strain of HIV the person is infected with. ~ Age. ~ Access to healthcare.

Question 36

What Causes Tuberculosis (TB)?

Answer 36

Mycobacterium tuberculosis.

Question 37

How Does A Person Become Infected With TB? (6 Points)

Answer 37

~ When tiny droplets containing the bacteria are inhaled into the lungs, inhaled from an infected persons cough or sneeze. ~ TB bacteria once in the lungs is engulfed by phagocytes, where it survives and reproduces. ~ Overtime the infected phagocytes become encased in tubercles in the lungs, where the bacteria will remain dormant. ~ The infected person shows no obvious symptoms at this point. ~ Later the dormant bacteria may become reactivated and overcome the immune system, usually done when the immune system is compromised and weakened. ~ The person will then develop TB, which varies between individuals.