infectious diseases (exam version)

what is a disease

a health condition in which the structure / function of parts of the body are negatively affected.

what is a sign

it can be observed and measured

what are examples of a sign

rashes, fever, high blood pressure

what is a symptom

can be described and felt by the patient but cannot be observed or measured

what are some examples of a symptom

nausea, fatigue, headache

what is the cause of infectious diseases

pathogens (microorganisms such as bacteria viruses fungi yeast)

causes of non-infectious diseases

hereditary (genes) / environment / lifestyle

bacteria

they are single-celled microorganisms which can cause infectious diseases and can be spread through bodily fluids, food and water

what are viruses

they are infectious agents that can cause various diseases and are often transmitted through direct contact, airborne transmission and contaminated surfaces

what are the structures inside a bacterial cell

• bacterial cell wall

• cytoplasm

• ribosome

• bacterial DNA

• plasmid DNA

• flagellum (optional)

function of bacterial cell wall

provide structural support and gives bacterial cell its shape

function of plasmid

small, circular DNA, responsible for antibiotic resistance (only some bacteria have this)

what is the function of flagellum

hair-like protein structure that helps the bacteria move by rotating

(one bacteria cell can have multiple, one, two, none, sixty seven…)

function of cytoplasm in bacteria

place where chemical reactions take place

ribosome function in bacteria

involved in protein synthesis

structure and function of genetic material in bacteria

• single strand circular DNA which is floating in the cytoplasm and not enclosed in nuclear membrane

is there nucleus in bacteria

haha no

how does virus reproduce and why

a virus needs to enter a host cell in order to reproduce because host cells contains the necessary materials for reproduction such as enzymes and ribosomes, which virus lacks

a virus cannot reproduce on its own because it does not have cellular structures such as cell membrane, cytoplasm or organelles like ribosomes and nucleus

what are the living and non-living characteristics of virus

non-living : it does not grow, feed, move, respire or excrete

living : reproduce?

what are the structures of protein

1. spike protein

2. membrane envelope

3. genetic material

4. protein coat

what is the location and function of spike protein

• found on membrane envelope

• spike protein helps virus bind to the host cell so that virus can enter the host cell and reproduce

what is the structure and function of membrane envelope

• made of lipids

• surrounds the protein coat as protection

(only some virus has it)

what is function of the protein coat

it is the outer covering that encloses the genetic material

compare the genetic material of virus and bacteria

virus : DNA or RNA

bacteria : DNA

how does the influenza virus transmit?

• respiratory droplets

• person touches surface contaminated with the virus and then touch nose eyes or mouth

how does the pneumococcal bacteria transmit

• respiratory droplets

what does the influenza virus target

respiratory systems

what does the pneumococcal disease target

ear, lungs, brain, spina cord, blood

what are the signs and symptoms of influenza

sign: high fever

symptom: headache, sore throat, chills, fatigue, muscle ache, unning nose

how to reduce transmission

1. avoid coming into close contact with infected people

2. wear a mask if feeling unwell

3. if you are sick, cover your mouth and nose with tissue when coughing or sneezing and dispose of the tissue properly

4. wash hands with soap and water or rub disinfectant if. you have touched objects contaminated with the pathogens

5. avoid touching eyes nose and mouth

6. get vaccinated

what is a vaccine

it contains an agent that resembles a pathogen and prevents infectious diseases by stimulating white blood cells ti quickly produce antibodies when the pathogen invades

FORMAT how does a vaccine work?

1. a vaccine contains an agent that resembles the pathogen or its antigen

2. when the agent enters the body, they stimulate the white blood cells cells to make antibodies to destroy pathogens

3. some of these WBCs who produced the antibodies remain in the bloodstream for a long time and offer long-term protection against a pathogen (memory cells)

4. in the future, if the live pathogen enter the bloodstream, memory cells will recognise them quickly and produce larger number of antibodies very quickly to destroy the pathogens before they can infect our cells and cause diseases

why won’t one type of vaccine work for another disease / another variant?

antibodies are specific in action, meaning that antibodies that destroy one type of pathogen will be ineffective against another type of pathogen

how do antibodies work?

they kill / prevent bacteria growth by:

1. inhibiting synthesis of bacterial cell wall

2. inhibiting cell membrane function

3. inhibition of protein synthesis

4. inhibition of enzyme action

antibiotics and cell wall?

1. cell wall is weakened

2. water enters the cell by osmosis

3. cell expands, bursts and dies

antibiotics and protein synthesis

1. ribosomes synthesis proteins

2. antibiotics bind to ribosomes

   1. prevent ribosomes from synthesising proteins and inhibits bacterial growth

antibiotics and enzyme action in cytoplasm

1. bacteria need flic acid or growth

2. some antibiotics inhibit enzymes needed to make folic acid

   1. inhibit bacterial growth

antibiotics and cell membrane

1. break up cell membrane

   1. cel no longer protected from its environment as any substances can move into and out of the cell

how does antibiotic resistance work?

1. in a population of bacterial cells, some are more sensitive to antibiotic X, wile others are less sensitive

2. when antibiotics X is taken, bacterial cells that are more sensitive are killed by initial dosage of antibiotics while less sensitive bacteria are not easily killed and may survive

3. if prescribed course of antibiotic X is not completed, less sensitive bacterial cells that survive will multiply and increase in numbers (less likely that all bacteria is killed)

   1. the subsequent generations of bacterial cells will be increasingly less sensitive to the antibiotics

how to reduce antibiotics resistance?

1. do not misuse or overuse antibiotics

2. complete full course of antibiotics prescribed by the doctor to ensure all bacterial cells are killed

   1. use antibiotics only when necessary and only for bacterial infection

why cant antibiotics work for viruses?

virus do not have cellular structures such as cel wall, cell membrane and ribosomes for antibiotics to act on

compare infectious diseases and no-infectious diseases

1. ID: can be transmitted NID: cannot be transmitted / non-transmissible

2. ID: caused by pathogen NID: caused by environmental, genetic, lifestyle factors

3. ID: direct contact transmission NID: cannot be spread through direct contact

why three injections of vaccine offer better protection than just one injection

• each injection boosts the production of memory cells

• leading other a stronger immune response with faster antibody recognition and quicker and higher antibody production

why are most vaccines given by injection rather than mouth?

1. antigens and agent is protein based

2. avoid alimentary canal because it will be denatured and digested by enzymes in the stomach acid

3. before they can be absorbed into the blood to function / stimulate WBCs

why do antibody concentration rise slower for vaccines

1. vaccine stimulate WBCs in blood to produce antibodies tat destroy the virus

2. time is needed for WBCs to recognise the new antigen in the vaccine

why antibody production speed is slower and peak antibody concentration is lower for first injection versus actual infection

1. when the vaccine is introduced, the WBCs take time to recognise the foreign antigens on the agent. WBCs multiply in numbers and produce antibodies that can destroy the agent

2. since vaccination causes some WBCs to remain in the bloodstream as memory cells, they were able to more quickly recognise the __ virus when the person is infected. this leads to a faster and greater antibody production to destroy the virus