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Biology U4 > 6A > Flashcards

6A Flashcards

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1
Q

What is DNA virus

A

Have DNA as their genetic material

Lambda phage

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2
Q

What is RNA virus

A

Viruses that have RNA as the genetic material

TMV and Ebola

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3
Q

RNA retrovirus

A

RNA that produces DNA
- reverse transcriptase catalyse the production of viral DNA from single strand of RNA

The new viral DNA is incorporated into the host DNA where it acts as a template to produce viral protein and RNA

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4
Q

Process of lysogenic step 1

A

Bacteriophage attaches to bacterium

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5
Q

Process of lysogenic step 2

A

Phage DNA is injected into host cell. It brings about the synthesis of viral enzyme

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6
Q

Process of lysogenic step 3a

A

Viral DNA is incorporated into host cell DNA

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7
Q

Process of lysogenic step 3a2

A

Viral DNA is replicated each time the bacterium divides without causing any damage

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8
Q

Process of lysogenic step 2 to 3B

A

Phage DNA inactivated the host DNA and takes over the cell biochemistry

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9
Q

Lag phase

A

Population increase slowly as the population adjust to the new environment and starts to reproduce

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10
Q

Log phase

A

Lots of nutrients and space - exponential growth of the population double each divisions

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11
Q

Stationary phase

A

Population reaches it maximum as it is limited by its environment
Eg. Lack of resources and toxic waste product

During this phase the no. Of microorganisms dying equals the number being produced by binary fission and the growth curve level off

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12
Q

Death phase

A

Lack of nutrients and build up of toxic waste , death rate exceed rate of reproduction- population decline

Death rate increases:
Nutrients insufficient for growth
Accumulating waste —> lower pH —> bacteria can’t grow

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13
Q

How are tuberculosis spread

A

By droplets infection airborne

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14
Q

Why is it difficult to control TB by vaccination

A

Increased in elderly people: less effective immune system

HIV:increase TB

Increased poverty:overcrowding

Wars and political unrest : densely populated

Mobile population: tourism , global trade and refugees

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15
Q

Where does the TB initially infect

A

Affects the respiratory system, damaging and destroying lung tissue

It suppresses the immune system making the body less able to fight the disease

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16
Q

Symptoms of TB

A

Fever

Fatigue

Coughing

Lung inflammation

May spread to other parts of the body which can cause organ failure

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17
Q

What happens in primary infection

A

Bacteria is inhaled into the lungs and slowly multiply causing no symptoms

If the immune system is fully active it will cause a localised inflammatory response , engulfing the bacteria and for making a mass of tissue called tubercule

After a while the inflammation would fully disappear and lungs heal

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18
Q

What happens in the active stage

A

Some bacteria is able to survive past the primary infection stage as they have an thick waxy outer layer which protects them from enzyme of the macrophages
—>which allows them to do so allowing them to remain dormant and reproduce until the immune system is weak the will cause active tuberculosis

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19
Q

Active stage continued step 1

A

Active TB result in deactivation of old or controlled infections

The bacteria reproduce rapidly causing rather noticeable symptoms
—> night sweat
Loss of appetite and weight loss

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20
Q

Active stage continued step 2

A

Patient will start to cough out liquid produced by the lungs called septum

If the infection gets more severe the lungs is damaged heavily the patient will start to cough blood

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21
Q

Active stage continued step 3

A

Alveoli start to breakdown and produce large inefficient air sacs

The bacteria also attacks T cell to stop production of antibodies
Although the body raise its temperature to kill bacteria
The bacteria can survive up until 42c and the metabolic enzyme start to denature at 40c

Eventually the patient dies due to organ failure no respiration or due to invasion by opportunistic disease

22
Q

What microorganisms provides to grow

A

Nutrients —> glucose/amino acids
=respiration —> energy

Oxygen —> respiration
*anaerobic microorganisms would require the absence of oxygen

Optimum pH - enzyme reaction

Optimum temperature- enzyme reaction

23
Q

Why microorganisms should be cultured with great care

A
  • always risk that a mutation could lead to the formation of pathogenic strains

-pathogenic bacteria from the environment could contaminate the bacterial culture being investigated

24
Q

State the hazard and precautions of this practical

A

Naked flame: keep away from flammable material

Bacteria is biohazard use disinfectant and wash hands, dispose of bacteria safely

Disinfectant is flammable keep away from naked flame

25
Q

Why should the lid not be completely taped to the Petri dish

A

To allow oxygen to enter the Petri dish preventing the growth of harmful anaerobic bacteria

26
Q

Why is the Petri dish incubated upside down

A

To prevent condensation from forming on the lid and dripping down onto the agar

27
Q

Aseptic technique

A

Buying sterile equipment or sterilizing reusable equipment with a Bunsen burner flame and ethanol

Cleaning surface before and after with ethanol

Using Bunsen burner or other flame to heat the air causing it to rise and carry away airborne microorganisms

28
Q

Stomach acid

A

If you eat or drink something that contains pathogens
—> killed by stomach acid due to acidic conditions of the stomach

Some may survive and pass into the intestines where they can invade cells of the gut wall and cause disease

29
Q

How can the Skin prevent infection

A

Acts as a physical barrier to pathogen

*if there is damage your skin , pathogen on the surface can enter your bloodstream

The blood clots at the area of damage to prevent pathogens from entering but some may get in before the clot form

30
Q

When Gut and skin flora prevent infection

A

Your intestine and skin are naturally covered with harmless microorganisms

Lactic acid is also released which kills bacteria

They compete with pathogens for nutrients and space
—> limit the number of pathogen living in the gut on the skin and make it harder for them to infect the body

31
Q

What can sebum protect against

A

An oily substance produced by the skin which contains chemical that inhibit the growth of microorganisms

*washing - using antibacterial soap can reduce your resistance to disease by destroying the natural pH balance and surface flora of the skin

32
Q

What is lysozyme prevent infection

A

Mucosal surface produce secretion . These secretion contain an enzyme lysozyme
—> lysozyme kill bacteria by damaging their cell wall
——-> makes bacteria burst open (lyse)

33
Q

Define endotoxins

A

Lipopolysaccharides that are integral part of the outer layer of the cell wall of gram negative bacteria and act s toxin to other cell
- effect around site of bacterial infection
—fever
— vomiting
—diarrhoea

34
Q

Define exotoxins

A

Soluble protein produced and released into the body by the bacteria as they metabolism and reproduce in the cell of their host; these proteins act as toxin in different ways

35
Q

Host tissue invasion

A

Pathogen is by invading host tissue and damaging the cells. The response of the host organism cell damage causes the symptoms of disease

36
Q

Eukaryotic vs bacteria

A

Bacteria contains:
-Cytoplasm that doesn’t have membrane bound organelle
-ribosome that are smaller (70s)
-no nucleus

37
Q

Capsule function

A
  • prevent dehydration of the bacteria
    -protects the bacteria as it cover the marker receptors
38
Q

Function of flagellum

A

Long hair like structure that rotates to make the prokaryotes cell move

39
Q

Function of pilli

A
  • attachment to host cell
    -for sexual reproduction ( gene transfer)
40
Q

Define plasmid

A

Small circular piece of DNA that code for specific aspect of bacterial phenotype

41
Q

Define nucleiod

A

The area in a bacterium containing the single circular loop of coiled DNA

42
Q

What does gram positive bacteria contain

A

Thick layer of peptidoglycan- teichoic acid

The crystal violet complex in the gram stain is trapped in the thick peptidoglycan layer and resist de colouring when bacteria are dehydrated using alcohol

Bacteria don’t pick up the red safranin counterstain and appear purple

43
Q

Gram negative bacteria

A

Thin layer of peptidoglycan with no teichoic acid between the two layers of membrane

Outer membrane is made up of lipopolysaccharides

This layer dissolves when the bacteria are ethanol

—> exposes the thin peptidoglycan layer and the crystal violet is washed out

The peptidoglycan takes up the red safranin counterstain - red

44
Q

What does virus have

A

1) all viruses have capsid made out of capsomere
2) nucleiod acid of DNA or RNA and antigens known as VAPs which target proteins in the host cell surface membrane
3) envelope

45
Q

Lysis step 1

A

The viral genetic material is transcribed and translated to produce new viral components

46
Q

Lysis step 2

A

The component assembled into mature virus that accumulated inside the host cell

47
Q

Lysis step 3

A

Eventually the host cell will burst which release large no. Of virus each of which can infect the new host cell - cell lysis

48
Q

Retrovirus

A

1) viral RNA entered the host cell.
2) viral RNA is translated to viral DNA by reverse transcriptase in the cytoplasm
3)viral DNA is incorporated into the host DNA in the nucleus where it acts as a template to produce viral proteins and RNA

49
Q

Method of spread vectors

A

Living organism that transmit from one host to another

50
Q

Inhalation

A

When you cough sneeze or talk droplets are expelled from your respiratory tract
1) when the droplets are inhaled by another individual the pathogens enter into a new respiratory tract and another infection is established

51
Q

Ingestion

A

Many pathogens that caus egut disease to be transmitted by faecally contaminated food or drink

52
Q

Describe the sequence of symptoms that result in the death of a person infected with mycobacterium tuberculosis

A

1) in the beginning the person will have breathing problems
2) as the infection become worse, lung tissue becomes damaged and blood is coughed up in the sputum
3) then TB causes suppression of immune system as T cell and antibodies reduces
4) the patient will high fever
5) as the lungs becomes less capable to take in oxygen for respiration death of the patient may result

Biology U4 (9 decks)

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