Global Influences of Microbes Flashcards
1
Q
What are the main protagonists of climate change?
A
CO2, methane and N2O
2
Q
Which organisms can fix carbon?
A
- Photoautotrophs (e.g. Cyanobacteria)
- Lithoautotrophs
- Facultative anaerobic purple bacteria
3
Q
What do photoautotrophs do?
A
Use energy from sunlight to convert CO2 and water into organic materials to be used in cellular functions such as biosynthesis and respiration
4
Q
Bind and convert Co2 into biomass
A
5
Q
What are the 2 parts to Co2 fixation by photoautrotrophs?
A
- Generation of energy
- Assimilation of Co2 through the Calvin cycle
6
Q
How does cyanobacteria generate energy for part 1 of Co2 fixation?
A
Through the light dependent reaction
7
Q
Describe the light dependent reaction
A
- Uses light energy to make energy storage molecule ATP and the reduced electron carrier NADPH
- Takes place in the thylakoid membranes of organelles (chloroplasts)
- Light is absorbed by pigments in PSII and passed between pigments to the reaction center
- Energy is transferred to P680, boosting an electron to a high energy level
- The high energy electron is passed to an acceptor molecule and replaced with an electron from water
- The splitting of water releases O2
- The high energy electron travels down an ETC, losing energy
- Some released energy drives the pumping of H+ ions from the stroma into the thylakoid interior, building a gradient
- As H+ ions flow down their gradient into the stroma, they pass through ATP synthase, driving ATP production (this is known as chemiosmosis)
8
Q
Describe the light independent (dark) reaction
A
- The electron from PSII arrives at PSI and joins the P700 special pair of chlorophylls in the reaction center
- Light energy absorbed by the pigments and passed into the reaction center boosts the electron in P700 to a very high energy level and it is transferred to an acceptor molecule
- The special pair’s missing electron is replaced by a new electron from PSII
- The high energy electron travels down a short second leg of the ETC where it is passed to NADP+ to make NADPH
9
Q
What are some impacts of climate change on oceans?
A
- influences composition, location and existence of carbon fixing microbes
- increased temperatures affects water salinity (ice cap melting) and wind
- may increase/decrease phytoplankton growth
- increase in surface runoff of nutrients (can lead to cyanobacterial blooms)
10
Q
What are cyanobacterial blooms?
A
Huge mat-like structures of organisms
11
Q
What are the 2 major consequences of cyanobacterial blooms?
A
- Biochemical O2 debt
- creation of anoxic regions
12
Q
What is biochemical O2 debt?
A
A decrease in O2 in the water due to microbial proliferation
13
Q
How are anoxic regions created?
A
- organisms sink to the floor when they die and are degraded by bacteria
- decaying plankton consume O2
14
Q
How does facultative anaerobic purple bacteria fix CO2?
A
Using the Calvin cycle
15
Q
How do Lithoautotrophs fix carbon?
A
Mostly under anaerobic conditions, generating their energy through the use of compounds (eg. hydrogen sulphide)
16
Q
True or False, both lithoautotrophs and facultative anaerobic purple bacteria use RuBisCo
A
True
17
Q
Describe the process of carbon cycling
A
- Primary fixers are consumed by grazers and decomposers
- Grazers are consumed by predators which are then consumed by higher predators
- Decomposers consume predators and higher predators
18
Q
Describe the role of the ocean as a carbon sink
A
- Co2 is absorbed by phytoplankton which sink to the ocean floor when they die
- These are not degraded fully as O2 is scarce
- This carbon has been compressed over millions of years => FOSSIL FUELS
19
Q
What are some ways carbon is released into the environment?
A
- Fossil fuels
- Respiration
- Methanogenesis
- Melting ice caps releases undecomposed organisms which then release carbon upon decomposition
20
Q
What are methanogens?
A
They are obligate anaerobes and chemoautotrophs
21
Q
How are methanogens chemoautotrophs?
A
They use H2 as a terminal electron acceptor during anaerobic respiration
(Generate energy by reducing Co2 to methane)
22
Q
Where do methanogens live?
A
In anoxic environments such as swamps and marshes, and the guts of most mammals
23
Q
What is the role of termites in relation to methanogens?
A
- Their gut contains a protist called Mixtricha paradoxa which degrades lignin to form acetate and organic acids
- ## The Co2 and H2 produced using fermentation are consumed by methanogens to make methane
24
Q
How can microbes be used as biofuels?
A
- A by-product of microbial fermentation is the production of alcohol
- Co2 is still produced but is carbon neutral (carbon fixed by plants = carbon used as fuel)
25
Advantages of bioethanol production
- Renewable energy source
- Carbon neutral
- Can be used alone or mixed with other liquid fuels
26
Disadvantages of bioethanol production
- Uses land to grow fuel crops that could have been used to feed people
- Production requires energy input
- Bioethanol can be damaging in non-compatible fuel systems
27
Rank the following feedstocks for ethanol production in order of easiest, harder, and hardest:
Sugar crops, Lignocellulosic material, Starch crops
Easiest = sugar crops
Harder = Starch crops
Hardest = Lignocellulosic material
28
Name the 4 diseases of cattle
- Bovine Tuberculosis (TB)
- Nagana
- Rinderpest
- Ringworm
29
What was the economic impact of Foot and Mouth disease?
- 6 million animals culled
- consequences to tourism, transport
- loss of £8 billion to economy
- Changes in food security practices
30
What are the symptoms of TB in cattle?
- Infected lymph nodes in head
- tubercles in the chest cavity and lungs
- weakness
- coughing
- weight loss
31
How is a mycobacterium killed by the immune system?
- Is phagocytosed into a phagosome (vacuole)
- The phagosome fuses with the lysosome
- Need activated macrophages to kill mycobacteria (activate by immune molecules to change the phenotype)
- T cell response produces cytokines which activate macrophages and eliminate bacteria
32
How does mycobacterium evade the immune system?
- They secrete protein and lipid factors that block phagosome maturation and prevent phagolysosome fusion
- Mycobacteria are resistant to acidification and reactive oxygen species
- Inhibits apoptosis and autophagy
33
How does TB evade the immune system long term?
Infected macrophages are phagocytosed by other macrophages and accumulate, forming lesions. This continues until death.
34
How is TB spread?
- Many potential reservoirs exist: deer, fox, rodents
- Badgers thought to transmit directly to cows
- Difficult to monitor and control spread from wildlife to cattle
35
Which strain of TB is used to vaccinate humans?
The Bacillus Calmette-Guerin (BCG) strain
36
What TB vaccines are available to cattle?
Vaccines are not successful in cattle, however injectable badger BCG vaccine has been working well so far in badgers
37
Which animals are affected by African animal trypanosomes (Trypanosomiasis)?
Cattle and other livestock
38
What are the symptoms of Trypanosomiasis in cattle?
- Swelling
- Fever
- Reduced milk production
- Fertility issues
- Weight loss
39
Which trypanosomes are responsible for Trypanosomiasis?
- T. congolense
- T. vivax
- T. brucei spp.
40
How do trypanosomes evade the immune response?
Antigenic variation
41
How does antigenic variation allow immune evasion of trypanosomes?
- Variant surface glycoprotein (VSG) switching alloes trypanosomes to change their coat protein, making it difficult to find one vaccine that will recognise all.
- Trypanosomes first induce an immune response and then change their antigen coat to prevent clearing
42
How is Trypanosomiasis treated?
Using drugs like diminazene aceturate, homidium bromide/chloride, isometamidium chloride
43
What are some measures used to prevent Trypanosomiasis?
- Breed trypanotolerant cattle
- Control vectors: remove fly using traps, bush clearing and insecticide
44
What is Rinderpest?
An acute, highly contagious viral disease of cattle, water buffalo and other wildlife
45
What virus is responsible for Rinderpest?
Morbillivirus
46
How is Rinderpest spread?
Through close contact - breath, secretions, excretions
47
What are some symptoms of Rinderpest?
Fever, diarrhoea, oral lesions
48
What is the long lasting effects of infection with Rinderpest?
Infected individuals develop a long lasting specific immune response to morbilliviruses:
- Reduced B cells, monocytes, neutrophils and some T cell types
49
Is Rinderpest eradicated?
Yes
50
What is ringworm?
It is a fungal infection of hair and keratinised layers of the skin (also known as dermatophytosis) (is a cattle infection)
51
Can zoonosis occur in ringworm from cattle to humans?
Yes, theough direct contact/bites
52
What is the name of the Ringworm fungi?
Trichophyton verrucosum
53
How do you treat ringworm?
Vaccines are available
54
What is the Foot and Mouth disease virus?
A picornavirus of cloven hoofed livestock (pigs, cows, sheep, goats)
55
How many serotypes of Foot and Mouth disease are there?
7, with serotype O responsible for 70% of global outbreaks
56
Describe how Foot and Mouth disease virus enters the cell
- The virus capsid protects the RNA genome while outside of the host cel and also allows entry into cells by binding to specific receptors
- RNA genome is then released into the cytoplasm of the cell
- Translation occurs to produce viral proteins, including non-structural proteins
- +ve sense RNA are packaged by capsid proteins to generate new virus particles
57
What are the symptoms of Foot and Mouth disease in cows?
- High fever
- loss of appetite and increased salivation
- depression
- drop in milk yield
- temporary immunosuppression
58
What are the long term effects of Foot and Mouth disease in cows?
Reduced milk production and lameness
59
Where is the primary site of infection and replication of FMDV?
In the mucosa of the pharynx
60
Describe the pathogenesis of FMDV in cows
- Virus can enter through skin lesions or GI tract
- Is then distributed throught lymphatic system
- Virus replicates in the epithelium of the mouth, muzzle, teats, feet, and areas of damaged skin
- Vesicles develop and rupture within 48 hours
- Animals that have been infected and recovered and those who have been vaccinated can become carriers
61
How is FMDV transmitted?
- Direct contact with infected animals
- Indirect contact with secretions or excretions from infected animals
- Mechanical vectors (people, horses, dogs, cats, birds, vehicles)
- Air movement over land or water
62
What makes FMDV so easily spread?
The virus is shed into milk in cows before clinical signs develop which means it can spread easily from farm to farm and cow to calf
63
Name 3 diagnostic tests used for FMDV?
- ELISA
- qPCR
- sequencing
64
Is there a vaccine for FMDV?
Yes, but immunity is short-lived
65
Name 4 challenges faced in vaccination against FMDV
- Existing vaccines are live, chemically attenuated so production is risky and costly
- There are 7 seeotypes, each with many variants due to a high mutation rate so it is challenging to produce a universal vaccine
- Intact virus is fragile and so costly to store and distribute
- Subunit vaccines are in development
66
What is Feline Immunodeficiency Virus (FIV)?
- Infection of T helper cells and thus impairs the immune system
- Is the cat equivalent of HIV so is a good model for HIV studies
67
What is a vaccine used against FIV?
Fel-O-vax, a chemical inactivated whole virus
68
What is Feline Leukaemia Virus (FeLV)?
Causes immunosuppression/deficiency, anaemia and lymphoma in cats
69
How is FeLV transmitted?
Through saliva, bites and licks
70
What are some symptoms of FeLV in cats?
- Loss of appetite
- Enlarged lymph nodes
- Persistent fever
- Pale gums
- Secondary infections
- Persistent diarrhoea
- Abortion
- inflammation of the gums
71
What are some treatments of FeLV?
- Vaccines (but not 100% effective)
- Treat secondary infections
- Keep cats indoors
72
How do you diagnose FeLV?
- ELISA
- PCR
- Virus culture
73
Why are diseases transmitted more easily in birds?
Because they travel much greater distances
74
What are the subtypes of avian influenza based off of?
Different combinations of haemagglutinin (H) and neuraminidase (N)
75
What is the role of haemagglutinin in avian influenza?
It recognises and binds to the host
76
What is the role of neuraminidase in avian influenza?
Release of new viral particles
77
Name some natural carriers of avian influenza that are resistant to severe infection
Wild migratory birds such as ducks, geese, gulls and shorebirds
78
How does direct infection occur?
Through exposure to saliva, mucus or faeces from infected birds
79
What are the two types of Avian influenza A viruses?
- Low pathogenicity avian influenza (LPAI) A viruses
- High pathogenicity avian influenza (HPAI) A viruses
80
What is the difference between LPAI and HPAI in terms of amino acids at the cleavage site?
LPAI do not contain a series of basic amino acids at the cleavage sites, whereas HPAI have multiple basic amino acids
81
What are some symptoms of avian influenza?
- Swollen head
- Closed, excessively watery eyes
- Lethargy, depression
- Loss of balance/tremors
- Drooping wings
- Twisting of head and neck
- Reduced egg production
- Respiratory distress
- Fever
- Loss of appetite
82
How is avian influenza diagnosed?
Based on history, clinical signs and post mortem analysis
83
How do you treat avian influenza?
There are no readily available treatments and it is difficult to treat all chickens due to vast number
84
What is trichomonosis?
A bird disease caused by the protozoan parasite Trichomonas gallinae
85
What are the signs of trichomonosis in birds?
Yellow deposits and lesions in the oral cavity which leads to malnutrition (can't eat properly) and then death
86
How is trichomonosis spread?
Via unwashed bird feeders
87
How do you prevent trichomonosis spreading?
Allow bird feeders to dry out
88
What is eimeria?
A parasitic infection that causes coccidosis in poultry and goats
89
How is eimeria transmitted?
Via the faecal-oral route
- is ingested, proliferates in the gut and is pooped out
- can be introduced through farmer's boots or new infected stock
90
What is the pathology of coccidosis?
- Replicates in intestinal epithelial cells
- Causes tissue damage, bloody diarrhoea, malabsorption of nutrients and death
91
What are some treatments of coccidosis?
- Chemotherapy
- Live-attenuated vaccine
- Housing of chickens that is not too warm, humid or crowded and ensure litter is cleared
92
Name 7 viruses that cause cancer in humans
- Epstein-Barr virus (EBV)
- Hepatitis B virus (HBV)
- Hepatitis C virus (HCV)
- Human papillomavirus (HPV)
- Kaposi's sarcoma herpesvirus (KSHV)
- Human T-lymphotrophic virus-1 (HTLV-1)
- Merkel cell polyomavirus (MCV)
93
What are some examples of cancer that EBV causes?
Burkitt's lymphoma, some Hodgkin's lymphoma, post-transplant lymphoma, and nasopharyngeal carcinoma
94
What type of cancer does HBV and HCV cause?
Liver cancer
95
Is there a vaccine available for HBV?
Yes
96
Is there a vaccine available for HCV?
No
97
Out of HBV and HCV, which is more prevalent?
HBV
98
What type of cancer does HPV cause, and is there a vaccine available?
Cervical cancer and yes
99
What are 2 examples of cancers that KSHV causes?
Kaposi's sarcoma and primary effusion lymphoma
100
Is there a vaccine against KSHV?
No
101
What cancer does HTLV-1 cause and is there a vaccine available?
Adult T-cell leukaemia and no vaccine
102
What cancer does MCV cause and is there a vaccine available?
Merkel cell carcinoma and no vaccine
103
Name 3 characteristics of a tumour causing virus
1. Persists in the host for a long time
2. Long interval before tumour development
3. Different mechanisms - direct or indirect
104
Name 3 viruses that have direct mechanisms of causing cancer
- Retrovirus
- KSHV
- HPV
105
Name 4 viruses that have indirect mechanisms of causing cancer (i.e. a side effect of infection)
- Retrovirus
- HCV
- HBV
- HIV-1
106
What are the 2 hypotheses that hypothesise why a virus would interfere with cell regulation?
The limited resource hypothesis and the anti-antivirus hypothesis
107
What is the limited resource hypothesis in cancer-causing viruses?
Where a virus infecting a cell to make a new virus uses a lot of amino acids and makes the cell utilise all of its resources into making new viral particles
108
What is the anti-antivirus hypothesis in cancer-causing viruses?
Where the virus combats the cell's anti-viral response (which is to go into senescence and die) to prevent the cell from dying
109
How does KSHV target cell growth pathways?
- Produces virus interleukin (makes new immune cells so virus can infect more cells)
- Sends signals for cells to constantly grow
- It controls apoptosis signals to keep the cell alive for production of more virus
-
110
What is p53 and what does it do?
It is a major anticancer that causes cells to go into apoptosis
111
How many types of HPV as cancer-causing?
There are 14 high-risk types
112
Which 2 HPV types cause 70% of cervical cancer and precancerous cervical lesions?
Types 16 and 18
113
Which levels are new viral HPV particles produced in the cervical epithelium?
L1 and L2
114
Which 2 E layers does differentiation occur in?
E2 to E1 layers
115
What are E6 and E7 and what do they do?
They are proteins of the HPV virus that interact with p53. E7 promotes cell proliferation E6 inhibits cell apoptosis
116
What happens when the HPV virus becomes integrated into the genome?
The E2 protein that normally controls E6 and E7 becomes disrupted and leads to aggressive tumours due to the now uncontrolled proliferation
117
How does cervical screening work in the UK?
- Sample cells from the cervix surface to look for signs of the basal layer at the top of epithelial cells
- If HPV is detected, the sample is checked under a microscope to look for abnormal cells
- If abnormal cells are detected then the patient is referred for a coloscopy
118
Which HPV types are the major causes of genital warts?
HPV 6 and 11
119
Which types if HPV does gardasil 9 protect against?
Types 6, 11, 16, 31, 33, 45, 52, and 58
120
How good is the HPV gardasil 9 vaccine?
Very good if given before the age of 17
121
What are 3 mechanisms that retroviruses use to create cancer?
Transducing, cis-activating, and trans-activating
122
What do transducing retroviruses have in their gene transcript?
A viral oncogene (v-onc) and sometime v-src
123
Name 3 things that cis-acting retroviruses do
1. Activate cellular oncogenes
2. Make RNA from DNA
3. Target regions of the genome that have roles in active transcription
124
Give 2 examples of cis-acting retroviruses
Avian leukosis virus and mouse mammary tumour virus
125
What occurs during viral insertional mutagenesis of cis-acting retroviruses?
Promoters and enhancers are inserted, which increases the amount of protein transcribed
126
What viral protein does trans-acting retroviruses contain?
Tax
127
What is Tax?
It is a transcriptional activator of LTR and a viral protein
128
What does Tax do to cause cancer?
- Regulates transcription of specific cellular genes
- Used by virus to turn on virus producer and own gene to drive growth
- Accidentally activates proliferator genes (e.g. rof-regulators in white blood cells)
129
Is HIV-1 an oncogenic virus?
No, it does not directly cause cancer itself
130
How does HIV-1 cause cancer?
It is an immunosuppressive disease which means that cancer cannot be eliminated by the immune system
131
What type of virus is HBV?
A DNA virus (double and single-stranded)
132
What is HBV?
It is a viral infection that attacks the liver and causes acute and chronic disease
133
What factor influences an individual's ability to clear HBV?
Age - young children have a weak immune system whereas >95% of adults clear infection
134
What conditions can develop in adults who are chronically infected with HBV?
Cirrhosis and/or liver cancer
135
What type of virus is HCV?
A cytoplasmic RNA virus
136
What is HCV?
A viral infection that attacks the liver can cause chronic or acute hepatitis
137
What is there a risk of within 20 years of HCV infection?
Cirrhosis
138
What can chronic HCV infection cause?
Hepatocellular carcinoma
139
How does HBV and HCV cause hepatocellular carcinoma?
- They drive the liver to a stage where cells are constantly dying and others are replicating to replace them
- Dysregulation of the mitochondria produces ROS free radicals
- The subsequent genome instability causes the cancer
140
Why does it take so long for cancer to develop in HBV and HCV?
Because the cells are constantly dying and being renewed
141
What vaccine is available for HBV?
The HBsAg vaccine
142
What long term therapy is available for HBV?
HBV antiviral drugs - reduces but does not eliminate risk of cancer
