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Biology: Alex > Topic 6 > Flashcards

Topic 6 Flashcards

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1
Q

Describe the role of Microorganisms in decomposing dead matter

A
  1. Secrete enzymes that decompose dead organic matter into smaller molecules they can respire
  2. With respiration methane and Co2 are released, recycling carbon into the atmosphere
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2
Q

Why is it useful to establish time of death

A
  1. Info about circumstances

2. Can be established by looking at 3 different factors

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3
Q

What are the 5 ways TOD can be established

A
  1. Body temperature
  2. Degree of muscle contraction
  3. Forensic entomology
  4. Extent of decomposition
  5. Stages of succession
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4
Q

Describe body temp for TOD

A
  1. Mammals produce heat from metabolic reactions
  2. Humans 37 degrees
  3. Metabolic reactions stop after death so body falls to temp equal to surroundings
  4. Human body’s cool at a rate of 1.5 -2 c and hour
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5
Q

What 3 things can affect cooling rate

A
  1. Air temp
  2. Body weight
  3. Clothing (insulated)
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6
Q

Degree of muscle contraction

A
  1. 4-6 hours after death s rigormortis
  2. Muscle cells deprived of oxygen so respite anairobicly, lactic acid build up
  3. pH of cells decrease due to acid, inhibiting ATP enzymes
  4. No ATP to break actin-myosin cross bridge so muscles become fixed
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7
Q

What affects rigor mortis

A
  1. Degree of muscle development
  2. Temperature
  3. Smaller muscles contract first and larger last
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8
Q

Forensic entomology

A
  1. Dead body quickly colonised
  2. Type of insect colonise at different stages
  3. Stage of lifecycle also useful
  4. Drugs and temp will affect life cycle
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9
Q

Extent of decomposition

A
  1. Immediately after death Bactria and enzymes decompose body
  2. Extent of decomposition to establish TOD
  3. Affected by temp and o2 availability
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10
Q

Name what a body looks like at each 5 stages

A
  1. Hour-few days: greenish, Bactria and enzymes break tissue and cells
  2. Days- weeks: bloated, skin blisters and falls off. Microorganisms decompose so give off gas
  3. Few weeks: tissue seeps out
  4. Months-years only skeleton
  5. Decades to centuries: skeleton disintegrates
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11
Q

Stage of succession

A
  1. Types of organisms found in body changes over time
  2. TOD by stage of succession
  3. Location and above ground affect this
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12
Q

What are the 5 stages of succession

A
  1. Immediately: bacteria
  2. As bacteria decompose tissue: flies and larve
  3. Break up more for beetles
  4. Drys up so flies leave and bettles stay
  5. When all tissue gone no organism
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13
Q

Name the 5 steps of creating a DNA profile

A
  1. DNA sample obtained
  2. PCR
  3. Fluorescent tag added
  4. Gel Electrophoresis to separate DNA
  5. Gel viewed under UV light
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14
Q

What is the purpose of PCR

A
  1. Polymerase chain reaction to make millions of copies so specific region
  2. Enough to make a profile
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15
Q

What’s in the PCR mixture

A
  1. DNA sample
  2. Free nucleotides
  3. Primers
  4. DNA polymerase
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16
Q

What is a primer

A

Short price of DNA, complementary to base at start of specific fragment

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17
Q

Describe PCR process

A 
1. Mixture heated to 95
To break H bonds 
2. Cooled to 55 so primers can bind 
3. Heated to 72 so DNA polymerase can line up nucleotides to complementary bases in template strand 
4. Base pairing forms new strand 
5. Lots of cycles
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18
Q

Fluorescent tag

A

Fluorescent tag added so DNA fragments can be viewed under UV light

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19
Q

Describe gel electrophoresis

A
  1. DNA placed in well in gel and covers in conducting buffer solution
  2. DNA negatively changed so moves towards positive electrode
  3. Shorter fragments move faster so travel further
  4. Ladder of fragments of known length used for comparison
20
Q

Name 7 features of a bacteria

A
  1. Flagellum for moving
  2. Ribosomes to make proteins from mRNA
  3. Cell wall
  4. Plasma (cell) membrane
  5. Protective slime capsule
  6. Plasmid loops of DNA
  7. Most DNA free floating in CYTOPLASM
  8. Pili to stick and chromosome transfer
21
Q

Describe the basic structure of a virus

A

Nucleus acid surrounded by protein coat

22
Q

Name 5 parts of a virus structure

A
  1. Core of nucleic acid (DNA or RNA)
  2. Protein coat (capsid) around core
  3. Envelop stolen from previous host cell
  4. Attachment proteins
  5. Some carry proteins inside their capsid
23
Q

Describe a pathogen

A
  1. Any organism that causes a disease

2. Inc bacteria fungi and all viruses

24
Q

How is HIV caught

A
  1. Inflected bodily fluids come into contact with mucosal surfaces or damaged tissue
  2. Enter bloodstream
  3. Sex
25
Q

Describe how HIV replicates

A
  1. Glucoprotien on capsid bind to CD4 receptor on T helper cell
  2. Binds to membrane and releases viral RNA into cytoplasm
  3. Reverse transcriptase used to make viral DNA gene using RNA as template
  4. Intergrase incorporates viral DNA to make viral proteins
  5. New virus assembled and leaves cell, taking part of membrane with it (destroys cell)
26
Q

When are people classed with AIDS

A
  1. When immune system deteriorates and fails

2. Symptoms of failing immune system

27
Q

What are opportunistic infections

A

Diseases that wouldn’t cause problems with healthy immune systems

28
Q

Name the 3 stages AIDS develops in

A
  1. Initial symptoms of minor infections and reoccurring respiratory infections
  2. T helper cell decrease leads to more serious infections
  3. Very low number of T helper cells leads to cancer or toxoplasmosis
29
Q

What affects survival time for someone with AIDS

A
  1. Existing infections
  2. Strain of HIV
  3. Age
  4. Healthcare
30
Q

What causes TB

A

Mycobacterium tuberculosis inhaled in tiny droplets from an infected person

31
Q

Why has TB occurrences declined

A
  1. Better living conditions

2. Anti-biotics

32
Q

Why is TB bacteria hard to kill?

A

Waxy cell wall makes very hard to hydrolyse. This means phagocytes cannot present antigen so lymphocytes cannot attach

33
Q

What is the body’s response when infected with TB

A
  1. Creates tubercles (mass of cells) around bacteria

2. Primary infection produces no symptoms

34
Q

How can TB be reactivated

A

When the infection was really big or the immune system is now weakened by something like AIDS

35
Q

What are the symptoms of active TB

A
  1. Persistent cough: irritated by tubercles
  2. Coughing up blood (vessels damaged)
  3. Breathing problems (reduces exchange surface)
  4. Extreme fatigue (lack of oxygen)
36
Q

Define anti-biotic

A

Chemicals that kill or inhibit growth of microorganisms

37
Q

What are the two types of antibiotic

A

Bactericidal: kill
Bacteriostatic: prevent bacteria growing

38
Q

Describe 2 ways antibiotics work

A
  1. Inhibit enzymes to make cell walls, means they burst because of osmosis
  2. Inhibit protein production by binding to bacterial ribosomes. Cannot carry out metabolic processes as no enzymes
39
Q

Why aren’t humans or viruses effected by antibiotics

A
  1. Eukaryotic cells don’t have cell walls, different enzymes and larger ribosomes. Can be designed to target only bacteria
  2. Viruses don’t have their own enzymes and ribosomes so aren’t affected
40
Q

What is an HAI

A

Hospital acquired infections

41
Q

What are the two types on incorrect diagnosis

A
  1. False negative: has disease but now shown

2. False positive: vaccine shows up as real infection

42
Q

Who is at most risk of acquiring active TB

A
  1. Babies and old people: weaker immune system
  2. People with chronic diseases
  3. HIV
  4. Those on immuneo suppressants
43
Q

Why are people more likely to become ill at a hospital

A
  1. Already weakened immune system

2. Around other ill people

44
Q

Name 3 measures taken to reduce HAIs

A
  1. Staff and visitors have to wash hands
  2. Surfaces and equipment disinfected (radiation)
  3. Contagious people isolated in wards
45
Q

Define anti-biotic resident bacteria

A
  1. More common In hospitals as more antibiotics used here

2. So more likely to have evolved a resistance

46
Q

What are 5 codes of practice to reduce antibiotic-resistant bacteria

A
  1. Antibiotics no prescribed for minor infections
  2. Only use narrow spectrum antibiotics
  3. Patient should complete course of antibiotics prescribed
47
Q

Describe heard immunity

A

Once 95% are immune it is unlikely the 5% will pass it on

Biology: Alex (44 decks)

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