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Topic 6 complete Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

how do microorganisms decompose dead matter?

A

they secrete enzymes that decompose the matter into small molecules that they can respire

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2
Q

when microorganisms respire what is released?

A

methane and carbon dioxide

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3
Q

what 4 things help determine time of death?

A

body temperature, forensic entomology, muscle contraction, extent of decomposition

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4
Q

what is the internal human body temperature?

A

37 degrees Celsius

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5
Q

what is algor mortis?

A

the process of the body cooling to match the temperature of the surroundings

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6
Q

how many degrees does body temperature drop per hour?

A

1.5-2

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7
Q

what 3 things can affect how quickly a body cools?

A

air temperature, clothing and body weight

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8
Q

what is rigor mortis?

A

the muscles of a dead body contracting and becoming stiff

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9
Q

when does rigor mortis occur?

A

4-6 hours after death

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10
Q

why does rigor mortis happen?

A

muscle cells become deprived of oxygen
anaerobic respiration takes place
lactic acid builds up and pH decreases
enzymes which produce ATP denature
bonds between myosin and actin remain fixed

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11
Q

what is forensic entomology?

A

the study of the body being quickly colonised by a variety of different insects

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12
Q

how can time of death be estimated using forensic entomology?

A

by identifying the type of insect present
flies after a few hours, beetles afterwards
blowfly eggs hatch 24 hours after being laid

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13
Q

what happens at hours- a few days after death?

A

cells and tissues broken down by bodies enzymes and bacteria
skin turns green

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14
Q

what happens a few days- a few weeks after death?

A

microorganisms decompose tissue and organs which produces methane- body bloats
skin blisters and falls off

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15
Q

what happens a few weeks after death?

A

tissues begin to liquify

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16
Q

what happens a few months- a few years after death?

A

only skeleton remains

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17
Q

what happens decades to centuries after death?

A

skeleton beings to disintegrate

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18
Q

what 2 things affect speed of decomposition?

A

temperature and oxygen availability

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19
Q

what are the stages of succession on the body?

A

bacteria decompose tissue
flies lay larvae
flies feed and make favourable conditions for beetles
body dies and flies leave
Beetles eventually leave

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20
Q

what are the 5 steps of DNA profiling?

A

obtain sample
PCR used to amply DNA
Fluorescent tag added
gel electrophoresis used to separate DNA
gel viewed under UV light

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21
Q

where can a sample of DNA be obtained from?

A

blood, saliva etc

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22
Q

what are the steps of PCR?

A

melt, anneal, extend

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23
Q

what happens during PCR melting?

A

reaction mixture of DNA, free nucleotides, primers and DNA polymerase set up
mixture heated to 95 degrees C to break H bonds

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24
Q

what are primers?

A

short pieces of DNA that are complementary to the bases at the start of the fragment you want

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25
Q

what is the enzyme used in PCR?

A

DNA dependant DNA taq polymerase- used due to high optimum temperature

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26
Q

what happened during PCR anneal?

A

mixture cooled to 50-65 degrees C so the primers can bind (anneal) to the strand

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27
Q

what happens during PCR extend?

A

mixture heated to 72 degrees C
(so Taq polymerase can work)
DNA polymerase lines up free nucleotides alongside each template strand
new strands are formed

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28
Q

how many strands are made in the first cycle of PCR?

A

2 strands (doubles each time)

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29
Q

why is a florescent tag added?

A

added to the DNA fragments so they can be viewed under uv light (in the practical we use stain)

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30
Q

why is gel electrophoresis used?

A

used to separate the DNA fragments by length

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31
Q

what are the steps of gel electrophoresis?

A

DNA is placed into well in gel
gel is covered with buffer solution that conducts electricity
current is passed through gel and DNA moves towards the positive anode
smallest moves furthest

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32
Q

what happens after gel electrophoresis?

A

gel is viewed under uv light
fragments are viewed as bands
can compare how closely related people are by comparing their brands

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33
Q

what are the 3 uses of DNA profiling?

A

seeing how closely related people are
can be used to prevent inbreeding in animals
can match people to evidence at crime scenes

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34
Q

are bacteria prokaryotic or eukaryotic?

A

prokaryotic- no nucleus

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35
Q

do bacteria or viruses have a membrane?

A

bacteria

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36
Q

do bacteria or viruses have a cytoplasm?

A

bacteria

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37
Q

do bacteria or viruses have ribosomes?

A

bacteria

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38
Q

do bacteria or viruses have flagellum?

A

some but not all bacteria

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39
Q

do bacteria or viruses have DNA?

A

chromosomal and plasmids in bacteria, viruses RNA or DNA

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40
Q

do bacteria or viruses have capsids?

A

viruses

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41
Q

do bacteria or viruses have pili?

A

bacteria

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42
Q

do bacteria or viruses have a slime capsule?

A

bacteria

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43
Q

do bacteria or viruses have a cell wall?

A

bacteria

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44
Q

do bacteria or viruses have an envelope?

A

viruses

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45
Q

do bacteria or viruses have attachment proteins?

A

viruses

46
Q

do bacteria or viruses have enzymes?

A

viruses

47
Q

are viruses or bacteria smaller?

A

viruses

48
Q

what is the function of flagellum?

A

rotate for movement

49
Q

what is the function of pili?

A

help stick cells together and used in gene transfer

50
Q

what is the function of the slime capsule?

A

helps protects the bacterium from immune system cells

51
Q

what are the folds in the plasma membrane called?

A

mesosomes

52
Q

what is the function of a cell wall?

A

supports the cell

53
Q

what is the bacterial cell wall made of?

A

peptidoglycan

54
Q

what size ribosomes do bacteria have?

A

70s (small)

55
Q

what is the function of ribosomes?

A

produce proteins

56
Q

where does the envelope of a virus come from?

A

stolen from the cell membrane of the previous host cell

57
Q

what is the function of attachment proteins?

A

let the virus attach to a host cell

58
Q

how do bacteria reproduce?

A

through binary fission

59
Q

how does HIV replicate?

A

virus binds to CD4 receptor on T-helper cell using GP120
capsid released into the cell and releases RNA
reverse transcriptase viral RNA->DNA
integrase inserts viral DNA into host DNA
host replicates all DNA
protease assembles new viral particles which are released killing the T-helper cell

60
Q

what is the latency period?

A

during initial infection of HIV person may experience flu-like symptoms, after this HIV drops to lower level and doesn’t experience any symptoms this is the latency period

61
Q

how does HIV cause AIDS?

A

HIV causes T-helper cells to drop
people are classed as having AIDS when their T-Helper cell levels drop below a certain level

62
Q

what are the steps after someone has AIDS?

A

minor infections due to low T-helper cell levels
more serious opportunistic infections
very serious and often deadly infections

63
Q

what are the stages of a TB infection?

A

droplets containing bacteria are inhaled
phagocytes in the lungs take up bacteria
bacteria survive and replicate in the phagocytes
immune system seals off infected phagocytes in tubercles
bacteria in tubercles become dormant
bacteria eventually become reactivated and overcome the immune system
TB can also spread from the lungs to other organs and can lead to organ failure and death if untreated

64
Q

what are the symptoms of TB?

A

cough, weight loss, chest pain, fever

65
Q

why can the TB bacterium in the tubercles not be destroyed by the immune system?

A

because the bacterium are in phagocytes which have self antigens

66
Q

what bacterium causes TB?

A

mycobacterium tuberculosis

67
Q

define pathogen

A

any organism that causes disease

68
Q

what are the 5 barriers of the non-specific immune response?

A

skin, gut and skin flora, stomach acid, hairs, lysozyme

69
Q

how does lysozyme kill bacteria?

A

by damaging their cell walls which makes the bacteria burst open

70
Q

define antigen

A

anything that causes an immune response

71
Q

what type of protein is lysozyme?

A

globular

72
Q

what is the first step of inflammation?

A

the blood clotting cascade

73
Q

what releases histamines in the non-specific immune response?

A

damaged white blood cells and mast cells

74
Q

what are the effects of histamine?

A

increase blood flow, permeability of capillaries increases, vasodilation occurs

75
Q

define oedema

A

swelling

76
Q

what are the 2 types of phagocytes?

A

neutrophils and macrophages

77
Q

what are phagocytes?

A

white blood cells that engulf bacteria

78
Q

what happens during phagocytosis?

A

macrophage ingests debris from damaged cells, material is enclosed in a vesicle/ phagocytic vacuole in the cytoplasm, lysosome fuses with vacuole releasing enzymes which breakdown material, phagocyte becomes an antigen presenting cell

79
Q

what are interferons?

A

globular proteins

80
Q

what do interferons do?

A

inhibit protein synthesis which stops viral replication, activates specific immune response

81
Q

what are the 2 stages of the specific immune response?

A

the humoral response and the cell mediated response

82
Q

what is the type of cytokine in the specific immune response?

A

interleukins

83
Q

what cell produces antibodies?

A

B cells/ plasma cells

84
Q

what are antibodies made of?

A

4 polypeptide chains- 2 heavy and 2 light

85
Q

what are the different regions in antibodies?

A

each chain has a variable region (where the antigen binds) and a constant region
both the heavy chains also have a hinge region

86
Q

what type of bonds hold the polypeptide chains in antibodies together?

A

disulfide bridges

87
Q

what are the 3 ways antibodies fight infections?

A

agglutinating pathogens- clumping pathogens together for easy phagocytosis
neutralising toxins- antibodies bind to toxins so toxins cannot affect host cells
prevent pathogen from binding to host cells- bind to antigen and block receptors

88
Q

what are the 2 types of antibody?

A

membrane-bound or secreted

89
Q

how are membrane-bound antibodies structurally different to secreted antibodies?

A

membrane bound have an extra section of protein that anchors them to the B cell

90
Q

what are the 4 types of immunity?

A

active natural, active artificial, passive artificial, passive natural

91
Q

give an example of active natural immunity

A

when you become immune after catching a disease

92
Q

give an example of active artificial immunity

A

when you create antibodies for an antigen from a vaccine

93
Q

give an example of passive natural

A

antibodies in breast milk

94
Q

give an example of passive artificial

A

immunity from a vaccine with antibodies

95
Q

does active immunity give long or short term protection?

A

long term but takes a while for the protection to develop

96
Q

does passive give long or short term protection?

A

short term but immediate

97
Q

what are the 6 ways pathogens can evade the immune system?

A
  1. variation in antigenic properties (mutations)-HIV &influenza
  2. kill host cells they infect-HIV
  3. hide inside cells-TB
  4. hide inside genome- HIV
  5. preventing phagocytosis- TB
  6. prevent antigen presentation- HIV
98
Q

what are the 2 types of antibiotics?

A

bacteriostatic and bactericidal

99
Q

what do bacteriostatic antibiotics do?

A

slows the bacteria reproduction and control the population numbers

100
Q

what do bactericidal antibiotics do?

A

kill bacteria

101
Q

what is the advantage of broad spectrum antibiotics?

A

good if you don’t know what the bacteria is

102
Q

what are the disadvantage of broad spectrum antibiotics?

A

will kill beneficial bacteria as well
expose lots of bacteria to the antibiotic and encourage more resistance

103
Q

what are the advantages of narrow spectrum antibiotics?

A

good if you know what your treating
less secondary infections
less bacteria exposed so less general resistance

104
Q

what are the disadvantages of narrow spectrum antibiotics?

A

time and money spent identifying bacteria

105
Q

what are narrow spectrum antibiotics?

A

antibiotics which are species specific

106
Q

what are broad spectrum antibiotics?

A

kill lots of different types of bacteria

107
Q

what should be done to stop HAIs spreading?

A

medical staff should wash hands between patients
equipment and bedding should be sterilised between uses
patients with HAIs should be isolated
staff should not wear long sleeves- bare below the elbows

108
Q

what should be done to prevent antibiotic resistance spreading?

A

doctors shouldn’t prescribe antibiotics for minor infections
doctors shouldn’t prescribe antibiotics for prevention
use narrow-spectrum antibiotics whenever possible
rotate use of antibiotics
patients should finish full course of antibiotics

109
Q

what are introns?

A

sections of DNA that don’t code for amino acids

110
Q

during transcription what is copied into pre-mRNA?

A

both introns and exons

111
Q

what is splicing?

A

introns are removed and exons are joined to form mRNA (this is post-transcriptional change)

112
Q

what is alternative splicing?

A

sometimes some exons are removed as well as the introns- this produced more than one amino acid sequence from one gene and so more than one protein can be made from one gene

Biology (9 decks)

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