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A Level Biology > Topic 2.2 Prokaryotic Cells > Flashcards

Topic 2.2 Prokaryotic Cells Flashcards

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1
Q

How else can you classify bacteria (not just by their cells walls)?

A

Shape e.g. cocci, bacilli, spirilla, vibrios

Respiratory requirements e.g. if they need oxygen or not, or if oxygen kills them(Obligate anaerobes)

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2
Q

What shape are cocci bacteria?

A

Spherical=cocci

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3
Q

What shape are bacilli bacteria?

A

Rod-shaped=bacillia

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4
Q

What shape are twisted bacteria?

A

Spirilla =twisted bacteria

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5
Q

Which bacteria are comma-shaped?

A

Vibrios=comma-shaped

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6
Q

Which bacteria need oxygen for respiration?

A

Obligate aerobes

Need oxygen for respiration

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7
Q

Which bacteria can use oxygen for respiration but can also manage without it?

A

Facultative anaerobes
use oxygen if available but can also manage without it
(Most human pathogens)

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8
Q

Which bacteria can only respire in the absence of oxygen?

A

Obligate anaerobes

Oxygen kills them

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9
Q

How are viruses classified?

A

Genome

Mode of replication

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10
Q

What are the different classifications of viruses?

A

DNA viruses
RNA viruses (positive and negative ssRNA)
RNA retroviruses

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12
Q

Classification of a DNA virus (what characteristics they have)

A

Genetic material = DNA

Viral DNA acts as a direct template (for both viral DNA replication and protein synthesis)

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13
Q

Examples of DNA viruses

A

Smallpox
Adenovirus (include colds and some bacteriophages)
Lambda phage

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14
Q

Classification of RNA viruses (characteristics they have)

A 
Genetic material =RNA
Do not produce DNA
Mostly ssRNA (single stranded RNA)
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15
Q

What are the differences between positive and negative ssRNA viruses?

A

Positive ssRNA viruses can be directly translated at the ribosomes
Negative ssRNA viruses have to be transcribed before being translated

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16
Q

Examples of animal and plant diseases caused by positive ssRNA viruses

A

Tobacco mosaic virus
SARS
Polio
Hepatitis C

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17
Q

Classification of RNA retroviruses (characteristics they have)

A

Protein capsid
Lipid envelope
Single strand of viral RNA detects the synthesis of reverse transcriptase and is translated into viral DNA by reverse transcriptase
Viral DNA incorporated into host cell DNA and used as template for new viral proteins

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18
Q

Examples of RNA retroviruses

A

HIV(human immunodeficiency virus)

Some forms of leukaemia

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19
Q

Examples of diseases caused by negative ssRNA viruses

A

Measles
Influenza
Ebola

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20
Q

What’s a hypertonic solution?

A

a solution with a higher concentration of solutes and lower concentration of water/solvent than the surrounding solution

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21
Q

What’s peptidogylcan?

A

a large, net-like structure found in the walls of bacterial cells made up of many parallel polysaccharide chains with short peptide cross-linkages

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22
Q

Wat are pili?

A

thread like protein projections found on the surface of some bacteria

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23
Q

What are bacteriophages?

A

viruses that attack bacteria

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24
Q

What are flagella?

A

many-stranded helices of the protein flagellin found on some bacteria. they move the bacteria by rapid rotations

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25
Q

What are mesomes?

A

infoldings of the bacterial cell membrane

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26
Q

What is a nucleoid?

A

area of bacterium where single length, coiled DNA is found

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27
Q

What are plasmids?

A

small circular pieces of DNA that code for specific aspects of the bacterial phenotype

28
Q

What is gram staining?

A

a staining technique used to distinguish different types of bacteria by their cells wall (positive or negative)

29
Q

What are gram-positive bacteria?

A

bacteria that contain teichoic acid in their cell walls and stain purple/blue with gram staining

30
Q

What are gram-negative bacteria?

A

bacteria that have no teichoic acid in their cell walls and stain red with gram staining

31
Q

What is teichoic acid?

A

a chemical found in the walls of gram-positive bacteria

32
Q

What is the purpose of a capsule?

A

protects the bacteria from phagocytosis from white blood cells and covers the cell markers on the cell membrane that identify the cell so it is undetectable by the immune system, made from starch, glycolipid, gelatin or protein

33
Q

What is an envelope?

A

a coat around the outside of the virus derived from lipids in the host cell

34
Q

What is the capsid?

A

the protein coat of a virus

35
Q

What is the capsid made from?

A

simple repeating units called capsomeres, arranged in different ways to minimise the amount of genetic information needed to code for coat production and so that assembling the virus in the host cell is as simple as possible

36
Q

State the advantage of an envelope

A

the virus can pass from cell to cell easier

37
Q

State the disadvantage of an envelope

A

makes them vulnerable to substances that could dissolve the lipid membrane

38
Q

What are capsomeres?

A

the repeating units which make up the capsule of a virus

39
Q

What are virus attachment particles (VAPs)?

A

specific proteins/antigens that target proteins in the host cell surface membrane

40
Q

What are DNA viruses?

A

composed of DNA as their genetic materia

41
Q

What are RNA viruses?

A

composed of RNA as their genetic material

42
Q

What are retroviruses?

A

a special type of RNA virus that control DNA production corresponding to the viral RNA and insert it to the host cell DNA

43
Q

What is reverse transcriptase?

A

an enzyme synthesised in the lifecycle of a retrovirus that makes DNA molecules corresponding to the viral RNA genome

44
Q

Define non-virulent

A

a microorganism that is not disease-causing

45
Q

Define virulent

A

a microorganism that is disease causing

46
Q

What is a provirus?

A

the DNA that is inserted into the host cell in the lysogenic pathway of reproduction of viruses

47
Q

What is lysogeny?

A

the period when a virus is part of the reproducing host cell but does not affect it adversely

48
Q

Define latency

A

the state of a non-virulent virus within the host cell

49
Q

What is ebola?

A

a highly infectious viral disease that causes fever and internal bleeding and death in around 50% of cases

50
Q

Define mortality rate

A

a measurement of the number of deaths in a given population or due to a specific cause

51
Q

Define a pandemic

A

an epidemic that takes place in several countries at once

52
Q

What is the process for the development medicines?

A
  • takes up to 10 years
  • early phase research (4-6 years)
  • pre-clinical testing (1 year)
  • 3 phase clinical trials (6-7 years)
  • regulatory review
  • scale up to manufacturing (0.5-2 years
  • post market surveillance is continuous
53
Q

What are the ethical factors that need to be considered before fast-tracking a drug in an epidemic?

A
  • severity of the disease
  • availability of other treatments
  • effectiveness of standard disease control measures in halting the spread of disease
  • transparency about the process and informed consent of those given the treatment
  • freedom of choice over participation
  • involvement of the affected community- community consent more valuable than individual consent
  • collection of clear medical data
54
Q

State the reasons against using untested drugs

A
  • people feel it is unethical
  • unexpected side effects could worsen the situation
  • difficulty deciding who gets the treatment
  • informed consent depends on level of education
  • issues of trust between individuals and healthcare workers, especially when supplies are limited
55
Q

State the characteristics of viruses

A
  • obligate intracellular parasites=can only exist + reproduce as parasites in the cells of other living organisms
  • not cells
  • invade and take over other cells which causes damage and disease
  • can withstand drying + long periods of storage, still maintaining the ability to infect cells
  • very few drugs effect viruses
56
Q

State the structure of viruses

A
  • geometric shapes and similar basic structures
  • variation of genetic material, structure of protein coat and envelope or not
  • protein coat/capsid made up of simple repeating proteins (capsomeres) arranged in different ways
  • repeating units minimise the amount of genetic material needed for coat production + ensures assembling the coat is simple
  • lipid envelope males it easier to pass from cell to cell but makes it more vulnerable to substances that can dissolve the lipid membrane
57
Q

What are the ways of classifying viruses?

A
  • VAPs (virus attachment particles) target the proteins in the host cell membrane
  • viruses are specific in the tissue they attack
  • classified by genomes and mode of replication
  • genetic material: DNA or RNA nucleic acid: single or double stranded
58
Q

Define DNA viruses

A

viral DNA acts directly as a template for new viral DNA and mRNA needed for synthesis of viral proteins

59
Q

Give examples of DNA viruses

A

smallpox, adenoviruses and lambda phage

60
Q

Define RNA viruses

A

70% of viruses have RNA as their genetic material and are more likely to mutate than DNA viruses. they don’t produce DNA as part of their lifecycle. positive ssRNA viruses have RNA that can be directly translated at the ribosomes. negative ssRNA viruses cannot be directly translated

61
Q

Examples of positive ssRNA viruses

A

tobacco mosaic virus, SARS, polio, hepatitis C

62
Q

Examples of negative ssRNA viruses

A

measles, influenza, Ebola

63
Q

Define RNA retroviruses

A

have a protein capsid and lipid envelope, single strand of RNA directs synthesis of enzyme reverse transcriptase- goes on to make DNA molecules corresponding to the viral genome. the DNA is then incorporated into the host cell DNA and used as a template for new viral proteins

64
Q

Examples of RNA retroviruses

A

HIV and some forms of leukaemia

65
Q

How do RNA retroviruses reproduce/ what is their life cycle?

A
  1. the retro virus attacks an animal cell
  2. viral RNA enters the host cell. this RNA cannot be used a mRNA
  3. viral RNA is translated into viral DNA by reverse transcriptase in the cytoplasm
  4. viral DNA is incorporated into the host DNA, it directs the production of new viral genome RNA, mRNA and coat proteins
  5. new viral particles are assembled and leave the host cell by exocytosis. viral DNA remains in the nucleus so the process is repeated

A Level Biology (32 decks)

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