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BO201 Molecular and Cellular Biology > Theme 1:Introduction to Molecular and Cellular Biology > Flashcards

Theme 1:Introduction to Molecular and Cellular Biology Flashcards

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1
Q

what is the mature cell wall is composed of?

A

The mature cell wall is composed of layers of peptidoglycan connected to each other

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2
Q

how does the cell wall get a ridgid mesh like structure

A

repeating disaccharide units bound together by glycosidic bonds between the sugars and layers of peptidoglycan connected by peptide bonds between the amino acid side chains give result in a rigid, mesh-like structure,

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3
Q

how does the cell wall get ridity and strength

A

repeating disaccharide units bound together by glycosidic bonds between the sugars and layers of peptidoglycan connected by peptide bonds between the amino acid side chains give result in a rigid, mesh-like structure., which gives the cell wall rigidity and strength.

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4
Q

what bond is between amino acid side chains?

A

peptide bonds

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5
Q

what are the Antibiotics that target the cell wall

A

b-lactams

Glycopeptides

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6
Q

what do b lactams do?

A

b-lactams bind directly to transpeptidase enzyme and inhibit its function (cross linking of peptide side chains)

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7
Q

what do glycopeptides do?

A

Glycopeptides bind to peptide side chains of NAM and prevent transpeptidase from cross linking

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8
Q

what is in a gram negative outer membrane?

A

Phospholipid-Lipopolysaccharide (LPS) bilayer
(extra lipid layer - mechanism of the Gram stain)

Cytoplasmic membrane is composed of a phospholipid bilayer – no polysaccharide

Hence the CM and OM are chemically very different

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9
Q

what is the major function of OM

A

structural

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10
Q

what is he composition of OM

A

Phospholipid layer similar to CM + Lipopolysaccharid

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11
Q

what does a lipopolysaccarcharide contain

A
  • lipid A
  • core polysaccharide
  • O-specific polysaccharide
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12
Q

what is the outermembranes most important biological properties?

A

its toxicity to animals

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13
Q

what does the outermembrane, specifically lp0s, of pathogenic gram negative bacteria represent

A

an important virulence determinant

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14
Q

what is immunogenicity of lps associated with?

A

with the polysaccharide components

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15
Q

what is toxicity in the outer membrane associated with?

A

lipid component (lipid A)

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16
Q

what is required for toxicity in the outer membrane

A

both lipid component A and polysaccharides components in vivo

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17
Q

when only is pls released in large amounts?

A

when cells lyse

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18
Q

how does a large amount of lps accure when cells lyse in vivo?

A

Autolysis of the bacteria,

External lysis mediated by immune system,

Phagocytic digestion of bacterial cells by immune cells

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19
Q

what is the role of lps in virulence?

A

LPS (Lipid A portion) binds to LPS binding protein in the blood

LPS-LPS binding protein binds to macrophage (phagocytic white blood cell) receptor

Macrophage activation

Produces defence proteins and chemicals called cytokines
and chemokines (Interleukins, tumour necrosis factor, PAF)

Promote inflammation and activate host defences

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20
Q

What is inflammation?

A

Localised protective response

Increased dilation and permeability of blood vessels

Allows defence chemicals and immune cells enter infected tissue

Pathogen and infected tissue are destroyed and removed

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21
Q

what happens during respiratory distress?

A

Increased blood vessel permeability

Fluids enter air spaces of the lungs

Impaired gas exchange

“Drowning”

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22
Q

how can plant tissues and organs be ditinguised?

A
  • the sources
    • the sinks
    • vascular tissues (exchanges of resources)
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23
Q

what do sinks do in regard to plants?

A

Sinks need to receive organic resources from the sources

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24
Q

what are sources in regards to plants?

A
  • mature/largely grown leaves
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25
Q

what parts of the plant are sinks?

A
  • meristems
    • young leaves
    • stems
    • roots
    • fruits/flowers
    • storage organs
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26
Q

what ensures the survival of the plant or new progeny?

A
  • fruits/flowers

- storage organs

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27
Q

in a plant there is a constant movement of resources. explain this.

A

-leaves provide organic compounds, recieve minerals from the roots

storage organs recieve everything

roots provide minerals , recieve organic compounds

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28
Q

what are the same principles that underlie early development in plants and animals?

A

cell division

patterning and organogenesis

differentiation and growth

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29
Q

what action allows post embryonic organ formation?

A

meristems

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30
Q

what does the shoot apical meristem make?

A

stem, leves ,flowers fruit and seeds

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31
Q

what does the root apical meristem make?

A

primary and lateral roots

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32
Q

what are The tiny leaves that surround the meristem called?

A

leaf primordia

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33
Q

what are plant organs made from?

A

meristems

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34
Q

what is the reason for the large diversity in plant organs?

A

the need to adapt to specific envoirnments

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35
Q

what family are cluster roots found in?

A

proteaceae

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36
Q

what sort of soil do proteaceae live on?

A

one of the oldest and poorest and dry soil in the world. it contains v low amounts of phosphorus leaving the plants to mine for it

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37
Q

what are some features of proteaceae?

A

stomatal crypts and suken stomata

38
Q

what does photosynethesis do?

A

converts water and CO2 to sugar molecules which provide energy and carbon for biosynthetic processes

39
Q

how do sugars provide energy in the dark?

A

through respiration

40
Q

is photosynthesis anabolic or catabolic

A

builds molecules= anabolic

41
Q

is respiration anabolic or catabolic

A

breaks down molecules=catabolic

42
Q

what is an oxidation chemical reaction?

A

loss of one or more electrons

43
Q

what is a reduction chemical reaction

A

gain of one or more electrons

44
Q

describe the two steps involved in photosynthesis in light stage

A

(Step 1) Light energy is captured by the light-dependent
reactions of photosynthesis

(Step 2) The captured light energy is used to fix CO2
as carbohydrate in the light-independent reactions of photosynthesis

Light energy is converted into
chemical energy

45
Q

what reactions occur in light dependant stage ?

A

light reactions

46
Q

what reactions occur in light independant stage ?

A

carbon reactions

47
Q

what is produced in light dependant stage ?

A

Splits H2O to produce O2, ATP and NADPH

48
Q

what are ATP and NADPH necessary for ?

A

to form sugars and for molecules such as amino acids, sulfur metabolitesetc

49
Q

what does photolysis mean?

A

light splitting (of water)

50
Q

what is the formula for photolysis

A

2 H2O + photons (light) ―› O2 + 4 H+ + 4 e-

51
Q

after photolysis what are the h+ and e- used for ?

A

to produce NADPH and ATP

52
Q

why do different species of plants use slightly different light wavelengths?

A

as they contain different types of pigments

53
Q

what are the 2 major carbohydrates made out of photosynthesis?

A

Sucrose and starch

54
Q

what is the principle photosynthetic product?

A

sucrose as it accounts for most of the CO2 absorbed

55
Q

what is the role of sucrose in plants ?

A

important storage sugar

(tap root of carrots and sugar beet (up to 20% dry weight)
and in leaves, eg 25% leaf dry weight in ivy)

major form for translocation of carbon
(from photosynthetic leaves (source leaves)
in germinating seedlings after starch or lipid breakdown)

56
Q

how are sugars produced in plants ?

A

by source tissues

in light period

57
Q

where does translocation occur?

A

source to sink over short term

from storage tissues to young tissues over long term

58
Q

what form do many plants store the CO2 that they have fixed?

A

glucose polymers (starch)

59
Q

how can starch granules be seen in plant cells

A

staining them with iodine

60
Q

name some features of starch

A
  • water insoluable

- size & shape is species specific

61
Q

when do plants use their leaf starch ?

A

Leaf Starch is used at night in a way that almost all is consumed during the night, BUT NOT ALL : plants avoid getting hungry

62
Q

how do plants allow growth at night?

A

Starch synthesis and degradation are tightly regulated to allow growth at night

63
Q

during the night what provides energy and building blocks for growth and maintenance in plants?

A

mitochondria

64
Q

what is the 2 mechanisms of growth?

A

division and expansion

65
Q

what is division in relation to plants?

A

cells are dividing. Mostly occurs in meristems

66
Q

what is expansion in relation to plants?

A

cells are growing and also differentiate. Widespread through tissues in many species

67
Q

how much do species increase their biomass by typically for most herbaceae species per day?

A

15-20%

68
Q

what do most scientists use to measure plant growth?

A

Relative Growth Rate (RGR), expressed as g.g-1.day-1 or mg.g-1.day-1

RGR = ln(W2)-ln(W1)
t2-t1

69
Q

how does plant biomass increase

A

exponentially

70
Q

what two issues explain largely the tissue, cellular and metabolic complexity of the plants

A

Plants are sessile: they cannot escape stressful environmental conditions

Most plants are autotrophs: they do not need organic compounds for their subsistance, they make them

71
Q

what are the roles of a cell wall?

A

1: maintaining/determining cell shape (analogous to an external skeleton for every cell). It controls the rate and direction of cell growth and regulates cell volume
2: Support and mechanical strength (allows plants to get tall, hold out thin leaves to obtain light)
3: Prevents the cell membrane from bursting in a hypotonic medium (i.e., resists water pressure)

72
Q

what are the roles of the vacuole?

A
  1. Containing water in plant cells
  2. Maintaining internal hydrostatic pressure or turgor within the cell – so allows plants to support structures such as leaves and flowers due to the pressure of the central vacuole
  3. Maintaining an acidic internal pH\
  4. Containing small molecules (storage)
  5. Isolating materials that might be harmful or a threat to the cell,
    e. g. glucosinolates in brassicaceae which are defense compounds
  6. Place to degrade unwanted substances
  7. In seeds, stored proteins needed for germination are kept in ‘protein bodies’, which are modified vacuoles.
73
Q

where do chloeoplasts within plant cells orginate from?

A

endosymbiotic event with photosynthetic cyanobacteria

74
Q

name 3 genomes that plants contain

A
  • nuclear (around 30000 genes)
    • chloroplastic (around 100-150 genes)
    • mitochondria (around 40 genes
75
Q

what do chloroplasts and mitochondria reply on to be functional?

A

nuclear genes

76
Q

what do the proteins encoded in the nuclear genome allow chloroplasts to do?

A

fix CO2

77
Q

where does translation occur?

A

in the nucleus/cytosol but also in the organelles

78
Q

where do polypetides encoded in the nucleus stay?

A

in the cytosol or can be transported to the organelles

chloroplasts – mitochondria

79
Q

what does a transit peptide allow?

A

allows polypeptides recognition and transported to the chlorplast

80
Q

Why more metabolites in plants than animals?

A
  • Plants are sessile and have to cope with their environment: they need a large panel of chemicals
    • Plants do not have nerves and use a wide range of chemical signals (for ex. Hormones, but not only) to organise and coordinate their responses between their different organs
    • Most plants do not uptake metabolites from their environment: they need to produce all of them
    • Plants make photosynthesis, which require a large panel of compounds such as pigments / antioxydants..
81
Q

what are the two main classes of metabolites?

A
  • primary metabolites

- mostly secondary metabolites

82
Q

what is primary metabolism

A

Primary metabolism is about reactions and compounds essential for survival of the plants

Primary metabolism is mostly the same for all plant species

83
Q

what is secondary metabolism?

A

Secondary metabolism is not essential for survival of the plants, or more precisely is not essential in optimal growth conditions

Secondary metabolism largely varies from species to species and also within a specie in response to environmental factors(stresses/situations)

Many secondary metabolites have medical applications

Secondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism

84
Q

difference between if primary metabolism stopped compared to secondary metabolism

A

Unlike primary metabolites, absence of secondary metabolites does not result in immediate death, but rather in long-term impairment of the organism’s survivability, fecundity, or aesthetics, or perhaps in no significant change at all.

85
Q

what are the functions of secondary metabolism?

A
  • defence
  • u-v protection and n-storage
  • attraction
86
Q

why are Metabolic pathways are very well coordinated/regulated

A

Several reasons:

- save energy (many reactions are less costly in the light when they occur in chloroplasts)
- co-factors are usually in very low amounts
- some intermediates are highly toxic for the cells (reactive oxygen species)

During Nitrate assimilation, Nitrite is very toxic. So Nitrate reductase is very tightly regulated

87
Q

describe plant mitochondria in comparison to animal mitochondria

A

1: Very large genome compared to animal, also very variable between species
2. Plant mitochondria have uncoupling protein that allows H+ to diffuse from the intermembrane space back to the matrix: dissipation of excess energy
3. They also have Alternative Oxidase (AOX) which provides alternative route for electrons passing through electron transport chain to reduce Oxygen to water.
3. NAD(P)H dehydrogenases, attached to the outer surface of the inner membrane facing the intermembrane space can oxidize cytosolic NADH and NADPH.
4. Plant mitochondria cannot oxidise fatty acids

88
Q

what is the main role of respiration?

A

A main role of respiration is about producing energy for non-photosynthetic cells or in the dark when photosynthesis cannot provide it

89
Q

what are the other functions of mitochondria apart from the main one?

A

Glycolysis and The TCA cycle (citric acid cycle) provide the substrates for the synthesis of a large number of amino acids

90
Q

what are some very important enzymes in the synthesis of amino acids?

A

amino transferases

91
Q

name some examples of amnio transferases

A

glutamate
oxaloacetate
aspartate
alpha-ketoglutarate

92
Q

how do some aminotransferases generated additional amino acids?

A

There is also aminotransferases which can transfer NH3+ group from alanine or gutamate to generate additional amino acids

BO201 Molecular and Cellular Biology (3 decks)

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