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Microbiology > Dr Bevington > Flashcards

Dr Bevington Flashcards

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Biology 101 flashcards
1
Q

Animals cells :

A
  • flagella
  • lysosomes
  • 2 centrioles within a Centrosome
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2
Q

Plant cells :

A
  • cellulose cell wall
  • chloroplasts
  • central vacuole
  • plasmodesmata
  • Centrosome
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3
Q

Cellular components common to all cells -

A
  • plasma membrane
  • cytosol
  • ribosome
  • chromosome
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4
Q

Only Eukaryotic cells have -

A
  • nucleus
  • mitochondria
  • endoplasmic reticulum
  • Golgi apparatus
  • Flagella
  • chloroplasts
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5
Q

In archaea membrane lipids usually contain…

A

Long hydrophobic prenyl chains comprising 20-25 carbon atoms instead of hydrophobic long chain fatty acids

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6
Q

Fluid mosaic model - current model =

A
  • Variable thickness
  • patchy
  • high level of proteins
  • may not be very fluid
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7
Q

Plasma membrane function :

A
  • impermeable to water and water soluble molecules
  • self healing
  • signalling and transport ( embedded proteins)
  • cell recognition
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8
Q

Trans membrane proteins are comprised of …

A

Polypeptide chains winding back and forth across the lipid bilateral

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9
Q

The capsule :

A

An additional thick polysaccharide layer secreted by some bacteria as an additional defensive layer

Encapsulated bacteria are resistant to phagocytosis

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10
Q

Extracellular =

A

Outside cell

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11
Q

Intracellular =

A

Inside cell

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12
Q

Intercellular =

A

Spanning between two cells

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13
Q

Polysaccharides -

A

Polymer of sugar units

E.g. cellulose & pectins in plant cell walls

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14
Q

Glycosaminoglycans -

A

Polymers of chemically modified sugars

E.g. in extracellular matrix in animals tissues

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15
Q

Glycoproteins -

A

Proteins with sugars covalently attached

E.g. cell surface proteins or secreted extracellular proteins in animals

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16
Q

Proteoglycans -

A

Glycoproteins in which a sugar polymer is a large part of the molecule

E.g. cell surface molecules or secreted extracellular matrix molecules in animals

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17
Q

Plant cell wall: structure

A

Primary cell wall - parallel aligned fibres ( flexible = deposited during growth )

Secondary cell wall - non aligned fibres ( rigid = deposited once growth has stopped )

Middle lamellar - sticky layer of polysaccharides hold adjacent cells together

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18
Q

Plant cell wall: function

A
  • inert - barrier, regulates entry/exit of substances
  • rigid ( nonaligned fibres) - maintains shape despite movement of water
  • flexible ( parallel aligned fibres of the primary cell wall) - allow growth
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19
Q

Animal cells don’t have cell walls they have…

A

They have extracellular matrix

made up of glycoproteins :

  • fibronectin ( binds to integrity proteins in membranes)
  • collagen ( binds to fibronectin)
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20
Q

Extracellular matrix :function:

A

Forms a gel - provides mechanical protection in tissues

Flexible - allows changes in shape + size

Communication - integrins can transmit signals between extracellular matrix and the inside of the cell

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21
Q

Ribosomes -

A

Structure found in the cytosol or on the rough endoplasmic reticulum

protein synthesis

Translates a messenger RNA nucleotides sequence into a protein amino acid sequence

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22
Q

Tetracycline antibiotic-

A

Act in bacteria :

Blocks binding of amino acyl-tRNA to A-site of ribosome

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23
Q

eukaryotes:

A 
Has a nucleus
Multiple chromosomes
Normally multicellular
Has membrane bound organelles 
Larger ribosomes
Only have cell walls in plants made of cellulose
Approximately 10-100um in size
 in multi cellular organisms, most cells are specialised for particular function 
yeast, animals, plants and Protista
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24
Q

prokaryotes:

A 
Doesn’t have a nucleus
One chromosome
Normally unicellular
No membrane bound organelles
Smaller ribosomes
Cell wall found in bacteria made of peptidoglycan
Approximately 1-10um in size
bacteria and archaea
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25
Q

Streptomycin antibiotic-

A

Prevents the transition from translation initiation to chain elongation and also causes miscoding

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26
Q

Chloramphenicol antibiotic -

A

Blocks the peptidyl transferase reaction on ribosome

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27
Q

Erythromycin antibiotic-

A

Binds in the exit channel of the ribosome and inhibits elongation of the peptide chain

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28
Q

last common known ancestor

A

Lokiarchaeota

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29
Q

eukaryotes and prokaryotes both have…

A

ribosomes
DNA
cytoplasm
plasma membrane

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30
Q

nucleus:

A

double nuclear envelope - separates cell content with nucleus content

nuclear pore - allows entry/exit of substances

nucleolus - production of ribosomes

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31
Q

chromatin:

A

the material in a chromosome

comprised of 8 core histones and DNA

Each histone octamer is composed of 2x histone proteins H2A, H2B, H3, and H4.

The function of chromatin is to efficiently package DNA into a small volume to fit into the nucleus of a cell and protect the DNA structure and sequence.

32
Q

chromatin can be stained…

A

blue by toluidine blue

33
Q

nuclear lamina -

A

maintains shape of nucleus

34
Q

chloroplast function:

A

photosynthesis:

stroma - light independent reaction
thylakoid - light dependent reaction

35
Q

plasmodesmata structure -

A

small holes in plant cell walls
lined by plasma membrane
cytosol of adjacent cells is continuous

36
Q

plasmodesmata function -

A

specific transport of water, small solutes, specific proteins, RNA

37
Q

cytosol -

A

semi fluid substance between plasma membrane and nucleus ( not including organelles)

environment for metabolic reactions

38
Q

mitochondrial matrix -

A

citric acid cycle

39
Q

mitochondrial cristae -

A

provide large surface area for membrane bound enzymes involved in electron transport and oxidative phosphorylation

40
Q

rough endoplasmic reticulum -

A

same as smooth endoplasmic reticulum but has ribosomes which synthesise secretory proteins

41
Q

smooth endoplasmic reticulum -

A

synthesises lipids
detoxifies proteins
stores calcium

42
Q

golgi apparatus -

A

modify/package proteins into vesicles

consist of flattened membrane sacs called cisternae

their structure and enzyme content changes from cis to trans faces

43
Q

protein synthesis and secretion-

A

1) transcribed mRNA leaves nucleus and attaches t a ribosome
2) ribosome synthesises a protein
3) a vesicle with the protein in pinches off of the rough endoplasmic reticulum
4) Golgi apparatus packages the protein
5) vesicle fuses to the plasma membrane where the protein is released via exocytosis

44
Q

why do cells perform different reactions in different sub-cellular compartments?

A

some enzymes may be incompatible in the conditions in different sub-cellular compartments

45
Q

glycolysis -

A

happens in cytosol

produces pyruvate that is converted to Acetyl CoA which drives ATP production in mitochondria

46
Q

how are organelles turned over?

A

membrane vesicles fuse and accumulate to form an autophagosome which engulfs the organelle

47
Q

lysosomes =

A

contain digestive enzymes

48
Q

protein degradation -

A

1) lysosomal and autophagosomal proteases which are optimal at low ph
2) calcium activate cytosolic proteases which are active at neutral ph
3) ubiquitin proteasome pathway

49
Q

the ubiquitin proteasome pathway-

A

ubiquitin = small protein which is covalently attached to proteins which have been targeted for degradation

proteasome = huge macromolecular cylindrical complex in the cytosol which contain proteases that degrade polyunbiquitinated proteins

50
Q

why is it necessary for macromolecules in cells to be turned over?

A

1) to control the time course of gene expression - proteins or mRNA may need turning off/on
2) proteins may misfold
3) cumulative damage to the molecule - nee to be removed and replaced

51
Q

reactive oxidation species =

A

produced as a by-product of electron transport and oxidative phosphorylation in mitochondria

produced by high energy radiation

= highly reactive oxidising molecules

= cause damage to biological molecules

52
Q

sometimes oxidising molecules are not degraded and replaced…

A

e.g. oxidised lipids in atherosclerosis = accumulation of partly oxidised low density lipoprotein in the walls of blood vessels = cardiovascular disease

53
Q

actin microfilaments =

A

made up of F-actin polymers

  • resist tension on cell
  • endocytosis/exocytosis
  • localised contractions of cell
54
Q

cytoskeleton structure -

A

microfilaments (actin)

microtubules (tubulin)

intermediate filaments (keratin)

55
Q

the cortex =

A

a branched network of actin microfilaments around the perimeter of a cell

56
Q

myosins (muscle contraction) -

A

motor proteins that pull actin filaments together and hydrolyse ATP to move away from the actin filament

57
Q

microtubules =

A

hollow tubes of tubulin dimers
moved by kinesin

  • compression resisting
  • supports cell structure
  • movement of vesicles
  • cell division
58
Q

cilia =

A

fluid circulation powered by dynein motor proteins e.g. move mucus

59
Q

flagella =

A

driving movement of animal sperm
one per cell
powered by dynein motor proteins

60
Q

intermediate filaments =

A

made up of keratin proteins assembled into fibrous subunits and supercoiled together

  • resist tension
  • maintain cell shape
  • fix position of organelles
61
Q

cell cycle : interphase -

A

G1: growth of organelles
S: DNA synthesis
G2: more growth

62
Q

cell division in multi celled organisms =

A 
mitosis = growth, tissue repair, development of fertilise egg
meiosis = generation of gametes
63
Q

centriole =

A

a pair of structures in each centreosome, made up of specialised microtubules.
synthesis of spindles for moving chromosomes

64
Q

centromere =

A

region of a chromosome where two sister chromatids join together

65
Q

kinetochore =

A

a protein structure that forms at the centromere during mitosis

66
Q

prophase

A

1st step of mitosis

chromatin condenses into chromosomes
centrioles move to opposite poles of the cell and form spindles

67
Q

prometaphase

A

between 1st and 2nd step of mitosis

nuclear envelope breaks down

68
Q

metaphase

A

2nd step of mitosis

chromosomes line up in middle of cell
spindles attach to the centromere

69
Q

anaphase

A

3rd step in mitosis

kinetochores are cleave by separase enzyme
the centromere splits
spindle fibres pull sister chromatids towards the poles
cell elongation caused by the kinesin motor proteins

70
Q

telophase

A

4th step in mitosis

nuclear envelope reforms
chromosomes become less condensed
spindle fibres disassemble
cell membrane starts to invaginate

71
Q

phenotype =

A

the visible characteristic

72
Q

an example of rapid cell differentiation =

A

somatic hyper mutation driven by DNA mutation in lymphocytes

73
Q

cannot just rely on necrosis to eliminate cells -

A

necrosis = uncontrolled release of prtoease enzymes

releases degradative enzymes which may cause necrosis in other cells

74
Q

apoptosis =

A

=programme cell death

  • controlled activation of caspase (protease enzymes)
  • cell dismantled from within without leaking toxic contents
  • expose molecules on their surface so they can be engulfed by phagocytosis
75
Q

virus =

A

protein complexes which replicate inside host cells

76
Q

prions =

A

infectious proteins which replicate in a host by copying an misfolded protein structure = created amyloids
( contain no DNA)

77
Q

smallest bacteria =

A

mycoplasma

Microbiology (3 decks)

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