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Cells 191 > Cell Structure and Diversity > Flashcards

Cell Structure and Diversity Flashcards

1
Q

what is the limitation of cell size

A

the rate at which molecules can pass through the cell membrane in order to support the metabolic processes of the cell

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2
Q

What are the three domains

A

bacteria, archaea, eukarya

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3
Q

what are the kingdoms

A

animalia, plantae, fungi, and the protists

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4
Q

what four things are needed for natural selection

A

time, genetic variation within the population, inheritance of genetic characteristics, and selection pressures

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5
Q

what size are eukaryote cells?

A

10 - 100 microns

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6
Q

what size are prokaryote cells?

A

0.1 - 5 microns

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7
Q

what are the features of the light microscope?

A
  • doesn’t need a stain
  • can be used to view living cells
  • colour images
  • 1000 magnification in air
  • 1400 magnification in oil
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8
Q

why does oil immersion allow greater magnification than air in light microscopes?

A

because of the reduced diffraction of light

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9
Q

resolution

A

the minimum distance which can separate two points and still have them visible as two separate points

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10
Q

magnification

A

the ratio of image size to actual size

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11
Q

what are the features of electron microscopes?

A
  • stain needed
  • can only view dead cells
  • max magnification of x100,000
  • black and white images
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12
Q

how does a scanning electron microscope work?

A

electrons are fired over the surface of the cell, showing the 3D surface of the cell

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13
Q

how does a transmission electron microscope work?

A

electrons are fired through a very thin sample of the cell, revealing the internal ultrastructure.

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14
Q

what is spontaneous generation?

A

the idea that life can spontaneously arise from non-living matter in the correct environmental conditions

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15
Q

what is germ theory?

A

the idea that microbes cause and spread diseases

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16
Q

what did Pasteur’s experiment prove?

A

the germ theory because life only developed after the infusion was contaminated when the environmental conditions were kept the same

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17
Q

What is sexual selection?

A

when a mate is chosen based on inheritable characteristics

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18
Q

what does sexual selection select for?

A

extreme phenotypes

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19
Q

what is sexual dimorphism?

A

sex based differences in size, colour, ornamentation, and behaviour

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20
Q

what are Koch’s postulates?

A
  • the suspected causative agent must be present in every case of the disease and generally not present in healthy organisms
  • the microbe must be able to be isolated and grown in pure culture
  • when a healthy host is infected with the microbe it must develop that specific disease
  • the microbe must be able to be isolated from the deliberately infected host
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21
Q

What are the most common atoms in the human body?

A

oxygen > carbon > hydrogen > nitrogen

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22
Q

what is the monomer of polysaccharides?

A

monosaccharides

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23
Q

what is a disaccharide?

A

a carbohydrate with two monosaccharide building blocks

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24
Q

what is an oligosaccharide?

A

a carbohydrate with 3 - 9 monosaccharide building blocks

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25
Q

what is the monomer of DNA / RNA?

A

nucleotides

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26
Q

what is the monomer of protein?

A

amino acids

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27
Q

what is the monomer of lipids?

A

none - they are heterogenous

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28
Q

what is the function of hexose?

A

monomer for carbohydrates

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29
Q

what is the function of pentose?

A

used as part of larger molecules eg DNA

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30
Q

what is the functions of carbohydrates?

A

energy source and storage, structure, cell to cell recognition

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31
Q

which polysaccharides are composed of alpha glucose monomers? why?

A

glycogen and starch. this is because they are energy storage molecules, and alpha glucose bonds can be broken by enzymes. this means that the energy stored in the bonds can be released for use by the cell

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32
Q

which polysaccharides are composed of beta glucose monomers? why?

A

cellulose. this is because it is a structural molecule, and beta glucose bonds cant be broken down by enzymes, so the structural integrity of the cell is maintained

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33
Q

what is the difference between alpha and beta glucose molecules?

A

they are geometric isomers. alpha glucose is cis for the OH group on carbons 1 and 2, and beta glucose is trans.

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34
Q

what are the functions of lipids?

A

energy storage, regulatory, structural

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35
Q

describe the structure of a phospholipid

A

hydrophyllic head, hydrophobic tail.

phosphate head, glycerol backbone, lipid tails.

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36
Q

describe the structure of a nucleotide

A

sugar with a phosphate bonded to carbon 5 and a nitrogenous base bonded to carbon 1

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37
Q

what are the differences between DNA and RNA?

A
  • DNA = double stranded, RNA = single stranded
  • DNA = deoxyribose sugar, RNA = ribose sugar
  • DNA = thymine base, RNA = uracil base
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38
Q

what are the functional groups on amino acids?

A

amine group and carboxyl group

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39
Q

what are the eight protein functions?

A 
structural
regulatory
contractile
toxic
storage
protective
catalytic
transport
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40
Q

what are the three prokaryote cell shapes?

A
  • spirochaete = spiral shaped
  • cocci = circular
  • bacilli = rod shaped
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41
Q

what are the features of the cytosol?

A
  • semifluid gel
  • mainly water
  • ions and proteins in it
  • ~7pH
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42
Q

what size are ribosomes?

A

25nm

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43
Q

what are the three functions of capsules?

A
  • resist dehydration
  • resist phagocytosis
  • increase adhesion to solid surface and other cells
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44
Q

what is a capsule?

A

a sticky protein or carbohydrate layer

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45
Q

what is the difference between a capsule and a slime layer?

A

a slime layer is less defined and less organised than a capsule

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46
Q

what is the function of the flagella?

A

motility via chemotaxis

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47
Q

what is the structure of the flagella?

A

flagellin protein arranged in alpha helix shape

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48
Q

describe the cell wall of Gram negative bacteria

A
  • more complex
  • two layers
  • permeable
  • less peptidoglycan
  • contain lipopolysaccharides
  • stains pink (crystal violet stain washes out)
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49
Q

describe the cell wall of Gram positive bacteria

A
  • less complex
  • one layer
  • impermeable
  • more peptidoglycan
  • stains purple (crystal violet stain can’t wash out)
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50
Q

what are the functions of the smooth ER?

A
  • lipid synthesis
  • calcium storage
  • detoxification of drugs and poisons
  • metabolism of carbohydrates
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51
Q

what are the functions of the rough ER?

A
  • protein synthesis
  • membrane factories
  • glycolisation of secretory proteins in the lumen
  • production of transport vesicles
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52
Q

what is the function of the fimbraie?

A

increased adhesion to solid surfaces

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53
Q

what is the function of the pili?

A

bacterial conjucation

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54
Q

describe the nucleoid

A
  • region of genetic information

- not membrane bound

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55
Q

what is an endospore?

A
  • survival mechanism against starvation / adverse conditions

- genetic material condensed into a spore which can survive adverse environmental conditions

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56
Q

what are the functions of the golgi body?

A
  • modifies proteins
  • glycolysation of cell surface proteins
  • manufacture of macromolecules eg polysaccharides (pectin)
  • direction of vesicles via vesicle markers
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57
Q

how are proteins processed through the golgi body?

A
  • enter at cis face
  • process through, being modified as they go
  • exit at trans face
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58
Q

what is the function of the central vacuole?

A
  • generate hydrostatic pressure

- maintain cell structure / integrity

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59
Q

which organelles are in plant cells but not animal cells?

A
  • chloroplast
  • plasmodesmata
  • cell wall
  • central vacuole
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60
Q

which organelles are in animal cells but not in plant cells?

A
  • centrosome with centromere
  • lysosome
  • flagella are more common
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61
Q

what size are viruses?

A

> 20nm

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62
Q

what is a capsid?

A

a protein coat around the virus

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63
Q

describe the structure of the bacteriophage

A
  • head where genetic information is stored
  • tail
  • sheath around tail
  • tail fibres
  • spikes
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64
Q

describe the lytic cycle

A
  • genetic information is inserted into cell
  • reverse transcription of RNA occurs using reverse transcriptase
  • DNA replication of single stranded genomes occurs
  • host cell genome is degraded
  • virus takes over host cell mechanisms to produce reverse transcriptase and replicate the viral genome
  • virus assembles within the cell
  • viruses exit cell, lysing it
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65
Q

describe the lysogenic cycle

A
  • genetic information is inserted into cell
  • reverse transcription of RNA occurs using reverse transcriptase
  • DNA replication of single stranded genomes occurs
  • virus integrates itself with the host genome, creating a prophage
  • virus exits genome when host cell replicates and forms a loop in the cytoplasm
  • virus reinfects daughter cells
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66
Q

what is a viroid

A

a plant pathogen composed of naked circular RNA

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67
Q

how is a viroid different to viruses?

A
  • much shorter - only a few hundred nucleotides
  • only infects plants
  • doesn’t produce proteins
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68
Q

what is a prion?

A

a misfolded protein which converts other proteins to prions

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69
Q

what effects on the cell do prions have?

A

disrupt cell function, causing the cell to eventually die

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70
Q

describe the structure of the cell membrane

A

semipermeable phospholipid bilayer

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71
Q

how does the chemical structure of phospholipid tails affect the cell membrane structure?

A

saturated tails = densely packed phospholipids, less fluid membrane.
unsaturated tails = less densely packed phospholipids, more viscous membrane.

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72
Q

how does cholesterol affect the cell membrane?

A

cholesterol increases the fluidity of the membrane at low temperatures and decreases it at higher temperatures

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73
Q

what functions do plasma membranes have?

A
  • separation of incompatible processes
  • creates different environments for different processes
  • allows concentration gradients to form
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74
Q

what are the functions of membrane proteins?

A
  • active transport
  • linking ECM and cytoskeleton
  • signal transduction
  • linking neighbouring cells
  • cell identification
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75
Q

what is passive transport?

A

movement of lipid soluble / hydrophobic molecules through a plasma membrane down a concentration gradient without the use of ATP

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76
Q

what is facilitated diffusion?

A

movement of water soluble molecules through a plasma membrane down a concentration gradient without the use of ATP. requires membrane proteins or channels.

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77
Q

what types of channels are used to enable facilitated diffusion?

A
  • voltage gated = ion fluxes

- ligand gated = open with extracellular signal

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78
Q

what is active transport

A

movement of molecules up their concentration gradient through a membrane with the use of ATP

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79
Q

how does cotransport work? use H+ / sucrose cotransporter as example

A
  • H+ ions pumped onto one side of membrane, creating a high concentration of H+ on one side
  • low concentration of sucrose on the same side
  • H+ ions flow through cotransporter, dragging sucrose along with them
  • sucrose is added to side with high concentration
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80
Q

what is the function of the endomembrane system?

A

manufacture and transport of material within the cell

81
Q

what are the functions of lysosomes?

A
  • break down endocytosed material
  • break down unwanted cellular structures
  • autophagy (preprogrammed whole cell death)
82
Q

what is endocytosis and how does it occur?

A

when materials are taken into the cell from the environment

works by having the cell fold around and form a vesicle with solutes enclosed in it

83
Q

what is phagocytosis?

A

uptake of food particles

84
Q

what is pinocytosis?

A

non-selective uptake of solutes

85
Q

what is receptor mediated endocytosis?

A

selective uptake of solutes, mediated by receptors on the cell membrane which bind with certain solutes

86
Q

what is exocytosis?

A

expulsion of materials from the cell

87
Q

what is the constitutive pathway?

A

exocytosis of materials needed for the ECM

88
Q

what is non-secretory exocytosis?

A

when materials are taken to the cell surface but are not excreted out of the cell

89
Q

what is regulated exocytosis?

A

when hormones and neurotransmitters are exocytosed, allowing for a rapid response

90
Q

what is the ECM made up of?

A

collagen embedded in a network of proteoglycans

91
Q

what do fibronectins do?

A

link the ECM to the cell

92
Q

what do integrins do?

A
  • form a communications link between the ECM and the cell

- links the ECM and cytoskeleton

93
Q

what is an important property of collagen?

A

it absorbs water, allowing the ECM to resist compression and retain its shape

94
Q

what is a tight junction?

A

a seal between neighbouring cells which prevents fluid from moving across the cell layer

95
Q

what is a desmosome?

A

a junction which anchors sheets of cells together

96
Q

what is a gap junction?

A

a point of cytoplasmic contact between cells which ions and molecules can move through, allowing for rapid intercellular communication

97
Q

what are two functions of the cytoskeleton?

A
  • maintaining cell shape

- positioning organelles

98
Q

what are the cytoskeleton components?

A

microfilaments, intermediate filaments, microtubules

99
Q

what is the diameter of microfilaments?

A

around 7nm

100
Q

what is the diameter of intermediate filaments?

A

8 - 12 nm

101
Q

what is the diameter of microtubules?

A

25nm

102
Q

what is the structure of microfilaments?

A

double chain of actin subunits

103
Q

what are the six functions of microfilaments?

A
  • cytoplasmic streaming in plants
  • resisting tension
  • maintaining cell shape
  • organelle movement
  • whole cell movement
  • change in cell shape
  • animal cell division
104
Q

what is the structure of microtubules?

A

tubulin subunits arranged into a hollow tube

105
Q

what are the functions of microtubules?

A
  • resisting compression
  • whole cell movement (controls cilia and flagella)
  • organelle movement (walk along microtubules using ATP)
106
Q

what are the structures of intermediate filaments?

A

cables of varying subunits. made of proteins such as keratin. supercoiled into coils.

107
Q

what are the functions of intermediate filaments?

A
  • very stable but not dynamic
  • therefore used to maintain cell shape
  • anchor organelles
  • neural processes
108
Q

reasons why cells need energy

A
  • active transport
  • organelle motility
  • whole cell motility
  • production of macromolecules
  • growth
  • repair
  • reproduction
109
Q

what is the size of the mitochondria?

A

1 - 10 microns long

110
Q

what is the structure of the mitochondria?

A
  • phospholipid membrane with embedded proteins
  • inner membrane is highly folded cristae
  • semiautonomous (mtDNA and ribosomes)
  • mitochondrial matrix is the fluid within the cristae
111
Q

what is glycolysis?

A
  • cytoplasm
  • glucose split into two pyruvate molecules
  • ATP produced
  • NADH produced
112
Q

what is pyruvate oxidation?

A

pyruvate is oxidised to acetyl co-enzyme A

113
Q

what is Citric Acid cycle?

A
  • matrix
  • processes acetyl co-enzyme A on sequence of enzymes
  • requires high concentration
  • produces ATP
  • NADH and FADH2 produced
114
Q

what are the two stages in oxidative phosphorylisation?

A
  • electron transport chain

- chemiosmosis

115
Q

what happens in the electron transport chain in cellular respiration?

A
  • cristae
  • e- passed along sequence of enzymes
  • energy released
  • used to pump H+ ions into matrix
  • creates high concentration of H+ ions in matrix
116
Q

what happens during chemiosmosis in cellular respiration?

A
  • H+ ions move through ATP synthase to area of lower concentration
  • go from matrix to intermembrane space
  • go down half channel
  • ATP synthase turns, smashing together ADP and P to produce ATP
  • H+ goes down other half channel and into intermembrane space
117
Q

what is the direction of proton flow in cellular respiration?

A

matrix to intermembrane space

118
Q

what is a endergonic process?

A

a process which absorbs energy

119
Q

what is an exergonic process?

A

a process which releases energy

120
Q

how does energy coupling work?

A

ATP transfers energy from exergonic processes to endergonic processes

121
Q

Describe the structure of ATP

A

sugar linked to a nitrogenous base and three phosphate groups

122
Q

what is ATP hydrolysis?

A
  • an exergonic process which breaks the phosphate-phosphate bond
  • couples to endergonic processes by transferring the phosphate
123
Q

what are the functions of vacuoles?

A

storage of primary and secondary metabolites

124
Q

what are primary metabolites?

A

growth related molecules eg ions, amino acids, lipids, and proteins

125
Q

what are secondary metabolites?

A

non-growth related molecules eg tannins, pigments, alkaloids

126
Q

what are proplastids?

A

undifferentiated plastids

127
Q

what is the function of chromatids?

A

production and storage of pigments

128
Q

what is the function of leucoplasts?

A

storage

129
Q

what is the function of chloroplasts?

A

photosynthesis

130
Q

how do plastids divide?

A
  • binary fission

- budding off

131
Q

what triggers the development of chromoplasts?

A

hormones

132
Q

what triggers the development of chloroplasts?

A

light

133
Q

what three molecules do chloroplasts use to capture light?

A
  • chlorophyll A
  • chlorophyll B
  • cartenoids
134
Q

what light colours does chloroplasts absorb

A
  • red

- blue violet

135
Q

describe the structure of the chloroplast

A
  • ctDNA
  • outer, inner, and thylakoid membranes
  • thylakoids stacked into grana
  • lumen = matrix within thylakoid membrane
  • stroma = matrix between thylakoid and inner membranes
136
Q

where do dark reactions occur?

A

stroma

137
Q

where do light reactions occur?

A

thylakoid membranes

138
Q

where are leucoplasts located?

A
  • roots

- parts of the plant which dont do photosynthesis

139
Q

Describe what happens in photosystem 2

A
  • photon hits Mg ion in head of chlorophyll
  • e- gets excited
  • e- jumps around chlorophyll molecules
  • e- goes to primary electron acceptor
  • water split to produce e- to replace e- (also produces O2 and H+ which go into lumen)
140
Q

describe what happens on the first electron transport chain of photosynthesis

A
  • e- falls down chain to photosystem 1
  • goes through cytochrome complex
  • energy used to generate ATP
  • puts more H+ into lumen
141
Q

describe what happens in photosystem 1

A
  • photon strikes a Mg atom and excites an electron
  • electron from Photosystem 2 replaces it
  • e- bounces around chlorophyll molecules
  • e- goes into primary electron receptor
142
Q

describe what happens in the second electron transport chain of photosynthesis

A
  • electron goes through NADP+ reductase

- produces NADPH

143
Q

describe what happens in carbon fixation

A

rubsico fixes carbon dioxide into an organic molecule

144
Q

what happens during reduction?

A

electrons from NADPH are added to the organic molecule, reducing it to form a sugar

145
Q

how is the carbon dioxide acceptor regenerated in photosynthesis?

A
  • carbon dioxide accepter is rubisco
  • 6 sugars are made but only one leaves the chloroplast
  • the other five are used to regenerate rubisco
146
Q

what are the stages of the Calvin Cycle?

A
  • carbon fixation
  • reduction
  • regeneration
147
Q

how do anaerobic organisms carry out photosynthesis?

A

they use nitrogen fixation and repress photosystem 2 so that no oxygen is produced

148
Q

What is the composition of the cell wall?

A
  • 25-30% cellulose
  • 15-20% hemicellulose
  • 35% pectin
  • 5-10% protein
149
Q

what are the two phases in the cell wall?

A
  • crystalline microfibre phase

- non-crystalline matrix

150
Q

what is the structure of the crystalline microfibre phase?

A

strong cable-like structures composed of cellulose microfibres

151
Q

what is the structure of the non-crystilline matrix?

A
  • hemicellulose linkes cellulose cables together

- pectin links neighbouring cell walls together

152
Q

what is the function of hemicellulose in the cell wall?

A

limits cell wall extensibility, so regulates cell enlargement

153
Q

what is the function of pectin in the cell wall?

A

traps water, increasing the elasticity. this is needed for cell wall expansion

154
Q

how much of the cell wall is water?

A

~6.5%

155
Q

which cell wall is secreted first?

A

primary, so it is on the outside of the cell

156
Q

where is the matrix of the primary cell wall formed?

A

Golgi body

157
Q

where is the extensin of the primary cell wall formed?

A

its a protein, so rough ER

158
Q

where is the cellulose in the primary cell wall formed?

A

rosettes on the cell wall

159
Q

what is the function of the middle lamella?

A

sticking adjacent primary cell walls together

160
Q

what is the function of the secondary cell wall?

A

strengthening the cell wall

161
Q

what is the structure of the secondary cell wall?

A

multiple lamaniated layers of microfibrils which are oriented in different directions

162
Q

how is the composition of the secondary cell wall different to the primary cell wall?

A
  • 15-35% ligin (adds strength)
  • more cellulose
  • more fibrin
163
Q

what is the plasmodesmata?

A

a channel between cell walls which makes the cytoplasm, ER, and plasma membrane of neighbouring cells continuous

164
Q

what is the function of the plasmodesmata?

A

hormones and other small molecules can pass through, allowing for rapid intercellular communication

165
Q

how do viruses pass through the plasmodesmata?

A

proteins on the plasmodesmata thread the viral genome through

166
Q

what is the panspermia theory?

A

the theory that the molecules of life had extraterrestrial origins

167
Q

what proof for the panspermia theory does the Mars meteorite offer?

A

contains water, carbon, and mangenite.

carbon and mangenite can only be produced by living organisms and water is essential for life

168
Q

what proof for the panspermia theory does the Murchison meteorite offer?

A

contained lipids, amino acids, nucleotides, and simple sugars. these molecules are unique to life

169
Q

what proof against the panspermia theory is there?

A
  • unlikely biological molecules could survive space
  • or descent to earth
  • contamination from earth
170
Q

what is the chemical evolution theory?

A

the idea that life arose by a series of chemical reactions

171
Q

what were the four steps in the chemical evolution theory?

A
  1. abiotic reactions formed amino acids and nitrogenous bases
  2. spontaneous abiotic production of macromolecules occurred
  3. a protocell formed after a membrane formed around macromolecules. this occurred by lipids being added to water
  4. self-replicating molecules developed
172
Q

what was the first self replicating molecule?

A

ribozymes, which were a combination of RNA and enzymes

173
Q

what environmental conditions were needed for the chemical evolution theory to occur?

A
  • reducing atmosphere
  • lightning / UV to act as a catalyst
  • certain types of clay
  • hydrothermal vents
174
Q

what evidence for the chemical evolution theory is there?

A

the Miller and Urey experiment which derived organic molecules from a simulation of early earth’s environment

175
Q

what is serial endosymbiosis?

A

the theory that eukaryotic cells arose due to failed phagocytosis of prokaryotes

176
Q

how were inner cell membranes developed?

A

the cell membrane folded inwards, forming the nuclear envelope and endoplasmic reticulum

177
Q

how did mitochondria arise?

A

a heterotrophic prokaryote was phagocytosed by a larger prokaryote but did not go to the endolysosome pathway

178
Q

how did chloroplasts arise?

A

a phototrophic prokaryote was phagocytosed by a larger prokaryote but did not go to the endolysosome pathway

179
Q

did chloroplasts or mitochondria arise first? why?

A

mitochondria bc all cells have them and only some cells have chloroplasts

180
Q

what evidence for the serial endosymbiosis theory is there?

A
  • inner plasma membranes of eukaryotes are very similar to cell membrane
  • mitochondria and chloroplasts are semiautonomous
  • mitochondria and chloroplasts are vunerable to some prokaryote antibiotics
  • the inner membrane of mitochondria and chloroplasts are like prokaryote membranes and the outer ones are like eukaryote cell membranes
181
Q

how would serial endosymbiosis be mutually beneficial?

A

eukaryote cell = new energy source

mitochondria and chloroplast = protection and constant environment

182
Q

what size is the nucleus diameter?

A

5 - 10 microns

183
Q

what cells do not have one nucleus? why?

A
  • red blood cells so they can carry more oxygen

- muscle cells because they are made up of multiple cells fused together

184
Q

what is the structure of the nuclear envelope?

A

double phospholipid bilayer

185
Q

what is the function of the nuclear envelope?

A

-protect the genetic material

186
Q

where is the nuclear lamina?

A

on the inside of the nuclear envelope

187
Q

what is the structure of the nuclear lamina?

A

made of intermediate filaments

188
Q

what is the function of the nuclear lamina?

A
  • provides support and shape for nucleus

- organises packing of DNA

189
Q

what is a nuclear pore?

A

a highly regulated channel on the outside of the nuclear envelope

190
Q

what does the nuclear pore allow to exit the nucleus?

A
  • mRNA
  • tRNA
  • rRNA
191
Q

what does the nuclear pore allow to enter the nucleus?

A
  • energy
  • materials
  • hormones
192
Q

what is the diameter of DNA?

A

-2nm diameter

193
Q

which proteins are used for DNA packing?

A

histones

194
Q

what is the first stage of DNA packing?

A
  • DNA combines with histones to form chromatin fibres
  • nucleosome beads
  • 10nm diameter
195
Q

what is the second stage of DNA packing?

A

histones twist the 10nm chromatin fibres to form a 30nm fibre

196
Q

what is the third stage of DNA packing?

A

30nm fibres supercoil around histone proteins to form 300nm fibres which then coil to form metaphase proteins

197
Q

what is euchromatin?

A

less dense areas of interphase DNA which is used more often

198
Q

what is heterochromatin?

A

more dense areas of interphase DNA which is used less often.

Cells 191 (3 decks)

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