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BIOL371 > Theme 1 > Flashcards

Theme 1 Flashcards

Evolutionary Underpinnings of Plant and Animal Biology

1
Q

What is an Organism?

A

a level in the hierarchy of the living world; can consist of a single cell or multiple cells & all of its component parts work together to promote the organism’s survival

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2
Q

The major divisions of the living world are defined by ______________________________.

A

cell characteristics

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3
Q

Name the three domains of life

A

Bacteria, Archaea, Eukarya

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4
Q

____________ networks support plasma membrane and organelles within cytoplasm

A

protein fibre

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5
Q

The cytoskeleton allows movement of ________________________ within the cell and maintenance of their spatial relationships.

A

organelles

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6
Q

Cytoskeleton allows cells to control their ____________ and to ________________.

A

shape; move

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7
Q

Microtubules

A
  • cytoskeleton
  • hollow tube formed from tubulin dimers
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8
Q

Intermediate filaments

A
  • cytoskeleton
  • strong fiber composed of intermediate filament proteins
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9
Q

Microfilaments

A
  • cytoskeleton
  • double helix of actin monomers
  • important for movement and intracellular transport
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10
Q

Cytoskeletal elements that allow cells to move or create currents:

A

cilia and flagella

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11
Q

There is usually a difference in _________________ & ______________ between cilia and flagella

A

length (flagella>cilia) and number (fewer flagella than cilia)

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12
Q

Eukaryote Endomembrane System’s function is to

A
  • efficient way of folding up large SA in a small volume, allowing for greater activity
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13
Q

The EES is a collective term for the ________________, _________, _____________, _____________, ________________.

A

nuclear envelope
lysosomes
Golgi apparatus
vacuoles
endoplasmic reticulum

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14
Q

EES has series of flattened sacs and tubes formed of ___________________________ membranes, which are directly interconnected by moving ____________. Their general functions are to:

A

lipid bilayer
vesicles

  • compartmentalize the interior of the cell, isolating incompatible biochemical processes and transferring products between the compartments to increase SA
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15
Q

Prokaryote genome a single loop of DNA, which is good for ___________________. A requirement for this is that ______________________.

A

rapid replication;
gene regulation must be simple as everything is on the same structure

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16
Q

Eukaryote genome is divided between a number of ________________________

A

linear chromsomes

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17
Q

Eukaryotic genome allows for

A

gene regulation
cell differentiation
prodiction of different tissue types
chromosome replication to take place in parallel

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18
Q

Eukaryotic gene ___ prokaryotic gene

A

>

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19
Q

Mitochondria

A

not found in prokaryote cells but some engage in oxidative phosphorylation

  • site of oxidative phosphorylation in eukaryotic cells
  • increase SA for these processes when compared to prokaryotes
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20
Q

Chloroplast

A

not found in prokaryote cells but some engage in photosynthesis

  • site of photosynthesis in eukaryotic cells
  • increase SA for these processes when compared to prokaryotes
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21
Q

Sexual production

The fusion of two haploid gametes from two parents form new individual genetically different from either parent; what is this process called?

A

vertical transmission (inheritance)
- generates genetic diversity through independent assortment and recombination

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22
Q

Evidence for endosymbiotic origins (__________________)

A

(lateral transfer)

  • circular DNA with highly reduced functional genes
  • independent fission - remove mitochon. or plastids from eukaryotic cell and it cannot produce new ones
  • size = 1-10 microns (bacteria size)
  • double membrane
  • certain proteins specific to bacteria cell membrane are also found in mito/chloro membranes
  • 70s ribosomes - different size than eukaryotic 80s ribosome
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23
Q

Primary Endosymbiosis Hypothesis P1

A

heterotrophic eukaryotes evolved first through the union of ancestral archaeon with aerobic a-proteobacterium –> which became mitochondrion

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24
Q

Primary endosymbiotic hypothesis P2

A

autotrophic eukaryotes evolved from heterotropihc eukaryotes through union with photosynthetic cyanobacterium which became chloroplasts

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25
Q

Endosymbiotic origins of mito/plastids

The aquisition of mitochondria and plastics by primary endosymbiosis is a form of __________________

A

lateral transfer

diagram on page 32

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26
Q

What are the two alternative scenarios for evolution of final form of eukaryote cell?

A

ancestral archaeon first evolved endomembrane system, then entered symbiosis with a-proteobacterium –> becoming mitochondrion

OR

ancestral archaeon entered symbiosis with a-proteobacterium, which became mitochondrion - endomembrane system then evolved subsequently

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27
Q

Page 35 - Endosymbiotic origins of mito/plastids

Prokaryote genes transferred to eukaryote _________.

What is this an example of?

A

nucleus
- this is a form of lateral transfer

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28
Q

What are the different forms/examples of lateral transfer

A
  • bacteria swapping DNA
  • endosymbiosis
  • chloroplast genome –> nuclear genome
  • lateral transfer through endoviruses
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29
Q

Modern Endosymbiosis - Aquisition of New Organelles

Braarudosphaera bigelowii

A
  • modern marine unicellular eukaryote alga
  • nitrogen-fixing organelle shown to originate from symbiotic nitrogen-fixing bacterium
  • they became organelle long time ago (100 My)

Host cell was already eukaryote and was able to engage in phagocytosis

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30
Q

Secondary Endosymbiosis

A
  • major eukaryote taxa arose as a result of *symbiosis of heterotrophic eukaryote cell *within an auxotropic eukaryote cell
  • 3 independent occurances

Page 37

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31
Q

_______________ was an important route for the acquisition of evolutionary novelties

A

lateral transfer

32
Q

SA-V Relationships - Cells

A

SA and V of a solid do not increase linearly with an increase in linear dimensions
- SA is proportional to length^2
- V is proportional to legnth^3

SA=V^2/3

  • the large cell and cluster of small cells have the same volume but the cluster of small cells has total SA of 162 units^2

CHECK slide 42

33
Q

Constraining Relationship

Exchange across membranes around or within a cell is by _____________ or ______________

When do both work effectively?

A

diffusion or active transport
- both only work effectively over very short distances and rates are dependent on SA

34
Q

Cube-Square Relationship

A

critical limiting relationship - this is why cells are small
- rates at which all materials enter or exit cell is a function of the SA

there must be a balance between SA and V in cells

  • rates at which gasses and nutrients are used and wastes produced are a function of the V
35
Q

Based on the Cube-Square Relationship, what type of cells can exchange materials more effectively with their environment?

A

small cells as the V increases more rapidly than the SA (check graph on page 44)

36
Q

SA/V Relationships in Eukaryotic Cells

What is the importance of SA/V in eukaryotic cells?

A

the endomembrane system and increased internal SA of chloroplasts and mitochondria involve elaborate folding of extensive membranes

  • allows for more scope for** membrane-associated processes**
  • allows eukaryotic cells to produce more energy and have greater synthetic scope
  • they can be BIGGER and MORE ENERGETIC than prokaryotes
37
Q

Types of Multicellularity

A

simple multicellularity
complex multicellularity

38
Q

Bulk Flow

A

movement of fluids or gasses through channels, rather than cell-to-cell

39
Q

Simple Multicellularity

A
  • cell adhesion
  • cell-cell communication but little less structurally simple
  • no bulk flow
  • most cells in direct contact with environment
  • related, simpler forms have fewer cells, little specialization
  • each stage has advantages
40
Q

Volvox

A

simple multicellularity example
- constituent cells specialized as flagellated photosynthesizers or reproductive cells

review figure 1.26 on slide 48

41
Q

Complex Multicellularity

A

cells adhere
communicate
differentiate
specialize
- formation of tissues

42
Q

Slime Molds

A

example of simple multicellularity
- they spend part of the life cycle as unicellular amoebas, congregate and produce mutlicellular structures under conditions of environmental stress

43
Q

Three Theories of Origins of Multicellular Life

A

symbiotic theory
syncytial theory
colonial theory

44
Q

Symbiotic theory

A
45
Q

Syncytial theory

A

undergoes mitosis - more copies of mucleus but do not split
undergoes cytokinesis with cells specializing

46
Q

Colonial theory

A

same species coming together

47
Q

6 times complex multicellularity arose independently in history of life

A
  • many unicellular eukaryotes have capacities needed for multicellularity (adhesion and communication)
  • plantae
  • amoebozoans
  • stramenopiles
  • alveolates
  • rhizarians, opisthokonts
  • discobids, metamonads
48
Q

What are the capacities needed for multicellularity

A

adhesion, communication

49
Q

Evolution of Multicellularity
1. Cyanobacteria - The Great Oxygenation Event

A

actually prolonged period in history - happened over the years

  • rise in environmental oxygen levels due to photosynthesis gave selective advantage to possesion of mitochondria and aerobic respiration = permitted multicellularity
50
Q

When does simple multicellularity appear? complex?

A

end of Great Oxygenation Event; complex appears with subsequent rise in environmental O2 levels

51
Q

ancestral holozoan

A

group that includes animals and their close relatives
- a recently found fossil shows evidence of cell-cell adhesion and cell differentiation

52
Q

Most evolutionary models begin with what? They required ___________, which affected?

A

flagellated unicellular organisms (choanoflagellates in case of animals)

They required:
- cells be able to adhere to each other
- cells to divide up tasks and specialize
- cells to learn to communicate with each other

This affected:
- each others behaviour
- influence each others development
- coordinate complex actions

Diagram on 56

53
Q

Which groups exhibit complex multicellularity?

A

brown algae (stramenopiles)
red, green algae (plantae)
land plants (archaeoplastids)
fungi
animals

54
Q

Why multicellularity?

A
  • unicellular organisms must carry out all functions of metabolism, homeostasis, reproduction, repair, etc. with the resources of a single cell
  • single isolated cells must deal directly with their environment
  • unicellular organism can’t get very big because the cube-square relationship keeps them small
55
Q

Selective advantages of multicellularity

A

divisions of labour and economy of scale
increased size

56
Q

What do the advantages of multicellularity allow?

A

avoid predation/eat larger things
exploid new environment
storage
increased feeding mechanisms/opp
protected internal environent that can be regulated (homeostasis)
specialization since internal env. is regulated
new metabolic functions
enhanced mobility
increased traction in currect/wind
share information with other cells

57
Q

Consequences of multicellularity

A

complexity
- predator/prey and host/parasite interactions
- increased opportunity for diversity in form/function an niches

58
Q

Challenges for being multicellular and large

A

intercellular communication - cells must be able to communicate with one another
- diffusion - can be use to communicate in short range
- gap junctions/plasmodesmata (equiv. of plants)
- bulk flow
- nerrves
- signalling molecules

**Cell Adhesion **- cells in the multicellular boy must stick together

Cube-Square Relationship
- volume increases as a function of the cube of linear dimensions with increasing size
- SA increases as a function of the square of the linear dimensions with increasing size

Structure and Support
- physical laws set absolute limits on animal size and performance
- morphology reflects accommoation with these limits
- challenges vary over animal boy size range

Homeostasis
- defend cells against hostile environment
- maintain stable internal environment for internal cells
- lot of exchange between intracelullar fluid and extracellular fluid - so composition and volume of extracllular flouid must be kept STABLE

Reproduction and Growth
- multicellular body must be able to produce new multicellular bodies
- development and differentiation require complex and flexible control systems

59
Q

As an organism gets larger, its SA becomes ___________ relative to its volume

A

smaller

60
Q

Metabolic rate in mammals is effectively measure by _____________________________________

A

organism’s O2 consumption (mLO2/hr)
- O2 consumption increases with body size

61
Q

Basal metabolic rate is much _____________ for an elephant than a mouse because?

A

lower; because constraint of SA/V ratio is much lower for an elephant than a mouse

check graph on page 68

62
Q

An elephant has proportionately much less __________________ for dissipation of heat than a rabbit; hence with greater _________, ______________ must decrease

A

SA; body size; mass-specific metabolic rate

63
Q

Adaptions for increasing SA

A

Gas Exchange
- gills bear lamellae, composed of flattened epithelial cells
- highly folded to pack greater SA into smaller V

Nutrient Absorption
- villi of small intestine epithelial cells increase SA for absorption within a small V

Filtration
- body’s combine capillary beds provide extremely large cummulative SA for exchange between blood and tissues

64
Q

SA/V Relationships

multicellular bodies therefore consist of very large areas of [blank] utlilzing [blank] to move materials across

this requires?

A

cell membranes; short-range transport molecules
- requires extensive folding to fit all this within a reasonable volume

65
Q

SA/V Relationships

larger boies must have what to ensure that materials reach every square unit of the total membrane SA for effective exchange across total membrane surface?

A

long-range transport systems
- bulk flow

66
Q

Most anatomical and physiological features of multicellular organisms are the result of accomodating what?

A

SA/V relationships - folding extensive membrane area into magageable volume, plumbing systems (bulk flow) to service this

67
Q

Example of homeostasis on page 74 as a challenge of being multicellular:

water content of a multicellular organism can be divided into two major compartments:

A
  • extracellular fluid compartment
  • intracellular fluid
68
Q

Example of homeostasis on page 74 as a challenge of being multicellular

What is intracellular fluid

water content of a multicellular organism can be divided into two major compartments:

A

all of the body’s water found within cells - liquid portion of cytoplasm

69
Q

Example of homeostasis on page 74 as a challenge of being multicellular

Extracellular fluid compartment

water content of a multicellular organism can be divided into two major compartments:

A

all the body’s water NOT FOUND within cell plasma membranes (this forms cell’s immediate environment)

70
Q

Why must the extracellular fluid’s compositon and volume be kept stable for homeostasis?

75

A

composition and volume of extracllular flouid must be kept STABLE because there is lots of exchange between intracellular and extracellular fluids and the amount of work cells must do to maintain their own individual homeostasis can be minimized this way.

71
Q

Cell Adhesion 78

Cells in multicellular bodies must be attached to one another or to a acellular matrix. What are the three types of junctions in animals:

A

tight junctions - penetrate cell membranes of adjacent cells, fix cells in place, prevent movement of liquids between cells
anchoring junctions - of adjacent cells link to each other and microfilaments or intermediate fibres of cyotskeleton
gap junctions - of adjacent cells form channels penetrating cell membranes of both cells
- signalling molecules and water can be passed directly from cell to cell
- hence they can communicate with each other

72
Q

How are cells able to communicate with each otehr?

A

gap junctions

73
Q

Tissue

A

group of similar cells and extracellular substances working together to carry out specific function for the organism

  • requires cells to attach to each other and communicate
  • both plants and animals are organized in tissue level
74
Q

Tissue in Animals: 4 types of tissues in triploblasts are? What do they arise from?

A
  • epithelia
  • connective tissues
  • muscle tissue
  • neural tissue
    embryonic germ layers
75
Q

Extracellular Matrix and Cells

Characteristic of animals’ extracellular matrix and cells

A

basic matrix is acellular (not alive but have to manage water)
- penetrated by network of collagen fibres
- varies greatly among diff organisms and types of connective tissues

76
Q

Collagen

A

extracellular fibrous protein found in connective tissues
- only in animals
- like rubber (strong but flexible)

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