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BIOL371 Comparative Biology of Plants and Animals > Theme 1 > Flashcards

Theme 1 Flashcards

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1
Q

The major divisions of the living world are defined by:

A

cell characteristics

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2
Q

Eukaryotes and prokaryotes have what in common?

A

plasma membrane

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3
Q

What is the cytoskeleton?

A
  • protein fibre networks support plasma membrane and organelles within cytoplasm, allowing movement and maintenance of spatial relationships within the cell among its elements
  • also allows cell to control its shape and to move
  • enables eukaryote cells to engulf food particles
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4
Q

The cytoskeleton is made up of?

A

microtubules, microfilaments, and intermediate filaments

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5
Q

What are microtubules?

A

hollow tubes formed from tubulin dimers

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6
Q

What are microfilaments?

A

double helix of actin monomers that are important in movement and intracellular transport

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7
Q

What are intermediate filaments?

A

strong fibers composed of intermediate filament proteins

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8
Q

Cilia and flagella

A

Cilia are short and abundant
Flagella are long and few
They are elements allowing the cell to move.
Cross section in cilium reveals the 9 + 2 arrangements of microtubules

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9
Q

Eukaryote Endomembrane System

A
  • collective term for nuclear envelope, lysosomes, golgi apparatus, vacuoles, and endoplasmic reticulum
  • series of flattened sacs and tubes formed of lipid bilayer membranes, directly interconnected or connected by moving vesicles
  • general function is to compartmentalize the interior of the cell, thus isolating incompatible biochemical processes, and to transfer products b/w these compartments
  • greatly increases available S.A for synthesis
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10
Q

Structure of Eukaryote Genome

A
  • divided between a number of linear chromosomes
  • allows for expression of genes on different parts of a single chromosome or on different chromosome (regulatory genes)
  • allows cell differentiation and production of different tissue types
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11
Q

Mitochondria is:

A
  • the site of oxidative phosphorylation in eukaryote cells
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12
Q

Chloroplasts are the site of:

A

photosynthesis in eukaryote cells

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13
Q

Mitochondria and chloroplasts greatly increase:

A

S.A available for their processes when compared to prokaryotes

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14
Q

Sexual Reproduction in eukaryotes

A
  • fusion of 2 haploid gametes from 2 parents to form a new individual genetically different from either parent (vertical transmission)
  • generates genetic diversity
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15
Q

What is the evidence for endosymbiotic origins?

A
  • Circular DNA
  • Independent fission (remove mitochondria or plastids from a eukaryote cell and it cannot produce new ones)
  • Size (same as bacteria)
  • Double membrane
  • Certain proteins specific to bacteria cell membranes are also in mito/chloro membranes
  • 70S ribosomes
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16
Q

Endosymbiotic hypothesis part 1:

A
  • heterotrophic eukaryotes evolved first through union of ancestral archeon with aerobic alpha-proteobacterium which became mitochondrion
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17
Q

Endosymbiotic hypothesis part 2:

A
  • autotrophic eukaryotes evolved from heterotrophic eukaryotes through union with photosynthetic cyanobacteria, which became chloroplasts
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18
Q

Endosymbiotic origin scenarios:

A
  1. Ancestral archaeon first evolved endomembrane system, then entered symbiosis with alpha-proteobacterium, which became mitochondrion
  2. Ancestral archaeon entered symbiosis with alkpha-proteobacterium, which became mitochondrion, then endomembrane system evolved subsequently
    (2 makes more sense, but both possible)
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19
Q

What is the cube-square relationship?

A
  • S.A and volume of a solid do not increase linearly with increase in linear dimensions:
  • S.A is propotional to length^2
  • vol is proportional to length^3
  • S.A is proportional to volume^2/3
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20
Q

Constraining relationship of S.A/vol

A
  • Exchange across membranes around or within a cell is by diffusion or active transport, both only work effectively over very short distances and are dependent on S.A
21
Q

Why is the cube-square relationship a critical limiting relationship?

A
  • is why cells are small
  • rates at which materials enter and exit cell is function of its S.A
  • rates at which gasses and nutrients are used and wastes produced are function of cell’s volume
  • small cells can exchange materials more effectively with their environment than large ones
22
Q

What is simple multicellularity?

A
  • cell adhesion but little else

- structurally simple

23
Q

What is complex multicellularity?

A
  • cells adhere, communicate, differentiate and specialize for formation of tissue
24
Q

Origins of multicellular life theories?

A
  1. Symbiotic theory: different species came together (unlikely)
  2. Syncytial theory: division without cytokinesis until a certain point then differentiation occurs (likely)
  3. Colonial theory: same species start living together eventually became one organism because it worked out so well, differentiated (MOST likely)
25
Q

Complex multicellularity arose independently at least:

A

6 times in the history of life

26
Q

Cyanobacteria, the Great Oxygenation Event

A

The rise in environmental oxygen gave a selective advantage to possession of mitochondria and aerobic respiration, which permitted multicellularity

27
Q

Origins of multicellularity

A
  • Most evolutionary models begin with flagellated unicellular organisms (choanoflagellates in case of animals)
  • Required that cells divide up tasks, specialize
  • Required that cells learn to communicate with one another (affect one another’s behaviour, influence one another’s development, coordinate complex actions)
28
Q

Simple Multicellularity

A
  • Evolved independently in multiple eukaryote lineages

- Few cell types, no bulk flow, no complex structures

29
Q

Unicellular organisms must carry out all functions of metabolism, homeostasis, reproduction, repair etc. with the resources of a

A

single cell

30
Q

Single isolated cells must deal directly with

A

their environment

31
Q

Unicellular organisms can’t get very big because

A

cube-square relationship keeps them small

32
Q

Selective Advantages of Multicellularity:

A
  • Division of labour and economy of scale
  • Increased size
  • Complexity
33
Q

Specific advantages of increased size:

A
  • Avoid predation/eat larger things
  • Exploit new environment, reach upwards
  • Storage
  • Increased feeding mechanisms/opportunities
  • Protected internal environment that can be regulated
  • Cells can specialize since the internal environment is protected
  • New metabolic functions
  • Enhanced motility
  • Increased traction in wind/current
  • Share info with other cells
34
Q

Specific advantages of complexity:

A
  • Predator/prey and host/parasite interactions

- An increased opportunity for diversity in form/function and niches

35
Q

Challenges of being multicellular and large

A
  • Surface area / Volume relationships
  • Must create solutions to allow exchange and rapid transport
  • Intercellular communication, cells must be able to communicate with one another
  • Cell adhesion (cells must stick together)
  • Structure and support (physical laws set limits on animal size and performance)
  • Homeostasis (defend cells against hostile environment, maintain stable internal environment for internal cells)
  • Reproduction and growth (the multicellular body must be able to produce new multicellular bodies)
36
Q

Oxygen consumption increases with

A

body size

37
Q

Adaptions for increasing surface area

A
  • Gas exchange (highly folded structures to pack more surface area in small volume)
  • Nutrient absorption (villi increase S.A area for absorption)
  • Filtration (capillary beds provide extremely large cumulative surface area for exchange between blood and tissues)
38
Q

Larger bodies must have long-range transport system to ensure that:

A

materials reach every square unit of the total membrane surface area for effective exchange across the total membrane surface

39
Q

What is extracellular fluid?

A

all of the body’s water not found within cell plasma membranes

40
Q

What is intracellular fluid?

A

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

41
Q

What are tight junctions?

A

junctions that penetrate cell membranes of adjacent cells, fix cells in place, prevent movement of liquids between cells

42
Q

What are adherence junctions?

A

junctions of adjacent cells link to each other and to microfilaments underlying cell membranes

43
Q

What are desmosomes?

A

adjacent cells link to one another and to intermediate filaments of cytoskeleton

44
Q

What are gap junctions?

A
  • adjacent cells form channels penetrating cell membranes of both cells
  • Signalling molecules and water can be passed directly from cell to cell
  • Cells can thus communicate with one another
45
Q

Tissues

A
  • Group of similar cells and extracellular substances working together to carry out a specific function for the organism as a whole
  • Requires that cells attach to one another and communicate with one another
46
Q

The organs of multicellular organisms are composed of:

A

basic tissue types, specialized in structure and functions to carry out different tasks for the organism as a whole

47
Q

Collagen and connective tissues

A
  • Connective tissues in animals consist of cells, extracellular matrix, and fibres
  • Collagen is a fibrous protein found in animal connective tissues
  • Forms fibres in polysaccharide matrix of connective tissues
48
Q

Extracellular Matrix and Cells

A
  • Basic matrix consists of glycoprotein/carbohydrate complexes – absorb water - penetrated by network of collagen fibres
  • Glycoproteins and collagen fibres attach to cell membranes by transmembrane protein, integens, which are attached to cytoskeleton – allow ECM to communicate with cell
  • Matrix produced and maintained by cells within it, influences the way in which cells interact with the rest of the body

BIOL371 Comparative Biology of Plants and Animals (10 decks)

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