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Bio 107 > Lecture 5- eukaryotic cell structure > Flashcards

Lecture 5- eukaryotic cell structure Flashcards

1
Q

origin of eukaryotes = the _____ hypothesis

A

endosymbiotic

good roommate

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2
Q

describe the ‘good roommate’ hypothesis

A
  • heterotrophic bacteria are sensitive to increasing [O2]
  • eukaryotes evolved O2 neutralizing enzymes
  • bacteria ingested but not digested… these became organelles mitochondria and chloroplast
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3
Q

endomembrane system=

A

membrane-bound organelles that arose from infoldings of membrane and are connected via vesicles

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4
Q

vesicle=

A

membrane-bound compartment that contains cargo

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5
Q

list the 4 organelles in endomembrane system

A
  • outer nuclear membrane
  • ER
  • golgi
  • lysosome
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6
Q

nucleus/ nucleolus city analogy:
____ is the whole city, ____ is downtown
(they are not physically separate)

A

nucleus

nucleolus

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7
Q

the nucleus stores ___ and is the site of ___ _____

A

DNA

gene expression

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8
Q

the ___ is double-membrane bound with the outer membrane continuous with the ___

A

nucleus

ER

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9
Q

What does the NPC (nuclear pore complex) do?

A

transmembrane complexes that span both bilayers

- allows nonspecific transport

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10
Q

____ is the site of ribosomal subunit assembly

- subunits associate with their rRNAs at the ____

A

nucleolus

nucleolus

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11
Q

ribosomal subunits leave the nucleus as independent subunits and come together in the ____ during ____

A

cytoplasm

translation

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12
Q

the nuclear envelope includes both nuclear membranes

  • function:
  • structure:
A 
fxn= protects DNA
structure = 2 lipid bilayers plus nuclear lamina
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13
Q

chromatin=

A

DNA associated with protein

- within a chromosome

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14
Q

why package DNA?

A

organize it and protect it from damage

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15
Q

what are the 4 orders of DNA packaging?

A
  1. nucleosome
  2. solenoid/ 30nm fiber
  3. looped domains
  4. mitotic chromosome
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16
Q

describe the 1st order of packaging

A

nucleosome:

- DNA wrapped around a histone octamer

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17
Q

describe the 2nd order of packaging

A

solenoid/ 30nm fiber

- nucleosomes stack with the help of histone H1

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18
Q

describe the 3rd order of packaging

A

looped domains

  • 30nm fiber loops off a non-histone protein scaffold
  • found in all cell stages
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19
Q

describe the 4th order of packaging

A

mitotic chromosome

  • fully condensed chromosome only appears during cell division
  • so tightly wound that you can’t get any info/ gene expression off it
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20
Q

histone =

A

pos charged proteins

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21
Q

the rough ER is covered in ___ which are the enzymes of____

A

ribosomes

translation

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22
Q

The ____ ___ is associated with translation of proteins destined for within the endomembrane system. They’re called ___ ribosomes (___ribosomes are free floating in cytoplasm)

A

rough ER
bound
free

23
Q

function of rough ER?

A
  • site of protein quality control (lots of chaperones, folding)
  • site of protein synthesis for proteins that fxn within the endomembrane system
24
Q

Proteins destined for the cytoplasm or nucleoplasm are synthesized on ____ ribosomes

A

free

25
Q

proteins destined for the plasma membrane or are exported/ secreted are synthesized on ___ ribosomes

A

bound

26
Q

the smooth ER has no ___

A

ribosomes

27
Q

List 4 examples of functions of the smooth ER

A
  • ion storage (Ca2+)
  • phospholipid synthesis
  • steroid synthesis
  • detoxification of drugs and alcohol
28
Q

The _____ _____ receives cargo from the ER (everything the ER makes) and sorts cargo to 3 different destinations:
1.
2.
3.

A

Golgi apparatus

  1. lysosome
  2. plasma membrane
  3. back to ER
29
Q

The golgi packages cargo into ___

it’s like the FedEx of the cell

A

vesicles

30
Q

The structure of the golgi is a set of flattened membranous sacs called ____

A

cisternae

31
Q

2 models of golgi trafficking

A
  1. Vesicle Trafficking:
    - cargo from ER moves through CIS, medial, and trans (vesicle containing cargo comes out of the shipping side- trans)
  2. Cisternal Maturation
    - cargo from ER enters CIS and stays there; the CIS moves, not the cargo (escalator analogy)
    - New CIS cisternae forms by fusion of vesicles from ER
    - trans golgi turns into vesicles
32
Q

Evidence for Vesicle trafficking model (Golgi)

A
  • small vesicles are associated w/ golgi

- there are cisternal- specific enzymes

33
Q

Evidence for Cisternal Maturation model (Golgi)

A
  • molecules too big to fit in the golgi- associated vesicles can move through golgi
34
Q

lysosomes can ___ anything

A

digest

35
Q

____ contain many hydrolytic enzymes that fxn best @pH=5

A

lysosomes

36
Q

How to lysosomes maintain low pH? Why is it important to maintain low ph?

A
  • they actively pump in H+

- low pH protects the cells from accidental autophagy (eating itself)

37
Q

example of lysosomal storage disorder?

A

Tay Sachs- lack an enzyme to digest a particular lipid

- therefore the lipid accumulated and causes neuronal death

38
Q

Vacuoles have different fxns depending on cell type. List 3

A
  • food vacuoles
  • contractive vacuoles: pump excess water out of the cell
  • cenrtal vacuole: specific organelle of plants - fxns in storage and part of plant endomembrane system
39
Q

List 3 organelles not in the endomembrane system.

Why aren’t they in the endomembrane system?

A
  • mitochondria and chloroplasts
  • peroxisomes (involved in detox of alcohol, metabolism of fats- dangerous rxns happen here)
  • cytoskeleton (fxn in support, motility and cell shape)

Because they have a different evolutionary origin

40
Q

what are the 3 different fibers that make up the cytoskeleton?

A
  • microtubules (MT)
  • microfilaments
  • intermediate filaments
41
Q

Microtubules are composed of ___ ___

A

tubulin dimers

42
Q

Function of microtubules:

A

compression resistance (rods prevent squish)

43
Q

tubulin (the monomer of microtubules) is a diamer of ___;___ tubulin monomers

A

alpha; beta

44
Q

motor protein=

A

protein that change shape with ATP hydrolysis that generates force

45
Q

2 motor proteins associated with microtubules

A
  1. Kinesin: (+) end directed MT motor; uses monkeybar movement
  2. Dynein: (-) end directed MT motor
    mechanism of dynein movement unclear
  • note: (-) end is on the left of the MT, (+) on right
46
Q

example of MT function

A

eukaryote flagellum

- movement is generated by dynein (kinesin moves vesicles)

47
Q

microfilaments (MF) or “actin filaments” are composed of ____ monomers and is a double twisted chain of ____ ____

A

actin

actin subunits

48
Q

fxn of microfilaments

A

tension resistance

- movement: cytokinesis and muscular contraction

49
Q

what’s the ‘motor’ of microfilaments?

A

myosin

eg. in muscles, pulling of myosin shortens the muscle

50
Q

Intermediate filaments function in ____ ___ (like MFs)

A

tension bearing

51
Q

structure of intermediate filaments

A

many different subunit types that form rope-like filaments

52
Q

do intermediate filaments have any associated motor proteins?

A

no

53
Q

give 2 examples of intermediate filaments

A
  • laminin (intermediate filament forming nuclear lamina)
    provides support
  • keratin- in hair and nails

Bio 107 (12 decks)

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