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BIO 110 > The Endomembrane System of Eukaryotes (CH 4.4) > Flashcards

The Endomembrane System of Eukaryotes (CH 4.4) Flashcards

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1
Q

What is an Endomembrane?

A
  • Located inside the eukaryotic cell
  • Membranes that form an elaborate internal of cell= fills the cell &; divides it into compartments
  • Fundamental distinction between prokaryotes & eukayotes
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2
Q

What is the job of the Endomembrane?

A
  • Channels the passage of molecules through interior of cell

- Provides surface for synthesis of lipids &; some proteins

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3
Q

What is the largest internal membrane?

A
  • Endoplasmic Reticulum (ER)= rough & smooth

- ER may also be connected to cytoskeleton= affects ER strucure &; growth

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4
Q

What is the Endoplasmic Reticulum made of?

A
  • Phospholipid bilayer embedded w/ proteins
  • Connected from one bit of RER to another bit of RER, one bit of SER to another bit of SER, & Be continuous between SER & RER
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5
Q

What are the 2 largest compartments in Eukaryotic cells?

A
  • Inner region of ER= Cisternal Space/ Lumen

- Outer region of ER= Cytosol= fluid compartment of cytoplasm containing dissolved organic molecules (proteins or ions)

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6
Q

What is the Rough Endoplasmic Reticulum made of &; what is it’s job?

A
  • Flattened sacs
  • Surface is covered in ribosomes
  • Site for protein synthesis
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7
Q

What happens to the proteins synthesized on RER’s surface?

A
  • Destined to export from cell
  • Sent to Lysosomes, Vacuoles, or embedded in Plasma Membrane
  • Enter Cisternal Space= 1st step of sorting proteins to their destinations
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8
Q

What does the sequence of the protein being synthesized determine?

A

-Whether the ribosome will become associated w/ ER or remain a cytoplasmic ribosome

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9
Q

What happens to newly synthesized proteins in ER?

A
  • Can be modified by the addition of short-chain carbos to form Glycoproteins=
  • Destined for secretion &; separated from other products & then packaged to be sent go Golgi Apparatus for further modification & transport to other locations
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10
Q

What makes up the Smooth Endoplasmic Reticulum?

A
  • Variety of structures

- Network of tubules, higher order tubular arrays

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11
Q

What does the membranes of SER contain?

A
  • Embedded enzymes
  • Involved in synthesis of variety of carbos & lipids
  • Membrane lipids are assembled & sent to wherever they need membrane components
  • Membrane proteins are in plasma membrane are inserted by ribosomes on the RER
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12
Q

What are the important functions of SER?

A
  • Store intracellular Ca2+= keeps cytoplasmic level low which allows Ca2+ to be used as a signaling molecule
  • Modification of foreign substances to make them less toxic (enzymes in liver carrying out detoxification by neutralizing peniclliin, etc)
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13
Q

What does the ratio of SER & RER depend on?

A
  • Cells function
  • Cells that carry out extensive lipid synthesis (testes, intestine, brain= more SER
  • Cells that synthesize proteins that are secreted= more RER
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14
Q

What is the Golgi Apparatus/ Body made of?

A
  • Flattened stacks of membranes

- Individual stacks= Cisternae & vary in # within Golgi body

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15
Q

What is a Golgi Ribbon?

A
  • Individual Golgi that are linked together

- Abundant in Glandular Cells (manufacture & secrete substances)

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16
Q

What is the Golgi’s job?

A
  • Collection, packing, distribution of molecles synthesized at one location &; used at another within cell/outside it
  • Synthesis for cell wall components & sent to plasma membrane
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17
Q

What is the front & back portions of the Golgi for?

A
  • The front= receiving end= Cis Face located near ER

- The back= Exporting= Trans Face

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18
Q

What occurs in the Cis Face & Trans face of the Golgi?

A
  • Material arrives in transport vesicles in the Cis Face

- Material exits via Trans Face where they are discharged in secretory vesicles

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19
Q

How does material transmit through the Golgi?

A

-Maturation of Cisternae from Cis to Trans

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20
Q

What happens to proteins & lipids manufacured on SER & RER?

A
  • Modified as they pass through Golgi

- Common alternation= addition/ modification of short sugar chains= Glycoproteins & Glycolipids

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21
Q

How do the enzymes in Golgi modify EXISTING Glycoproteins & Glycolipids?

A
  • Cleaving a sugar from the chain

- Modifiying one or more of their sugars

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22
Q

What are Lysosomes?

A
  • Formed from vesicles budding off of Golgi
  • Contain high level of Hydrolytic (degrading) enzymes= catalyzes rapid break down of proteins, nucleic acids, lipids, & carbos
  • Elimnate other cells that the cell has engulfed by Phagocytosis
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23
Q

How are Lysosomes & their digestive enzymes activated?

A
  • Fusing w/ food vesicle produced by Phagocytosis
  • Or by fusing w/ an old/ worn-out organelle
  • Fusion activates proton pumps in lysosomal membrane= low pH= Lysosomal digestive enzymes are activated= degredation of macromolecules in food V/ old organelles
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24
Q

Why are the accumulations of Glycolipid in Lysosomes bad?

A

-Affects nerve cell function= variety of symptoms like seizure & muscle regidity

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25
Q

What are Microbodies?

A
  • Diverse category of organelles
  • Variety of enzyme-bearing membrane enclosed vesicles
  • Found in plants, animals, protists
  • Distribution of enzymes into microbodies= principle way eukaryotic cells organize their metabolism
26
Q

What is Perixisome?

A
  • Important microbody= contains digestive & detoxifying enzymes that produce hydrogen perooxide as a by-product
  • Contain enzyme catalase which breaks down hydrogen peroxide into water & oxygen
27
Q

How do Perixomes form?

A

-From the fusion of ER-derived vesicles= important Perixsomal proteins to form a mature Perixsome

28
Q

What are Vacuoles?

A
  • Located in Plants
  • Membrane-bounded structure
  • Stores dissolved subtances & can expand in size to increase tonocity of plan cell
  • Kinds & # of vacuoles in cell depends on it’s particular needs
29
Q

What is the Tonoplast?

A
  • Membrane surrounding vacuole
  • Contains channels for water that help maintain its tonocity/ osmotic balance= allows cell to expand & contract depending on conditions
30
Q

What is the structure of a nucleus?

A
  • Surrounded by nuclear envelope= double membrane connected to each other (each membrane is one lipid bilayer w/ other components)
  • Has Inner & Outer bilayer
  • Has Nuclear Pores
31
Q

What does the Inner bilayer of a Nucleus have?

A

-Special proteins connected to Nuclear Lamina= associated w/ functions inside the nucleus (expression of genes, replication)

32
Q

What does the Outer bilayer of a Nucleus have?

A
  • Ribosomes & connected to RER

- Associated w/ functions outside the nucleus (cytoplasm)

33
Q

How many bilayers does a molecule have to go through to reach the nucleus?

A

3 bilayers

  • Plasma membrane
  • Outer Nuclear Envelope
  • Inner Nucler Envelope
34
Q

What are the 3 functions of the Nucleus?

A
  • Contains & protects genetic info long term
  • Expression of genetic info
  • Determines which part of genetic info should be expressed @ which time & which cells
35
Q

What kind of genetic info does the nucleus protect?

A
  • It protects the info of Somatic cells for a lifetime (Non sperm/ egg cells) bc damage to somatic cell can cause cancer
  • Its effective storage in germ-line cells bc if DNA is damaged then mutations can be passed down to generation
36
Q

How does the Nucleus express genetic info?

A

-Starts w/ transcription (DNA is copied into new RNA & then that RNA leaves via nuclear pore)

37
Q

How is Eukaryotic DNA organized?

A

-Linear double-stranded DNA= chromosomes

38
Q

What is Chromatin?

A
  • The stuff of chromosomes
  • Includes noncovalently attached proteins (Histones) that protect & regulate DNA
  • Histones wrapped around DNA molecules into coils which are then further wrapped & condensed into chromosomes
39
Q

What do Chromosomes contain?

A
  • Genetic material DNA

- RNA that was made by transcription

40
Q

What are the 2 types of Chromatin?

A
  • Euchromatin

- Heterochromatin

41
Q

What is Euchromatin?

A
  • DNA being actively transcribed

- Also contains DNA that IS actively being expressed

42
Q

What is Heterchromatin?

A
  • Contains DNA thats NOT actively being transcribed

- DNA not being expressed at that particular time

43
Q

How is DNA organized in the nucleus?

A
  • Specifically organized in the nucleus
  • Chromosomes occupy separate volumes= territories
  • Some genes are also in particular places relative to genes
  • Location of euchromatin & heterchromatin is part of that organization
44
Q

What is the Nucleolus?

A
  • Special region within the nucleus
  • Site of transcription in RNA components for ribosomes
  • Site of Ribosomal assembly (RNA + protein from cytoplasm)
45
Q

What is the Nuclear Lamina?

A

-Mesh of polypeptides

46
Q

Where is the Nuclear Lamina located?

A

-On inner surface of inner membrane is connected to inner membrane of nuclear envelope

47
Q

What is the Nuclear Matrix?

A

-2nd mesh of polypeptides

48
Q

Where is the Nuclear Matrix located?

A

-Throughout internal volume of nucleus

49
Q

What is the structure for Ribosomes?

A
  • Large complex of noncovalently associated ribosomal RNA & protein assembled in Nucleolus
  • Some are free-floating in nucleus & other are attached to RER
  • 5 different molecules/ rRNA & more than 50 protein components
  • Have large & small units (large stays large, small stays small)
50
Q

What is the function of Ribosomes?

A
  • Site where mRNA directs protein synthesis
  • Makes covalent bonds (amide/peptide) that links w/ amino acid= made by dehydration synthesis & catalyzed by rRNA component
51
Q

What is mRNA?

A

-Subset thats copied from DNA in euchromatin= the sequence that determines the sequence of amino acids in polypeptides that are made on ribosomes

52
Q

What is rRNA?

A

-Speeds up a reaction that is normally very slow (formation of peptide bonds via DHR)= has large activation energy

53
Q

What is the order for Protein Synthesis?

A
  • mRNA transcribed in nucleus in Euchromatin
  • mRNA exits via Nuclear pore
  • mRNA meets small subunit joined by large subunit
  • mRNA is translated into protein
54
Q

Why are proteins important?

A

-Their sequnce determines structure & that structure determines function

55
Q

What is the central dogma of molecular biology?

A

-DNA–>RNA–> PROTIEN

56
Q

What are Vesicles?

A

-Small spherical sacs of membrane for transport between compartments

57
Q

What do Vesicles do?

A
  • Contains proteins, & other materials like membrane components , P.lipids & other molecules
  • Move around cell & “budd off” ER or Golgi to go to another compartment
  • Can have different names depending on origin & destination (can be called transport, lysosomal, secretory)
58
Q

What is the pathway for Protein Secretion?

A
  • Start inside RER
  • Then in transport vesicle
  • Then inside sacs of Cis Face golgi
  • Then inside sacss of Trans Face golgi
  • Then inside secretory vesicles
  • Then these vesicles fuse w/ plasma membrane which releases the contents that are inside the vesicle into the extracellular space where they diffuse away
59
Q

What is Exocytosis?

A

-When secretory vesicles fuse w/ plasma membrane

60
Q

How are antibodies secreted into extracellular space?

A
  • By plasma cells

- ABS= made on RER & then travel to golgi in vesicles where they are sorted, modified, etc

61
Q

What is the pathway for Membrane proteins?

A

-Similar to the pathway for protein secretion except that they are partly in the ER lumen during exocytosis

62
Q

What is the pathway for proteins destined to be organelles?

A

-The same as protein synthesis EXCEPT that vesicles leaving the golgi are either becoming organelles themselves (maturing) OR gonna fuse w/ existing organelles to deliver their protein cargo to it

BIO 110 (45 decks)

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