Week 5 (organelles) Flashcards

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1
Q

What are organelles?

A
  • discrete structures of a eukaryotic cell
  • membrane enclosed
  • carry out specialised functions - distributed throughout the cytoplasm
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2
Q

What is the difference between the cytoplasm and the cytosol?

A

Cytoplasm:

-cell contents (including organelles) within plasma membrane (except nucleus)

Cytosol:

-contains large and small molecules - concentrated aqueous gel around organelles - site of many chemical reactions

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3
Q

Describe the properties of the nucleus?

A
  • most prominent organelle
  • characteristic of eukaryotes
  • contains the genome (chromosomes and protein)
  • site of DNA and RNA synthesis - nuclear envelope surrounds nucleoplasm
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4
Q

When do chromosomes become visible?

A

Condense and become visible as a cell is about to divide

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5
Q

Describe the function and properties of the nucleolus

A
  • site of ribosome production
  • rRNA synthesis
  • variable in size depending on number of ribosomes produced (Not membrane bound)
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6
Q

Describe the properties of the nuclear envelope

A

A double lipid bilayer (4 leaflets) with pores (filled with proteins) where inner and outer membranes connect

  • envelope penetrated by pores
  • act as gates to permit RNA proteins and other molecules to move appropriately)
  • provides QC (only mature mRNA leave) ~1000 NPCs in a nuclear envelope of a vertebrate cell
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7
Q

What support is in the nucleus?

A
  • supported mechanically by networks of intermediate filaments (outside)
  • Inside the nuclear envelope= nuclear lamina (dense layer of microfilaments continuous with nuclear membrane
  • Fibrous network surrounding the nucleus (cytoskeleton)
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8
Q

Do all eukaryotic cells contain a nucleus?

A

No E.g. erythrocytes

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9
Q

Do some eukaryotic cells have more than one nucleus?

A

Yes Skeletal muscle cells

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10
Q

Describe the properties of the endoplasmic reticulum

A
  • massive membrane system
  • interconnecting labyrinth of branches and flattened sacs
  • contains over 50% of a cells membrane
  • continuous with nuclear envelope
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11
Q

Describe the function of the rough endoplasmic reticulum

A
  • central role in biosyntheis and modification of lipids and proteins e.g. adding sugar to make glycoproteins
  • protein for:

export

some organelles

-proteins can move into the ER whilst being made

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12
Q

What is the difference between rough and smooth ER?

A

SER:

  • ER without ribosomes
  • Phospholipid synthesis
  • Lots in hepatocytes (liver cells)

RER:

  • ER with ribosomes
  • Protein modification and secretion
  • Lots in specialised secretory cells like plasma cells
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13
Q

Describe the properties and functions of the smooth ER?

A
  • abundant in cells involved in lipid metabolism e.g. steroid hormone production from cholesterol
  • often occurs within regions of RER (one connected system of membrane)
  • involves in Ca2+ storage Involved in rapid cellular processes
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14
Q

Describe the properties and function of the Golgi apparatus

A
  • Works closely with ER
  • Made of flattened membrane bound sacs aka cisternae

Two sides and a middle:

  • Entry side: ‘Cis’ Golgi (facing ER membrane)
  • Middle: ‘Medial’ Golgi
  • Exit side: ‘trans’ Golgi (facing plasma membrane)
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15
Q

Describe the function of the Golgi apparatus

A
  • functions to process, pack and export protein and lipids in vesicles
  • Lipids and protein enter at the cis side
  • Progress through different levels of cisternae via transport vesicles
  • different layers contain different enzymes that modify proteins
  • Further sugar modifications occur here
  • Packed in vesicles to be transported
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16
Q

Describe the properties of the mitochondria

A
  • the site of energy generation (ATp production) in the cell
  • independent genome (DNA), their own ribosomes, tRNA and they synthesise their own proteins: Although some proteins in mitochondria are self syntheised some come from the nucleus
  • two membranes (outer and inner): -inner membrane is highly convoluted —> Cristae (large surface area)
  • outer membrane is permeable to recieve things from the cytosol - site of generation of ATP
  • Matrix inside the inner membrane
  • resemble prokaryotic organism
17
Q

Describe the properties of the lysosomes

A
  • acidic organelles
  • involved in degradation and recycling: (unwanted organelles-autophagy) phagocytosed things e.g. bacteria
  • breaks things down to their building blocks some of which can be recycled and used again
  • contains acid hydrolases a range of enzymes that only work at low pH (pH5) - proton pump and chloride channel maintains low pH H+ and Cl- enter lumen (inside) of lysosome acidic: H+ +Cl- —-> HCl
  • single membrane
18
Q

Where are SER abundant?

A

in cells involved in lipid metabolism e.g. steroid hormone production from cholesterol

19
Q

What would happen if the lysosomal membrane got damaged and the enzymes leak out?

A

Cell would not get damaged because lysosomal enzymes only work at low pH

20
Q

Can there be more than one nucleolus?

A

Yes Depending on the cellular needs (amount of protein synthesis)

21
Q

What is the perinuclear splace?

A

Space between RER membrane and nuclear membrane

22
Q

Does the Golgi apparatus use just one enzyme?

A

No

-A range of different enzymes are localised through the structure

23
Q

what organelles are present in yeast?

A
  • Nucleus
  • Golgi apparatus
  • mitochondria
  • endoplasmic reticulum
  • vacuole
  • cytoskeleton
24
Q

D

What is the difference between prokaryotic and eukaryotic cells?

A