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BIOL4002 - Cell biology > Cell Organisation and Organelle Function > Flashcards

Cell Organisation and Organelle Function Flashcards

1
Q

What is the Cell Theory?

A

The Cell Theory is a fundamental principle of biology that states:
- all living organisms are composed of one or more cells
- cells are the smallest units of life
- new cells come only from pre-existing cells by cell division

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2
Q

What are the two categories of life?

A

Prokaryotes anf eukaryotes

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3
Q

What are Prokaryotes?

A

Prokaryotes are a category of life that have:
- simple cell structure
- no nucleus

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4
Q

What are the 2 major categories of Prokaryotes?

A

Bacteria and archaea

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5
Q

What are Eukaryotes?

A

Eukaryotes are a category of life that have:
- more complex cells
- DNA enclosed within a membrane-bound nucleus
- internal membranes that form organelles

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6
Q

What are some examples of Eukaryotes?

A

Animals, plants, fungi, and protists

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7
Q

What are some characteristics of Bacteria?

A
  • small cells, 1 μm – 10 μm in diameter
  • very abundant in the environment & our bodies
  • vast majority of bacteria are not harmful to humans
  • some species can cause disease
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8
Q

What are some characteristics of Archaea?

A
  • small cells, 1 μm – 10 μm in diameter
  • less common than bacteria
  • often found in extreme environments
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9
Q

Where is DNA located in Eukaryotic cells?

A

DNA is housed inside a membrane-bound nucleus

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10
Q

What are organelles in Eukaryotic cells?

A

Specialized compartments that carry out specific functions

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11
Q

What are the types of organelles present in eukaryotic cells?

A
  • membrane-bound compartments
  • non-membrane bound structures
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12
Q

What are some membrane-bound compartments in the organelles of eukaryotic cells?

A
  • endoplasmic reticulum
  • Golgi apparatus
  • mitochondria
  • chloroplasts (in plant cells)
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13
Q

What are some non-membrane bound structures in the organelles of eukaryotic cells?

A
  • cytoskeleton
  • ribosomes
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14
Q

What is the function of organelles in Eukaryotic cells?

A

Carry out specialized functions such as:
- protein synthesis
- energy production
- intracellular transport

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15
Q

Are all Eukaryotic cells the same size and shape?

A

No, there is a wide variety of cell sizes, shapes, and functions, particularly between specialized cell types.

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16
Q

What are the typical components inside the plasma membrane of a typical bacterial cell?

A
  • cytoplasm
  • nucleoid region (DNA locateed)
  • ribosomes (protein synthesis)
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17
Q

What are the typical components outside the plasma membrane of a typical bacterial cell?

A
  • cell wall (support & protection)
  • glycocalyx
  • appendages (pilli & flagella)
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18
Q

What is the glycocalyx in a bacterial cell?

A

Sticky layer of carbohydrates that helps to:
- trap water
- provide protection
- help evade the immune system

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19
Q

What are appendages in a bacterial cell?

A

Structures that extend from the cell surface, e.g.:
- pilli (used for attachment)
- flagella (used for movement)

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20
Q

What are some of the organelles present inside a typical animal cell?

A
  • nucleus
  • endoplasmic reticulum
  • mitochondria
  • Golgi apparatus
  • plasma membrane
  • ribosomes
    (all membrane bound except plasma membrane)
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21
Q

What is the nucleus in an animal cell?

A

Contains the chromosomes

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22
Q

What is the endoplasmic reticulum in an animal cell?

A

The ER is a network (=reticulum) of membranes that form flattened, fluid-filled tubules or cisternae - where proteins are modified & sorted.

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23
Q

What is the mitochondria in an animal cell?

A

Responsible for producing ATP, the cell’s main energy source.

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24
Q

What are the main structural features of mitochondria?

A
  • mitochondria have an outer and inner membrane
  • which surround the intermembrane space and the mitochondrial matrix
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25
Q

What are some other functions of mitochondria besides ATP production?

A

Also involved in the synthesis, modification, and breakdown of several types of cellular molecules

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26
Q

What is the Golgi apparatus in an animal cell?

A

A stack of flattened, membrane-bounded compartments/organelles in cells

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27
Q

What are some other names for the Golgi apparatus?

A
  • Golgi body
  • Golgi complex
  • Golgi
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28
Q

How do vesicles transport materials within the Golgi apparatus in animal cells?

A

Vesicles transport materials between stacks in animal cells

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29
Q

What are the three overlapping functions of the Golgi apparatus?

A

The three overlapping functions of the Golgi apparatus are protein:
- secretion
- processing
- sorting

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30
Q

What is the plasma membrane in an animal cell?

A

A thin, flexible, and selectively permeable barrier that surrounds the animal cell.

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31
Q

What are the functions of the plasma membrane?

A
  • transports molecules in & out of the cell with selective permeability
  • cell signaling using membrane receptors to respond to external stimuli
  • cell adhesion to other cells or the extracellular matrix to maintain cell structure & organization
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32
Q

What are ribosomes in an animal cell?

A

Responsible for synthesizing polypeptides, which are the building blocks of proteins

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33
Q

What are the primary differences between plant cells and animal cells?

A

Plant cells lack lysosomes & centrioles but have:
- large central vacuole & chloroplasts
- cell wall made of carbohydrate & protein

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34
Q

What is the function of the central vacuole in plant cells?

A

Storage and regulation of cell volume

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35
Q

What is the purpose of the cell wall in plant cells?

A

Provides support and protection for the cell

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36
Q

Does the size and shape of eukaryotic cells vary?

A

Yes, the size and shape of eukaryotic cells show great variation

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37
Q

Can cells with the same genome have different morphologies?

A

Yes, even cells that share the same genome can have very different morphologies

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38
Q

What largely determines the characteristics of a cell?

A

The proteome

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39
Q

How does a single organism produce different types of cells if the DNA is identical in each cell?

A

Cell differentiation
- even though the DNA is identical in each cell of an organism,
- different types of cells can be produced by expressing different sets of genes
- which leads to the production of different proteomes (protein populations)

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40
Q

How does the size of a cell affect its surface area-to-volume ratio?

A

As cells get larger, the SA to V ratio gets smaller

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41
Q

How does the surface area-to-volume ratio affect cell function?

A
  • as SA to V ratio decreases
  • cells struggle to import & export enough material
  • which affects cell function
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42
Q

What is the surface area-to-volume ratio of a cell with a radius of 1 micrometer?

A

A cell with a radius of 1μm has a SA:V ratio of 3:1

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43
Q

What is the surface area-to-volume ratio of a cell with a radius of 100 micrometers?

A

A cell with a radius of 100μm has a SA:V ratio of 0.03:1

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44
Q

What is the cytosol?

A

Fluid region (subset) of the cytoplasm that is outside the cell organelles but inside the plasma membrane

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45
Q

What is the cytoplasm?

A

The cytoplasm includes everything inside the plasma membrane, excluding the nucleus, such as:
- cytosol
- endomembrane system
- semiautonomous organelles

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46
Q

What is molecular synthesis and breakdown?

A

Refer to the processes by which cells build and break down molecules, respectively.

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47
Q

What is cell metabolism?

A

The sum of all chemical reactions by cells

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48
Q

What is catabolism?

A

Process by which cells break down molecules into smaller components, usually releasing energy in the process

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49
Q

What is anabolism?

A

Process by which cells synthesise cellular molecules and macromolecules, usually requiring energy input

50
Q

What is the central coordinating region for metabolic activities of eukaryotic cells?

A

The central coordinating region for metabolic activities of eukaryotic cells

51
Q

What is the cytoskeleton?

A

A network of 3 types of protein filaments that provide structural support and shape to cells
(cell’s skeleton)

52
Q

What are the 3 types of protein filaments in the cytoskeleton?

A
  • microtubules
  • intermediate filaments
  • actin filaments
53
Q

What are microtubules?

A

Microtubules are long, hollow cylindrical structures made of protein called tubulin

54
Q

What is the function of microtubules?

A

Function in:
- maintenance of the shape of the cell
- organization of cell organelles
- intracellular movement of cargo
- cell motility via cilia & flagella

55
Q

What are intermediate filaments and where are they not found?

A

A type of protein filament that is intermediate in size & form twisted, rope-like structures
- not found in plant cells

56
Q

What is the function of intermediate filaments?

A

Function in:
- shape of the cell
- providing cells with mechanical strength
- anchorage of cell & nuclear membranes

57
Q

What are actin filaments also known as?

A

Microfilaments

58
Q

What is the function of actin filaments?

A

Function in:
- shape of the cell
- cell strength
- muscle contraction
- cell movement
- cytokinesis in animal cells

59
Q

What are actin filaments?

A

Long, thin fibers made of protein called actin

60
Q

What are cytoskeleton-associated motor proteins?

A

A group of proteins that interact with the cytoskeleton and use ATP as a source of energy for movement

61
Q

What is the role of ATP in motor protein movement?

A

ATP serves as the source of energy for motor protein movement

62
Q

What is an example of a motor protein?

A

Myosin

63
Q

How do motor proteins (like myosin) move?

A

Move using their 3 domains:
- 1st: head is released from the filament it is bound to
- 2nd: head cocks forward and binds to the filament further forward than it was originally bound
- 3rd: head cocks backward, moving the tail of the motor protein forward
- this process is repeated for movement

64
Q

How do motor proteins move along microtubules?

A

Motor proteins walk along microtubules from one end to the other

65
Q

How do motor proteins cause filaments to move?

A

When the filament moves, the motor proteins are fixed in place and cause a filament to move

66
Q

What happens when filaments bend and how do motor proteins contribute to this process?

A

When filaments bend, both the motor protein and the filaments are fixed in place so the actions of the motor proteins cause microtubules to bend instead.

67
Q

What are the main differences between flagella and cilia?

A
  • flagella are usually longer than cilia
  • flagella present singly or in pairs, cilia covers all/part of cell surface
68
Q

What is the structure of flagella and cilia?

A

Both have a 9+2 microtubule array structure
(slide 19)

69
Q

How does movement occur in flagella and cilia?

A
  • flagella move in whip-like motion
  • cilia move by the propagation of a bend, beginning at the base and moving toward the tip.
70
Q

What is the endomembrane system?

A

The endomembrane system is a network of membranes found in eukaryotic cells.

71
Q

What are the different organelles of the endomembrane system?

A

The different organelles of the endomembrane system include:
- the nuclear envelope
- endoplasmic reticulum
- Golgi apparatus
- lysosomes
- vacuoles
- plasma membrane

72
Q

How do different organelles of the endomembrane system communicate with each other?

A

Different organelles of the endomembrane system may be directly connected to each other or pass materials via vesicles.

73
Q

What is the nuclear envelope?

A

The nuclear envelope is a double-membrane structure that encloses the nucleus of eukaryotic cells.

74
Q

How is the outer membrane of the nuclear envelope connected to the endoplasmic reticulum membrane?

A

The outer membrane of the nuclear envelope is continuous with the endoplasmic reticulum membrane.
(physically connected & have a similar structure)

75
Q

What is the function of nuclear pores in the nuclear envelope?

A

Nuclear pores provide passageways for molecules to move in and out of the nucleus.

76
Q

Are materials within the nucleus part of the endomembrane system?

A

No, materials within the nucleus are not part of the endomembrane system.

77
Q

What are chromosomes?

A

Chromosomes are structures made up of DNA & proteins called chromatin. They carry genetic information in the form of genes.

78
Q

What is chromatin?

A

Chromatin is the complex of DNA & proteins that makes up chromosomes.

79
Q

What is the nuclear matrix?

A

The nuclear matrix is a filamentous network of proteins that provides structural support to the nucleus and organises the chromosomes.

80
Q

What is the function of the nucleolus?

A

The nucleolus is involved in ribosome assembly, which is the process of making ribosomes, the cellular structures responsible for protein synthesis.

81
Q

What is the ER lumen?

A

Internal space or cavity enclosed by the ER membrane to separate it from the cytoplasm.

82
Q

What is the Rough Endoplasmic Reticulum (rough ER)?

A

The rough ER is studded with ribosomes and is involved in protein synthesis and sorting.

83
Q

What is the Smooth Endoplasmic Reticulum (smooth ER)?

A

The smooth ER lacks ribosomes and is involved in:
- detoxification
- carbohydrate metabolism
- calcium balance
synthesis
- modification of lipids

84
Q

What is the pathway of secreted proteins through the endomembrane system?

A

Secreted proteins move sequentially through organelles of the endomembrane system

85
Q

Who conducted pulse-chase experiments to trace the path of radioactive proteins through the endomembrane system?

A

George Palade conducted pulse-chase experiments to trace the path of radioactive proteins through the endomembrane system.

86
Q

Which cells did George Palade study to investigate the pathway of secreted proteins?

A

Pancreatic cells, whose primary function is protein secretion

87
Q

What did the dark spots in TEM images reveal during George Palade’s experiments?

A

The dark spots in TEM images revealed the location of radioactive proteins.

88
Q

What was the significance of George Palade’s experiments?

A

Provided the first evidence that secreted proteins are inserted into the rough ER and move through a series of compartments before secretion.

89
Q

What are vacuoles?

A

Vacuoles are membrane-bound organelles found in eukaryotic cells.

90
Q

How do the functions of vacuoles vary?

A

The functions of vacuoles are extremely varied and differ among cell types and environmental conditions.

91
Q

What is the function of central vacuoles in plants?

A

The function of central vacuoles in plants is for storage and support.

92
Q

What is the function of contractile vacuoles in protists?

A

The function of contractile vacuoles in protists is for expelling excess water.

93
Q

What is the function of phagocytic vacuoles in protists and white blood cells?

A

The function of phagocytic vacuoles in protists and white blood cells is for degradation of materials.

94
Q

What are peroxisomes?

A

Organelles found in eukaryotic cells that contain enzymes which catalyze certain reactions that break down molecules by removing H or adding O.

95
Q

What is the byproduct of peroxisomal reactions?

A

The byproduct of peroxisomal reactions is hydrogen peroxide (H2O2)

96
Q

What enzyme breaks down hydrogen peroxide in peroxisomes?

A

Catalase breaks down dangerous H2O2 into water and oxygen within peroxisomes.

97
Q

What are semiautonomous organelles?

A

Organelles that are partially self-sufficient in terms of their reproduction and maintenance but still rely on the cell for some resources.

98
Q

Which organelles are considered semiautonomous?

A

Mitochondria and chloroplasts

99
Q

How do semiautonomous organelles reproduce?

A

By growing and dividing to form new organelles - still depend on the cell to produce material for synthesis of their internal components.

100
Q

What is the main function of chloroplasts?

A

Photosynthesis
- Capture light energy and use some of that energy to synthesise organic molecules such as glucose

101
Q

In what types of organisms are chloroplasts found?

A

In nearly all species of plants and algae

102
Q

What is the basic structure of chloroplasts?

A

Chloroplasts have an outer & inner membrane, which surround the intermembrane space

103
Q

What is the intermembrane?

A

A fluid-filled region containing the thylakoid membranes

104
Q

Do chloroplasts and mitochondria contain their own DNA?

A

Yes, chloroplasts and mitochondria contain their own DNA, which is separate from the nuclear DNA of the cell.

105
Q

How do chloroplasts and mitochondria reproduce?

A

Reproduce by binary fission

106
Q

What is endosymbiosis?

A

Endosymbiosis is a theory that explains the origin of eukaryotic cells

107
Q

What is the origin of mitochondria?

A

Mitochondria are believed to have originated from purple bacteria, which are a type of α-proteobacteria.

108
Q

What is the origin of chloroplasts?

A

Chloroplasts are believed to have originated from cyanobacteria, which are photosynthetic blue-green bacteria.

109
Q

What is protein sorting?

A

Proteins are sorted to their correct destination within a cell

110
Q

What 2 mechanisms are used to sort proteins to different organelles?

A
  • cotranslational sorting
  • post-translational sorting
111
Q

What is cotranslational sorting?

A

Proteins are destined for the:
- ER
- Golgi
- lysosomes
- vacuoles
- plasma membrane
- secreted proteins

112
Q

When does sorting begin in cotranslational sorting?

A

Sorting begins in the cytosol during the early stages of protein production.

113
Q

What is an ER signal sequence in cotranslational sorting?

A

A specific sequence of amino acids that serves as a signal for cotranslational sorting.

114
Q

What is the first step in cotranslational sorting?

A

The first step is when the signal recognition particle (SRP) binds to the ER signal sequence of the protein being built.

115
Q

What happens after the SRP binds to the ER signal sequence during cotranslational sorting?

A

The SRP then binds to an SRP receptor in the ER membrane, releasing the growing protein.
The protein moves through a channel in the ER membrane and is released into the ER lumen.

116
Q

What is the second step in cotranslational sorting?

A

Vesicles bud from the ER membrane and fuse with the target membrane (e.g. Golgi apparatus) to deliver proteins to other organelles.

117
Q

What is post-translational sorting?

A

For most proteins destined for the nucleus, mitochondria, chloroplasts, and peroxisomes are synthesised in the cytosol and taken up by the target organelle.

118
Q

What is the matrix-targeting sequence?

A

(In post-translational sorting)
A short amino acid sequence at one end of a protein that directs the protein to its target organelle

119
Q

How does a protein get taken up by its target organelle in post-translational sorting?

A
  • matrix-targeting sequence of the protein binds to a receptor on the surface of the target organelle
  • protein is then transferred to a channel in the target organelle’s membrane and released into the organelle
120
Q

What are the characteristics of bacterial cells?

A

Have:
- cell wall
- plasma membrane
- sometimes flagella
- have ribosomes
- circular chromosome
but lack many organelles found in eukaryotic cells.

121
Q

What are the characteristics of animal cells?

A

Have:
- no cell wall
- may have cilia or flagella present
- multiple linear chromosomes
- an endomembrane system
- mitochondria
and other organelles.

BIOL4002 - Cell biology (7 decks)

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