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LC Principles Histology > Anatomy of the cell - histology 1 > Flashcards

Anatomy of the cell - histology 1 Flashcards

1
Q

What is the highest cellular component in a cell?

A

Water - embryonic cells the most, old cells the least

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2
Q

What are features common to all eukaryotic cells?

A

Outer membrane
Inner cytosol
Cytoskeleton
Membrane bound organelles

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3
Q

What is a eukaryotic cell?

A

A cell with a true nucleus

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4
Q

What is the plasmalemma?

A

It separates the cytoplasm from the outside environment - it is amphipathic

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5
Q

What types of integral proteins might the plasmalemma include?

A

Receptors, channels, transportors, enzymes and cell attachment proteins

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6
Q

What is the plasmalemma made of?

A

Its a phospholipid bilayer with integral and peripheral proteins and cholesterol embedded in ti

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7
Q

What is the function of the mitochondria?

A

Energy production

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8
Q

What is the function of the RER - rough endoplasmic reticulum?

A

Protein synthesis

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9
Q

What is the function of the SER - smooth endoplasmic reticulum?

A

Cholesterol and lipid synthesis/detoxification

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10
Q

What is the function of the golgi apparatus?

A

Modification and packaging of secretions

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11
Q

What is the function of lysosomes?

A

Hydrolytic enzymes for intracellular digesion

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12
Q

What is the function of the nucleus?

A

Contains the genetic code

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13
Q

What are inclusions and what do they represent?

A

Dispensable and may be present only as transients, they represent components that have been synthesises by the cell itself or taken up from the extracellular environment

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14
Q

What are the 3 main classes of filaments and what do they do?

A

Microfilaments
Intermediate filaments
Microtubules

These filamentous proteins become attached to the cell membrane and to each other by anchoring and joining proteins to form a dynamic 3-dimensional internal scaffolding in the cell.

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15
Q

Describe microfilaments, what are they made of?

A

They are composed of the protein actin

  • Actin molecules can assemble into filaments and later dissociate, making them very dynamic cytoskeletal elements.
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16
Q

Describe intermediate filaments?

A

Composed of 6 main proteins which vary in different cell types

  • Bind intracellular elements together and to the plasmalemma
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17
Q

Describe microtubules?

A

They are composed of two tubular proteins

  • hollow tubule composed of two types of tubulin subunits, α & β in an alternating array.
  • Originate from a special organising centre called the centrosome.
  • Include stabilizing proteins: microtubule-associated proteins (MAPS)
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18
Q

Are microtubules polar or non polar?

A

The are polar as the polymerise in the central portion of the cell and radiate outwards

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19
Q

What proteins attach to the microtubules and travel along them?

A

Dynein - ATPase that moves towards the cell periphery

Kinesin -ATPase that moves towards the cell centre

20
Q

What is the nucleus enclosed by?

A

A nuclear envelope composed of an inner and outer nuclear membrane with membrane pores providing continuity with the cytoplasm

21
Q

Where does RNA synthesis take place?

A

In the nucleus

22
Q

Where are mRNA and tRNA transcribed?

A

In the nucleus

23
Q

Where is rRNA transcribed?

A

In the nucleolus - within the nucleus

24
Q

What is DNA that is actively undergoing transcription called?

A

Euchromatin

25
Q

What is DNA that is condensed and not undoing transcription called?

A

Heterochromatin

26
Q

Describe ribosomes?

A

They are formed in the nucleolus and are instrumental in protein synthesis

Each ribosome is made up of a small subunit which binds RNA and a large subunit which catalyses the formation of peptide bonds

27
Q

What is the rough endoplasmic reticulum studded with?

A

Ribosomes

28
Q

What does the amount of ER present in a cell vary with?

A

How active the cell is, the more active - the more ER present

29
Q

Describe the steps in protein synthesis and RER?

A

1 - the free ribosome attaches to the mRNA
2 - If ER signal sequence is present, the growing peptide is inserted into a pore in the ER
3 - growing peptide forms in the ER, signal sequence is removed
4 - ribosome detaches. Most proteins then enter the SER

30
Q

What does the SER continue doing and what does it play a vital role in?

A

It continues the processing of proteins produced in the RER

It plays a vital role as the site of lipid synthesis

31
Q

What is the golgi apparatus composed of?

A

A group of flattered, membrane bound cisternae arranged in sub-compartments

32
Q

What arrives at the golgi\?

A

Transport vesicles arrive at the golgi from the SER

33
Q

What does the golgi apparatus do?

A

It modifies and packages the macromolecules that were synthesised in the ER

  • adds sugars
  • cleaves some proteins
  • sorts macromolecules into vesicles
34
Q

What are mitochondria and what are they composed of?

A

They are organelles

They are composed of an outer and inner membrane.

The inner membrane is extensively folded to form cristae which act to increase the available surface area

35
Q

What do the mitochondria produce?

A

They produce ATP via oxidative phosphorylation and they can synthesis certain lipids and proteins

36
Q

What do mitochondria have?

A

They have their own DNA and system for protein production

37
Q

What are adipose cells specialised for?

A

Triglyceride storage

38
Q

What are intercellular junctions?

A

Intercellular junctions are specialized membrane structures which link individual cells together into a functional unit.

39
Q

What are the 3 types of intercellular junctions?

A

Occluding junctions (tight/zonula junctions)
Anchoring junctions
Communicating junctions

40
Q

Describe occluding junctions?

A

They link cells to form a diffusion barrier. (prevent diffusion)

41
Q

Describe anchoring junctions?

A

provide mechanical strength.
Link submembrane actin bundles of adjacent cells.

Transmembrane cadherin molecules bind to each other in the extracellular space, and, through link molecules, to actin of the cytoskeleton.

Desmosomes: Link submembrane intermediate filaments of adjacent cells.

Hemidesmosomes: Link submembrane intermediate filaments of a cell to the extracellular matrix through transmembrane proteins.

42
Q

What do desmosomes (anchoring junctions) do?

A

Link submemnrane intermediate filaments of adjacent cells

Very common in the skin

43
Q

What do hemidesmosomes (anchoring junctions) do?

A

Hemidesmosomes: Link submembrane intermediate filaments of a cell to the extracellular matrix through transmembrane proteins.

44
Q

What is a junctional complex?

A

A close association of several types of junctions found in certain epithelial tissues

45
Q

Describe communicating junctions?

A

allow selective movement of molecules between adjacent cells.

Also known as gap junctions

Found in epithelia but also in some smooth and cardiac muscle where is it critical for the spread of excitation

Pores are produced by connexon proteins

46
Q

Describe phagocytosis?

A

Bacteria or large particle from the extraceulluar space can be incorporated into the cell by phagocytosis

Bacterium binds to the cell surface and the cell engulfes it forming a phagosome

The phagosome binds with a lysosome carrying digestive enzymes producing a phagolysosome

LC Principles Histology (3 decks)

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