Cells Ultrastructure (not a lecture) Flashcards

1
Q

What features does a nucleus have:
State functions.

A

Nuclear DNA: euchromatin is actively transcribing chromatin,
heterochromatin in less active cell
Nucleolus - forms rRNA
Nuclear membrane - double membrane, perforated with pores

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2
Q

What features does a mitochondria have:
State functions.

A

Site of oxidative phosphorylation
Double membrane: Outer is smooth for lipid synthesis + fatty acid metabolism, Inner is folded and has cristae for respiratory chain, ATP production
Matrix - Site of Krebs cycle
Intramembranous space - Nucleotide phosphorylation APD to ATP

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3
Q

What features does a RER have:
State functions.

A

Site of protein synthesis.
Highly folded flattened membrane sheets

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4
Q

What features does a SER have:
State functions.

A

Site of lipid synthesis
Processes and stores synthesised proteins
Highly folded flattened membrane sheets

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5
Q

What features does a Golgi apparatus have:
State functions.

A

Processing and modification of proteins
Parallel stacks of membrane - processes and modifies macromolecules
Cis face - receives vesicles from SER, for protein phosphorylation
Medial face - form complex oligosaccharides by adding sugars to lipids and peptides
Trans face - proteolysis of peptides into active forms

Close to the nucleus of the cell
Can’t be seen in most cells but in a plasma cell, perinuclear hoff

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6
Q

What features does a vesicles have:
State functions.

A

Very small, spherical membrane-bound organelles - transport & store material + exchange cell membrane between compartments
Types: Cell-surface derived pinocytotic and phagocytotic vesicles
Golgi- derived transport vesicles + ER - derived transport vesicles
Lysosomes
Peroxisomes

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7
Q

Explain the function of lysosomes:

A

Contains digestive enzymes, site of breakdown for most molecules.
They also breakdown debris from dead cells & bacteria and damaged cell organelles.

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8
Q

Explain function of peroxisomes:

A

Small, membrane-bound organelles containing enzymes which oxidase long-chain fatty acids - beta oxidation ?
Also produce hydrogen peroxide that can destroy pathogens.

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9
Q

What is the cytoskeleton?

A

Filamentous proteins which brace the internal structure of the cell
Helps cells maintain their shape and internal organisation

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10
Q

What are the three parts of the cytoskeleton? In size order from smallest to biggest

A

Microfilaments, Intermediate filaments, microtubules

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11
Q

What are microfilaments?

A

Smallest 5nm.
Actin protein forms a bracing mesh on the inner surface of cell membrane

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12
Q

What are intermediate filaments?

A

10nm.
Anchored transmembrane proteins which can spread tensile force through tissues.
6 types:
- Cytokeratins - epithelial cells
- Desmin - myocytes
- Glial fibrillary acidic protein - astrocytic glial cells
- Neurofilament protein - neurons
- Nuclear laminin - nuclei of all cells
- Vimentin - mesodermal cells

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13
Q

What are microtubules?

A

25nm. Tubulin protein
In all cells except erythrocytes due to lack on nucleus

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14
Q

What storage products and inclusion found in cells?

A
  • Lipofuscin - Membrane-bound orange-brown pigment, degradation of lipids common in heart and liver
  • Lipid - Non-membrane-bound vacuoles, appears as empty space in histology since dissolved in processing, stored in adipocytes and liver
  • Glycogen - CHO polymer in cytoplasm, normally seen on electron microscopy
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