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MHIS 1513 > Session 2: Characteristics, structure & functions of a cell > Flashcards

Session 2: Characteristics, structure & functions of a cell Flashcards

1
Q

Define membranous and non-membranous organelles and give examples.

A

Membranous organelles: organelles that are surrounded by a plasmamembrane and are isolated from the cytosol, e.g mitochondria

Non-membranous organelles: organelles that are not surrounded by a plasmamembrane and are in direct contact w/ cytosol, e.g ribosomes, microtubuli

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2
Q

List the different cytoplasmic organelles that occur and state the function of each.

A

Endoplasmic Reticulum: contain large amounts of protein

Golgi apparatus: transported substances from the ER are processed to form lysosomes, transport vesicles, etc.

Lysosomes: serve as the intracellular digestive system

Peroxisomes: oxidizes substances that might be poisonous to the cell

Secretory vesicles: store protein proenzymes

Mitochondria: powerhouse of the cell

Cytoskeleton( filament and tubular structures): provides rigid, physical structures for certain parts of the cell

Nucleus: control centre of the cell

Nuclear membrane: large complexes of protein molecules attached at the edges of the pores

Nucleolus: some synthesised RNA is stored

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3
Q

List the different cytoplasmic organelles that occur and state the function of each.

A

Endoplasmic Reticulum: contain large amounts of protein

Golgi apparatus: transported substances from the ER are processed to form lysosomes, transport vesicles, etc.

Lysosomes: serve as the intracellular digestive system

Peroxisomes: oxidizes substances that might be poisonous to the cell

Secretory vesicles: store protein proenzymes

Mitochondria: powerhouse of the cell

Cytoskeleton( filament and tubular structures): provides rigid, physical structures for certain parts of the cell

Nucleus: control centre of the cell

Nuclear membrane: large complexes of protein molecules attached at the edges of the pores

Nucleolus: some synthesised RNA is stored here

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4
Q

Describe the structure of a cell membrane.

A
  • Double layer of phospholipid molecules
  • Cholesterol
  • Integral and peripheral proteins
  • Contains lipids, carbohydrates and functional proteins
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5
Q

What are the 4 functions of the cell membrane?

A
  1. Physical isolation - acts as a barrier
  2. Regulates exchange with the external environment - diffusion, osmosis, phagocytosis
  3. Monitors the environment - extracellular fluid composition & chemical signals
  4. Structural support - anchors cells and tissues
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6
Q

Explain the 4 steps of endocytosis.

A
  1. Receptors accumulate on the cell membrane
  2. Receptors bind to target molecules
  3. Target molecules form vesicle-like invagination on plasmamembrane
  4. Proteins and receptors are pulled into the forming vesicle
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7
Q

Explain exocytosis

A

Substances (proteins and receptors) exit the cell

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8
Q

What is the functional role of endosomes in a cell?

A

Sort and recycle proteins internalized by endocytosis

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9
Q

Describe the 3 functions of lysosomes?

A
  1. Intracellular digestion
    * break down molecules
    * attack bacteria
    * recycle basic components of broken down damaged
    organelles
    * ejects waste by exocytosis
  2. Autolysis of tissue
  3. Defends the body against certain bacterial invaders
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10
Q

Define the term primary lysosome.

A

Formed by Golgi and inactive enzymes

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11
Q

Define the term secondary lysosome.

A
  • Lysosome fused with phagosome or damaged organelle
  • Digestive enzymes activated
  • Toxic chemicals isolated
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12
Q

Define the term residual body.

A

Vesicles containing indigestible material

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13
Q

Define autophagy.

A

Processs that maintains normal functioning of the cell by protein degradation and turnover of the dstroyed cell organelles for new cell formation.

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14
Q

Define heterophagy.

A

Digestion of a substance in the cell’s environment through pinocytosis or phagocytosis.

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15
Q

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

A

Exporting in protein synthesis

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16
Q

In what type of cells would the rER be well-developed and why?

A

…

17
Q

What are the 9 functions of the smooth-surfaced endoplasmic reticulum?

A
  1. Absorbed fatty acids are resynthesized
  2. Transcellular transport of fats
  3. Lipoprotein synthesis
  4. Role in muscle contraction
  5. Secretion of Cl- ions
  6. Synthesie steroid hormones
  7. Oxidation to detoxify poisonous substances
  8. Break down of glycogen
  9. Triglyceride synthesis
18
Q

What are the functions of the

A
  1. Connected w/ protein production
  2. Protein undergo changes in sacculae
  3. Produce secretory vesicles, enzymes, hormones
  4. Add carbohydrates to proteins (glycoproteins)
19
Q

Describe the basic structure of mitochondria.

A
  • Have smooth outer membrane and folded inner membrane(cristae)
  • Matrix around the cristae
20
Q

What are the functions of mitochondria?

A

Produces energy needed for the functioning and survival of the cell by:

  • houses the chains of enzymes responsible for cell respiration
  • require O2 & organic substrates
  • generate CO2 & ATP
21
Q

What are the 4 functions of peroxisomes?

A
  1. Breaks down fatty acids and organic compounds
  2. Contains oxidases and regulates H2O2 levels
  3. Site of urate oxidase
  4. Possibly responsible for gluconeogenesis
22
Q

What is the function of microtubules?

A
  1. Attach to the centrosome
  2. Anchor organelles and strengthen cells
  3. Change cell shape
  4. Move vesicles within the cell
  5. Form spindle apparatus
23
Q

What are the structural differences between basal bodies and centrioles?

A

A centriole is surrounded by cytoplasm AND basal bodies have no cytoplasm surrounding it

24
Q

Describe the 4 pathways for the ingestion of particles by a cell.

A
  • Diffusion- substances move thru cell membrane pores
  • Active transport- actual carrying of substances by a physical protein structure that penetrates all the way thru the mebrane
  • Pinocytosis- ingestion of minute particles that form vesicles of ECF
  • Phagocytosis- ingestion of large particles
25
Q

Describe the pathway for the digestion of particles by a cell.

A
  • Lysosomes attach to the vesicle
  • A digestive vesicle is formed inside the cytoplasm
  • The proteins, carbs, lipids, etc are hydrolyzed
26
Q

Describe the pathway of secretion of particles by a cell.

A

The residual body with indigestible substances is excreted externally through exocytosis.

27
Q

Describe the synthesis and secretion of proteins by a cell.

A
  • Proteins are synthesized by ribosomes

* Synthesized proteins are extruded to the cytosol by ribosomes

28
Q

Describe the pathway for the synthesis of proteins for intracellular use.

A

Some synthesized proteins are extruded to the ER by ribosomes into the endoplasmic matrix.

29
Q

Define autodigestion.

A

The digestion of tissue by enzymes produced by the organism itself.

30
Q

Explain the various ways of passage through the cell membrane.

A
  • Diffusion
  • Active transport
  • Phagocytosis
  • Pinocytosis

MHIS 1513 (15 decks)

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