1. Fibrillar center 2. Fibrillar material 3. Granular material

Lecture1 Flashcards by Chanmi Park

basic set of organelles

Nucleus, Ribosomes, Endoplasmic reticulum, Golgi, Lysosomes, Mitochondria & Peroxisomes

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Components of cell nucleus

Nuclear envelope
Nuclear lamina
Nuclear pores
Nucleolus
Nucleoplasm

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Faces the nucleoplasm, and is in contact with the nuclear lamina
- Function as a scaffold stabilizing the nuclear envelope

Inner nuclear membrane

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faces the cytoplasm and continues with endoplasmic reticulum

Outer nuclear membrane

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Thin, sheet-like meshwork beneath the inner nuclear membrane

Nuclear Lamina

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What is nuclear lamina made up of

Lamin A&B

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What does Lamin A mutation cause?

Hutchinson-Gilford Progeria syndrome (preaging)

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Roles of nuclear lamina

Scaffold for nuclear envelope, chromatin & Nuclear pores

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A complex that spans inner and outer nuclear membrane, and allows transport of molecules between nucleus and cytoplasm

Nuclear Pore Complex (NPC)

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The site of ribosome production (ribosome factory)

Nucleolus

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3 Zones of nucleolus

Fibrillar center
Fibrillar material
Granular material

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Staining of fibrillar center

pale staining

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Role of fibrillar center

Contain DNA loops of rRNA genes for creating ribosome

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Staining of fibrillar material

Dark staining

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Role of fibrillar material

transcription of rRNA genes

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Role of granular material

initial ribosomal assembly occurs

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2 types of chromatin

Euchromatin & Heterochromatin

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Staining of euchromatin and its transcription state

Light staining, and active transcription

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Staining of heterochromatin and its transcription state

Dark staining, and less transcriptionally active

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Complex of DNA and histones

Beads on a string chromatin

Nucleosome

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When nucleosomes are packed together, it forms …

30-nm chromatin fiber

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When 30-nm chromatin fiber loosely arrange, it becomes

Euchromatin

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When Euchromatin and heterochromain pack together, it forms

Chromosome

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Specific specialized nucleotides sequences in all chromosomes (3)

Centromere
Telomere
Replication origin

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Centric heterochromatin Holds sister chromatids together Site of kinetochore formation

Centromere

Clinical correlation of telomere

cancer & aging

2 populations of ribosome (2 ways of protein trafficking)

1. Membrane-bound ribosomes | 2. Free ribosomes

Many ribosomes bound to a singles mRNA molecule

Polyribosome

Clinical correlation with abnormal ribosome

Ribosomopathies

Proteins that are synthesized by being translocated into the ER lumen on membrane-bound ribosomes (3)

1. Lysosomal proteins 2. Secreted proteins 3. Plasma membrane proteins

Where are membrane-bound ribosomes found?

rER

What is the special feature of mRNA that is translated by membrane-bound ribosomes?

Contain an ER signal sequence which direct mRNA to rER for translation.

Pathway of protein that are translated by membrane-bound ribosomes

ribosome (rER) >> Golgi >> lysosome or secretion or membrane

Proteins that are synthesized by free ribosomes (4)

1. Nuclear proteins 2. Mitochondrial proteins 3. Cytosolic proteins 4. Peroxisomal proteins

Largest organelle by size

What is abundant in cells specialized in protein synthesis? (give an example)

rER EX) Secretory cells producing proteins for extracellular export

Site of initial post-translational modification & folding

rER

What is cresyl violet used for? And how is it useful for viewing rER?

Cresyl violet is used for staining DNA. Since rER has DNA components, rER will be stained purple, which makes it detectable.

What is abundant in cells specialized in lipid metabolism?

sER

Role of sER (3)

1. Lipid metabolism 2. Detoxification (Cytochrome P450 System) (Heapatocytes) 3. Sequester calcium in muscle cells or SR

Which organelle is well developed in secretory cells? | What are the 2 examples of secretory cells?

Golgi Apparatus 1. Plasma cells (secrete antibody) 2. Pancreatic acinar cells (secrete digestive enzymes)

Which is entry point of golgi? cis or trans

cis

rER & Golgi transport is mediated by...

Coatomer-coated vesicles

2 ways of Coatomer-coated vesicle transport

1. COP-I coated vesicle | 2. COP-II coated vesicle

Which is retrograde transport COP-I or COP-II?

COP-I (CGN back to rER)

Functions of golgi apparatus (3)

1. Post-translational modification 2. Sorting 3. Packaging

4 post-translational modification and where are these happening?

1. Glycosylation 2. Sulfation 3. Phosphorylation 4. Proteolysis happens at golgi apparatus

3 Ways of vesicular trafficking

1. Constitutive secretory pathway 2. Regulated secretory pathway 3. Lysosomal pathway

Which pathway of vesicular traffcking is this? ; vesicles are stored & secreted with stimulus. Also give an example.

Regulated secretory pathway | ex) neurons, acinar cells of pancreas

Digestive organelles that function in the controlled intracellular digestion of macro molecules

Lysosomes

Require acidic envrionment and contains more than 40 types of hydrolytic enzymes. What is this organelle

Lysosomes

With what can we visualize lysosome?

Acid phosphatase

Role of Mannose 6-Phosphate in terms of lysosome

M6P adds to lysosomal hydrolases or lysosomal enzyme precursors which binds to M6P receptors in the TGN. This leads to transport of lysosomal enzyme to lysosome. So M6P is essential in transport of lysosomal enzyme from GA to lysosome.

Lysosomal storage diseases (LSDs) that is deficient of HEXA due to autosomal recessive disorder. It results in the accumulation of GM2 canglioside, leading to dath of neurons in brain and Spinal cord.

Tay-Sachs Disease

Results of lysosomal storage diseases (LSDs)(3)

1. Accumulation of undigested products 2. Disruption of normal cell function 3. Cell death

3 pathways to lysosomal digestion

1. Phagocytosis 2. Endocytosis 3. Autophagy

Known as 'self-eating', it is a major cellular pathway to degrade proteins and organelles in lysosome

Autophagy

Pathway of autophagy

1. intracellular membrane such as SER surrounds organelle and cytoplasm which forms autophagosome. 2. Autophagosome fuse with lysosome then contents are degraded, recycled and reused.

Double membrane vacuole

Autophagosome

Target protein for destruction using ubiquitin. It uses ATP to degrade proteins without involving lysosomes. What is the pathway?

Proteasome-mediated protein degradation

Example of proteasome-mediated protein degradation

1. Cyclins, transcription factors, tumor suppressors that are abnormal proteins or normal short-lived regulatory proteins

Where in mitochondria does ATP generation takes place?

Inner mt membrane

Structures of mitochondria (5)

1. Inner membrane 2. Intermembrane space 3. Outer membrane 4. Matrix 5. Crista