Lecture 1 Flashcards
What are the domains of cellular life?
The domains of cellular life are bacteria, archaea, and eukaryota
What components make up the nucleus?
nuclear envelope, nuclear lamina, nuclear pores, nucleolus, and nucleoplasm
what components make up the nuclear envelope and what are their functions?
The inner nuclear membrane which stabilizes the nuclear envelope
The outer nuclear membrane is continuous with with rER
What is the structure of the nuclear lamina?
Thin sheet like meshwork that is below the inner nuclear membrane.
Hutchinson-Gilford progeria syndrome and other laminopathies?
Mutation in the lamin proteins. They are a type of intermediate filament in the nuclear lamina.
Describe the function of the nuclear pore complex?
This complex allows for the transport of molecules between the nucleus and cytoplasm
Purpose of the nucleolus?
It is the site of ribosome production
What zones make up the nucleolus and what are their roles?
Fibrillar center- pale staining and contains rRNA genes
Fibrillar material- transcription of rRNA genes
Granular material- initial ribosomal assembly
What is chromatin?
Chromosomes that are in various degrees of uncoiling
Normally packaged into nucleosomes (wrapped around histones)
What are the two types of chromatin and what are their characteristics?
Euchromatin- lightly stained, less condensed, more transcriptionally active
Heterochromatin- dense staining, more condensed, less transcriptionally active
Describe the nucleosome
Fundamental structural unit of chromatin
eight histone molecules (octomer) 2 loops of DNA around the core of the octomer
found in both types of chromatin
What three parts make up the chromosome?
Centromere, telomere, and the replication origin
What are the purposes of the three parts of the chromosome?
centromere- helpful during mitosis
telomere- at the ends of the chromosomes. they are repeated sequences that allow for replication
Replication origin- locations were DNA replication begins
Clinical importance of telomerase enzyme?
cancer and aging
What is the structure and function of the ribosome?
The ribosome is made up of two RNA subunits and is used for translation
What are the two different types of ribosomes?
membrane-bound and free
Where are membrane bound ribosomes and what proteins do they synthesize?
They are found in the rER and they synthesize lysosomal proteins, secreted proteins, and PM proteins
mRNA contains an ER signal sequence!
typically secreted
Where are free ribosomes located and what proteins do they synthesize?
They are unattached to any membrane and the mRNA does not have an ER signal sequence
They synthesize nuclear proteins, mitochondrial proteins, cytosolic proteins, and peroxisomal proteins
typically keep in cytosol
What are the two regions of the ER and what are their functions?
Smooth ER- synthesis of lipids and detoxification
Rough ER- to synthesize proteins destined for the PM, lysosomes, or secretion. site of post-translational modification and folding
What kinds of cells is the rER found in abundance?
cells that specialize in protein synthesis
Ex: secretory cells
characteristics of the sER
region of the ER that does not have any bound ribosomes.
Functions of the sER
seen in large amounts in cells that specialize in lipid metabolism.
Ex: cells that secrete steroids
Plays a major role in detoxification.
Ex: Large amount in liver!
Cytochrome P450 system
Also functions to sequester calcium
Ex: muscle cells
What is the structure of the golgi?
Complex of flattened membrane enclosed cisternae
Located next to the nucleus and centrosome
Has a cis face and a trans face
cis face and trans face of the golgi?
Cis face is the entrance into the golgi (Cis golgi network)
trans face is the exit of the golgi (trans golgi network)
What kind of cells have well developed golgi’s?
cells that secrete
Ex: plasma cells and digestive cells
What are the purpose of coatomer coated vesicles?
they medicate the bidirectional nature between the Er and golgi
COP-I vesicles?
retrograde transport
cis golgi back to rER
COP-II vesicles?
Anterograde transport
newly made proteins from rER to cis golgi
What are the functions of the golgi?
- post translational modification such as glycosylation, sulfation, phosphorylation, and proteolysis
- sorting
- packaging
What are the three vesicular trafficking pathways?
- constitutive secretory pathway- continuous secretion
- regulated secretory pathway- secreted with stimulus
- lysosomal pathway
What are lysosomes?
They are organelles that are used for the destruction of macromolecules
environment must be acidic
Symptoms of lysosomal storage diseases?
often result from mutations in genes that code for lysosomal enzymes
results in the accumulation of undigested products and lack of proper cell function.
normal birth
slower growth
bone and joint deformity
lung infections and heart disease (frequent)
Tay-Sachs disease
deficiency of the HEXA enzyme
results in the accumulation of GM2 ganglioside
Death of neurons in the spinal cord and brain
Hurler syndrome
alpha-L- iduronidase dysfunction
accumulation of dermatan sulphate
skeleton and nervous system are impacted
Pompe
alpha-1,4 glucosidase dysfunction
accumulation of glycogen
skeleton and NS are impacted
Gaucher
dysfunction in the glucocerebrosiase enzyme
accumulation of glucosylceramide
impacts liver and spleen
I-cell disease
dysfunction of phosphotransferase for M6P formation
lysosomal hydrolases are not present
impacts skeleton and NS
What are the pathways of lysosomal digestion?
- phagocytosis
- endocytosis
- autophagy
What is autophagy?
major pathway used to digest proteins and organelles in the lysosome
self eating, per say
Autophagsome is formed (double membrane)
What is the proteasome and why is it important?
This organelle is used for protein degradation (ATP dependent)
can degrade proteins without the use of a lysosome
proteins that are tagged with ubiquitin are targeted for destruction.
destruction of short lived or abnormal proteins
cyclins
transcription factors
tumor suppressors
What is the use of the peroxisome?
Important for the role of lipid metabolism
EX: very long chain fatty acid beta oxidation
Can degrade toxic reactive oxygen molecules
Ex: convert hydrogen peroxide to oxygen and water
Ex: detoxification of ingesting alcohol (liver mainly)
how are peroxisome proteins synthesized
By the use of free ribosomes
Explain zellweger syndrome?
it is caused by a mutation in peroxisome genes that lead to dysfunction or no presence
mitochondrial disease
usually due to a mutation in a mitochondrial gene
leads to defective mitochondrial enzymes
lower ATP yield…. impacts neurons and muscles
