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Flashcards in Cellular Structure pt 2 Deck (35)
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1
Q

Lysosomes: recycling system of the cell

A

membrane enclosed organelles that consist of 50-60 hydrolytic enzymes most active at acidic pH:

capable of breaking down proteins, carbohydrates, lipids, and nucleic acids.

monomers escape through membrane and can be reused by cell

removes both material OUTSIDE the cell and obsolete components of the cell itself

morphologically diverse

2
Q

Lysosomal Sorting Pathway: step 1

A

phosphorylation of lysosomal enzymes via mannose-6-phosphate

3
Q

Lysosomal Sorting Pathway: step 2

A

binding of lysosomal enzyme to M6P receptor, followed by budding via clathrin coated pits

clathrin–adaptin–M6P receptor through membrane–M6P-L.Enzyme

4
Q

Primary Lysosomes

A

enzymes inactive
storage site of lysosomal hydrolases
homogenous enzymes

5
Q

Secondary Lysosomes

A

site of catalytic process
carries digestive enzymes
actively enzymatic

6
Q

Pathways for intracellular degradation

A
  1. Receptor mediated endocytosis
  2. Autophagy
  3. Phagocytosis
7
Q

Development of Lysosomes

A

Primary Lysosome buds from Golgi and fuses with an early endosome. Clathrin recycled.

Early endosome matures into Late endosome, secondary lysosome buds from late endosome

8
Q

Lysosomes are formed from

A

fusion of transport vesicle with endosome

9
Q

internal pH of late endosome =

A

5.5

10
Q

Familial hypercholesterolemia

A

mechanism of cholesterol uptake is disrupted

elevation of LDL, the predominant cholesterol transport protein in plasma

11
Q

Primary defect of hypercholesterolemia

A

defect in LDL receptor

12
Q

Peroxisomes, also called

A

microbodies

13
Q

Peroxisomes are a diverse group of organelles. They contain enzymes that ______ and which in turn can be broken down by ______

A

produce hydrogen peroxide

H2O2 is then broken down by catalase

14
Q

function of the microbody (peroxisome)

A

hydrogen peroxide production
beta oxidation of long chain fatty acids
bile and cholesterol synthesis
detoxify alcohol

15
Q

what do we “often” find in the core of the peroxisome

A

“urate oxidase” crystalline core

16
Q

Peroxisome disorder

A

Zellweger spectrum disorder
peroxisome biogenesis disorder
12 genes required for peroxisome synthesis: defect in any one of these genes will result in disorders on the Zellweger Spectrum

17
Q

Zellweger syndrome

A

absent or reduced number of peroxisomes in the cells

syndrome present in patients at birth, has no cure, causes dead within the first year of life

18
Q

spaces in the mito

A

intermembrane space
cristae space
matrix

19
Q

space mitochondria take up in the cell

A

around 20%

20
Q

mitochondria are associated with what cellular skeletal system

A

microtubular cytoskeleton

21
Q

Where are the mitochdonria the least dynamic and why

A

high energy cells: they are more “fixed”, and have to pack into tight spaces between myofibrils around flagellum of sperm cells

22
Q

two associations of the mito in the cell talked about in class

A

mito associated with microtubular cytoskeleton

mito associated with ER (ER can cleave the mito)

23
Q

3.75 billion years

A

first living cells

24
Q

2 billion years

A

aerobic respiration becomes widespread

25
Q

1 million years

A

first multicellular plants and animals

26
Q

Evolutionary sequence leading to present day mito carrying eukaryote

A

an anaerobic prokaryote split into an anaerobic eukaryote and an aerobic prokaryote

eukaryote consumed the prokaryote
symbiosis

27
Q

components of mtDNA

A

ATP Synthase subunits, NADH dehydrogenase subunits, cytochrome oxidases, cytochrome b,

28
Q

Differences between the mitochondrial code and the “universal code”

A

UGA doesnt make STOP is makes Trp
AUA doesnt make Ile it makes Met
AGA/AGG doesn’t make Arg it makes STOP

29
Q

200 diseases related to mitochondrial DNA defects. What do a large number of these diseases effect?

A

tRNA genes: often mutations prevent tRNA aminoacylation

30
Q

UGA codes for ____ and ____ in universal vs mtDNA

A
STOP = universal
Trp = Mt
31
Q

AUA codes for _____ and _____ in universal vs mtDNA

A
Ile = universal 
Met = mt
32
Q

AGA/AGG codes for _____ and _____ in universal vs mtDNA

A
Arg = universal 
STOP = mt
33
Q

Mitochondrial DNA diseases can come from two places

A

either nucleus encoded or defects in mtDNA

34
Q

Mother’s Curse

A

theory: susceptibility to mito disease come from mom. this allows male harming defects to accumulate in mitochondrial genomes: they may benefit women but harm the dudes

35
Q

Mitochondrial DNA and Aging

A

accumulation of ROS-generated by the respiratory chain can cause mito damage

less efficient DNA replication and repair mechanisms

ROS increases with AGE: