Cellular Structure pt 2

Question 1

Lysosomes: recycling system of the cell

Answer 1

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

Question 2

Lysosomal Sorting Pathway: step 1

Answer 2

phosphorylation of lysosomal enzymes via mannose-6-phosphate

Question 3

Lysosomal Sorting Pathway: step 2

Answer 3

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

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

Question 4

Primary Lysosomes

Answer 4

enzymes inactive
storage site of lysosomal hydrolases
homogenous enzymes

Question 5

Secondary Lysosomes

Answer 5

site of catalytic process
carries digestive enzymes
actively enzymatic

Question 6

Pathways for intracellular degradation

Answer 6

1. Receptor mediated endocytosis
2. Autophagy
3. Phagocytosis

Question 7

Development of Lysosomes

Answer 7

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

Question 8

Lysosomes are formed from

Answer 8

fusion of transport vesicle with endosome

Question 9

internal pH of late endosome =

Answer 9

5.5

Question 10

Familial hypercholesterolemia

Answer 10

mechanism of cholesterol uptake is disrupted

elevation of LDL, the predominant cholesterol transport protein in plasma

Question 11

Primary defect of hypercholesterolemia

Answer 11

defect in LDL receptor

Question 12

Peroxisomes, also called

Answer 12

microbodies

Question 13

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

Answer 13

produce hydrogen peroxide

H2O2 is then broken down by catalase

Question 14

function of the microbody (peroxisome)

Answer 14

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

Question 15

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

Answer 15

“urate oxidase” crystalline core

Question 16

Peroxisome disorder

Answer 16

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

Question 17

Zellweger syndrome

Answer 17

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

Question 18

spaces in the mito

Answer 18

intermembrane space
cristae space
matrix

Question 19

space mitochondria take up in the cell

Answer 19

around 20%

Question 20

mitochondria are associated with what cellular skeletal system

Answer 20

microtubular cytoskeleton

Question 21

Where are the mitochdonria the least dynamic and why

Answer 21

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

Question 22

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

Answer 22

mito associated with microtubular cytoskeleton

mito associated with ER (ER can cleave the mito)

Question 23

3.75 billion years

Answer 23

first living cells

Question 24

2 billion years

Answer 24

aerobic respiration becomes widespread

Question 25

1 million years

Answer 25

first multicellular plants and animals

Question 26

Evolutionary sequence leading to present day mito carrying eukaryote

Answer 26

an anaerobic prokaryote split into an anaerobic eukaryote and an aerobic prokaryote eukaryote consumed the prokaryote symbiosis

Question 27

components of mtDNA

Answer 27

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

Question 28

Differences between the mitochondrial code and the "universal code"

Answer 28

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

Question 29

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

Answer 29

tRNA genes: often mutations prevent tRNA aminoacylation

Question 30

UGA codes for ____ and ____ in universal vs mtDNA

Answer 30

``` STOP = universal Trp = Mt ```

Question 31

AUA codes for _____ and _____ in universal vs mtDNA

Answer 31

``` Ile = universal Met = mt ```

Question 32

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

Answer 32

``` Arg = universal STOP = mt ```

Question 33

Mitochondrial DNA diseases can come from two places

Answer 33

either nucleus encoded or defects in mtDNA

Question 34

Mother's Curse

Answer 34

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

Question 35

Mitochondrial DNA and Aging

Answer 35

accumulation of ROS-generated by the respiratory chain can cause mito damage less efficient DNA replication and repair mechanisms ROS increases with AGE: