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FoundSci I Unit 3 > Mitochondria & Energy Storage > Flashcards

Mitochondria & Energy Storage Flashcards

1
Q

What are the functions of the smooth endoplasmic reticulum?

A

Primarily synthesizes phospholipids and cholesterol, can make most lipids

Main calcium storage site in cell - regulates release into cytosol and recapture

Drug detox

Assists in glucose metabolism

Synthesizes steroid hormones

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2
Q

What lipids are produced in the cytosol?

A

Synthesizes most fatty acids and triglycerides

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3
Q

What lipids are produced in the mitochondria and peroxisomes?

A

Specific membrane lipids

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4
Q

SER cisterns are ____ and branching and lack ____

A

Tubular
Ribosomes

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5
Q

How does the SER synthesize membrane phospholipids?

A

Substrates in cytosol bind to lipid synthesizing enzymes in SER’s cytosolic monolayer

Newly made phospholipids are in cytosolic monolayer at first and then are moved to the lumen facing monolayer of SER

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6
Q

Phospholipid Translocator Proteins that move phopholipids from cytosolic monolayer to the lumen facing monolayer of SER

A

Flippases and floppases

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7
Q

What is the main flippase in SER?

A

Scramblase

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8
Q

What phospholipids can scramblase move?

A

Choline-containing phospholipids

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9
Q

Are the phospholipids symmetrical in SER membrane?

A

No! Asymmetry maintained after leaving SER

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10
Q

How are phospholipids transferred from the SER to mitochondria or peroxisomes?

A

Phospholipid transfer proteins

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11
Q

What phospholipids does mitochondria synthesize?

A

Cardiolipin

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12
Q

What glycerolphospholipid do peroxisomes produce?

A

Plasmalogens

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13
Q

What other lipids are assembled in SER? Where are they sent?

A

Glycolipids - send to cis-Golig in a vesicle

Cholesterol and ceramides sent to RER via lateral membrane transfer and then to Golgi via a vesicle

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13
Q

What direction do lipids travel through the Golgi?

A

cis to trans direction

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14
Q

Is the SER acidophilic or basophilic? Can you see it in LM?

A

Acidophilic. Cannot see it in LM but it contributes to acidophilic cytoplasm

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15
Q

Glycogenolysis - SER function

A

Enzymatic breakdown of glycogen - enzyme on lumen side of SER

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16
Q

Gluconeogenesis - SER function

A

Supplies glucose during fasting. Enzymes on lumen side of SER

17
Q

Why does SER function in drug detox?

A

Makes enzymes that metabolize ethanol and barbiturates on lumen side on SER

18
Q

Barbiturates

A

Depressant drug. Used to treat seizures, migraines, or insomnia.

19
Q

How does the SER participate in tolerance?

A

Prolonged alcohol or drug use can lead to tolerance, which increases SER volume.

More SER = more enzymes and faster metabolism of ethanol and barbiturates. Need more SER to get same effect

20
Q

How do cells create energy in the form of ATP? What are the main substrates?

A

Cellular Respiration. Substrates are simple sugars and lipids.

21
Q

What are the main functions of mitochondria?

A

Breakdown short, medium, and long fatty acids via Beta-oxidation

Produce most of cell’s ATP via aerobic cellular respiration

Decides whether cell lives or dies

Temporary storage, release, and recapture of calcium

22
Q

What are some characteristics of mitochondria? (location, number, changing?)

A

Located all throughout cell
Vary in number depending on the cell type
Number of mitochondria is always changing

23
Q

Describe the structure of mitochondria

A

Outer mitochondrial Membrane

Intermembranous membrane

Inner mitochondrial membrane

Matrix space

24
Q

What are the characteristics of the outer mitochondrial membrane?

A

High protein content

Porins form channels that permit water soluble molecules to cross

Has proteins that synthesize mitochondrion specific lipids, metabolize fatty acids, and act as receptors for proteins heading to intermembranous space

25
Q

What are the characteristics of the intermembranous space?

A

Contents are similar to cytosol

Contains enzymes like cytochrome c

26
Q

Cytochrome c

A

Enzyme located in the intermembranous space of the mitochondria and triggers the caspase cascade during apoptosis

27
Q

What are characteristics of the inner mitochondrial membrane?

A

75% protein –> very active membrane

Involves protein complexes involved in ATP synthesis

Forms numerous cristae that increase surface area for ATP synthesis and electron transfer chain

28
Q

What is the inner mitochondrial membrane impermeable to? Why?

A

Charged particles!

Cardiolipin decreases the permeability

Allows inner mitochondrial membrane to make hairpin turns

29
Q

Why is it important that cardiolipin decreases permeability of charged particles into the inner mitochondrial membrane?

A

Proton leak - when protons re-enter matrix without contributing to ATP synthesis

30
Q

Why is a proton leak bad for cells? When is it nonpathological?

A

Problematic –> wastes energy and creates reactive oxidative species that damage mitochondria and cell

Nonpath –> Brown fat cells initiate proton leak via thermogenin which drives non-shivering thermogenesis

31
Q

What are the characteristic of the matrix space?

A

Viscous gel

Contains mitochondrial genome, ribosomes, and electron dense matrix granules

32
Q

What do matrix granules in the mitochondria do?

A

Bind calcium and regulate concentration in the mitochondria.

33
Q

Are mitochondria acidophilic or basophilic?

A

Acidophilic - contribute to acidophilia of cytoplasm

34
Q

What would we use to locate mitochondria specific proteins?

A

Immunohistochemistry

35
Q

How does glycogen stain in H&E and PAS?

A

Glycogen does not stain in H&E and is PAS+

36
Q

Where is glycogen located?

A

Normally in cytosol in electron dense clusters

37
Q

Clusters of glycogen

A

Glycogen rosettes

38
Q

How do lipids stain in H&E and osmium?

A

Do not stain in H&E

Stained directly by osmium stains

39
Q

What type of phospholipid layer do lipid droplets have?

A

Singler monolayer

FoundSci I Unit 3 (13 decks)

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