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C Bio > Lecture 22 - Cell Energetics & Mitochondria (22) > Flashcards

Lecture 22 - Cell Energetics & Mitochondria (22) Flashcards

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Biology 101 flashcards
1
Q

what do organisms use E for?

A

build complex molecules

maintain their structure

move

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2
Q

what are the 2 sources of E available to organisms?

A

electromagnetic - light E

chemical - E of molecules & eletrons

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3
Q

glycolysis chemical formula

A

glucose –> 2 pyruvate + 2 ATP + 2 NADH

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4
Q

why does glycolysis not require?

A

oxygen

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5
Q

where does glycolysis occur?

A

cytoplasm

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6
Q

where does the citric acid cycle occur?

A

mitochondria

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7
Q

chemical formula of the citric acid cycle & TCA

A

Pyruvate –> acetyl CoA (+NADH) –> 3 NADH + FADH2 + CO2 + GTP `

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8
Q

what does the ETC use to generate ATP?

A

NADH & FADH2

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9
Q

what is the net gain of ATP from TCA + ETC?

A

36 ATP

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10
Q

what is the main function of mitochondria?

A

production of ATP

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11
Q

structure of mitochondria

A

Outer membrane: impermeable, contains porins forming non-selective membrane channels, porins don’t require a mitochondria localization signal

Intermembrane space

Inner membrane:
ETC
ATP synthase
Contain cristae which are highly folded to increase the SA for ATP machinery

Matrix:
TCA
DNA
Ribosomes

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12
Q

what does the mitochondria vary in?

A

shape: filamentous to spherical
number: oocytes have more than spermatozoa

number & shape of cristae

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13
Q

how many mitochondria do oocytes have?

A

300,000

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14
Q

why do oocytes have more mitochondria than spermatozoa?

A

undergoes division without gaining size, require the production of many daughter cells prior to growing

undergo many cell divisions

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15
Q

what cell type has the greatest amount of mitochondria?

A

egg

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16
Q

where do mitochondria cluster in sperm cells?

A

around the base of the flagellum

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17
Q

where do mitochondria cluster in renal tubular cells?

A

b/w basolateral membrane invaginations at the periphery which contain ATPase pumps for establishing gradients

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18
Q

how are mitochondria similar to bacteria?

A

Double membrane

Membrane composition (ex: cardiolipin –> a gene sequence only found in the mitochondria membrane)

Divide by fission, independent of the host

Circular DNA encoding unique rRNAs & tRNAs

13 PROs in the ETC are similar to bacteria PROs

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19
Q

Endosymbiotic theory

A

mitochondria in eukaryotes evolved from aerobic bacteria living within their cells

symbiotic relationship

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20
Q

where does ETC occur?

A

inner membrane of the mitochondrial

21
Q

steps of ATP production

A

TCA cycle: NAD+ & FADH –> NADH & FADH2

Electrons are fed into enzyme complexes & end up on an oxygen molecule
H+ move to the intermembrane space creating the H+ electrical/concentration gradient
Electrons are transferred to an oxygen which also picks up 2H+ –> H2O
No consumption of ATP, conformational changes are caused
Electron will be received by H –> H-

H+ ions are returned to the mitochondrial matrix by ATP synthase for ATP production

22
Q

movement of H+ in ETC

A

from the matrix to the intermembrane space

23
Q

what is the terminal electron acceptor in the ETC?

A

oxygen

24
Q

how much E in the ETC is stored due to the concentration diff of H+?

A

20%

25
Q

How much of E stored is electrogenic in the ETC? & why is this?

A

80%

the membrane isn’t permeable to the counter-ions –> protects cytoplasm from being too acidic

26
Q

if too many H+s are pumped out, what can happen?

A

they can leak through the proins & cause the cytoplasm to become acidic
that is why it is important for ATP synthase to bring them back

27
Q

structure of ATP synthase?

A

F1 headpiece projects into matrix, responsible for ADP phosphorylation

F0 base piece is embedded in the lipid bilayer, contains the H+ ion channel

28
Q

what does the movement through the H+ channel induce?

A

conformational changes & drives ATP formation

29
Q

each NADH produces how many ATP molecules?

A

3

30
Q

each FADH2 produces how many ATP molecules?

A

2

31
Q

how does the movement of H+ produce ATP?

A

H+ flow through the channel causes a rotation of the F0 rotator

this spin causes a conformational change in the F1 headpiece

Change of shape enables the phosphorylation of ADP

kinetic E (of the F0 rotator) is used to create chemical E

32
Q

how is ATP synthase being utilized in nanotechnology?

A

Production of a microscopic motorized propeller: F0 + actin filament
Feed an ATP solution through the propeller & rotation occurred

This could lead to the production of nano-bots, which would be sent throughout the body carrying out various functions
Ex: delivery of medication

33
Q

how do PROs enter mitochondria?

A

through a signal system which includes carrier PROs & a mitochondrial receptor

PROs require a presequence (target sequence), directs PRO to mitochondria

cytosolic chaperone PROs on the outer membrane recruit & unfold the PRO enabling it to enter through the pore

once the PRO enters the mitochondria matrix, the sequence is cut off & the PROs refold

(pass through the outer membrane & inner membrane)

34
Q

where are most mitochondrial PROs encoded?

A

nuclear genome (except 13)

35
Q

proton leak or mitochondrial uncoupling & what is the result?

A

protons re-enter the mitochondrial matrix without contributing to ATP synthesis, this is accomplished by facilitated diffusion through a proton channel called thermogenin

potential E of the H+ gradient is released as heat

36
Q

where is thermogenin located?

A

brown adipose tissue (in newborns)

37
Q

non-shivering thermogenesis

A

primary means of heat generation in newborns & hibernating mammals

production of heat, but no ATP

ATP synthase is blocked

38
Q

what causes mitochondrial DNA damage

A

oxygen molecules become superoxide ions if they aren’t coupled with H quickly in the ETC

39
Q

Why do mitochondria have multiple c’some copies?

A

Divide by fission, require DNA copies to share with daughter cells

Highly metabolic organelle requires a high amount of PRO production

Enables removal of damaged DNA copies, damage occurs frequently since it is an oxidative organelle

40
Q

how do mitochondria contribute to aging? & what is the evidence?

A

Gradual accumulation of mutations in mitochondrial DNA may be the cause of aging

Old people have more mutated mtDNA than young
Mutator strain of mice have 3-8x more mtDNA mutations than normal mice age prematurely & die at half the normal age

41
Q

peroxisomes

A

membrane-bound vesicles with a core of oxidative enzymes

42
Q

what are 3 similarities b/w mitochondria & peroxisomes?

A

oxidative metabolism

import PROs

Formed from pre-existing organelles

43
Q

what are peroxisomes involved in metabolizing?

A

FAs

44
Q

what are the enzymes in peroxisomes?

A

urate oxidase & AA oxidase

45
Q

what is the by-product of peroxisomes?

A

hydrogen peroxide (toxic) causes damage to membranes & PROs

46
Q

how many oxidative enzymes do peroxisomes have?

A

over 50

47
Q

catalase location

A

peroxisomes & mitochondria

48
Q

catalase

A

removes highly reactive peroxide & other oxygen free-radicals

49
Q

what evidence is there that suggests that catalase prevents aging?

A

Fruit flies with extra copies of catalase genes live longer than normal flies

Nematodes that are induced by drugs to increase catalase activity lived longer than control nematodes

C Bio (30 decks)

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