Exam 2: Lecture 12 Apoptosis

when occurs when cell damage cannot be repaired?

accumulation of active p53 triggers apoptosis

apoptosis is an important feature of animal ____________ as well as cellular and genetic ________________

development; stability

what is apoptosis

programmed cell death

T/F: Apoptosis is a key component of homeostasis

true

What are some good reasons for a cell to undergo apoptosis?

cells with damaged DNA

Excess cells during tissue/organ development

infected cells (viruses)

apoptosis is the __________ ___________ for cells unless they are provided survival factors/signals and is a _______________ developmental process

default pathway; controlled

Why is balancing cell division and apoptosis critical for homeostasis?

an imbalance can lead to the development of tumors

What is necrosis?

cell death caused by infection, injury, or lack of blood supply (avascular)

Does apoptosis lead to inflammation?

no

Does necrosis lead to inflammation?

yes

Why does necrosis lead to inflammation?

it involves a leukocytic cell response

What is phosphatidylserine?

it is present in the outer leaflet and acts as a phagocytosis "eat me" signal

What is the outcome of cell cytoplasm that is released as membrane-enclosed apoptotic bodies?

they are phagocytosed by other cells

Caspace proteases undergo an _______________ cascade that controls apoptosis

activation

what are initiator caspases?

initiated by a pro-apoptotic signal to start the cascade

what are executioner caspases?

activated by initiator caspases to finish the job

C-ASP-ASE = ???

proteASE with a Cysteine in its active site that cleaves target proteins at an ASPartate

Does the caspase activation cascade cause an amplication or attenuation of protease activity?

amplification

How many proteins are degraded by Caspases to break down the cell

more than 1000

Apoptosis involves controlled _______________ of the genome by caspase-activated _____ endonucleases

fragmentation; DNA

What are the two ways in which initiator caspases can be activated?

Extrinsic pathway (death receptor pathway)

Intrinsic pathways (mitochondrial pathway)

The extrinsic pathway of apoptosis is activated by cell-surface ___________ receptors

death

what are the functions of the extrinsic pathway of apoptosis?

Contact dependent signaling through death-inducing signaling complex (DISC)

Elimination of harmful adaptive immune cells

Elimination of virus-infected cells

what does the outer mitochondrial membrane release to activate the intrinsic pathway of apoptosis

cytochrome c

What is the relationship between UV radiation and DNA damage?

leads to cytochrome c leakage from mitochondria into the cytoplasm

What governs the mitochondrial membrane permeability?

Bcl-2 family

What group(s) of proteins in the Bcl-2 is anti-apoptotic?

Bcl-2 (B-cell lymphoma)

What group(s) of proteins in the Bcl-2 is pro-apoptotic?

Bax (Bcl-2-associated protein X)

Bad (Bcl-2-associated death promoter)

What does the aggregation of the pro-apoptotic protein Bax form?

pore in the mitochondrial outer membrane

T/F: p53 triggers apoptosis by increasing Bcl-2

false

T/F: pore formation is controlled by the balance of pro-apoptotic and anti-apoptotic proteins

true

Why do survival signals modulate Bcl2 levels and Bad activity?

prevention of apoptosis

In order to block apoptosis you should (activate/inactivate) Bad and (increase/decrease) expression of Bcl2

inactivate; increase

What can happen if a disfunction of apoptosis occurs?

tumor/cancer

developmental defects

What is microphthalmia?

small eye phenotype that is a result of too much apoptosis in the developing eye. Can be a result of maternal vitamin A deficiency

How does double-muscling occur?

too much proliferation in developing muscle

Why is myostatin important?

regulates muscle size and acts as a negative regulator of myogenesis that inhibits proliferation and differentiation.

T/F: myostatin promotes apoptosis in muscle cells

true

What are examples, from class, of animals that lacked myostatin?

"mighty" mice

Texel sheep

Belgian Blue Cattle

T/F: whippets are never found with myostatin mutations

false

How is increased muschle mass caused within Whippets?

two-base pair deletion in the myostatin gene

What is syndactyly?

digital fusion that results due to incomplete apoptosis of interdigital cells