Biology of Ageing 1

Question 1

Which cellular process is responsible for destroying old organelles and damaged macromolecules?

Answer 1

Autophagy is a catabolic process in eukaryotic cells that delivers cytoplasmic components and organelles to the lysosomes for digestion. Lysosomes are specialized organelles that break up macromolecules, allowing the cell to reuse the materials.

Question 2

What organisms can undergo autophagy and why?

Answer 2

Most organisms can = prok and euk because it is an evolutionarily conserved survival mechanism

Question 3

Define aggrephagy

Answer 3

The selective degradation of protein aggregates by macroautophagy is called aggrephagy

Question 4

Define ferritinophagy

Answer 4

Ferritinophagy, a form of autophagy, is also an important part of ferroptosis, a type of regulated cell death resulting from abnormal iron metabolism involving the production of ROS

Ferritinophagy is a new autophagy process associated with ferroptosis in which the binding of nuclear receptor coactivator 4 (NCOA4) and ferritin in autophagosomes causes autophagic degradation

Question 5

Define lysophagy

Answer 5

During lysophagy, a damaged lysosome is sensed and the site of membrane rupture is ubiquitinated, leading to the recruitment of autophagy receptors to the damaged site

Question 6

Define reticulophagy

Answer 6

ER-phagy (reticulophagy) defines the degradation of portions of the endoplasmic reticulum (ER) within lysosomes or vacuoles

Question 7

Define nucleophagy

Answer 7

Removal of damaged or non-essential nuclear material (such as nuclear lamina and DNA) from a cell through autophagy pathway is known as nucleophagy, a selective subtype of autophagy.

Question 8

Define lipophagy

Answer 8

Lipophagy is defined as the autophagic degradation of intracellular lipid droplets

Question 9

Define ribophagy

Question 10

Define pexophagy

Answer 10

Peroxisomes are well characterized for their roles in ROS production and scavenging; however, it also appears that an increase in cellular oxidative stress can induce pexophagy.

Question 11

Define mitophagy

Answer 11

Mitophagy is a specialized form of autophagy that regulates the turnover of damaged and dysfunctional mitochondria

Question 12

Define xenophagy

Answer 12

xenophagy is defined as a type of selective macroautophagy/autophagy that is used for eliminating invading pathogens

Question 13

Which of the following cellular components lacks an inherent repair mechanism?

mtDNA - RNA - proteins - DNA***

Answer 13

Only DNA has the ability to repair

Question 14

What are the two theories of ageing?

Answer 14

Program theories of ageing = fundamental limitation
Damage theories of ageing = deterioration accumulation

Question 15

What is the program theory of ageing?

Answer 15

Telomere attrition and stem cell exhuastion

Fundamental limitation = it is an irreversible process controlled by internal factors that we can only slow down the ageing process

Question 16

What is the damage theory of ageing?

Answer 16

Mitochondrial dysfunction and chronic inflammation

Deterioration accumulation = it is a reversible process affected by external factors that can be rejuvenated when we remove the risk factors

Question 17

What are the 12 hallmarks of ageing?

Answer 17

Dysbiosis/Chronica inflammation/Altered intercellular communication/Stem cell exhaustion

Deregualted nutrient-sensing/Mitochondrial dysfuction/cellular senescence

Genomic instability/Telomere attrition/Epigenetic alterations/Loss of proteostasis/Disabled macroautophagy

Question 18

Which of the 12 hallmarks of ageing take place in the nuclei?

Answer 18

Genomic instability/Telomere attrition/Epigenetic alterations/Loss of proteostasis/Disabled macroautophagy

Question 19

Which of the 12 hallmarks of ageing take place in the cytoplasm?

Answer 19

Deregualted nutrient-sensing/Mitochondrial dysfuction/cellular senescence

Question 20

How do telomeres predict species life span?

Answer 20

The rate at which telomeres shorten predicts species life span

The faster telomeres shorten = the shorter the lifespan, this is regardless of initial length of telomeres

Question 21

Name 3 techniques to measure telomere length

Answer 21

Southern blotting
Q-PCR&raquo_space;> genome wise sequence
FISH = fluorescence in situ hybridization

Question 22

Can we enhance telomere length to reverse ageing? ***

Answer 22

Cancer cells reactivate telomerase so they maintain telomere = allowing them to live longer and continuously replicate

Question 23

What are the two outcomes of mitosis?

Answer 23

Proliferation and growth

Post-mitotic cells don’t proliferate, they grow in size

Question 24

Name some post-mitotic cells

Answer 24

Neurones
Mature muscle cells

Question 25

What are Jurkat cells?

Answer 25

Jurkat cells are an immortalized human T-lymphocyte cell line derived from acute T-cell leukemia.

Widely used in immunology, they model T-cell signaling, cytokine production, apoptosis, and cancer research.

They are suspension cells, expressing CD4, CD3, and the T-cell receptor (TCR), making them ideal for studying T-cell-related pathways.

Question 26

Why do G2/M cells have a higher dye fluorescence in flow cytometry?

Answer 26

Because they have two copies of DNA

The dye used is small enough to infiltrate the cell membrane

Question 27

What order do cyclins rise and fall in from G1 to M phase?

Answer 27

Cyclin D > E > A > B

Question 28

What order do CDK bind cyclins in from G1 to M phase?

Answer 28

CDK4/D
CDK6/D
CDK2/E
CDK2/A
CDK1/A
CDK1/B

Question 29

What does G1 check-point check?

Answer 29

Checks whether cell has enough energy and resources to replicate each chromosomes in the nucleus

Question 30

What does G2 check-point check?

Answer 30

Checks whether replicated DNA is completed/not damaged AND whether proteins and organelles are properly duplicated

Question 30

What does M check-point check?

Answer 30

Checks whether all chromosomes are lined up in center for segregation

Question 31

How do the checkpoints halt the cell cycle?

Answer 31

Inhibit cyclin-CDK complexed via regulatory proteins