Lecture 22: Aging

Question 1

life history trade offs

Answer 1

small clutch size, slow growth rate = longer lifespans and lower life history traits
large clutch size, fast growth rate = shorter lifespan and higher life history traits

Question 2

tradeoffs

Answer 2

• larger clutch size = lower adult survival
• smaller clutch size = higher adult survival

Question 3

Pace of life: “fast living”

Answer 3

• juveniles mature quickly
• short life span
• large number of offspring
• high mortality
• minimal parental care

Question 4

examples of “fast living” species

Answer 4

rodents, marsupials

Question 5

semelparity

Answer 5

• characterized by a single reproductive event, after which most adults die
• extreme level of “fast living”

Question 6

example of semelparity

Answer 6

• antechinus marsupial
• 2 week mating season, body tissue disintegrates over time, and they die

Question 7

pace of life: “slow living”

Answer 7

• juveniles mature slowly
• long life span
• few number of offspring
• low mortality
• high parental care

Question 8

examples of “slow living” species

Answer 8

elephants

Question 9

survivorship curves

Answer 9

Type I = species like humans and elephants exhibit high survival in early and middle life, with significant mortality in old age
Type II = species like lagomorphs (rabbits) have a constant rate of survival/mortality across their lifespan
Type III = species like frogs experience high early life mortality, but survivors tend to live much longer thereafter

Question 10

disposable soma theory of aging

Answer 10

a biological theory proposing that organisms allocate energy between reproduction and bodily maintenance, influencing aging and lifespan

Question 11

disposable soma theory of aging graph

Answer 11

A: more resources are devoted to growth and reproduction the expense of anti-aging repair mechanisms, leading to a shorter lifespan
B: resources allocated toward anti-aging repair rather than growth and reproduction, resulting in a longer lifespan

Question 12

mechanisms of aging

Answer 12

oxidative damage and telomere shortening

Question 13

oxidative damage

Answer 13

refers to harm caused by free radicals, which are unstable molecules that can damage cells and contribute to aging

Question 14

telomere shortening

Answer 14

involves the gradual reduction of protective end caps on chromosomes (telomeres) with each cell division, limiting a cell’s lifespan

Question 15

oxidative stress and free radical damage

Answer 15

• production of free radicals and hydrogen peroxide by mitochondria
• resulting oxidative stress can damage cellular structures like proteins and membranes

Question 16

hydrogen peroxide

Answer 16

a reactive molecule produces during cellular metabolism that can contribute to oxidative stress

Question 17

mitochondrial DNA damage and oxidative stress

Answer 17

• reactive oxygen species (ROS) generation: the mitochondria produce ROS as a byproduct of electron transport
• components involved: NADH, FMN, FeS, O2, Q, CIII, CIV, and H2O2
• formation of 8-oxodG and MDA: damage to mitochondrial DNA leads to the production of 8-oxodG fragments and malondialdehyde (MDA), contributing to oxidative stress
• ROS and H2O2 accumulate in the intermembrane space

Question 18

free radicals

Answer 18

one electron in orbit, very unstable

Question 19

antioxidants can

Answer 19

neutralize free radicals

Question 20

ROS impact on membrane

Answer 20

• liquid peroxidation
• damage to membranes and lipoproteins

Question 21

ROS impact on DNA

Answer 21

• DNA strand breaks
• mutations leading to cancer

Question 22

ROS impact on proteins

Answer 22

• aggregation and fragmentation
• enzyme inhibition

Question 23

ROS impact on membrane, DNA, proteins lead to

Answer 23

oxidative stress, disease and aging

Question 24

relationship between longevity and H2O2 production

Answer 24

• species with longer life spans tend to have lower rates of H2O2 production

Question 25

peroxidation index vs maximum life span of species

Answer 25

- long-lived species tend to have lower peroxidation indexes, suggesting reduced membrane damage

Question 26

what we lose with age

Answer 26

- telomeres: end caps that protect the chromosome

Question 27

relationship between age and telomere length in birds

Answer 27

- all species (zebra finches, barn swallows, and Adelie penguins) exhibit a negative correlation between age and telomere length, emphasizing that telomeres shorten as birds age

Question 28

rates of telomere shortening predicts life span

Answer 28

- species with slower rates of telomere shortening tend to live longer, both in maximum and average lifespans

Question 29

body size x maximum lifespan across various animal species

Answer 29

- the larger the body size, the longer the maximum lifespan - the naked mole rate has smaller body size and lives longer than expected - humans are larger in size and live longer than expected - elephants are very large and show a long lifespan

Question 30

naked mole rat

Answer 30

- can live up to 29 years - social animals, living in colonies - polygamous: multiple mates

Question 31

what adaptations do naked mole rates have that allow them to live so long?

Answer 31

- adaptations

Question 32

comparison of hydrogen peroxide production in the mitochondria of mice vs mole rate in different tissues including the heart, skeletal muscle, kidney

Answer 32

heart tissue: naked mole rats produced significantly more H2O2 in heart mitochondria compared to mice; might seem unusual as higher H2O2 levels are typically associated with oxidative stress, but naked mole rates skeletal muscle tissue: mice show higher H2O2 production than naked mole rates in skeletal muscle mitochondria; this aligns with the naked mole rat's well known lower metabolic rate and efficient oxidative processes kidney tissue: mice again have higher H2O2 production in kidney mitochondria relative to naked mole rats

Question 33

reduction process of the electron transport chain: enzymes that play a pivotal role in protecting cells from oxidative stress by neutralizing reactive oxygen species

Answer 33

superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT)

Question 34

superoxide dismutase (SOD)

Answer 34

converts harmful superoxide radicals into hydrogen peroxide and oxygen effectively reducing the damage caused by these reactive molecules

Question 35

glutathione peroxidase (GPX)

Answer 35

further detoxifies hydrogen peroxide into water using reduced glutathione (GSH), a key antioxidant

Question 36

catalase (CAT)

Answer 36

breaks down hydrogen peroxide into water and oxygen, preventing accumulation that could harm cells

Question 37

telomerase

Answer 37

enzyme that rebuilds the protective caps (telomeres) on chromosomes, preventing them from shortening during cell division

Question 38

telomerase activity in mice

Answer 38

decreases with age, leading to shorter telomeres and aging related effects