Module Six

Question 1

What is lactose?

Answer 1

Lactose is the main carbohydrate (sugar) found in milk, providing energy for young mammals, including human infants

Question 2

What type of sugar is lactose chemically?

Answer 2

A disaccharide made of glucose + galactose

Question 3

How is lactose digested in the human body?

Answer 3

Lactase (an enzyme) in the small intestine breaks lactose into glucose and galactose, which are then absorbed

Question 4

What happens in lactase non-persistence?

Answer 4

Lactase production decrease decreases after childhood = lactose isn’t efficiently digested = un digested lactose reaches colon = bacteria, fermentation produces gas, bloating, cramps, and diarrhoea

Question 5

Is lactose intolerance a disease?

Answer 5

No, it’s the normal genetic condition for most humans

Question 6

What is lactase persistence?

Answer 6

The continued ability to digest lactose in adulthood due to mutations keeping the lactase gene active

Question 7

How is lactase persistence inherited?

Answer 7

Dominant trait: LL or Ll = lactase persistence

Lactase nonpersistent = recessive trait (ll)

Question 8

How did lactase persistence evolve?

Answer 8

Through multiple independent mutations in populations practising dairy herding. Example of convergent evolution.

Question 9

What is convergent evolution?

Answer 9

The process were unrelated organisms independently evolved similar traits typically occur occurs when species face similar challenges, such as finding food or surviving in a particular climate

Ex: Europeans and African groups independently evolving the mutation of lactase persistence

Question 10

Why did lactase persistence evolve in the last 10,000 years?

Answer 10

Domestication of animals and milk consumption created selective pressures for adult adults who could digest milk

Question 11

What is the gene culture co-evolution hypothesis?

Answer 11

Milk consumption created selection pressures which led to the spread of lactase, persistence, mutations, and increased milk consumption and the gene reinforced each other

Question 12

How does fermentation affect lactose digestion?

Answer 12

Lactic acid bacteria in fermented products breaks down lactose making it easier to digest causing less gas, even lactose intolerant people can consume yogurt/cheese

Question 13

What evolutionary advantages does milk provide?

Answer 13

Calcium for bones
Protein
Vitamins: A, D, B12, riboflavin
Energy and fat
Clean liquid source compared to contaminated water

Question 14

Why was milk especially important in northern latitudes?

Answer 14

Low sunlight = less vitamin D, so milk helped with calcium absorption and bone health, which was a strong selection for lactase persistence

Question 15

How is ethanol produced naturally?

Answer 15

Yeasts ferment sugars from fruits or grains, and produce ethanol and carbon dioxide

Question 16

What are the effects of ethanol on the body?

Answer 16

It’s a central nervous system depressant, slows brain activity, causes, relaxation, slower, reaction time, poor coordination, and impaired judgement

Question 17

When did humans evolve the ability to metabolize ethanol safely?

Answer 17

Around 4 million years ago in early apes, allowed consumption of fermenting fruit without dangerous intoxication

Question 18

How is alcohol and metabolized in humans?

Answer 18

ADH converts ethanol into acetaldehyde (which is toxic)

ALDH converts acetaldeyhde into acetate (non toxic)

Acetate is broken down into CO2 and Water

Question 19

What happens if ALDH (aldehyde dehydrogenase) doesn’t work efficiently?

Answer 19

Aceteyldehyde (which is toxic) accumulates, causing flushing, nausea, rapid heartbeat, headache and lowers alcohol tolerance

Question 20

What is the evolutionary reason for ADH (alcohol dehydrogenase)/ALDH variants?

Answer 20

Unpleasant reactions reduce heavy drinking, which lower the risk of alcoholism making it a reproductive advantage

Question 21

What is ALDH2 variant?

Answer 21

It’s common in east Asians and it greatly reduces acetaldehyde breakdown, causing facial flushing, nausea, rapid heartbeat, and reducing the risk of alcohol dependence

Question 22

What cancers are associated with ALDH2 deficiency?

Answer 22

Esophageal, head and neck cancer is due to acetaldehyde buildup

Question 23

Why might some east Asians still drink despite ALDH2 variant?

Answer 23

Heterozygotes experience milder symptoms (they have one normal and one variant ALDH2 allele), cultural + social, business pressures encouraged drinking, so tolerance develops overtime

Question 24

What are ADH and ALDH

Answer 24

These are the liver enzymes responsible for breaking down alcohol

Question 25

What is the Asian flush?

Answer 25

Facial redness, nausea, itching, rapid heartbeat after drinking, caused by aceteyldehyde buildup due to ALDH2 variant

Question 26

Why do some regions not incorporate dairy into diets?

Answer 26

East & Southeast Asia (china, Japan, Korea) have a high prevalence of lactose non-persistent

Question 27

How do traditional recipes reflect, genetic makeup?

Answer 27

Populations adapt cuisine to foods they can safely digest

Question 28

How can diet ensure adequate vitamin B12 where meat is scarce?

Answer 28

Consume, fermented or pickled foods

Question 29

What is the evolutionary advantage of G6PD mutation?

Answer 29

It makes males less susceptible to malaria

Question 30

Why is inability to digest milk considered genetic?

Answer 30

Lactase gene normally switches off after weaning making lactose intolerance, the default human state

Question 31

What is the selective advantage of lactase persistence?

Answer 31

Adult adults can digest milk, access to clean nutrient into which food, survival advantage

Question 32

What is the common ingredient in central European recipes?

Answer 32

Cream yogurt, soft cheeses

Question 33

Why do east Asians experience facial flushing after alcohol?

Answer 33

Genetic variance in ADH and ALDH cause acetaldehyde buildup leading to the Asian flush

Question 34

How does Julius Lou’s ALDH2 mutation affect him?

Answer 34

Because his mutated a LDH2 enzyme does not efficiently break down acetaldehyde it causes toxic acetyldehyde to accumulate turning Julius red, nausea, itchiness when drinking

Question 35

Why do some people take Pepcid AC for Asian flush?

Answer 35

It blocks histamine, receptors and reduces visible flushing and redness, but does not prevent long-term acetyldehyde damage

Question 36

What can fava beans trigger?

Answer 36

Fava beans can trigger oxidative stress in those with G6PD deficiency

Question 37

What is G6PD deficiency?

Answer 37

The body doesn’t produce enough of the G6PD enzyme, which is crucial for protecting red blood cells from damage

Question 38

What is the gene cultural evolution?

Answer 38

The process were cultural habits influenced genetic evolution. The theory suggests that cultural innovations, create new environments, and select selection pressures which drive genetic changes

Question 39

Describe how G6PD deficiency provides resistance to malaria and explain the potential downside of this mutation

Answer 39

G6PD deficiency makes red blood cells more vulnerable to oxidative stress, red blood cells breakdown before parasites can multiply allowing malaria protection Fava beans and some drugs create pre-oxidative stress and red blood cells burst inhibiting the growth and development of the parasites That’s why G6PD deficiency makes males less susceptible to severe malaria 

Question 40

Vitamin B12

Answer 40

Required for proper RBC information neurological function and DNA synthesis can be obtained from meat products but is not present in plant foods