What happens to lactase production in most mammals after weaning?
It decreases, reducing the ability to digest lactose.
What do genetic mutations enable lactase persistence in some human populations?
They enable lactase production to continue into adulthood.
What did dairy historically supply, and how did fermented milks help?
Calories, protein, and fat; preservation and improved milk safety.
Which nutrients does milk contain?
Calcium, phosphorus, high-quality protein, vitamins B2 and B12, iodine, and potassium.
At what age is a dairy cow bred?
At 15–18 months of age.
How long is a dairy cow’s gestation period?
About 9–10 months.
How long does a dairy cow produce milk after calving?
About 10 months.
How many mammary glands make up the bovine udder?
Four.
Which routes do mammary epithelial cells use to secrete milk components during lactation?
Exocytosis, fat secretion, vesicular transcytosis, transporter-mediated movement, and the paracellular pathway.
Which two lipid types make up most milk lipids?
Triglycerides and phospholipids.
Which casein subgroups are the four main ones?
αs1-casein, αs2-casein, κ-casein, and β-casein.
What sugars compose lactose?
Glucose and galactose.
What is lactose?
A milk sugar and disaccharide found only in milk.
What percentage of milk is lactose?
3.6 to 5.5%.
Where does the lactalbumin–β4-galactosyl transferase complex catalyze lactose formation?
In the Golgi.
Through which transporter does glucose enter the cell and Golgi during lactose biosynthesis?
GLUT1.
Where is UDP-galactose formed during lactose biosynthesis?
In the cytoplasm.
What size range characterizes milk exosomes?
30–150 nm.
What evidence mainly supports current understanding of milk-exosome effects?
In vitro and animal studies.
What evolutionary pressures are believed to have shaped lactase persistence?
Dairy-animal domestication and milk consumption.
How does lactase persistence vary among human populations?
It varies widely.
How rapidly have lactase-persistence mutations spread in human history?
They are among the fastest-spreading mutations in human history.
When was dairy-animal domestication placed, and what preceded it?
Approximately 6000–4000 BCE, after the agricultural revolution.
What nutrients did milk supply in low-sunlight regions during harsh winters?
Calcium, protein, and energy.
Which health associations does the course list for dairy and fermented products?
Bone health, muscle maintenance, metabolic regulation, probiotics, and gut health.
How much dairy do Nordic nutritional recommendations advise daily?
350–500 ml, including milk, yogurt, and cheese, with low-fat options encouraged.
What cardiometabolic associations does the lecture report for fermented and low-fat dairy?
Inverse associations with risk factors such as total and LDL cholesterol.
Which organization concluded that dairy has a protective association with colorectal cancer?
World Cancer Research Fund.
How long can a dairy cow’s non-lactating period last before the next calving?
Up to 60 days.
For how many years is a dairy cow economically productive?
3–5 years.
What can happen to a dairy cow’s productivity beyond its typical economic period?
It can remain productive longer.
What factors cause milk composition and production to vary?
Genetics, diet, and stage of lactation.
What supports the bovine udder?
A double-sheeted medial suspensory ligament.
What divides the bovine udder into two halves?
A fine membrane.
How many quarters does each bovine udder half contain?
Two.
Which major routes secrete milk components in mammary epithelial cells?
The cytoplasmic lipid droplet pathway, the microlipid droplet pathway, and the secretory pathway for skim-milk components.
What stages are involved in milk-fat synthesis?
Fatty-acid synthesis and uptake, transport and desaturation, triacylglycerol synthesis, and lipid-droplet secretion.
What are the two main categories of milk proteins?
Caseins and whey proteins.
About what fraction of milk proteins are whey proteins?
About four-fifths.
What kind of proteins are caseins, and what variation do they exhibit?
They are heterogeneous phosphoproteins with several genetic variants.
Which proteins are included in the whey-protein mixture?
β-lactoglobulin, α-lactalbumin, immunoglobulins, serum albumin, lactoferrin, and lactoperoxidase.
Which cells naturally secrete milk exosomes?
Mammary epithelial cells.
How may milk exosomes affect intercellular communication?
By modulating the immune system and cell growth.
What health areas may milk exosomes support?
Gut health and development.
What may milk exosomes carry that resists digestion?
Bioactive molecules.
What processes may milk exosomes modulate?
Inflammation and metabolism.
What aspect of milk-exosome stability remains under investigation?
Stability during processing, including pasteurization and fermentation.
Answer 17 questions on Milk Biosynthesis and Composition.
1. What typically happens to lactase production in most mammals after weaning?
2. What allows some human populations to continue producing lactase into adulthood?
Go over the full study guide for Milk Biosynthesis and Composition.
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