Mammary physiology Final

Question 1

Which of these makes mammals unique, compared to other classes of vertebrates:
a. integumentary system b. nervous system c. digestive system d. circulatory system

Answer 1

a

Question 2

Which of the following was most likely present in the milky secretions of the first mammals in evolution.
a. -casein b. lactose c. lactoferrin d. -lactalbumin (used to make lactose)

Answer 2

c

Question 3

What is a “pluripotent mammary stem cell”?
a. alveolar cell at the end of a mammary ductal branch, or stem
b. myoepithelial cell that can still proliferate
c. mammary cell that can become anything
d. alveolar cell that is differentiated and producing milk

Answer 3

c

Question 4

. Keeping concentrations of this hormone low (compared to high) has been shown to decrease the risk of breast cancer.
a. somatotropin b. estrogen c. insulin-like growth factor-I d. epidermal growth factor

Answer 4

b

Question 5

How much time will likely elapse between the formation of a new tumor cell and clinical diagnosis of breast cancer via a mammogram or palpation?
a. < 6 months b. 6 -12 months c. 1 to 5 years d. > 5 years

Answer 5

d

Question 6

. In this type of secretion, part of the cell membrane is lost during secretion; fat is secreted into milk this way.
a. apocrine b. holocrine c. lipocrine d. merocrine e. none of these

Answer 6

a

Question 7

What is BRCA-1 and why does it matter in breast cancer risk?
a. an inherited mutation that disables the normal function of a tumor-suppressor gene
b. an inherited disorder that disables normal glucose transport
c. a mutation that prevents effective lactation
d. an epigenetic methylation that increases cancer risk after exposure to manmade carcinogens

Answer 7

a

Question 8

What is “apoptosis”
a. it describes the process in which mammary cells normally die as they age or develop a defect
b. it describes the mechanism in which testosterone inhibits teat formation in male mice
c. it separates the front quarters from rear quarters of the mammary gland of the cow
d. it defines the joining of two blood vessels

Answer 8

a

Question 9

Some environmental compounds permanently alter the expression of genes not by changing the arrangement of the DNA nucleotides but by adding methyl or acetyl groups. This is known as:
a. genetics b. pseudogenetics c.epigenetics d. fake genetics

Answer 9

c

Question 10

This feeding program increases the future milk production of a dairy heifer calf.
a. feeding more milk per day than the traditional milk replacer programs that usually limit growth rates
b. feeding less milk to slow down growth
c. feeding a milk replacer that is all protein and has no fat
d. none of these would improve milk production

Answer 10

a

Question 11

T F One clue about mammary gland origins is that the monotremes (like platypus) essentially sweat milk onto hairs on patches of their bellies.

Answer 11

T

Question 12

T F Normal cells can use multiple substrates to produce ATP, but tumor cells rely almost exclusively on glucose.

Answer 12

T

Question 13

T F A basic characteristic of tumor cells is uncontrolled and relentless cell proliferation with the new cells having no beneficial functions—they just like to proliferate.

Answer 13

T

Question 14

T F Based on molecular markers, heat stress in utero should cause drops in milk production later in life; however, there is no practical production data to support this. (In other words, the experiments show no difference in milk production of cows whose mothers were cooled versus heat stressed during pregnancy).

Answer 14

F

Question 15

Why might feeding a high energy diet to heifers between weaning and puberty decrease mammary development? Choose two.
a. High energy diets fed to dairy heifers increases fattening, which may inhibit mammary development
b. High energy diets hasten the timing of puberty so shorten the time for allometric mammary growth
c. High energy diets decrease blood progesterone concentrations and therefore increase differentiation
d. High energy diets decrease blood concentrations of leptin, which is needed for proper mammary development

Answer 15

a and b

Question 16

Which of the following are true regarding the physiology of breast tumors compared to normal mammary tissue.
a. Tumor cells proliferate, but after puberty, normal mammary epithelial cells do not.
b. Normal mammary epithelial cells may undergo apoptosis at some point, but tumor cells usually do not.
c. Estrogen only stimulates proliferation in normal mammary tissue.
d. Tumors can recruit more blood supply, but normal body tissues do not.

Answer 16

b

Question 17

Which of these are FALSE when comparing general chemotherapy and targeted therapy approaches?
a. Chemotherapy interferes with cell division throughout the body and thus has more negative side effects
b. If chemotherapy does not work, the oncologist will recommend trying one of the newer untested targeted therapies
c. If the cancer cells are estrogen receptor positive, then blocking estrogen synthesis or actions is warranted
d. If the cancer cells are HER-2 positive, then an antibody that helps kill cells expressing the HER-2 protein is warranted.

Answer 17

b

Question 18

This process is the creation of new blood vessels in a tissue. It is a critical part of cancer because tumors can produce signals such as Vascular Endothelial Growth Factor (VEGF) to increase blood supply.

Answer 18

Angiogenesis

Question 19

Some environmental compounds permanently alter the expression of genes not by changing the arrangement of the DNA nucleotides but by adding methyl or acetyl groups. What is the name of this phenomenon? (hint: starts with an “e”)

Answer 19

Epigenetics

Question 20

What is the name of the phenomenon that describe the spread of cancer cells to other tissues in the body? (hint: starts with “m” and is 10-letters)

Answer 20

Metastasis

Question 21

The first allometric growth phase of mammary development starts soon after birth. An increase in the concentration of this hormone is key to ending it.

Answer 21

Progesterone

Question 22

Lactation can decrease the incidence of breast cancer later in life. How can you explain this? (at the level of mammary physiology)

Answer 22

Involution follows lactation; useless pre-tumor cells are likely removed with old cells.

Question 23

The primary sugar of milk: a. lactose b. glucose c. galactose d. ribose e. cellulose

Answer 23

a

Question 24

Which of the following occurs in the Golgi bodies of mammary epithelial cells in a lactating cow? a. lactose synthesis b. fatty acid synthesis c. ATP production d. casein synthesis from mRNA

Answer 24

a

Question 25

Casein is secreted by which mode?a. holocrine b. apocrine c. merocrine d. protocrine

Answer 25

c

Question 26

This fatty acid is polyunsaturated; it has more than 1 double bond and can only come from blood) a. Palmitic b. Linoleic d. Oleic e. Butyric

Answer 26

b

Question 27

This fatty acid is often the first fatty acid in a triglyceride for cows milk and it helps keep the milk fat fluid at body temperature.
a. Palmitic b. Linoleic d. Oleic e. Butyric

Answer 27

e

Question 28

This fatty acid is monounsaturated and can be synthesized in the gland if necessary to help keep milk fat fluid at body temperature. a. Palmitic b. Linoleic d. Oleic e. Butyric

Answer 28

d

Question 29

Some of this fatty acid found in milk fat comes directly from blood and some is synthesized from acetyl-CoA in the mammary epithelial cells. a. Palmitic b. Linoleic d. Oleic e. Butyric

Answer 29

a

Question 30

Which major milk protein coagulates to form cheese? Bovine milk has a lot of it, human milk does not. a. Lactose b. Lactein c. Rennin d. Alpha lactalbumin e. None of these

Answer 30

e

Question 31

Which of these sows will eat the most food calories per day? The diet is the same in every case and is high in starch. a. Sow fed ad libitum and nursing 12 piglets
b. Sow fed at restricted intake and nursing 12 piglets
c. Sow fed ad libitum and nursing 6 piglets
d. Sow fed at restricted intake and nursing 6 piglets

Answer 31

a

Question 32

Which of these sows will produce the most milk per day? The diet is the same in every case and is high in starch. a. Sow fed ad libitum and nursing 12 piglets
b. Sow fed at restricted intake and nursing 12 piglets
c. Sow fed ad libitum and nursing 6 piglets
d. Sow fed at restricted intake and nursing 6 piglets

Answer 32

a

Question 33

For which of these sows, will body tissue gain be the highest per day. The diet is the same in every case and is high in starch.
a. Sow fed ad libitum and nursing 12 piglets
b. Sow fed at restricted intake and nursing 12 piglets
c. Sow fed ad libitum and nursing 6 piglets
d. Sow fed at restricted intake and nursing 6 piglets

Answer 33

c

Question 34

Even though the amino acid leucine is not generally considered to be limiting for milk protein synthesis, studies show that leucine may actually increase milk synthesis. Why?
a. leucine can be converted to lysine in mammary epithelial cells
b. leucine is interchangeable with isoleucine which is sometimes limiting
c. leucine may stimulate the protein synthetic machinery
d. leucine is converted to lactose, the osmotic regulator of total milk production

Answer 34

c

Question 35

What blood compound is the precursor for most milk fatty acid carbons that are synthesized de novo in the mammary gland of a ruminant?

Answer 35

Acetate or Acetic acid

Question 36

What is the protein subunit of lactose synthase that makes galactosyl transferase specific for making lactose. It is also one of the major whey proteins found in milk?

Answer 36

alpha-lactalbumin

Question 37

Name a hormone that partitions nutrients toward milk and away from adipose tissue.

Answer 37

somatotropin, growth hormone, or prolactin

Question 38

What hormone is increased by a high starch diet in ruminants and, in turn, increases body fat storage more than it increases milk production partly because the glucose transporters of adipose tissue are sensitive to it, but the glucose transporters of mammary cells are not?

Answer 38

insulin

Question 39

The National Zoo wants to know the composition of panda milk so that they can develop a milk substitute in case the mother rejects her baby. A milk sample is collected once per day over a week by tranquilizing mom and giving her oxytocin to cause milk ejection. The concentration of protein and lactose are consistent but the concentration of fat bounces considerably. Why might the fat concentration change so much from day to day?

Answer 39

fat globules can be trapped in the alveoli causing milk fat concentration to fluctuate

Question 40

What is the name of the process in which mRNA is used to make a chain of amino acids?

Answer 40

translation

Question 41

The concentration of protein in cow’s milk is relatively constant. Why?

Answer 41

lactose synthesis depends on alpha-lactalbumin. Lactose draws water. More protein means more lactose and water. concentration stays constant.

Question 42

A polar bear in early lactation nurses her cubs while still hibernating (and not eating). Her milk has lots of fat and very little lactose. Why is this milk composition a good metabolic strategy?

Answer 42

Mother has fat readily available and would need to use energy to make lactose.

Question 43

Many mammals, including seals, cats, and dogs, store up body calories during pregnancy so that they can use them to support lactation.

True
False

Answer 43

False - Seals and cats store calories but dogs do not.

Question 44

Genomic selection for a trait like milk fat production in Holsteins works because one gene (DGAT) has a major impact on milk fat; unfortunately, most traits are controlled by lots of genes, so genomic selection does not work for them.

True
False

Answer 44

False - Genomic selection works even when traits are controlled by lots of genes; this is true for milk production, body weight, and body conformation. The fact that one gene has a major impact on milk fat composition of Holsteins is why we have made really fast progress on milk fat in the past ten years.

Question 45

Which mammal has the following milk composition: % lactose = 7
% protein = 1.1
% fat = 4.2
% of fatty acids with 14 or less carbons = 8
% fatty acids with 18 or more carbons = 60
ME density = 0.7
% calories from protein = 7

Answer 45

Human in mid lactation

Question 46

Which mammal has the following milk composition: % lactose = 4.8
% protein = 5.8
% fat = 8.2
% of fatty acids with 14 or less carbons = 3
% fatty acids with 18 or more carbons = 63
ME density = 1.2
% calories from protein = 22

Answer 46

A pig eating a high starch diet in early lactation

Question 47

Which mammal has the following milk composition: % lactose = 4.9
% protein = 3.1
% fat = 3.8
% of fatty acids with 14 or less carbons = 40
% fatty acids with 18 or more carbons = 60
ME density = 0.7
% calories from protein = 21

Answer 47

A cow in mid lactation

Question 48

Which mammal has the following milk composition: % lactose = 1
% protein = 5
% fat = 60
% of fatty acids with 14 or less carbons = 4
% fatty acids with 18 or more carbons = 80
ME density = 5.7
% calories from protein = 4

Answer 48

A hooded seal in early lactation

Question 49

Which of the following is most likely to limit the milk production of dairy cows in the future?

a. the activity of the DGAT gene

b. the ability of the cow to eat enough to meet her nutrient needs

c. the ability of the cow to mobilize body reserves to support lactation

d. the ability of the farm to collect all the milk the gland can produce

Answer 49

b

Question 50

Usually, when suckling has ceased for 5 days, the mammary gland begins to involute and milk synthesis stops. Which animal can continue to synthesize milk while not nursing for >10 days.

a. polar bear

b. Himalayan cat

c. blue whale

d. fur seal

Answer 50

d

Question 51

For lactating mammals that nurse while fasting, which of the following groups of fatty acids would you expect their milk to be enriched in?

a. C4 to 14 FA

b. C16 FA

c. C18 FA

d. The milk FA content will be the same whether fasting or fed.

Answer 51

c

Question 52

For lactating mammals that eat diets low in fat and high in fiber and have fermentation compartments to digest the fiber, which of the following groups of fatty acids would you expect their milk to be enriched in?

a. C4 to 14 FA

b. C16 FA

c. C18 FA

d. The milk FA content will be the same whether fasting or fed.

Answer 52

a

Question 53

In general, as dairy animals produce more milk per day, they also:

a. produce more milk per unit of food

b. produce more milk per acre of crops

c. produce less methane per unit of milk

d. enable more people to be fed per unit of land

e. all of these

Answer 53

e

Question 53

An elephant’s milk is about 5% fat, 4% protein, and 5% lactose. How much milk must its baby consume to grow 1200 g per day—it will require 7000 kcal of ME per day to grow this fast. ME values for fat, protein, and lactose are 9.0, 4.6, and 4.0 kcal/g.

Answer 53

• Calculate energy for 100 g of milk: 5 g fat x 9 kcal/g fat + 4 g protein x 4.6 kcal/g protein + 5 g lactose x 4 kcal/g lactose = 83 kcal ME/100 g milk
• Calculate milk needed per day: 7000 kcal ME x (100 g milk / 83 kcal ME) = 8400 g milk /d or 8.4 kg.

Question 53

Examine the table. Explain why the cow with high genetic merit has a greater response to being milked more times per day than the cow with low genetic merit. 30 words max.

                                            Milk production :                     2X per day         4X per day 
                                        Low genetic merit cow             25 kg/d               27 kg/d

                                         High genetic merit cow            50 kg/d               58 kg/d

Answer 53

Milk synthesis stops when the alveoli are full. This happens for high cow milked 2X. Milking 4X lets her produce more. Low cow is not limited by milk removal

Question 53

Beef cattle and horses eat similar diets (high in fiber), both usually have single births and similar lactation lengths, and their offspring grow at similar rates. Compared to bovine milk, equine milk contains the same amount of protein per unit energy, but has considerably less fat and more lactose. Why does this seem reasonable? Consider digestion and metabolism of the mom and the nursing behavior of the offspring.

Answer 53

• Cow’s diet is low in fat and carbs convert to acetate; glucose must be made in liver, little for lactose production. Milk stays unabsorbed in foal’s stomach longer, causing less spikes in glucose absorption and insulin – longer time between nursing bouts.
• mares digest and absorb starch and sugar in hindgut; low fat diet encourages production of lactose rather than fat; foal nurses frequently to prevent overconsumption of lactose at one time. Milk content is digested and absorbed quickly.

Question 53

Your parakeet’s cage was ripped open and he is missing. You suspect it is your neighbor’s cat, which you know is nursing kittens. The only clue is a drop of milk, which you had analyzed. It is 3.0% lactose. 11% protein, and 11% fat, so looks like cat milk. You know they feed her lots of canned catfood high in oily fish. What else could you test in the milk to help prove she is the guilty party? 30 words max. (In reality, you could probably not make these measures with 1 drop of milk, but for this question, assume you can).

Answer 53

Measure fatty acid profile. If it is high in long chain omega-3 FA, it was from a cat eating oily fish! (21 words)