FL 6 - Bio/Biochem

Question 1

At a pH below their pI, proteins carry a net (positive/negative) charge; above their pI they carry a net (positive/negative) charge.

Answer 1

At a pH below their pI, proteins carry a net positive charge

At a pH above their pI they carry a net negative charge.

Question 2

Why is it useful to use 3 pKa values when finding the isoelectric point?

Answer 2

IT IS NEVER USEFUL.

Isoelectric point will always be found by averaging only 2 pKa value. For an uncharged amino acid, it is simply the average of the amino group and carboxy group.

for acidic amino acids, the pI is the average of the two lowest pK_a values; for basic amino acids, the pI is the average of the two highest pK_a values. Be careful to avoid averaging all three values given; the pI is always the average of two, not three, pK_a values.

Question 3

A single nucleotide substitution that codes for an altered protein product without also altering the length of the protein is likely a ________ mutation.

Answer 3

A single nucleotide substitution that codes for an altered protein product without also altering the length of the protein is likely a missense mutation.

Question 4

This mutation type almost always results in a radically different protein product. A ______ mutation involves insertion of a premature stop codon. Such a change would almost certainly shorten the length of the translated protein.

Answer 4

This mutation type almost always results in a radically different protein product. A nonsense mutation involves insertion of a premature stop codon. Such a change would almost certainly shorten the length of the translated protein.

Question 5

_______ mutations do not alter the function of the protein produced because of the degeneracy of the genetic code.

Answer 5

Silent mutations do not alter the function of the protein produced because of the degeneracy of the genetic code.

Question 6

__________ are responsible for the myelination of axons in the peripheral nervous system.

Answer 6

Schwann cells are responsible for the myelination of axons in the peripheral nervous system.

Question 7

While _________ are indeed responsible for the myelination of neurons (corresponding to faster signal transduction), these are only responsible for myelination of neurons from the central nervous system

Answer 7

While oligodendrocytes are indeed responsible for the myelination of neurons (corresponding to faster signal transduction), these are only responsible for myelination of neurons from the central nervous system

Question 8

Interneurons connect motor and sensory neurons, and are found exclusively in the _______ nervous system.

Answer 8

Interneurons connect motor and sensory neurons, and are found exclusively in the central nervous system.

Question 9

________ primarily play a role in the immune system and defense of neuronal cells in the central nervous system.

Answer 9

Microglia primarily play a role in the immune system and defense of neuronal cells in the central nervous system.

Question 10

_________ is an amino acid neurotransmitter, which necessarily utilizes cell surface receptors that are integrated into the plasma membrane.

Answer 10

Glutamate is an amino acid neurotransmitter, which necessarily utilizes cell surface receptors that are integrated into the plasma membrane.

Question 11

A higher K_d is (more/less) likely to dissociate

Answer 11

A higher K_d is more likely to dissociate

Question 12

Answer 12

Question 13

What is a vertical pattern of inheritance?

Answer 13

Vertical patterns of inheritance are typical in dominant traits where the phenotype is very likely to show up in every generation. A vertical pattern of inheritance for a recessive trait is possible if the trait is extremely common in the population.

Question 14

The GI system develops from the ________ layer

Answer 14

The GI system develops from the endodermal layer.

The endoderm is basically responsible for the interior linings of the body, including the linings of the gastrointestinal system, the pancreas and part of the liver, the urinary bladder and part of the urethra, and the lungs.

Question 15

What is the term for the primitive gut (the cavity in the gastrula)?

Answer 15

Archenteron

Question 16

What is the archenteron?

Answer 16

The archenteron is the primitive gut (the cavity in the gastrula)

Question 17

True or False:

Antigen presentation is a function of macrophages.

Answer 17

True. Antigen presentation is a function of macrophages.

Question 18

True or False:

Cytokine release is not a function of macrophages.

Answer 18

FALSE.

Cytokine release IS a function of macrophages.

Question 19

True or False:

Opsonization is a function of macrophages

Answer 19

False.

Opsonization is the process by which antibodies bind to and recognize antigens on the surface of a pathogen. The antibodies then attract macrophages to phagocytose the invader.

Question 20

Diabetes mellitus results from the dysregulation of insulin. Type ___ diabetes is caused by an autoimmune attack on the pancreatic beta cells, which produce insulin. Type ___ diabetes results from a more gradual breakdown of the degree to which target cells respond to insulin signaling. This loss of responsiveness is termed insulin insensitivity. Individuals with type __ diabetes are dependent upon the administration of exogenous insulin, because they no longer produce the hormone in sufficient quantity to properly regulate blood glucose levels. Patients with type __ diabetes are generally initially treated with dietary modifications and/or anti-hyperglycemic medications, but they may eventually require insulin treatment as well.

Answer 20

Diabetes mellitus results from the dysregulation of insulin. Type 1 diabetes is caused by an autoimmune attack on the pancreatic beta cells, which produce insulin. Type 2 diabetes results from a more gradual breakdown of the degree to which target cells respond to insulin signaling. This loss of responsiveness is termed insulin insensitivity. Individuals with type 1 diabetes are dependent upon the administration of exogenous insulin, because they no longer produce the hormone in sufficient quantity to properly regulate blood glucose levels. Patients with type 2 diabetes are generally initially treated with dietary modifications and/or anti-hyperglycemic medications, but they may eventually require insulin treatment as well.

Question 21

A person with increased levels of insulin most likely has a decreased level of _________

Answer 21

A person with increased levels of insulin most likely has a decreased level of blood glucose

Question 22

This question asks us to determine what best explains the effectiveness of bile in lipid digestion. We know that bile works to form micelles and is able to do this because it has both ________ and _________ portions. This is what “__________” means.

Answer 22

This question asks us to determine what best explains the effectiveness of bile in lipid digestion. We know that bile works to form micelles and is able to do this because it has both hydrophobic and hydrophilic portions. This is what “amphipathic” means.

Question 23

Lack of bile acids could lead to deficiency in which of the following?

1. Cholesterol
2. Glucose
3. Vitamin K
4. Glycine

Answer 23

This question is asking us to determine which of the four options is fat-soluble˜ and thus will be taken up from the small intestine with the help of bile. We should know that vitamin K is a fat-soluble vitamin (as are A, D, and E) and thus its absorption depends on fat’s absorption from the small intestine.

Question 24

In the plasma membrane, cholesterol increases fluidity at _____ temperatures and reduces fluidity at _____ temperatures, in both cases by moderating the tendency of phospholipids to clump together (at ____ temperatures) or to diffuse through the membrane (at ____ temperatures).

Answer 24

In the plasma membrane, cholesterol increases fluidity at low temperatures and reduces fluidity at high temperatures, in both cases by moderating the tendency of phospholipids to clump together (at low temperatures) or to diffuse through the membrane (at high temperatures).

Question 25

Another important cholesterol derivative is vitamin __, which functions in calcium absorption and bone growth.

Answer 25

Another important cholesterol derivative is vitamin D, which functions in calcium absorption and bone growth.

Question 26

Where in a eukaryotic cell would you be most likely to find the highest concentration of lipid peroxides?

Answer 26

The Inner Mitochondrial Membrane.

Lipid peroxides are formed by free-radical attack on a lipid. Thus, we expect the location with the most lipid peroxidation to be someplace where oxygen is participating in a redox reaction. As it so happens, the electron transport chain, which is located on the inner mitochondrial membrane, has oxygen as its terminal electron acceptor.

Question 27

True or False:

Supercoiling is important for DNA packaging within all cells - it reduces the space and allows for more DNA to be packaged.

Answer 27

True.

Supercoiling is important for DNA packaging within all cells - it reduces the space and allows for more DNA to be packaged.

Question 28

True or False:

Supercoiling is required for DNA and RNA synthesis

Answer 28

True.

Supercoiling is required for DNA and RNA synthesis. During transcription, RNA polymerase (RNAP) tracks the helical groove of DNA, overtwisting DNA downstream and undertwisting DNA upstream.

Question 29

DNA is normally ________ supercoiled. This is naturally prevalent, because it prepares the molecule for processes that require separation of the DNA strands.

Answer 29

DNA is normally negatively supercoiled. This is naturally prevalent, because it prepares the molecule for processes that require separation of the DNA strands.

Question 30

In Drosophila, the white allele for eye color is a recessive mutation on chromosome X. Affected Drosophila exhibit white eyes, while wild-type Drosophila have red eyes. If a white-eyed female Drosophila is crossed with a wild-type male Drosophila, what percent of their female offspring will have white eyes?

Answer 30

0

If a wild-type allele for white eye is designated as ‘X’ and the mutated allele as ‘x’, the white-eye female is xx. The wild-type male is XY. A female offspring will receive a healthy X chromosome from the father and a mutated one from the mother.

However, because the trait is recessive and a female has two X chromosomes, none of the female offspring will be white-eyed. Notice that for male offspring, they will all be white-eyed, because they receive the mutated X from mother and a Y from father. Since the males have only one copy of the X chromosome, the trait will be expressed and all males will be white-eyed.

Question 31

What condition does trisomy 21 cause?

Answer 31

trisomy 21 causes Down syndrome

Question 32

What types of inhibitors are Drugs A and B?

Answer 32

Drug A is a non-competitive inhibitor, and Drug B is a competitive inhibitor.

A non-competitive inhibitor will not alter the Km of the associated reaction, but it will lower the v_max. This will result in the same x-intercept and an increased y-intercept on a Lineweaver-Burke plot.

A competitive inhibitor will yield the same v_max with a higher Km for the enzyme-catalyzed reaction, which will result in the same y-intercept and a decreased x-intercept on a Lineweaver-Burke plot.