Mcat Biological Sciences Review

Front 1

Which hormone or hormone class are found in the hypothalmus?

Back 1

Releasing and inhibiting factors (peptide-based) that act on the anterior pituitary to modify its functions

Front 2

Are is the function of the releasing/inhibiting peptide hormones secreted by the hypothalamus?

Back 2

To modify the activity of the anterior pituitary

Front 3

Which hormones are secreted from the anterior pituitary gland?

Back 3

Peptide Hormones:
Growth hormone (GH)
Prolactin
Thyroid Stimulating Hormone (TSH)
Adrenocorticotropic Hormone (ACTH)
Lutenizing Hormone (LH)
Follicle Stimulating Hormone (FSH)

Front 4

What is the origin and function of GH?

Back 4

Growth hormone is produced secreted from the anterior pituitary, and acts on bone and muscle to increase tissue growth and cell turnover rate.

Front 5

What is the origin and function of prolactin?

Back 5

Prolactin is produced and secreted from the anterior pituitary, and acts on the mammary gland to induce milk production.

Front 6

What are the tropic hormones, and from where are they secreted?

Back 6

Thyroid Stimulating Hormone (TSH)
Adrenocorticotropic Hormone (ACTH)

Secreted from the anterior pituitary

Front 7

What is the origin and the function of TSH?

Back 7

Thyroid stimulating hormone is secreted from the anterior pituitary acts on the thyroid to increase synthesis/release of thyroid hormone (TH)

Front 8

What is the origin and the function of ACTH?

Back 8

Adrenocorticotropic hormone is secreted from the anterior pituary acts on the adrenal cortex to increase growth and secretory activity

Front 9

What are the gonadotropic hormones, and from where are they secreted?

Back 9

Luteinizing hormone (LH)
Follicle Stimulating Hormone (FSH)

Secreted from the anterior pituary

Front 10

What is the origin and function of LH?

Back 10

Luteinizing hormone is secreted from the anterior pituitary and acts on the ovary to induce ovulation and the development of the corpus luteum or on the testes to induce testosterone synthesis and secretion.

Front 11

What is the net yield of ATP from glycolysis?

Back 11

2 ATP

Front 12

True or False: Oxygen is required directly for the Krebs Cycle

Back 12

False: Oxygen is required only indirectly through the replenishing of NAD+ and FAD via electron transport chain

Front 13

What is the direction of proton flow (and across which membrane) in the ETC?

Back 13

In the ETC protons are pumped out of the mitochondria matrix, across the inner mitochondrial membrane, and into the intermembrane space

Front 14

How many hydrogen bonds form between guanidine and cytosine?

Back 14

3

Front 15

How many hydrogen bonds form between adenosine and thymine?

Back 15

2

Front 16

Which is stronger, the G-C or A-T base pair and why?

Back 16

The G-C pair is stabilized by an additional hydrogen bond, making it more stable than the A-T bond.

Front 17

For which base pair does uracil substitute in RNA?

Back 17

Thymine

Front 18

Define: Nucleoside

Back 18

Ribose or deoxyribose sugar attached to a nitrogenous base (G,C,A,T,U)

Front 19

Define: Nucleotide

Back 19

-Nucleoside with phosphate groups
-Building block of nucleic acid polymers

Front 20

Define: Nucleosome

Back 20

-Level of DNA organization
-Double-stranded DNA wound about a histone octamer

Front 21

Which bases are pyrimidines, and how many rings are in their structure?

Back 21

C,U,T
Mono-cyclic

Front 22

Which bases are purines and how many bases are in their structure?

Back 22

A,G
Bi-cyclic

Front 23

Define: nonsense mutation

Back 23

Mutation in the nucleic acid sequence by insertion of a stop codon

Front 24

Define: conservative missense mutation

Back 24

Mutation at a single codon that changes the amino acid coded for in a way that does not alter protein function

Front 25

What is the distinction between (+)RNA and (-)RNA?

Back 25

Proteins are translated using the (+)RNA template. (-)RNA appears in viruses as genetic information.

Front 26

Define: endosomes

Back 26

Acidic, membrane-bound intracellular compartments

Front 27

Define: pleitropism

Back 27

The idea that a single gene may affect seemingly disparate systems (exhibited by altering the gene)

Front 28

What is the origin of EPO?

Back 28

Erythropoeitin (EPO) is produced and secreted by the kidneys, in response to low blood oxygen levels as detected in the peritubular capillaries. It is also produced in the liver. It acts on the bone marrow to increase production of red blood cells (erythrocytes).

Front 29

What is the function of EPO?

Back 29

Erythropoeitin (EPO) acts on bone marrow to increase production of erythrocytes (red blood cells) as a long-term response to low blood oxygen levels. It is produced and secreted by the kidneys and liver.

Front 30

What is the origin and function of calcitriol?

Back 30

Calcitriol is formed in the kidneys from calicidiol (a vitamin-D3 derivative formed in the liver) whose ultimate effect is an increase in systemic [usable Ca].

-@Bones: May stimulate osteoclasts, but this is a minor function
-@Kidney: Increased reabsorption of phosphorus
-@GI tract: Increased intestinal absorption of Ca2+ and phosphate

Front 31

What is the pKa of an alkane hydrogen?

Back 31

~50

Front 32

What is the pKa of an alkene hydrogen?

Back 32

~35

Front 33

What is the pKa of an alkyne hydrogen?

Back 33

~25

Front 34

Rank the pKa's (ascending) of hydrocarbons in terms of the degree of saturation of the bond:

Back 34

alkynes < alkenes < alkanes

At ~25, 35, and 50, respectively

Front 35

What is the pKa of an alcohol?

Back 35

~16

Front 36

What is the pKa of an H on an amine?

Back 36

~35

Front 37

What is the pKa of an H on an ammonium functional group?

Back 37

~10

Front 38

What is the pKa of the (alpha)-hydrogen on a ketone?

Back 38

~20

Front 39

What is the pKa of the alpha hydrogen on an aldehyde?

Back 39

~17

Front 40

What is the pKa of the alpha hydrogen on an ester?

Back 40

~25

Front 41

What is the pKa of a carboxylic acid?

Back 41

~5

Front 42

What is the pKa of water?

Back 42

~16

Front 43

How does stability of carbocations trend with degree of substitution?

Back 43

Tertiary > Secondary> Primary > Methane

Due to the induction-stabilization by electron-donating alkyl groups

Front 44

How does the stability of a radical trend with degree of substitution?

Back 44

Radicals have lost one electron, so need to be stabilized by charge donation, therefore:

Tertiary > secondary> primary> methyl

Front 45

How does the stability of a carbanion trend with degree of substitution?

Back 45

Carbanions are destabilized by an excess of electron density, so are de-stabilized by electron-donating alkyl groups, therefore:

methane > primary > secondary > tertiary

Front 46

Give the reactivity order of leaving groups (ascending)

Back 46

-NH2 < OH-< H2O< Cl-< Br-< I- < -OTos

Front 47

What is the relationship of nucleophilicity to electronegativity?

Back 47

Nucleophilicity decreases with increasing electronegativity

Front 48

How does nucleophilicity trend within a group?

Back 48

Nucleophilicity increases from top to bottom within a group due to increasing polarizeability

Front 49

In TLC, the stationary phase is _____, which is (polar/non-polar). Therefore, the mobile phase will be (polar/non-polar).

Back 49

silica gel
polar
non-polar

Front 50

How many RNA polymerases does a eukaryotic cell have? A prokaryotic cell?

Back 50

A eukaryotic cell has 3 RNA polymerases (I for rRNA, II for mRNA, and III for tRNA), whereas a prokaryotic cell has only one.

Front 51

How many DNA polymerases does a eukaryotic cell have? A prokaryotic cell?

Back 51

A eukaryotic cell has only one (DNA pol), whereas a prokaryotic cell has DNA pol I-III

Front 52

What is the function of DNA pol I, and in what cell type is it found?

Back 52

Prokaryotic cell: Functions as DNA pol III, except also has 5'->3' exonuclease activity

Front 53

What is the function of DNA pol II, and in what cell type is it found?

Back 53

Prokaryotic cell. Unknown function.

Front 54

What is the function of DNA pol III, and in what cell type is it found?

Back 54

Prokaryotic cell. Fast elongation (5'-->3'), and "proof-reading" exonuclease ability in the 3' --> 5' direction

Front 55

At a high pH, species in a solution are more likely to be _________ (protonated/deprotonated)?

Back 55

Deprotonated

Front 56

Below the isoelectric point of a given zwitterion, the species is more likely to carry a ________ (positive/negative) charge.

Back 56

Positive, because pH < isoelectric point => higher probability of protonation. More protonation => less negative/more positive charge.

Front 57

What is likely to be the nature of a reaction that occurs through the addition of KMnO4?

Back 57

An oxidation reaction