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bio and biochem notes: mcat > Test 4 Review > Flashcards

Test 4 Review Flashcards

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MCAT flashcards
1
Q

What is the function of TSH ?

A

TSH stimulates thyroid production

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2
Q

What is the function of thyroid hormone receptor ? What happens if receptor is deceptive (not working) ?

A

Thyroid hormone receptor is responsible for hormone signaling, including feedback inhibition by thyroid hormone.
If thyroid hormone receptor is defective, this will prevent feedback inhibition, causing TRH and TSH levels to become ELEVATED

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3
Q

What releases TRH (thyroid releasing hormone) ?

A

hypothalamus

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4
Q

What releases TSH (thyroid stimulating hormone) ?

A

Anterior Pituitary

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5
Q

What kind of hormones are T3 and T4 ? What kind of transport do they use?

A

T3 and T4 are peptide hormones, - they diffuse through the plasma membrane to bind to an intracellular receptor that goes into the nucleus to regulate transcription

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6
Q

What happens to cells that have not completed meiosis I yet?

A

They are DIPLOID

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7
Q

When are primary oocytes arrested?

A

prophase I

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8
Q

What is synapsis ?

A

When homologous chromosomes are brought together during meiosis I so that crossing over can occur

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9
Q

what is the pka of Histidine?

A

pka= 6.0

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10
Q

what happens when pH is less than pI?

A

when pH < pI, there is a net positive charge (Amino acid will be PROTONATED)

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11
Q

What is role of conjugation in bacteria ?

A

Conjugation will increase genetic diversity

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12
Q

What is role of binary fission in bacteria ?

A

binary fission is how bacteria reproduce and hence increase the population

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13
Q

What are three processes that can aid in speciation ?

A
  • geographic isolation
    -Genetic diversity
    -natural selection
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14
Q

What happens if Hardy-Weinberg theory is maintained?

A

If Hardy-Weinberg is maintained, then there can be NO changes in the allele frequencies in the gene pool of a population and NO evolution, which would not allow speciation

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15
Q

What are characteristics of enzymes?

A

. Enzymes lower the activation energy of reactions to speed them up Enzymes have great stereospecificity in the reactions they catalyze
-frequently regulated by feedback inhibition by products

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16
Q

What do enzymes NOT do?

A

they do NOT alter the potential energy of reactants and products or the reaction equilibrium,

( only the rate at which equilibrium is reached )

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17
Q

How do substances cross the placental barrier ?

A

the only way substances can cross the placental barrier is if they are LIPID SOLUBLE or if they are actively transported

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18
Q

What part of fetus has most oxygenated blood?

A

umbilical vein

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19
Q

What part of fetus has deoxygenated blood?

A

umbilical artery (carries deoxygenated blood from fetus to placenta)

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20
Q

What is the role of ductus arteriosus?

A

The purpose of the ductus arteriosus is to help shunt blood past the inactive fetal lung

21
Q

What kind of curve does hemoglobin have?

A

Hemoglobin binds oxygen cooperatively, and so has a SIGMOIDAL binding curve

22
Q

Which has higher oxygen affinity : fetal Hb or Maternal Hb?

A

Fetal hemoglobin must have a higher oxygen affinity than maternal hemoglobin to be able to bind oxygen at lower partial pressures than maternal hemoglobin

23
Q

What is the melting temperature ?

A

The melting temperature is the temperature at which half of the DNA strands are in the random coil or single-stranded state.

24
Q

what must happen to DNA strand if there is a lower melting temperature ?

A

In order to have a LOWER melting temperature, the oligonucleotide must contain FEWER GC nucleotides than the given oligonucleotide. This is because GC base pairing involves three hydrogen bonds while AT only involves two.

25
Q

What results in diarrhea ?

A

. When water is not reabsorbed from the large intestine

(can be caused by lack of digestion of fats and carbs and it will pass in large intestine)

26
Q

What must occur for hydrogen bonding?

A

In order for a hydrogen bond to form, H must be bonded to F, O, or N in one molecule to give it a partial positive charge.

27
Q

What is the function of aldosterone ?

A

.Aldosterone causes
- increased sodium reabsorption,
and because of rise in systemic Na+, there is a decreased water loss,
-increased extracellular fluid volume, increased blood pressure

28
Q

What kind of property is OSMOSITIC Pressure ?

A

COLLIGATIVE: which means it depends only on the concentration of solute particles, and NOT their identity.

29
Q

How does osmotic pressure move ?

A

Osmotic pressure will drive movement of water from the LOWER concentration solution to the higher concentration solution

30
Q

What happens in PDC cycle ?

A

PDC Cycle (pyruvate decarboxylase enzyme)
-Pyruvate is converted to Acetyl CoA in mitochondria matrix. (pyruvate is also decarboxylated)

31
Q

What happens if there is deficiency of PDC (pyruvate decarboxylase)? What could happen to body?

A

In PDC deficiency, the pyruvate cannot be converted to acetyl-CoA and therefore, the cells can only undergo glycolysis and anaerobic respiration. The end product of anaerobic respiration in humans is lactic acid.
Hence humans can experience lactic acidosis

32
Q

How does Gel Electrophoresis work?

A

Gel electrophoresis separates molecules based on SIZE.
Larger substances tend to stay closer to the top (near the wells) and smaller substances travel more towards the bottom of the gel.

33
Q

What is RT-PCR? What is used for?

A

RT-PCR uses reverse transcriptase to make cDNA from mRNA. The cDNA can then amplified, and then tested for.
This is the only method listed that can be used to test for the presence of mRNA and determine if transcription of the gene is occurring

34
Q

What are Buffered solutions? Give an example

A

Buffered solutions are commonly made with weak acids and their conjugate bases.
Ex: Carbonic acid (H2CO3-)
H2CO3 (aq) —-> H + (aq) + HCO3- (aq)

35
Q

What kind of enzyme is used for monounsaturated fatty acids for beta-oxidation

A

Monounsaturated fatty acids require an** isomerase enzyme* to move the double bond during β -oxidation

36
Q

What kind of enzyme is used for polyunsaturated fatty acids during Beta oxidation ?

A

Polyunsaturated fatty acids require both an isomerase and a reductase enzyme to complete β -oxidation; this also requires the reducing agent NADPH

37
Q

What occurs within sarcomere during contraction ?

A

During contraction, the overlap between actin and myosin make the sarcomere Shorter.

(neither myosin nor actin filaments individually get shorter)

38
Q

What does amphoteric property of amino acid describe?

A

The amphoteric character of amino acids describes their ability to:
1. accept a proton or donate a proton. In other words, amino acids can act as either an acid or a base.
2. When the amino portion of an amino acid deprotonates its own carboxylic acid, a DIPOLAR ION (or zwitterion) forms. This is a direct result of the amphoteric character of the amino acid.

39
Q

What process follows Fertilization (sperm and ovum fusing together) ?

A

Ova releases second polar body from fertilized ova (occurs during 2nd Meitotic cell division)

40
Q

What is Zona pellucida?

A

a Protective acellular layer located just outside the plasma membrane in the ovum

41
Q

Where are secretory pathways usually located ?

A

Rough Endoplasmic reticulum

42
Q

What are the steps for infection of E.Coli by phage T1 (virus)

A
  1. the expression of the viral DNA polymerase must come
  2. replicate the genome.
  3. Infectious virus can then be assembled
  4. then virus is released by cell lysis induced by viral lysozyme
43
Q

What is transformation (bacteria) ?

A

transformation is the process in which naked DNA, is taken into a cell and changes the genetic characteristics of that cell

44
Q

What is conjugation ?

A

conjugation involves direct transfer of DNA between bacteria

45
Q

How many isoprene units does a diterpenoid have?

A

FOUR isoprene units

46
Q

What are the characteristics of blood brain barrier ?

A

The blood-brain barrier is a highly selective permeability barrier that separates the circulating blood from the central nervous system.
-It is formed by endothelial cells which are connected by tight junctions

47
Q

What is a hallmark of apoptosis ?

A

Genome fragmentation is one of the hallmarks of apoptosis

48
Q

What do tumor cells have a high rate of ?

A

Tumor cells have high PROLIFERATION rates and so will be actively replicating the genome.

49
Q

What are characteristics of Krebs cycle? Where do most of energy produced during cycle come from?

A

oxaloacetate is combined with acetyl-CoA to form citrate
- most of the energy is produced from the production of high-energy electron carriers (NADH and FADH2). -Approximately 18 of the 20 ATP that are associated with Krebs are from these high-energy electron carriers (after they are oxidized in the electron transport chain).
-six NADH, two FADH2, and two GTP are produced in the Krebs cycle per glucose.

bio and biochem notes: mcat (14 decks)

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