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Discrete MCAT Questions > Biology > Flashcards

Biology Flashcards

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MCAT flashcards
1
Q

Mitochondrial dna is

A

Circular, self replicating, and double stranded. Made of double stranded DNA that can replicate during binary fission.

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2
Q

What is the role of the smooth ER?

A

Lipid synthesis
Poison detoxification
Transport of proteins

Rough ER——> Smooth ER——> golgi

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3
Q

What is the nucleolus?

A

Dense structure within the nucleus where ribosomal RNA is synthesized

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4
Q

What organelle is surrounded by a single membrane?

A

Lysosomes

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5
Q

What organelles are surrounded by double membranes?

A

Mitochondria and nucleus

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6
Q

What are the ribosomal subunits of prokaryotes?

A

30s and 50s which add up to 70s

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7
Q

What are the ribosomal subunits of eukaryotes?

A

40s and 60s that add up to 80s

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8
Q

What contains tubulin?

A

Cilia, flagella and centrioles.

Microfilaments DO NOT contain tubulin

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9
Q

What are microfilaments composed of?

A

Actin

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10
Q

What occurs during the lytic cycle?

A

Virus DNA takes control of the body cells genetic machinery, manufacturing numerous progeny. In the end the host cell lyses and releases new virions, each capable of infecting new cells

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11
Q

What occurs during the lysogenic cycle?

A

Viral DNA is added to the host genome where it can remain dormant for days or years. Either spontaneously or as a result of the environment the provirus can re-emerge and enter the lytic cycle

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12
Q

What is the difference between positive and negative sense RNA?

A

Positive sense is like mRNA and can be directly translated into a protein

Negative sense RNA is complementary to mRNA and must be converted to positive sense RNA by an RNA polymerase before being transcribed

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13
Q

What is the correct sequence of the development of a mature sperm cell?

A

Spermatogonium-> primary spermatocyte—-> secondary spermatocyte—-> spermatid ——> spermatozoan

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14
Q

When are all egg cells arrested?

A

From time of birth until shortly after ovulation they are arrested at the prophase stage of meiosis 1.

They are called primary oocytes at this stage.

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15
Q

What does the egg cell complete at ovulation?

A

Completed meiosis 1 and is not arrested in metaphase 2 as a haploid cell called a secondary oocyte.

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16
Q

What does an egg complete when a sperm penetrates the outer layers?

A

When a sperm penetrates the outer layers of the secondary oocyte it completes meiosis 2 to become a mature ovum.

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17
Q

When do spindle apparatuses attach to the kinetochore fibers?

A

End of prophase.

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18
Q

What occurs during metaphase?

A

Second step of cell division, chromosomes are aligned at the equator of the cell

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19
Q

What happens during prophase?

A

Chromatin condenses, spindle microtubules grow and extend from each pole to the equator. Nuclear envelope disintegrates. Spindle fibers first touch kinetochores

Crossing over occurs in meiosis

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20
Q

What happens during anaphase?

A

Replicated chromosomes are split and moved to opposite ends of the cell. Shortening of the kinetochore microtubule. Increasing separation of poles

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21
Q

What happens during telophase?

A

Nuclear envelope reforming around individual chromosomes. Unraveling chromosomes. Increasing separation of poles.

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22
Q

G1 stage

A

Growth stage where cellular components excluding the chromosomes are duplicated

(Before S phase and after mitosis)

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23
Q

S phase

A

Each chromosome is duplicated

Occurs after G1 and before G2

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24
Q

G2 phase

A

The cell double checks the duplicated chromosomes for error and makes any repairs. Then begins mitosis again.
After S phase

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25
Q

What is estrogen known to cause?

A

Growth of the endometrial lining during the follicular phase of the menstrual cycle and its levels stay high in the luteal phase to promote vascularization and glandularization of this tissue.

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26
Q

Where is the oocyte released upon ovulation?

A

Into the abdominal cavity, close to the entrance of the fallopian tube.

Cilia beat to draw it into the fallopian tube. If it is fertilized in the fallopian tube it will implant in the uterine wall. If fertilization does not occur it will be expelled along with the uterine lining during menstruation

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27
Q

What are the seminal vesicles?

A

Produce alkaline fructose containing secretions

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28
Q

What is the epididymis?

A

Site of sperm maturation at the posterior side of the testis. Sperm gain motility here and are stored until ejaculation

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29
Q

What does the Vas deferens do?

A

Tube connecting the epididymis to the ejaculatory duct.

Surrounded by muscle that raises and losers the testis to maintain a constant temperature suitable for sperm production

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30
Q

What does Cowpers glands do?

A

Produce a fluid to clear traces if urine in the urethra

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31
Q

What is the last point in the meiotic cycle in which the cell has a diploid number of chromosomes?

A

Telophase 1

At the end of telophase 1, cytokinesis occurs resulting in two haploid (n) daughter cells.

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32
Q

During which phase of the menstrual cycle does progesterone concentration peak?

A

Luteal phase, as it supports the endometrium for potential implantation of a blastula.

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33
Q

When are progesterone levels relatively low?

A

Follicular stage and ovulation.

Withdrawal of progesterone causes menses.

34
Q

What is GnRH?

A

Gonadotropin releasing hormone

Responsible for the release of FSH and LH from the anterior pituitary.

35
Q

What hormone changes occur during pregnancy?

A

High levels of hCG in the first trimester
High levels of progesterone throughout the pregnancy
Low levels of FSH in the first trimester

36
Q

Resting membrane potential depends on

A

Differential distribution of ions across the axon membrane

Active transport of ions across the membrane

37
Q

Myelin sheath

A

Faster conduction of nerve impulses
Nodes of ranvier forming gaps along the axon
Saltatory conduction of action potentials (action potential jumping from node to node)

38
Q

Action potentials

A

All or nothing response. Once an action potential is triggered, an impulse of a given magnitude and speed is produced. Neuronal info is coded by the frequency and number of action potentials, not the size

39
Q

Nerves

A

Collections of neurons in the peripheral nervous System and may contain multiple types of information (sensory or motor); they contain cell bodies in ganglia

40
Q

Tracts

A

Collections of neurons in the central nervous system and contain only one type of information; they contain cell bodies in nuclei

41
Q

Sensory neurons

A

Considered afferent neurons ( carrying signals from peripheral to central nervous system) and enter the spinal cord on the dorsal side

42
Q

Motor neurons

A

Considered efferent (carrying signals from CNS to peripheral Ns) and exit spinal cord on the ventral side

43
Q

When a sensory neurons receives a stimulus that brings it to a threshold it will

A

Become depolarized
Transduce the stimulus to an action potential

Cause the release of neurotransmitters onto cells in the CNS

44
Q

Hyperpolarization

A

When the potential across the axon membrane is more negative than the normal resting potential
Caused by excess potassium editing the neuron

45
Q

Somatic division of the peripheral nervous system

A

Pathways innervate skeletal muscle
Pathways are usually voluntary
Some of its pathways are referred to as reflex arcs
Pathways of the somatic division can involve two,three or more neurons depending on the signal

46
Q

Parasympathetic nervous system

A

Governs rest and digest

Slows heart rate, decreases blood pressure, promotes blood flow to GI tract, constricts pupils

47
Q

Sympathetic nervous system

A

Governs fight or flight, including increased heart rate and blood pressure, decreased blood flow to digestive tract, increases blood flow to the muscles

48
Q

What neurotransmitter is used in the ganglia of both the sympathetic and parasympathetic NS?

A

Acetylcholine.
Released by preganglionic neuron in both the sympathetic and parasympathetic nervous systems.

The postganglionic neurons in the sympathetic Ns usually releases norepinephrine while the postganglionic neurons in the parasympathetic nervous system releases acetylcholine

49
Q

In which neural structure are ribosomes primarily located?

A

Soma.

The cell body contains the nucleus, er and ribosomes

50
Q

Voltage gated ion channels

A

When the nerve terminal depolarizers, voltage gated ion channels open allowing for influx of calcium. Triggers fusion of the synaptic vessels containing neurotransmitters with the membrane of the neuron at the nerve terminal. Allows for exocytosis if the neurotransmitters into the synapse. If a disease targets these channels then the neuron can’t transmit excitatory signals to the muscle. Flaccid paralysis results

51
Q

Summation

A

Some neurons require multiple instances of excitatory transmission to be brought to threshold. Multiple presynaptic cells have to release neurotransmitter into the dendrites of the neuron

52
Q

Schwann cells

A

Type of glial cells of the peripheral nervous system that help form the myelin sheath around the nerve fibers

53
Q

Peripheral nervous system

A

Includes the somatic and autonomic nervous system. Autonomic nervous system is composed of both the parasympathetic and sympathetic nervous systems

54
Q

Dorsal root ganglion

A

Contains cell bodies of sensory neurons only. If a dorsal root ganglion is disrupted at a certain level there will be loss of sensation at that level

55
Q

Aldosterone

A

Is a mineralcorticoid
Testosterone is a cortical sex hormone
Cortisone is a glucocorticoid and ADH is a peptide hormone produced by the hypothalamus and released by the posterior pituitary that promotes water absorption’s

56
Q

What hormone directly stimulates a target tissue that is not an endocrine organ

A

GH

Also known as a direct hormone.

57
Q

Direct hormones

A

Secreted by the anterior pituitary gland.

Prolactin, endorphins, and growth hormone

58
Q

Tropic hormones

A

Hormones of the anterior pituitary gland .

FSH, LH, adrenicorticitropic hormone (ACTH) and thyroid stimulating hormone (TSH)

59
Q

Increased synthetic activity of the parathyroid gland would lead to

A

And increase in renal calcium reabsorption.
Parathyroid gland secreted parathyroid hormone that functions to increase blood calcium levels.
The increased blood calcium levels is accomplished through increased calcium reabsorption in the kidneys, increases bone resorption and increases absorption of calcium from the gut via activation of vitamin D

60
Q

Acromegaly

A

Result of too much growth hormone as an adult. Enlargement of the small bones in the extremities and of certain facial bones such as the jaw

61
Q

Iodine deficiency may result in

A

Cretinism: poor neurological and physical development. Inflammation of the thyroid or iodine deficiency can cause hypothyroidism in which not enough thyroid hormone is secreted.

62
Q

Galactorrhea

A

Associated with prolactin

63
Q

What hormones are derived from cholesterol?

A

Aldosterone, estrogen and progesterone. All steroid hormones. Include the hormones of the adrenal cortex and gonads

64
Q

Somatostatin

A

Is always inhibitory
The stimuli for its release include high blood glucose or amino acids as well as certain gastrointestinal hormones
Leads to both increased insulin and glucagon secretion

65
Q

Beta cells

A

Responsible for insulin production in the pancreases.
Insulin lowers blood glucose levels by promoting influx of glucose into cells and by stimulating anabolic processes such as glycogenesis or fat and protein synthesis

66
Q

Adolsterone regulation

A

Renin converts the plasma protein angiostensin to angiostensin 1
Angiostensin 1 is converted to angiostensin 2 by angiostensin converting enzyme
Angiostensin 2 stimulates the adrenal cortex to secrete aldosterone.
Aldosterone helps to restore blood volume by increasing sodium reabsorption in the kidney leading to an increase in water reabsorption

67
Q

Calcitonin

A

Lowers blood calcium concentrations

68
Q

Parathyroid hormone

A

Increases blood calcium concentration

69
Q

Aldosterone

A

Main mineralcorticoid hormone.
Is a steroid hormones produced by the adrenal cortex in the adrenal gland.
Stimulates kidney to reabsorb sodium and water which increases blood volume

70
Q

Thymosin

A

Secreted by the thymus
Stimulates production of T cells which are apart of the immune system.

Also assists in the development of B cells to plasma cells to produce antibodies

71
Q

Oxytocin and ADH (antidiuretic hormone or vasopressin) are

A

Peptide hormones produced by the hypothalamus and released by the pituitary.

Remember the posterior pituitary does not synthesize any hormones itself.

72
Q

Prolactin

A

Dopamine secretion prevents prolactin release.

Prolactin is the hormone that tells the body to make breast milk

Production of prolactin occurs in the pituitary gland

73
Q

Hypothalamus hormones

A 
Vasopressin 
Oxytocin
Corticotropin releasing hormone
Gonadotropin releasing hormone
Somatostatin
Growth hormone releasing hormone 
Dopamine
Thyrotropin releasing hormone
74
Q

Thyroid hormones

A

Thyroxine (T4)
Triiodothyronine (T3)
Calcitonin

75
Q

Pineal gland hormones

A

Melatonin

76
Q

Anterior pituitary hormones

A 
Growth hormone 
Thyroid stimulating hormone
Adrenocorticotropic hormone
Follicle stimulating hormone
Luteinizing hormone
Prolactin
77
Q

Posterior pituitary

A

Oxytocin stored

Vasopressin (ADH) stored

78
Q

Intermediate pituitary hormones

A

Melanocyte stimulating hormone

79
Q

Hypothalamus function

A 
Hunger 
Thirst 
Body temp 
Sexual activity 
Arousal
Homeostasis 
Parenting 
Blood pressure
Heart rate
Circadian rythyms
Sleep
80
Q

Pituitary function

A

Growth
Blood pressure
Reproduction
Master gland

Discrete MCAT Questions (6 decks)

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