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MCAT > Biology > Flashcards

Biology Flashcards

1
Q

Prions

A

Infectious proteins - protein misfolding - alpha to beta reduces solubility

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2
Q

Viroids

A

Short ssRNA that infect plants - silence RNA genes - prevents synthesis of proteins

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3
Q

Viruses with envelopes vs without

A 
Envelopes = easy to kill
No = difficult to kill
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4
Q

Virus replication

A

Can’t replicate independently because don’t have ribosomes

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5
Q

How do retroviruses synthesize DNA?

A

Reverse transcriptase

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6
Q

How is viral progeny released?

A
  1. Apoptosis
  2. Lysis
  3. Fusion with pals a membrane
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7
Q

Classifications of bacteria (shape)

A
  1. Cocci
  2. Bacilli
  3. Spirilla
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8
Q

Asexual reproduction of prokaryotes

A

Binary fission

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9
Q

Bacterial genetic recombination

A
  1. Transformation - foreign DNA in host genome
  2. Conjugation - bacterial form of mating
  3. Transduction - requires a host, ie bacteriophage
  4. Transposons - capable of inserting and removing themselves
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10
Q

Bacterial growth

A

Lag phase > exponential phase > stationary phase > death phase

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11
Q

Stages of Interphase

A

G1
S
G2

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12
Q

G1

A

Cells create fuel and increase in size

Also restriction point for S phase

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13
Q

S phase

A

Replicates genetic material - chromatids

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14
Q

G2

A

Twice as much DNA as G1

Another checkpoint

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15
Q

M phase

A

Prophase, metaphase, anaphase, and telophase

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16
Q

What molecules are responsible for cell cycle?

A

Cyklins > CDK > cyklin-CDK complex > (phosphate) > phosphorylated TFs > transcription

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17
Q

Where does mitosis occur?

A

Somatic cells or cells not involved in sexual reproduction

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18
Q

What types of cells do animals have? Germ cells?

A

Diploid

Haploid

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19
Q

Prophase

A

Chromatin > chromosomes

Spindles go to opposite poles

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20
Q

Metaphase

A

Kinetochores align chromosomes along metaphase plate

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21
Q

Anaphase

A

Centromeres split sister chromatids

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22
Q

Telophase and cytokinesis

A

Opposite of prophase - reappearance of nuclear membrane

Separation of daughter cells

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23
Q

Where does mitosis happen? Product?

A

Gametocytes (germ cells)

4 nonidentical gametes (sex cells)

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24
Q

Meiosis 1

A

Prophase 1 - 2 homologous chromosomes > tetrad connected at chiasma > crossing over > recombinant chromosomes
Metaphase 1 - metaphase plate alignment of tetrads
Anaphase 1 - chromosomes separated from tetrad - disjunction
Telophase 1 - 2 haploid cells with one homologous chromosome

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25
Q

Meiosis 2

A

Prophase 2 - nuclear envelope disappears, nucleoli disappear, centrioles migrate
Metaphase 2 - metaphase plate
Anaphase 2 - split into sister chromatids
Telophase 2 - 4 haploid daughter cells

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26
Q

How is biological sex determined?

A

23rd chromosome

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27
Q

Sex linked is X linked

A

Men will most likely display sex linked disorders while females can be heterozygous or homozygous cause they have 2 Xs

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28
Q

How many sperm per spermatogenesis?

A

4

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29
Q

What does the mid piece of sperm contain and why?

A

Mitochondria for energy to swim

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30
Q

What hormones do the ovaries produce?

A

Estrogen and progesterone

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31
Q

Oogenesis

A

Production of female gametes

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32
Q

Where are primary oocytes suspended and until when? Secondary oocytes?

A

Prophase 1 until first menses

Metaphase 2 until fertilization

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33
Q

How is sexual development restricted before puberty?

A

Hypothalamus is prevented from producing GnRH, but once produced will activate anterior pituitary that produces FSH and LH

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34
Q

FSH and LH in males

A

FSH - sperm

LH - testosterone

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35
Q

FSH and LH in females

A

FSH - estrogen

LH - progesterone

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36
Q

What happens during female reproductive years?

A

Estrogen and progesterone levels rise and fall, which causes the endometrial lining to grow and shed

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37
Q

Stages of the mistrial cycle

A
  1. Follicular - low FSH and LH stimulate increase GnRH increasing these, develop follicles, produce estrogen, negative feedback on hormones
  2. Ovulation - estrogen causes flux in hormones, but increased LH causes ovulation
  3. Luteal - increased LH so increased progesterone
  4. Menstruation - decrease estrogen and progesterone
  5. Pregnancy - increased hCG
  6. Menopause - no longer sensitive to FSH and LH
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38
Q

Blastulation

A

Morula forms blastula - hollow ball of cells

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39
Q

Gastrulation

A

Generation of 3 distinct cell layers

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40
Q

What does the archenteron form? Blastopore? Ectoderm? Mesoderm? Endoderm?

A

Gut
Anus (human) or mouth
External layer: Epidermis, hair, nails, epithelia, nervous system, adrenal medulla, pituitary gland
Middle layer: Musculoskeletal, circulatory, and excretory systems, adrenal cortex
Internal layer: Epithelial linings of tracts, pancreas, liver, thyroid, lung, bladder, urethra

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41
Q

How does differentiation occur? How is it mediated?

A

Selective transcription

Inducers, is growth factors

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42
Q

Neurulation

A

Development of the nervous system

43
Q

What does the notochord become? Neural tube? Neural crest cells?

A

Spine
Nervous system
Peripheral NS

44
Q

Teratogens

A

Interfere with development

45
Q

Potency of cells

A

Totipotent
Pluripotent
Multipotent

46
Q

Morphogens

A

Cause differentiation of cells

47
Q

Regeneration capacity

What do humans usually show?

A

Complete vs incomplete (humans)

48
Q

Senescence

A

Biological aging

49
Q

Astrocytes

A

Nourish neurons and form blood-brain barrier

50
Q

Ependymal cells

A

Line ventricles of brain and produce cerebrospinal fluid

51
Q

Microglia

A

Phagocytic cells in CNS

52
Q

Oligodendrocytes (CNS) and Schwann cells (PNS)

A

Produce myelin around axons

53
Q

What are the 4 divisions of the spinal cord?

A

Cervical, thoracic, lumbar, and sacral

54
Q

Peptide hormones

A 
Second messenger systems
Short lived 
Rapid
Water soluble
Can’t pass membrane
55
Q

Steroid hormones

A 
Derived from cholesterol
Produced from gonads and adrenal cortex
Can pass membrane cause no polar 
Not water soluble 
(End in -one, -ol, -oid)
56
Q

Amino acid derivative hormones

A

E and NE - fast, short lived
Thyroxine and triiodothyronine - longer, slower onset - regulate metabolic rate
(End in -in or -ine)

57
Q

Direct vs tropic hormones

A

Don’t need intermediary

Need intermediary, ie GnRH

58
Q

Tropic hormones of the hypothalamus to anterior pituitary

A

GnRH > FSH, LH
Growth hormone releasing hormone (GHRH) > growth hormone (GH)
Thyroid releasing hormone (TRH) > thyroid stimulating hormone (TSH)
Corticotropin releasing factor (CRF) > adrenocorticotropic hormone (ACTH)

59
Q

How is cortisol activated and mediated?

A

ACTH stimulates the adrenal cortex to produce cortisol, but cortisol will have a negative feedback effect on the anterior pituitary and hypothalamus

60
Q

What hormones are secreted by the posterior pituitary?

A

Oxytocin - contractions during labor and lactation

ADH - reabsorption of water in the kidneys

61
Q

Direct hormones of the anterior pituitary

A

Prolactin - milk production
Endorphins - decrease affects of pain
Growth hormone

62
Q

Two major functions of the thyroid

A
  1. Setting basal metabolic rate - mediated by T3 and T4

2. Calcium homeostasis - mediated by calcitonin

63
Q

Hypothyroidism

A

Iodine deficiency

Sx: lethargy, decreased body temp, slowed HR, and weigh gain

64
Q

Hyperthyroidism

A

Excess of TSH

Sx: tumor, heightened activity, increased body temp, increased HR, and weight loss

65
Q

Calcitonin

A

Tones down calcium levels by increased excretion by kidneys, decreased absorption by gut, and increased storage of calcium in bone

66
Q

Parathyroid hormone (PTH)

A

Opposite of calcitonin

Activates vitamin D

67
Q

Adrenal cortex hormones

A

Glucocorticoids - cortisol and cortisone - increase blood glucose - under control of ACTH
Mineralocorticoids - aldosterone - water and sodium reabsorption - controlled by renin
Cortical sex hormones - androgens and estrogens

68
Q

Adrenal medulla hormones

A

E and NE

69
Q

Pancreatic hormones

A

Glucagon - high when glucose is low - breakdown of fat and protein
Insulin - high when glucose is high
Somatostatin - inhibits glucagon and insulin

70
Q

Pineal gland

A

Melatonin

71
Q

Diaphragm

A 
Under somatic control
Divides thoracic (chest) cavity
72
Q

Inhalation

A

Diaphragm flattens, chest wall expands and pulls lungs
Volume increases so pressure decreases -> results in negative pressure breathing because atmospheric pressure (outside) is now higher

73
Q

What prevents the collapse of alveoli? How?

A

Surfactant by reducing surface tension

74
Q

Where is ventilation regulated? What neurons?

A

Medulla oblongata

Chemoreceptors - sensitive to CO2 lvls

75
Q

Where does gas exchange occur?

A

Capillaries bring deoxygenated blood to pulmonary arteries (right), pulmonary veins carry oxygenated blood (left)

76
Q

What is the driving force of gas exchange?

A

Pressure differential

77
Q

How is heat regulated?

A

Vasodilation (thermal energy dissipated) and vasoconstriction (thermal energy conserved)

78
Q

How to lungs fight off invaders?

A

Macrophages, antibodies, mast cells

79
Q

How do the lungs control pH?

A

Bicarbonate buffer system

  • increased H+ will increase CO2, increasing respiratory rate
  • decreased H+ will decrease CO2, decreasing respiratory rate
80
Q

What nerve slows down the heart?

A

Vagus nerve

81
Q

Equation for cardiac output

A

CO = HR x SV

82
Q

What does low BP and high BP release in relation to the CV system?

A

Low BP - aldosterone and ADH

High BP - ANP

83
Q

How are clots broken down?

A

Plasmin

84
Q

Antigen

A

RBC - surface proteins - target for immune system response (antibodies)

85
Q

Rh factor

A

Antigens - The + or - part of blood types

86
Q

What produces leukocytes

A

Bone marrow

87
Q

B cells vs T cells

A

Part of the adaptive immune system

B - turn into plasma cells that later become antibodies
T - cell-mediated immunity

88
Q

What do leukocytes become?

A

Granulocytes

Agranulocytes

89
Q

What is the complement system?

A

Proteins in the blood that act in a nonspecific defense to bacteria - punches hole in bacteria to make it osmotically unstable

  • classical - antibody to pathogen
  • alternative - no antibody
90
Q

Interferons

A

Defense against viruses - decrease protein production

91
Q 
MHC class 1
MHC class 2
A

Present pathogens to the adaptive immune system

1 - endogenous pathway - present antigen from inside
2 - exogenous pathway - present antigen from outside

92
Q

Natural Killer Cells

A

Recognize the Dow regulation of MHC by pathogens avoiding immune response and cause apoptosis of affected cell

93
Q

Mast cells

A

Release histamine and other chemicals to promote inflammation

94
Q

What are the 3 responses of antibodies?

A
  1. Opsonization - attract more leukocytes to attack antigen
  2. Agglutinate - cause pathogen to clump together
  3. Prevent pathogen from entering tissue
95
Q

What connects the heavy and light chains of antibodies?

A

Disulfide bond

96
Q

Duodenum

A

Chemical digestion with some absorption

97
Q

Where is bike created?

A

Liver

98
Q

Colon

A

Absorbs water and salt

99
Q

What accounts for the concentration of urine

A

Collecting duct

100
Q

Where does most reabsorption in the excretory system occur

A

Proximal convoluted tubule

101
Q

Missense vs nonsense mutations

A

Missense - changes AA

Nonsense - changes to stop codon

102
Q

Genetic drift

A

More pronounce in small populations - changes to gene pool

103
Q

Founder effect

A

Small population in reproductive isolation

- inbreeding may occur

MCAT (3 decks)

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