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MCAT Quicksheets > Biology > Flashcards

Biology Flashcards

1
Q

Nucleus

A

Contains all of the genetic material necessary for replication of the cell

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2
Q

Mitochondrion

A

Location of many metabolic processes (pyruvate dehydrogenase, CAC, ETC, oxidative phosphorylation, β-oxidation, some of gluconeogenesis, urea cycle) and ATP production

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3
Q

Lysosomes

A

Membrane-bound structures containing hydrolytic enzymes capable of breaking down many different substrates

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4
Q

Rough ER

A

Interconnected membranous structure with ribosomes studding the outside; site of synthesis for proteins destined for insertion into a membrane or secretion

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5
Q

Smooth ER

A

Interconnected membranous structure where lipid synthesis and detoxification occurs

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6
Q

Golgi apparatus

A

Membrane-bound sacs where posttranslational modification of proteins occurs

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7
Q

Peroxisomes

A

Organelle containing hydrogen peroxide; site of β-oxidation of very long chain fatty acids

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8
Q

Fluid mosaic model and membrane traffic

A

Phospholipid bilayer with cholesterol and embedded proteins
Exterior: hydrophilic phosphate head groups
Interior: hydrophobic fatty acids

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9
Q

Cell theory

A

All living things are composed of cells; the cell is the basic functional unit of life; cells arise only from preexisting cells
A fourth tenet has been added: cells carry genetic information in the form of DNA

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10
Q

Eukaryotes

A

Contain membrane-bound organelles such as a nucleus, while prokaryotes are simpler cells without a nucleus

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11
Q

Prokaryotes

A

All divide by binary fission; circular chromosome replicates and attaches to the cell wall; the plasma membrane and cell wall grow along the midline, forming daughter cells

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12
Q

Flagella

A

Eukaryotes: contain a basal body that serves as the engine for motion

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13
Q

Gram-positive

A

Have large quantities of peptidoglycan in the cell wall

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14
Q

Gram-negative

A

Have much smaller quantities of peptidoglycan with lipopolysaccharides

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15
Q

Shapes of bacteria

A

Cocci: spherical
Bacilli: rod-shaped
Spirilli: spiral-shaped

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16
Q

Cell division

A

G1: cell increases its organelles and cytoplasm
S: DNA replication
G2: same as G1
M: the cell divides in two
Mitosis: PMAT
Meiosis: PMAT X 2

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17
Q

Meiosis I

A
  • Two pairs of sister chromatids form tetrads during prophase I
  • Crossing over leads to genetic recombination in prophase I
  • Homologous chromosomes separate during metaphase I
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18
Q

Meiosis II

A
  • Essentially identical to mitosis, but no replication
  • Meiosis occurs in spermatogenesis (sperm formation) and oogenesis (egg formation)
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19
Q

Four stages of early development

A
  1. Cleavage: mitotic divisions
  2. Implantation: embryo implants during blastula stage
  3. Gastrulation: ectoderm, endoderm, and mesoderm
  4. Neurulation: germ layers develop a nervous system
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20
Q

Ectoderm

A

“attract”oderm
- NS, epidermis, lens of eye, inner ear

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21
Q

Endoderm

A

“endernal” organs
- Lining of digestive tract, lungs, liver, and pancreas

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22
Q

Mesoderm

A

“means”oderm
- Muscles, skeleton, circulatory system, gonads, kidney

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23
Q

The liver’s role in homeostasis

A
  1. Gluconeogenesis
  2. Processing of nitrogenous wastes (urea)
  3. Detoxification of wastes/chemicals/drugs
  4. Storage of iron and vitamin A
  5. Synthesis of bile and blood proteins
  6. β-oxidation of fatty acids to ketones
  7. Interconversion of carbohydrates, fats, and AA
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24
Q

Layers of the skin

A

Stratum corneum, statum lucidum, stratum granulosum, stratum spinosum, stratum basalis

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25
Q

Osmoregulation

A
  • Filtration at the glomerulus; filtrate (fluid and small solutes) passes through passive
  • Secretion of acids, bases, and ions from interstitial fluid to filtrate; maintains pH, [K+] and [waste] passive and active
  • Reabsorption: essential substances and water flow from filtrate to blood; enabled by osmolarity gradient and selective permeability of the walls passive and active
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26
Q

Aldosterone

A

Stimulates Na+ and water reabsorption
- Secreted from adrenal cortex in response to low blood pressure
- Regulated by the renin-angiotensin-aldosterone system

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27
Q

ADH (vasopressin)

A

Increases collecting duct’s permeability to water to increase water reabsorption
- Released from the posterior pituitary in response to high blood osmolarity

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28
Q

Four stages of the menstrual cycle

A
  1. Follicular: FSH causes growth of a follicle
  2. Ovulation: LH causes follicle to release egg
  3. Luteal: corpus luteum forms
  4. Menstruation: endometrial lining sheds
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29
Q

Mechanisms of hormone action

A

Peptides act via second messengers and steroids act via hormone/receptor binding to DNA; AA-derivative hormones may do either

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30
Q

Resting potential

A
  • Na+/K+ ATPase creates gradient of high [Na+] outside the cell, and high [K+] inside
  • Movement of ions down their concentration gradient through leak channels establishes resting potential
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31
Q

Action potential

A
  • Stimulus acts on the neuron, depolarizing the membrane of the cell body
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32
Q

Impulse propagation

A

Depolarization (Na+ rushing into axon) followed by repolarization (K+ rushing out of axon) along the nerve axon

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33
Q

The synapse

A
  • At the synaptic knob, voltage-gated Ca2+ channels open, sending Ca2+ into the cell
  • Vesicles fuse with presynaptic membrane sending the neurotransmitter across the synaptic cleft
  • Neurotransmitter binds to receptors on the postsynaptic membrane, triggering depolarization
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34
Q

Gates in action potential

A

I: Rest - all gates closed
II: Depolarization - Na+ gates open
III: Repolarization - Na+ gates inactive; K+ gates open
IV: Hyperpolarization - all gates closed

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35
Q

NS Flowchart

A

NS
Central: brain and spinal cord
Peripheral: sensory and motor - somatic and automatic - parasympathetic and sympathetic

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36
Q

Follicle-stimulating (FSH)

A

Source: anterior pituitary
Action: stimulates follicle maturation; spermatogenesis

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37
Q

Luteinizing (LH)

A

Source: anterior pituitary
Action: stimulates ovulation; testosterone synthesis

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38
Q

Adrenocorticotropic (ACTH)

A

Source: anterior pituitary
Action: stimulates adrenal cortex to make and secrete glucocorticoids

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39
Q

Thyroid-stimulating (TSH)

A

Source: anterior pituitary
Action: stimulates the thyroid to produce thyroid hormones

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40
Q

Prolactin

A

Source: anterior pituitary
Action: stimulates milk production and secretion

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41
Q

Endorphins

A

Source: anterior pituitary
Action: inhibits the perception of pain the brain

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42
Q

Growth hormone

A

Source: anterior pituitary
Action: stimulates bone and muscle growth/lipolysis

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43
Q

Oxytocin

A

Source: hypothalamus; stored in posterior pituitary
Action: stimulates uterine contractions during labor, milk secretion during lactation

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44
Q

Antidiuretic (ADH, vasopressin)

A

Source: hypothalamus; stored in posterior pituitary
Action: stimulates water reabsorption in kidneys

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45
Q

Thyroid hormones (T3, T4)

A

Source: thyroid
Action: stimulates metabolic activity

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46
Q

Calcitonin

A

Source: thyroid
Action: decreases (tones down) blood calcium level

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47
Q

Parathyroid hormone

A

Source: parathyroid
Action: increases blood calcium level

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48
Q

Glucocorticoids

A

Source: adrenal cortex
Action: increases blood glucose level and decreases protein synthesis; anti-inflammatory

49
Q

Mineralocorticoids

A

Source: adrenal cortex
Action: increases sodium and water reabsorption in kidneys

50
Q

Epinephrine, norepinephrine

A

Source: adrenal medulla
Action: increases blood glucose level and heart rate

51
Q

Glucagon

A

Source: pancreas
Action: stimulates conversion of glucogen to glucose in the liver; increases blood glucose

52
Q

Insulin

A

Source: pancreas
Action: lowers blood glucose; increases glycogen stores

53
Q

Somatostatin

A

Source: pancreas
Action: suppresses secretion of glucagon and insulin

54
Q

Testosterone

A

Source: testes
Action: maintains male secondary sex characteristics

55
Q

Estrogen

A

Source: ovary/placenta
Action: maintains female secondary sex characteristics

56
Q

Progesterone

A

Source: ovary/placenta
Action: promotes growth/maintenance of endometrium

57
Q

Melatonin

A

Source: pineal
Action: regulates sleep-wake cycles

58
Q

Atrial natriuretic peptide

A

Source: heart
Action: involved in osmoregulation and vasodilation

59
Q

Thymosin

A

Source: thymus
Action: stimulates T-cell development

60
Q

Sarcomere

A
  • Contractile unit of the fibers in skeletal muscle
  • Contains thin actin and thick myosin filaments
61
Q

Initiation

A

Depolarization of a neuron leads to an action potential

62
Q

Sarcomere shortening

A
  • Sarcoplasmic reticulum releases Ca2+
  • Ca2+ binds to troponin on the actin filament
  • Tropomyosin shifts, exposing myosin-binding sites
  • Myosin binds, ATPase activity allows myosin to pull thin filaments towards the center of the H zone, and then ATP causes dissociation
63
Q

Relaxation

A

Ca2+ is pumped back into the sarcoplasmic reticulum

64
Q

Bone formation and remodeling

A
  • Osteoblast: builds bone
  • Osteoclast: breaks down bone
  • Reformation: inorganic ions are absorbed from the blood for use in bone
  • Degradation (resorption): inorganic ions are released into the blood
65
Q

Circulatory pathway through the heart

A

Super and inferior vena cava - right atrium - right ventricle - pulmonary arteries - lungs - pulmonary veins - left atrium - left ventricle - aorta - body

66
Q

Three portal systems:

A

Blood travels through an extra capillary bed before returning to the heart
- Liver (hepatic), kidney, and brain (hypophyseal)

67
Q

Fetal circulation

A
  • Foramen ovale: connects right and left atria
  • Ductus arteriosus: connects pulmonary artery to aorta; along with foramen ovale, shunts blood away from lungs
  • Ductus venosus: connects umbilical vein to inferior vena cava, connecting umbilical circulation to central circulation
68
Q

Plasma

A

Aqueous mixture of nutrients, wastes, hormones, blood proteins, gases, and salts

69
Q

Erythrocytes (RBCs)

A

Carry oxygen
- Hemoglobin: four subunit carry O2 and CO2; iron controls binding and releasing
- Oxygen-hemoglobin dissociation: right shift of curve - increase temp, Bohr effect, decrease pH, increase pCO2, O2 release to tissues enhanced when H+ allosterically binds to Hb, increase pCO2 leads to increase [H+]

70
Q

Leukocytes (WBCs)

A

Function in immunity

71
Q

Platelets

A

Clotting
- Platelets release thromboplastin, which (along with cofactors Ca and vitamin K) converts inactive prothrombin to active thrombin
- Thrombin converts fibrinogen into fibrin, which surrounds blood cells to form the clot

72
Q

Blood typing and Rh

A
  • Blood cells with Rh factor are Rh+; these individuals produce no anti-Rh antibody.
  • Rh- blood cells lack the antigen; these individuals produce an antibody if exposed
  • If type A: antigen A, antibodies (anti-B)
73
Q

Gas exchange

A
  • Exchange occurs across the thin walls of alveoli
  • Deoxygenated blood enters the pulmonary capillaries that surround the alveoli
  • O2 from the inhaled air diffuses down its gradient into the capillaries, where it binds with hemoglobin and returns to the heart
  • CO2 from the tissues diffuses from the capillaries to the alveoli, and is exhaled
74
Q

Fetal respiration

A
  • Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin
  • Gas and nutrient exchanges occur across the placenta
75
Q

Lipid digestion

A
  • When chyme is present, the duodenum secretes the hormone cholecystokinin (CCK) into the blood
  • CCK stimulates the secretion of pancreatic enzymes and bile and promotes satiety
  • Bile is made in the liver and emulsifies fat in the small intestine; it’s not an enzyme
  • Lipase is an enzyme made in the pancreas that hydrolyzes lipids in the small intestine
76
Q

Salivary amylase (ptyalin)

A

Production site: salivary glands
Function site: mouth
Hydrolysis rxn: starch –> maltose

77
Q

Pancreatic amylase

A

Production site: pancreas
Function site: sm intestine
Hydrolysis rxn: starch –> maltose

78
Q

Maltase

A

Production site: intestinal glands
Function site: sm intestine
Hydrolysis rxn: maltose –> 2 glucoses

79
Q

Sucrase

A

Production site: intestinal glands
Function site: sm intestine
Hydrolysis rxn: sucrose –> glucose, fructose

80
Q

Lactase

A

Production site: intestinal glands
Function site: sm intestine
Hydrolysis rxn: lactose –> glucose, galactose

81
Q

Pepsin

A

Production site: gastric glands (chief cells)
Function site: stomach
Function: hydrolyzes specific peptide bonds

82
Q

Trypsin

A

Production site: pancreas
Function site: sm intestine
Function: hydrolyzes specific peptide bonds; converts chymotrypsinogen to chymotrypsin

83
Q

Chymotrypsin

A

Production site: pancreas
Function site: sm intestine
Function: hydrolyses specific peptide bonds

84
Q

Carboxypeptidases A and B

A

Production site: pancreas
Function site: sm intestine
Function: hydrolyzes terminal peptide bond at C-terminus

85
Q

Aminopeptidase

A

Production site: intestinal glands
Function site: sm intestine
Function: hydrolyzes terminal peptide bond at N-terminus

86
Q

Dipeptidases

A

Production site: intestinal glands
Function site: sm intestine
Function: hydrolyzes part of AAs

87
Q

Enteropeptidase

A

Production site: intestinal glands
Function site: sm intestine
Function: converts trypsinogen and procarboxypeptidases to active form

88
Q

Memory cells

A

(B-lymphocyte)
- Remember antigen, speed up secondary response

89
Q

Plasma cells

A

(B-lymphocyte)
- Make and release antibodies (IgG, IgA, IgM, IgD, and IgE) which induce antigen phagosytosis

90
Q

Active immunity

A

Antibodies are produced during an immune response

91
Q

Passive immunity

A

Antibodies produced by one organism are transferred to another organism

92
Q

Cytotoxic T-cells

A

(T-lymphocytes)
- Destroy cells directly

93
Q

Helper T-cells

A

(T-lymphocytes)
- Activate B- and T-cells and macrophages by secreting lymphokines

94
Q

Suppressor T-cells

A

(T-lymphocytes)
- Regulate B- and T-cells to decrease anti-antigen activity

95
Q

Memory cells

A

Also T-lymphocytes

96
Q

Nonspecific immune response

A

Includes skin, passages lined with cilia, macrophages, inflammatory response, and interferons (proteins that help prevent the spread of a virus)

97
Q

Lympathic system

A
  • Lymph vessels meet at the thoracic duct in the upper chest and neck, draining into the left subclavian vein of the cardiovascular system
  • Vessels carry lymph (excess interstitial fluid), and lacteals collect fats by absorbing chylomicrons in the sm. intestine
  • Lymph nodes are swellings along the vessels with phagocytic cells (macrophages); they remove foreign particles from lymph
98
Q

Law of segregation

A

Homologous alleles (chromosomes) separate so that each gamete has one copy of each gene
- If both parents are Rr, the alleles separate to give a genotypic ration of 1:2:1 and a phenotypic ration of 3:1

99
Q

Law of independent assortment

A

Alleles of unlinked genes assort independently in meiosis
- For two traits: AaBb parents will produce AB, Ab, aB, and ab gametes
- The phenotypic ratio for this cross is 9:3:3:1

100
Q

Genetic mapping

A
  • Crossing over during meiosis I can unlink genes (prophase I)
  • Genes are most likely unlinked when far apart
  • One map unit is 1% recombinant frequency
101
Q

Autosomal recessive

A

May skip generations

102
Q

Autosomal dominant

A

Appears in every generation

103
Q

X-linked (sex-linked)

A

No male-to-male transmission, and more males are affected

104
Q

Hardy-Weinberg equilibrium

A

No mutations, large population, random mating, no migration, and equal reproductive success
p + q = 1; p^2 + 2pq + q^2 = 1
p: dominant allele
q: recessive allele
p^2: dominant homozygotes
2pq = heterozygotes
q^2: recessive homozygotes

105
Q

Nucleic acids

A

Basic unit: nucleotide (sugar, nitrogenous base, phosphate)
- 2 types of bases: double-ringed purines (adenine, guanine) and single-ringed pyrimidines (cytosine, uracil, and thymine)
- A = T, C (triple)G

106
Q

Structural genes

A

Have DNA that codes for protein

107
Q

Operator gene

A

Repressor binding site

108
Q

Promoter gene

A

RNA polymerase’s 1st binding site

109
Q

Inducible systems

A

Need an inducer for transcription to occur

110
Q

Repressible systems

A

Need a corepressor to inhibit transcription

111
Q

Point mutation

A

One nucleotide is substituted by another; they are silent if the sequence of AA doesn’t change

112
Q

Frameshift

A

Insertions or deletions shift reading frame; protein doesn’t form, or is nonfunctional

113
Q

Viruses

A

Acellular structures of double- or single-stranded DNA or RNA in a protein coat

114
Q

Lytic cycle

A

Virus kills the host cell

115
Q

Lysogenic cycle

A

Virus enters the host genome

116
Q

Plasmids

A

Extragenomic material; they can be integrated into the genome, but are then called episomes

117
Q

Transformation

A

Occurs when a bacterium acquires a piece of genetic material from the environment and integrates that piece of genetic material into the host cell genome. This is a common method by which antibiotic resistance can be acquired

118
Q

Conjugation

A

Bacterial form of mating (sexual reproduction)
- 2 cells forming a cytoplasmic bridge allowing for transfer of genetic material; transfer is from donor male (+) to recipient female (-)
- Bridge is made of sex pili; to form the pilus, bacteria must contain plasmids known as sex factors

119
Q

Transduction

A

Occurs when a bacteriophage acquires genetic information from a host cell. Sometimes, when the new virions are assembled in a host cell is packaged along with the viral genetic material.
- Then, the bacteriophage infects another bacterium, resulting in transfer of bacterial genetic material

MCAT Quicksheets (6 decks)

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