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NPLEX I (passing this time lol) > Biochem/cell cycles/etc etc etc > Flashcards

Biochem/cell cycles/etc etc etc Flashcards

1
Q

Codominance definition and example

A

Both alleles contribute to phenotype of heterozygote

Ex: A/B/AB blood groups, a1-antitrypsin def, HLA groups

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2
Q

Variable expressitivity definition and example

A

Pts with same genotype dont always have same phenotype

Ex: 2 pts with neurofibromastosis type I may have varying disease severity

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3
Q

Incomplete penetrance definition and example

A

Not all ppl with mutant genotype show mutant phenotype (% penetrance x probability of inheriting gene = risk)

Ex: BRCA1 genes dont always cause breast or ovarian cancer

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4
Q

Pleiotropy definition and example

A

One gene contributes to multiple phenotypic effects

Ex: untreated phenylketonuria (PKU) manifests with light skin, intellectual disability, and musty body odor

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5
Q

Anticipation definition and example

A

Increased severity or earlier onset of disease in succeeding generations

Ex: trinucleotide repeat diseases (hungtinton)

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6
Q

Loss of heterozygosity definition and example

A

If a patient inherits or develops a mutation in a tumor suppressor gene, the complementary allele must be deleted/mutated before cancer develops. This is not true of oncogenes.

Ex: retinoblastoma and the “two hit hypothesis”, lynch syndrome (HNPCC), li-fraumeni syndrome

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7
Q

Dominant negative mutation definition and example

A

Exerts a dominant effect. Heterozygote produces a non-functional altered protein that also prevents the normal gene product from functioning.

Ex: mutation of a TF in its almost eric site. Non functioning mutant can still bind to DNA, preventing wild type TF from binding.

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8
Q

Linkage disequilibrium definition

A

Tendency for alleles at 2 linked loci to occur together more/less often than chance predicts. Measured in populations, not family, varies by population.

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9
Q

Mosaicism definition and example

A

Presence of genetically distinct cell lines in the same individual

Ex: McCune Albright syndrome

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10
Q

Locus heterogeneity definition and example

A

Mutation at different loci can product a similar phenotype

Ex: albinism

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11
Q

Alleles heterogeneity definition and example

A

Different mutations in same locus produce same phenotype

Ex: beta-thalassemia

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12
Q

heteroplasmy definition and example

A

Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrially inherited disease

Ex: mtDNA passed from mother to all children

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13
Q

Uniparental Disomy definition and example

A

Offspring receives 2 copies of a chromosome from 1 parent, and none from the other parent.

Ex: consider in a pt with a recessive disorder when only one parent is a carrier, such as prader-willi and Angelina syndromes

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14
Q

Hardy Weinberg law assumptions include

A

No factors altering genetic selection:

No mutation occurring at locus

Natural selection is not occurring

Completely random mating

No net migration

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15
Q

What does the hardy weinburg equilibrium represent?

A

Hypothetical state of balance in a population where the frequency of dominant and recessive alleles is the same from one generation to the next

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16
Q

What is genetic drift

A

Small lot = greater risk of losing alleles from one generation to next because not everyone reproduces

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17
Q

The process of making new gametes is

A

Meiosis

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18
Q

Define independent assortment

A

Alleles inherited for one trait (such as eye color) don’t affect those for another (such as hair color)

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19
Q

Define crossing over

A

In meiosis, homogolous chromosomes exchange equivalent parts of themselves that carry the same types of genes

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20
Q

What is genetic linkage

A

Chance that 2 genes are inherited together depends on the distance separating them; common exemption to law of independent assortment

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21
Q

For 2 genes to be linked:

A

Chance of ending up on different gametes <50%

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22
Q

Parental vs recombinant gamete’s

A

Parental - linked genes inherited together
Recombinant - crossing over separated linked genes

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23
Q

The cell cycle is regulated by:

A

Cyclins
Cyclin-dependent kinases
Cyclin-CDK complexes
Tumor suppressors

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24
Q

What are cyclins?

A

Regulatory proteins that control cell cycle events; phase specific, activate CDKs

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25
Q

What do cyclin-CDK complexes do

A

Phosphorylate other proteins to coordinate cell cycle progression; must be activated and inactivated at appropriate times for cell cycle to progress

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26
Q

What do tumor suppressors do?

A

P53 induces p21 which inhibits CDKs
>hypophosphorylatoin (activation) of Rb
>inhibition of G1-S progression

Mutations in tumor suppressor genes can result in unrestrained cell division (eg Li-Fraumeni syndrome)

GF (eg insulin, PDGF, EPO, EGF) bind tyrosine kinase receptors to transition the cell from G1 to S phase

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27
Q

What is the shortest phase of the cell cycle

A

M phase

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28
Q

M phase includes:

A

Mitosis and cytokinesis

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29
Q

Stages of mitosis

A

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

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30
Q

what is cytokinesis?

A

Cytoplasm splits in two

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31
Q

Phases of cell cycle

A

M phase (mitosis and cytokinesis)
G0
G1
S
G2
Interphase

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32
Q

Permanent cells definition and examples

A

Remain in G0, regenerate from stem cells

Neurons, skeletal and cardiac muscle, RBCs

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33
Q

Stable (quiescent) cells definition and examples

A

Enter G1 from G0 when stimulated

Hepatocytes, lymphocytes, PT, periosteal cells

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34
Q

Labile cells definition and examples

A

Never go to G0, divide rapidly with a short G1. Most affected by chemo

Bone marrow, gut epithelium, skin, hair follicles, germ cells

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35
Q

Rough ER cells definition and examples

A

Site of synthesis of secretory (exported) proteins and N linked oligosaccharide addition to lysosomal and other proteins

Nissl bodies (RER in neurons) - synthesize peptide NTs for secretion
Freee ribosomes - unattached to any membrane, site of synthesis of cytosolic, Pedro is Al, and mitochondrial proteins

Mucus secreting goblet cells of small intestine, antibody secreting plasma cells rich in RER

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36
Q

Smooth ER cells definition and examples

A

Site of steroid synthesis and detox of drugs and poisons. Lacks surface ribosomes.

Liver hepatocytes and steroid hormone-producing cells of the adrenal cortex and gonads rich in SER

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37
Q

What cells go through cell cycle?

A

All except reproductive; varies in length

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38
Q

Cell cycle phases

A

Interphase
Mitosis

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39
Q

Interphase v mitosis

A

Interphase:
Long
State of prep
Cell performs basic functions
Grow and replicates DNA

Mitosis:
Cellular division

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40
Q

Interphase subphases

A

G1 - gap or growth 1 (longest): growth, organelles synthesize proteins and produce energy. Chromosomes are chromatids.

G1 checkpoint - checks for damaged DNA, right proteins. safe to divide?

G0 - repair issues

S - synthesis, DNA replication
Structural proteins, enzymes, energy

G2 - gap/growth 2; duplicate organelles for daughter cells

G2 checkpoint

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41
Q

Mitosis subphases

A

Divides into two daughter cells
Separates DNA to two nuclei > karyokinese
Separate daughter cells > cytokinesis

Please Make Another Two Cells
Prophase - nuclear membrane disintegrates, chromosomes condense
Metaphase - chromosomes > middle
Anaphase - centromeres pull sister chromatids apart
Telophase - nuclear membrane reforms
Cytokinesis cell membrane pinches, daughter cells separate

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42
Q

Cell signaling classification

A

Autocrine: from cell to own receptors
Paracrine: to target cells nearby
Endocrine: to target cells further away

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43
Q

Signaling molecules are called

A

Ligands

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44
Q

What ligands need carrier proteins?

A

Hydrophobic ones

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45
Q

What ligands need transmembrane receptors?

A

Hydrophilic

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46
Q

Stages of cell signaling pathways

A
  1. Reception - receptors bind to ligand
  2. Transduction - receptor protein changes, activates intracellular molecules (2nd messengers)
  3. Cells response to signal
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47
Q

3 major classes of transmembrane receptors

A

G protein coupled
Enzyme coupled
Ion channel

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48
Q

G protein couple receptors

A

7 pass transmembrane receptors
Bind to GDP when inactive, GTP when active > alpha subunit separates and converts GTP > GDP to turn it off

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49
Q

G protein types

A

Gq
Gi
Gs

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50
Q

Protein Gq actions

A

activates phospholipase C in cell membrane > cleaves phosphytidylinositol 4,5-biphosphate into
>DAG; remains attached to membrane, binds to kinase C (relies on Ca to activate) > activates protein by adding phosphoryl groups to them
>inositol triphosphate; soluble, diffuses freely through cytoplasm and into ER where it opens Ca channels > [Ca] higher in ER, flows out to cytoplasm > depolarization of cell

Ca out of ER to cytoplasm > depolarization

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51
Q

Protein Gs

A

Stimulates enzyme adenylate cyclase, removes 2 phosphates from ATP > cAMP

cAMP moves throughout cytoplasm and binds to protein kinase A regulatory subunit > regulatory subunit dissociates from catalytic subunit > catalytic subunit phosphorylates target proteins that trigger a cellular response

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52
Q

Protein G1

A

Bound to adenylate cyclase (inhibits in) > neg feedback protein Gs, inactivates cells

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53
Q

Enzyme coupled receptors

A

Single pass transmembrane proteins
Intrinsic enzyme activity

Two parts with different functions: receptor domain
enzyme domain - usually a protein kinase that phosphorylates receptor domain

54
Q

Receptor tyrosine kinases

A

most common, many subfamilies. Can’t phosphorylate own tyrosine side chains.

Ligands bind > two receptor chains dimerize > cross phosphorylate each other at multiple tyrosine residues > high affinity binding sites for second messengers (can be phosphorylated and activated) > triggers signaling

55
Q

types of enzyme coupled receptors

A

Based on amino acid at which receptor is phosphorylated

Receptor tyrosine kinases
Tyrosine kinase associated receptors
Receptor serine/threonine kinases

56
Q

Tyrosine kinase associated receptors

A

Work similarly to receptor tyrosine kinases but they have no intrinsic enzyme activity. Associated with cytoplasm is tyrosine kinases.

When receptors bind their ligand, cytoplasm tyrosine kinases phosphorylate various target proteins to relay the signal

57
Q

Receptor serene/threonine kinase

A

Serine/threonine kinase domain on intracellular end. Two classes: type 1 and type 2, structurally similar.

Ligand binding brings type I and type II receptors together so that the type II receptor can phosphorylate and activate the type I receptor > type I recruits and phosphorylates various target proteins to relay the signal

58
Q

Ion channel receptors

A

Generally closed
Open once they bind a specific ligand

Allow ions like Cl-, Ca2+, Na+, and K+ to passively flow down their gradient > shift in charge distribution inside cell > cellular response

59
Q

Cell membrane components

A

Barrier of 2x lipids + protein and carbs

60
Q

Categories of molecular studies trying to cross membrane

A

Small + non-polar (O2, CO2) - able to diffuse rapidly through membrane

Small polar like water - can cross slowly

Large, non polar like Vit A - slow to cross

Large polar like glucose, and highly polar ions like Na, K, Cl and charged like amino acids - highly unlikely to get across cell membrane on their own

61
Q

Examples of transport proteins

A

Channels like aquaporins and chloride channels

Carriers like glucose transporter

62
Q

Do endocytosis and exocytosis need energy?

A

Both need adenosine triphosphate (ATP)

63
Q

Types of endocytosis

A

Phagocytosis
Pinocytosis
Receptor mediated endocytosis

64
Q

Phagocytosis

A

Used by WBC like macrophages and neutrophils

> phagosome

Electron pump uses ATP into phagosome > lowers pH

Phagosome and lysosome fuse, forming phagolysosome > lysosome digestive enzymes destroy bacteria in the acidic pH

Lysosome expels materials out of cell membrane into extra cellular space

65
Q

Pinocytosis

A

“The cell drinks”
Cells plasma membrane invaginates to form a small cup around extracellular fluid and solutes not dissolved enough > edges of cup come together to form vesicle > motors proteins like kinesin or dynein use ATP to carry the vesicle deeper into the cytosol. At the same time the vesicle slowly releases the extracellular fluids and solutes into cytosol as well

Nonspecific way for cells to take in solute

66
Q

Receptor mediated endocytosis

A

E.g. transferrin (iron binding protein), low density lipoproteins (LDLs)

On surface of cell membrane there are indented pits with receptors for the molecules. These pits are covered on intracellular side by clathrin proteins (coated pits). LDL (ex) binds to receptor > edges of pits come together > clathrin link up link sturdy shell > vesicles pinch off > clathrin detach

Inside the cell the vesicle merges with endosome (fuse with ingested vesicles, separates LDL from receptor with its ATP proton pump to lower pH) > vesicle splits into 2 (one with LDL, one with LDL receptors) > LDL vesicle > lysosome for digestion. Receptor vesicle > releases receptor on cell membrane (receptor recycling)

67
Q

Exocytosis

A

Starts in Golgi apparatus > takes proteins, lipids, and hormones from RER and SER > packages in vesicle that can be zip lined around cell using cytoskeleton (cytoskeleton is make of proteins like micro filaments, micro tubules, and intermediate filaments which all provide stability), allows cell to change shape and helps structures move from one area to another

Secretory vesicles + motor proteins > move cell along microtubules with ATP, ruptures outside membrane

68
Q

vit A function

A

antioxidant
constituent of visual pigments
differentiation of epithelial cells > specialized tissue (pancreatic cells, mucus secreting cells)
prevents squamous metaplasia
used to treat measles and acute promyelocytic leukemia

69
Q

sources of vit A

A

liver and leafy vegetables

70
Q

vit A def

A

Night blindness (nyctalopia)
Dry scaly skin (xerosis cutis)
Corneal squamous metaplasia > bitot spots (foamy keratin debris on conjuntiva)
Corneal degerneration (keratomalacia)
Immunosuppression

71
Q

vit A excess

A

Acute toxicity - N/V, vertigo, blurred vision
Chronic toxicity - alopecia, dry skin, hepatotoxicity and enlargement, arthralgias, idiopathic intracranial HTN

72
Q

vit A teratogenic?

A

cleft palate
cardiac abnormalities

73
Q

vit B1 name

A

thiamine

74
Q

vit A name

A

retinol

75
Q

B1 function

A

in thiamine pyrophosphate (TPP) - cofacactor for lots of dehydrogenase enzyme reactions

Be APT
Branched chain ketoacid d
a-ketoglutarate d (TCA)
pyruvate d (links glycolysis to TCA)
transkelotase (HMP shunt)

76
Q

B1 def

A

impaired glucose breakdown > ATP depletion worsened by gljucose infusion, highly aerobic tissues (brain, heart) affected first

wenickle korsakoff (confusion, ophthalmoplegia, ataxia)

dry beriberi - polyneuropathy, sym muscle wasting

wet beriberi - high output CF (dilated cardiomyopathy), edema

77
Q

vit B2 name

A

riboflavin

78
Q

vit B2 function

A

component of FAD and FMN, used as cofactors in redox reactions, esp the succinate dehydrogenase reaction in the TCA cycle

79
Q

B2 def

A

cheilosis (inflammation of lips, FAD/FMN fissures)
corneal vascularization

80
Q

vit B3 name

A

niacin

81
Q

B3 function

A

constituent of NAD+ and NADP+ (used in redox reactions)

NAD/B3 = 3 ATP

derived from tryptophan, needs B2 and B6 for synthesis

treats dyslipidemia, lowers VLDL, raises HDL

82
Q

B3 def

A

glossitis
severe def > pellagra; sx of pellagra 3D’s - diarrhea, demetia/hallucinations, dermatitis (broad collar rash)

hyperpigmentation of exposed limbs

can be caused by hartnup disease (def of neutral amino acid)

83
Q

B3 excess

A

podagra
facial flushing (induced by prostaglandins, not histamine)
hyperglycemia
hyperuricemia

84
Q

vit B5 name

A

patothenic acid

85
Q

vit B5 function

A

essential component of CoA (cofactor for acetyl transfers) and fatty acid synthase

86
Q

B5 def

A

dermatitis
enteritis
alopecia
adrenal insufficiency

87
Q

B6 name

A

pyridoxine

88
Q

B6 function

A

converted to PLP, cofactor in transamination (ALT, AST) decarb rxns, hlycogen phosphorylase

synthesis of cystathionine, heme, niacin, histamine, and NTs like serotonin, epi, norepi(NE), dopamine, and GABA

89
Q

B6 def

A

convulsinos
hyperirritability
peripheral neuropathy (induced by isoniazid and OCs)
sideroblastic anemia

90
Q

B7 name

A

biotin

91
Q

B7 function

A

cofactor for carboxylation enzymes, which add a 1-carbon group:
-pyruvate carboxylase: pyruvate (3C) > oxaloacetate (4C)
-acetylCoA carboxylase: acetyl CoA (2C) > malonynl CoA (3C)
-propionyl CoA carboxylase: propionylCoA (3C) > methylmalonyl-CoA (4C)

92
Q

B7 def

A

rare
dermatitis
enteritis
alopecia

caused by long term antibiotic use or excessive ingestion of raw egg whites

adivin in egg whites avidly binds biotin

93
Q

vit B9 name

A

folate

94
Q

B9 function

A

converted to tetrahydrofolic acid THF, coenzyme for 1-C transfer/methylation in DNA and RNA

imp for synthesis of nitrogenous bases in DNA and RNA

95
Q

sources, absoprtion, storage of B9

A

leafy green veggies , absorbed in jejenum, small reserve pool in liver

96
Q

B9 def

A

macrocytic, megaloblastic anemia; hypersegmented polymorphonuclear cells (PMNs)
glossitis
no neuro sx
inc homocysteine

alcoholism and pregnancy , sulfa drugs, methotrexate

97
Q

vit B12 name

A

cobalamin

98
Q

B12 function

A

cofactor for methionine synthase (transfers CH3 groups as methylcobalamin)

imp for DNA synthesis

99
Q

B12 sources, syntehsis, reserve

A

found in animal products
synthesized only by microorganisms
large, several year reserve pool in liver

100
Q

causes of B12 def

A

malabsorption (sprue, enteritis, bacterial overgrowth, alcohol, etc)
lack of IF (pernicious anemia, gastric bypass)
absence of terminal ileum (surgery for crohns)
drugs like metformin
insufficient intake

101
Q

B12 def

A

macrocytic, megaloblastic anemia
hypersegmented PMNs
paresthesias and subacute combined degernation due to abnormal myelin

inc serum homocysteine and methylmalonic acid
2nd degree foalte def

prolonged def > irreversible nerve damage

102
Q

B1 def causes

A

alcohol abuse (interferes with thiamin conversion to active form and prevents absorption, cirrhosis sotrage interfereence) and malnourishment

103
Q

vit C name

A

ascorbic acid

104
Q

vit C sources

A

fruits and veggies

105
Q

vit C function

A

antioxidant
facilitates iron absorption by reducing it to Fe2+ state
necessary for hydroxylation of proline and lysine in collegane synthesis
necessary for doapmine b-hydroxylase, which converts dopamine > NE

106
Q

vit C def

A

scurvy - sweollen gums, easy bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, corkscrew hair, immunodeficiency

vit C causes sCurvy due to a Collagen synthesis defect

107
Q

vit C excess

A

nasuea, vommiting
diarrhea
fatigue
calcium oxalate nephrolithiasis
inc iron toxiciity in predisposed individuals

108
Q

vit D forms and sources

A

D2 (ergocalciferol) - plants, fungi, yeast
D3 (cholecalciferol) - stratam basale from sun, fish, milk, plants

both converted to 25-OH D3 (storage form) in liver and to the active form 1,25-(OH)2D3 (cacitriol) in kidney

109
Q

vit D function

A

inc intestinal absorption of Ca2+ and Po43-
inc bone mineralization at low levels
inc bone resoprtion at higher levels

110
Q

vit D regulation

A

inc PTH, dec Ca2+. dec PO43- > inc 1,25-(OH)2D3 production

1,25-(OH)2D3 feedback inhibts its own production

inc PTH > inc Ca2+ reabsorption and dec PO43- reabsorption in kidney

111
Q

vit D def

A

rickets in children (deformity, genu varum bowlegs)
osteomalacia in adults(bone pain and muscle weakness)
hypocalcemic tetany

112
Q

vit D def causes

A

malabsorption
dec sun exposure
poor diet
CKD
advanced liver disease

113
Q

vit D excess

A

hypercalcemia
hypercalciruia
loss of apetite
stupor

seen in granulmatous disease

114
Q

vit E name

A

tocopherol, tocotrienol

115
Q

vit E def

A

hemolytic anemia
acanthocytosis
muscle weakness
demyelination of posterior columns (dec position and vibration sensation) and spinocerebellar tract (ataxia)

neuro presentation similar to B12, labs different

116
Q

vit E excess

A

risk of enterocolitis in infants
alter vit K metabolism, inc anticoagulant effect of warfarin

117
Q

vit K names

A

phytomenadione, phylloquinone, phytonadione, menaquinone

118
Q

vit K function

A

reduced form is a cofactor for y-carboxylation of glutamic acid residues on various proteins required for blood clotting (clotting factors II, VII, IX, C and proteins C and S)

synthesized by intestinal flora

119
Q

vit K def

A

neonatal hemorrhage with inc PT and inc a PTT but normal bleeding time

can occur after prolonged use of broad spectrum antibiotics

120
Q

types of collagen

A

Be (So Totally) Cool, Read Books

type I (90%) - Bone, Skin, Tendon

type II - cartilage

type III - Reticulin (skin, BVs, uterus)

type IV - Basement membrane (basal lamina)

121
Q

steps of collagen synthesis and processing

A

synthesis
hydroxylation
glycosylation
exocytosis
proteolytic processing
cross-linking

122
Q

collagen synthesis

A

translation of collagen a chains (preprocollagen) - usually Gly-X-Y (proline or lysine).

glycine content best reflects collagen synthesis since it makes up 1/3

123
Q

collagen hydroxylation

A

hydroxylation of specific proline and lysine residues; requires vit C (def = scurvy)

124
Q

collagen glycosylation

A

glycosylation of pro-a-chain hydroxylysine residues and formation of pro-collagen via hydrogen and disulfide bonds (triple helix of 3 collagen alpha chains)

problems forming triple helix = osteogenesis imperfecta

125
Q

collagen exocytosis

A

exocytosis of procollagen into extracellular space

126
Q

collagen exocytosis

A

exocytosis of procollagen into extracellular space

127
Q

collagen proteolytic processing

A

cleavage of disulfide rich terminal regions of procollagen > insoluble tropocollagen

problems with cleavage > ehlers danlos syndrome

128
Q

collagen cross-linking

A

reinforcement of many staggered tropocollagen molecules by covalent lysine-hydroxylysine cross linkage (stabilized by copper containing lysyl oxidase) to make collagen fibrils.

problems with crosslinking = EDS, menkes syndrome

129
Q

Osteogenesis imperfecta

A

Genetic “brittle bone disease” caused by gene defects, usually COL1A1 and COL1A2

Most commonly autosomal dominant with dec of type I collagen

BITE
Bones (multiple fractures)
I (eye, blue sclerae)
Teeth (dental imperfections)
Ear (hearing loss)

129
Q
A

NPLEX I (passing this time lol) (2 decks)

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