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MCAT biology > Ch. 1 The Cell > Flashcards

Ch. 1 The Cell Flashcards

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1
Q

Discovery of cells

A
  • Robert Hooke - made microscope to observe “cells” in cork
  • Anton van Leeuwenhoek - used microscope to observe living cells
  • Rudolph Virchow - diseased cells arise form normal cells
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2
Q

cell theory

A
  • all living things are made of cells
  • cellis functional unit of life
  • cells arise only from preexisting cells
  • cells carry genetic info via DNA which is inherited
    • Viruses are not living organisms
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3
Q

organelles of eukaryote

A
  • float in the cytosol
  • membrane bound organelles allow for compartmentalization of functions
  • nucleus
  • mitochondris
  • lysosome
  • endoplasmic reticulum
  • golgi apparatus
  • peroxisomes
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4
Q

nucleus

A
  • surrounded by nuclear membrane (envelope) - double membrane
  • nuclear pores - selective exchange
  • linear DNA around histone proteins that wind into chromosomes
  • nucleolus - rRNA synthesized (darker spot in the nucleus)
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5
Q

mitochondria

A
  • outer membrane - barrier
  • inner membrane - has inner foldings called cristae and contains molecules/enzymes for ETC
    • cristae increase surface area
  • intermembrane space - between membranes
  • matrix - inside inner membrane
  • protons from matrix to intermembrane space establishes proton motive force that leads to ATP
  • semiautonomous - some of own genes and replicate via binary fission
  • cytoplasmic or extranuclear inheritance - transmit genes without nucleus
  • evolved from anaerobic prok engulfing an aerobic prok
  • can begin apoptosis by releasing ETC enzymes
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6
Q

lysosomes

A
  • membrane bound
  • hydrolytic enzymes that break down waste products and endocytosed material
  • work with endosomes that transport, package, and sort material to and from cell membrane
  • lysosome keeps enzymes from breaking down cell parts, but can also release enzymes to cause autolysis and kill the cell
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7
Q

endoplasmic reticulum

A
  • continuous with nuclear envelope
  • double membrane that folds to make conplex structure
  • rough ER - studded with ribosomes, translate proteins to be secreted into lumen
  • smooth ER - no ribosomes, lipid synthesis and detoxify drugs/poison
    • transport proteins from Rough ER to Golgi
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8
Q

golgi apparatus

A
  • membrane bound sacks
  • from ER to Golgi in vesicles then modified by adding carbohydrates, phosphates, sulfates
  • can introduce signal sequence to cellular product - directs delivery to place in cell
  • repackaged into vesicles that are transferred
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9
Q

peroxisomes

A
  • contain hydrogen peroxide
  • perform beta oxidation of long chain fatty acids
  • synthesize phospholipids and enzymes in pentose phosphate pathway
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10
Q

cytoskeleton

A
  • maintain shape
  • transport material
  • microfilaments
  • microtublules
  • intermediate filaments
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11
Q

microfilaments

A
  • made of rods of actin
  • interact with myosin and use ATP for muscle contraction
  • cytokinesis - divide daughter cells - microfilaments form cleavage furrow
    • actin contracts to close rings and pinch off seperate cells
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12
Q

microtubules

A
  • hollow polymers of tubulin
  • throughout cell - pathways for kinesin and dynein to work as motor proteins
  • cilia and flagella
    • 9 pairs of microtubules make outer ring
    • 2 microtubules in center
    • 9 + 2 structure
  • centrioles - found in centrosome
    • 9 triplets with hollow center
    • mitosis - centrioles to poles and organize mitotic spindle, attach to chromosome via kinetochores and pull apart sister chromatids
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13
Q

Intermediate Filaments

A
  • filamentous proteins - keratin, desmin, vimentin, lamins
  • cell to cell adhesion and integrity of cytoskeleton
  • make cell rigid by withstanding tension
  • anchor organelles
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14
Q

epithelial tissue

A
  • protection, absorption, secretion, sensation
  • connected to the basement membrane
  • parenchyma - functional part of organ ex. nephron, hepatocytes in liver
  • one side on lumen and other side underlying vessels or structures
  • simple - one layer
  • stratified - mutliple layers
  • pseudostratified - one layer that appears to be more
  • cuboidal, comulnar or squamous (flat/scale like)
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15
Q

connective tissue

A
  • stroma - support structure
  • bone
  • cartilage
  • ligaments/tendons
  • adipose tissue
  • blood
  • secrete collagen and elastin to make extracellular matrix
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16
Q

archaea

A
  • single celled
  • more similar to eukaryotes than bacteria
  • extremophiles
  • use alternative energy sources
  • single circular chromosome
  • binary fission
  • similar structure to bacteria
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17
Q

mutualistic symbiotes

A
  • both human and bacteria benefit from relationship
  • opposite of a pathogen - no advantage to human and cause disease
18
Q

Bacteria shape

A
  • cocci - sphere
  • bacilli - rod
  • spirilli - spiral
19
Q

aerobes/anaerobes

A
  • obligate aerobes - require oxygen
  • obligate anaerobes - cant survive in oxygen
  • facultative anaerobes - metabolic processes with or without oxygen
  • aerotolerant anaerobes - can survive in oxygen but only metabolic processes without oxygen
20
Q

Gram positive

A
  • stains purple due to crystal violet
  • thick PGN made of amino acids and sugars
  • lipoteichoic acid
21
Q

Gram negative

A
  • very thin
  • stain pink due to safranin
  • cell wall and cell membrane are seperated by the periplasmic space
  • outer membrane - phospholipids and lipopolysaccharides (LPS)
    • LPS trigger immune response - strong inflammation
22
Q

Flagella

A
  • bacteria can have several flagella
  • move away or towards food/chemicals/immune cells
  • filament - hollow made of flagellin
  • basal body - anchors to membrane and motors flagella
  • hook - connects filament and basal body
    • transfer torque to filament from basal body
  • also in archaea
23
Q

Plasmids and Prokaryote ribosome

A
  • pro ribosome - 30S and 50S subunits
  • plasmids - small circular
    • codes for DNA that is not necessary for survival. Ex. antibiotic resistance
    • virulence factors - increase pathogenicity via toxins or ability to avoid immune response
24
Q

Binary fission

A
  • produce rapidly
  • 2 identical daughter cells
  • bacteria
  • circular chromosome attaches to cell wall and replicates and cell grows
  • septum forms and invagination begins
  • midline forms and cells seperate
25
Q

episomes

A

plasmids that can integrate into the genome of bacterium

26
Q

transformation

A
  • integrate foreign genetic material into host genome
  • originate from lysed bacteria
  • common in gram neg bacilli
27
Q

Conjugation

A
  • transfer of plasmid between bacteria
  • form conjugation bridge using sex pili
    • sex factors are required to have a sex pili
      • most common is F factor
  • transfer antibiotic resistance and virulence factors
28
Q

High frequency of recombination

A
  • Hfr
  • bacterial conjugation and sex factor under goes transformation into the genome
  • donor cell attempts to transfer entire genome into recipient
  • if successful than cells are considered Hfr
29
Q

Transduction

A
  • requires a vector - virus carries genetic info
  • bacteriophages - viruses that care the genetic info of other bacteria
  • phage infects bacteria and transfers genetics
  • genetics integrated into host genome
  • transposons - genetic elements capable of inserting and removing themselves from the genome. In pro and euk
30
Q

bacterial growth phases

A
  • lag phase - adapting to conditions
  • exponential (log) phase - growth increases
  • stationary phase - resources and space reduced
  • death phase - environment depleted
31
Q

capsid

A

protein coat on virus

32
Q

viruses (overview)

A
  • genetic info - circular or linear, single or double stranded, RNA or DNA
  • some have an envelope - phospholipids and proteins
    • surrounds capsid
    • easily denatured by heat and not resistant to sterilization
  • obligate intracelluar parasites
    • must express and replicate genetics in a host cell
  • make virions that are progeny
33
Q

Bacteriophages

A
  • inject genetic material
  • tail sheath as syringe
  • tail fibers determine which host cell
  • perform transduction
34
Q

Viral genome

A
  • when ssRNA
    • positive sense - genome directly translated to proteins by host ribosome
    • negative sense - must synthesize complementary RNA to strand before translation
      • requires RNA replicase
  • retrovirus - enveloped, ssRNA
    • usually 2 identical RNA molecules
    • reverse transciptase - synthesize DNA from ssRNA
      • DNA integrated into host and infected indefinitely
    • Ex. HIV
35
Q

HIV life cycle

A
  • envelope on virus binds to CD4 and CCR5 on the cell surface
  • fuse with cell to release contents
  • reverse transcriptase makes viral RNA into dsDNA
  • integrase inserts copy into host DNA
  • cell machinry transcirbe viral genome back into RNA and its used to translate proteins
  • viral RNA and proteins bud off as an immature virus
  • HIV protease matures the virus so it can infect again
36
Q

How viruses infect

A
  • enveloped viruses fuse with the plasma membrane
    • must bind to specific receptors on host cell
  • phages use tail fibers to anchor themselves and inject genetic material
    • may have enzymatic activity that penetrates cell membrane and forms pores
37
Q

Translation/progeny creation

A
  • most DNA viruses got to nucleus to make mRNA
  • positive sense RNA - directly translated by host ribosome
  • negative sense RNA - RNA replicase synthesizes a complementary RNA strand that is used for translation
  • retroviruses - reverse transcription to make DNA that goes to nucleus and integrates into host genome
  • viral genome must be in original form to be packaged into the capsid
38
Q

progeny release

A
  • initiate host cell death
  • lyse host cell
  • extusion - bud off of host cell membrane
    • productive cycle - host cell remains alive, can be continually used
39
Q

lytic cycle

A
  • virulent bacteria
  • lytic cycle - phage injects, use host machinary to replicate viral genome, assemble progeny, lysis of host cell
  • lytogenic cycle - provirus or prophage are viruses that integrate into the host genome
    • virus is reproduced as host cell replicates
    • less vulnerable to superinfection - simultaneous infection with another phage
    • may re-enter the regular lytic cycle
    • when progeny leaves genome it can take some bacterial geneome and trasnfer it to another cell (specialized transduction)
40
Q

prions

A
  • infectious proteins
  • trigger misfolding of proteins
  • may convert alpha helix to beta pleated sheet
  • protein aggregates form
  • cell funtion reduced
41
Q

viroids

A
  • small pathogens
  • short circular ssRNA that infects plants
  • silences genes
  • prevent synthesis
  • human example - hepatitis D virus which silences function of hepatocytes when hep B virus is present

MCAT biology (11 decks)

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