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MCAT Biology > Ch 1 - The Cell > Flashcards

Ch 1 - The Cell Flashcards

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1
Q

What are the 4 fundamental tenets of the cell theory?

A
  • all living things are composed of cells
  • the cell is the basic functional unit of life
  • cells arise only from pre-existing cells
  • cells carry genetic information in the form of deoxyribonucleic acid (DNA) and this genetic material is passed on from parent to daughter cell
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2
Q

What is the main difference between prokaryotic and eukaryotic cells?

A
  • pro: always single-celled with no nucleus

- eu: can be unicellular or multicellular and contain a true nucleus enclosed in a membrane

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3
Q

Where are organelles found?

A
  • each cell has a membrane enclosing a semifluid cytosol (cytoplasm) where organelles are suspended
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4
Q

What does the membrane in eukaryotic cells consist of and why is it unique?

A
  • consist of a phospholipid bilayer
  • its surfaces are hydrophilic, electrostatically interacting with the aqueous environment inside and outside the cell, while its inner portion is hydrophobic, which helps to provide a highly selective barrier between the interior of the cell and the external environment
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5
Q

What is the nucleus?

A
  • control center of the cell
  • contains all the genetic material necessary for replication of the cell
  • site of transcription
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6
Q

What surrounds the nucleus?

A
  • nuclear membrane (envelope)

- a double membrane that maintains a nuclear environment separate and distinct from the cytoplasm

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7
Q

What are nuclear pores?

A
  • in the nuclear membrane that allows selective 2-way exchange of material between the cytoplasm and the nucleus
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8
Q

Genes?

A

coding region in genetic material (DNA)

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9
Q

Histones?

A
  • organizing proteins that linear DNA wounds around
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10
Q

Chromosomes?

A

after linear DNA wounds around histones, they then further wind into linear strands = chromosomes

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11
Q

Nucleoulus?

A
  • where rRNA is synthesized
  • takes up approximately 25% of the volume of the entire nucleus and can often be identified as a darker spot in the nucleus
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12
Q

What is Mitochondria?

A
  • powerhouse of the cell due to their important metabolic function
  • semiautonomous: contain some of their own genes and replicate independently of the nucleus via binary fission
  • capable of killing the cell by releasing enzymes from the ETC
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13
Q

What is the difference between the outer and inner membrane of the mitochondria?

A
  • outer: serves as a barrier between the cytosol and the inner environment of the mitochondrion
  • inner: (arranged into numerous folding - cristae - that increase surface area for ETC enzymes) contains the molecules and enzymes of the electron transport chain
  • intermembrane space: space between the membranes containing the mitochondrial matrix
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14
Q

What is extranuclear inheritance (cytoplasmic)?

A
  • the transmission of genetic material independent of the nucleus
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15
Q

Apoptosis?

A

programmed cell death

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16
Q

Lysosomes?

A
  • membrane-bound structure containing hydrolytic enzymes that are capable of breaking down substances ingested by endocytosis and cellular waste products
  • surrounded by a single membrane
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17
Q

Autolysis?

A
  • release of hydrolytic enzymes transported by endosomes/lysosomes leading to degradation of cellular components
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18
Q

Endoplasmic reticulum?

A
  • a series of interconnected membranes that are actually contiguous with the nuclear envelope
  • double membrane is folded into numerous invaginations, creating complex structures with a central lumen
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19
Q

What are the 2 types of ER?

A
  • rough: with ribosomes, synthesizes protein destined for secretion
  • smooth: lacks ribosomes and is utilized primarily for lipid synthesis and the detoxification
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20
Q

Golgi Apparatus?

A
  • consists of stacked membrane-bound sacs in which cellular products can be modified, packaged, and directed to specific cellular locations
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21
Q

Perioxisomes?

A
  • contain hydrogen peroxide
  • breaks down long chain fatty acids via beta-oxidation
  • synthesize lipids
  • contribute to pentose phosphate pathway
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22
Q

Cytoskeleton?

A
  • provides structure to the cell and helps it to maintain its shape
  • provides transport pathways for molecules within the cell
  • 3 parts: microfilaments, microtubules, intermediate filaments
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23
Q

Microfilaments?

A
  • composed of actin.
  • provide structural protection for the cell and can cause muscle contraction through interactions with myosin
  • help form the cleavage furrow during cytokinesis in mitosis
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24
Q

Microtubules?

A
  • composed of tubulin
  • create pathways for motor proteins like kinesin and dynein to carry vesicles
  • contribute to the structure of cilia and flagella
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25
Q

What is the difference between cilia and flagella?

A
  • cilia: projections from a cell that are primarily involved in the movement of materials along the surface of the cell
  • flagella: structures involved in the movement of the cell itself
  • they share the same structure: organized into 9 pairs of microtubules in a ring with 2 microtubules at the center (9+2 structure)
26
Q

Why are viruses not considered living things?

A

they are acellular, cannot reproduce without the assistance of a host cell, and may use RNA as their genetic material

27
Q

Cytosol?

A

suspends the organelles and allows diffusion of molecules throughout the cell

28
Q

Centrioles?

A
  • found in centrosomes and are involved in microtubules organization in the mitotic spindle
29
Q

Intermediate filaments?

A
  • involved in cell-cell adhesion and maintenance of the integrity of the cytoskeleton
  • help anchor organelles
  • keratin, desmin, vimentin, lamins
30
Q

Epithelial tissue?

A
  • cover the body and line its cavities, protecting against pathogen invasion and desiccation
  • some absorb or secrete substances or participate in sensation
31
Q

Parenchyma?

A
  • the functional parts of the organ

- in most organs, formed by epithelial cells

32
Q

How can epithelial cells be polarized?

A

with one side facing a lumen or the outside world and the other side facing blood vessels and structural cells

33
Q

How are epithelia classified by the number of layers?

A
  • simple: have one layer
  • stratified: have many layers
  • pseuodostratified: appear to have multiple layers due to differences in cell heights, but actually only have one layer
34
Q

How are epithelia classified by the shapes of the cells?

A
  • cubodial: cube-shaped
  • columnar: long and narrow
  • squamous: flat and scalelike
35
Q

Connective tissue?

A
  • support the body and provide framework for epithelial cells
  • in most organs, CT forms the stroma or support structure by secreting materials to form an ECM
  • bone, cartilage, tendons, ligaments, adipose tissue, and blood
36
Q

What are the 3 overarching domains of life?

A
  • archae: extremophiles, living in harsh environments and often use chemical sources of energy rather than light (similarities to both eukaryotes - start translation with methionine, RNA polymerases, histones- and bacteria - single circular chromosome, divide by binary fission/budding
  • bacteria: many similar structures to eukaryotes and have complex relationships with humans, including mutualistic symbiosis (good bacteria) and pathogenesis
  • eukaryoa: only non-prokaryotic domain
37
Q

How can bacteria be classified by shape?

A
  • cocci: spherical
  • bacilli: rod shaped
  • spirilli: spiral shaped
38
Q

How can be bacteria be classified based on metabolic processes?

A
  • obligate aerobes: require oxygen for metabolism
  • obligate anaerobes: cannot survive in oxygen-containing environments and can only carry out anaerobic metabolism
  • facultative anaerobes: can survive in environments with or w/o oxygen and will toggle between metabolic processes based on the environment
  • aerotolerant anaerobes: cannot use oxygen for metabolism, but can survive in an oxygen-containing environment
39
Q

What forms the envelope in bacteria?

A
  • the cell wall and cell membrane

- together, they control the movement of solutes in and out of the cell

40
Q

How can gram staining with a crystal violet stain followed by a counter stain with safranin classify bacteria?

A
  • gram positive: turns purple, have thick cell wall composed of peptidoglycan and lipoteichoic acid
  • gram negative: turns pink-red, thin cell wall composed of potidoglycamn and an outer membrane containing phospholipids and lipopolysaccharides
41
Q

What is chemotaxis and what role does it play with bacteria flagella?

A
  • bacteria may have 1, 2, or many flagella that generate propulsion to move the bacterium toward food or away from immune cells
  • moving in response to chemical stimuli = chemotaxis
  • bacterial flagella contain a filament composed ot flagellin, a basal body that anchors and rotates the flagellum and a hook that connects the 2
42
Q

How to prokaryotes carry out the electron transport chain?

A

using the cell membrane

43
Q

How do ribososmes compare between eukaryotes and prokaryotes?

A

prokaryotic ribosomes are smaller than eukaryotic (30s and 50s, rather than 40s, and 60s)

44
Q

Binary fission?

A
  • how prokaryotes multiply
  • chromosomes replicate while the cell grows in size until the cell wall begins to grow inward along the midline of the cell and divides into 2 identical daughter cells
45
Q

What can plasmids carry and what are their characteristics?

A
  • extrachromosomal material can be carried in plasmids
  • may contain Abx resistance genes or virulence factors
  • can integrate into the genome = episomes
46
Q

Transformation?

A

occurs when genetic material from the surroundings is taken up by a cell, which can incorporate this material into its genome

47
Q

Conjugation?

A
  • the transfer of genetic material from one bacterium to another across a conjugation bridge
  • a plasmid can be transferred from F+ cell to F- cells, or a portion of the genome can be transferred from an Hfr cell to a recipient
48
Q

Transduction?

A

the transfer of genetic material from one bacterium to another via a bacteriophage vector

49
Q

Transposons?

A

genetic elements that can insert into or remove themselves from the genome

50
Q

What is the pattern of bacterial growth?

A
  • lag phase: the bacteria adapt to new local conditions
  • exponential (log) phase: growth then increases exponentially
  • stationary phase: as resources reduce, growth levels off
  • death phase: as resources deplete
51
Q

Capsid?

A
  • viruses contain genetic material, a protein coat (caspid), and sometimes lipid-containing envelope
52
Q

Why are viruses considered intracellular parasites?

A

they cannot survive and replicate outside of a host cell

53
Q

Virions?

A

individual virus particle

54
Q

What are bacteriophages and their components?

A
  • viruses that target bacteria
  • contain a tail sheath: injects the genetic material into a bacterium
  • contain a tail fiber: allow the bacteriophage to attach to the host cell
55
Q

What are the different compositions of viral genomes made of?

A
  • DNA or RNA and may be single or double stranded
  • sing stranded RNA virus may be positive sense (can be translated by host) or negative sense (require complementary strand to be synthesized by RNA replicase before translation)
  • retroviruses have single stranded RNA genome that a complemntary DNA strand is made using RT
56
Q

How do viruses infect cells?

A

by attaching to specific receptors, and can then enter the cell by fusing with the plasma membrane, being brought in by endocytosis or injecting their genome into the cell

57
Q

How do viruses reproduce?

A

by replicating and translating genetic material using the host cells ribosomes, tRNA, amino acids, and enzymes

58
Q

How are viral progeny released?

A

through cell death, lysis, or extrusion

59
Q

What are the 2 life cycles for bacteriophages?

A
  • lytic: the bacteriophgage produces massive numbers of new virions until the cells lyse (virulent)
  • lysogenic: the virus integrates into the host genome as a provirus or prophage, which can then reproduce along with the cell; provirus can remain in the genome indefinitely, or may leave the genome in response to a stimulus and enter the lytic cycle
60
Q

Prions?

A
  • infections proteins that trigger misfolding of other proteins, usually converting alpha-helical structure to a beta-pleated sheet
  • this decreases the solubility of the protein and increases its resistance to degradation
61
Q

Viroids?

A
  • plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and potentially cell death

MCAT Biology (12 decks)

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