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MCAT > Biologia (Italia) > Flashcards

Biologia (Italia) Flashcards

1
Q

who invented the first microscope

A

Robert Hooke in 1665

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2
Q

what are the 4 tenets of the cell theory

A
  1. all living things are composed of cells
  2. the cell is the basic functional unit of life
  3. cells arise only from preexisting cells
  4. cells carry genetic information in the form of DNA. this genetic material is passed on from parent to daughter cell.
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3
Q

T or F. eukaryotic cells are always multicellular

A

False
eukaryotic cells can be unicellular or multicellular ; prokaryotic cells are always single-celled

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4
Q

which organelles are double-membrane bound?

A

mitochondria, chloroplasts, and the nucleus

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5
Q

what organizing proteins is linear DNA wound around?

A

histones

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6
Q

what is the nucleolus

A

subsection of the nucleus where ribosomal RNA (rRNA) is synthesized

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7
Q

describe in detail the structure of the mitochondria

A
  • has two layers: the outer and inner membranes
  • the inner membranes are arranged into folds known as cristae which contain the molecules and enzymes of the electron transport chain
  • the space between the inner and outer membranes is called the intermembrane space and the space inside the inner membrane is called the mitochondrial matrix
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8
Q

why is the pumping of protons from the mitochondrial matrix to the intermembrane space important?

A

establishes the proton-motive force
these protons flow through ATP synthase to generate ATP during oxidative phosphorylation

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9
Q

what is cytoplasmic or extranuclear inheritance?

A

the transmission of genetic material independent of the nucleus
example: mitochondria as they contain their own genes and replicate independently via binary fission

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10
Q

What is the serial endosymbiosis theory?

A

posits that certain organelles (like mitochondria and chloroplasts) were formed by the engulfing of one prokaryote by another in a symbiotic relationship and that’s why they’re membrane bound

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11
Q

other than providing energy, what is the other important function of the mitochondria?

A

kick-starting apoptosis (programmed cell death) by release certain enzymes from the electron transport chain

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12
Q

what are lysosomes

A

membrane-bound structures containing hydrolytic enzymes that are capable of breaking down many different substrates
- work in conjunction with endosomes
- can release its enzymes to cause autolysis (self-destruction of cell)

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13
Q

what are endosomes

A

organelles that transport, package and sort cell material traveling to and from the membrane

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14
Q

T or F: all cells have the same distribution of organelles

A

False
- form follows function
- cells that require a lot of energy will have more mitochondria, cells involved in secretion have more ER and golgi, red blood cells have no organelles at all

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15
Q

what are the functions of the rough ER versus the smooth ER

A

rough ER - studded with ribosomes, permits for translation of proteins directly into its lumen
smooth ER - used primarily for lipid synthesis, detoxification, and transportation of proteins from RER to Golgi

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16
Q

what are the main functions of the golgi apparatus

A

modifies (through addition of groups like phosphates or signal sequences which are like location directions) and sorts cellular products which then get repackaged in vesicles and directed to the correct location

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17
Q

what are peroxisomes and why are they important

A

contain hydrogen peroxide and are important in the breakdown of very long fatty acid chains via B-oxidation
- also participate in the synthesis of phospholipids and contain some of the enzymes involved in the pentose phosphate pathway

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18
Q

what are the three components of the cytoskeleton

A

microfilaments, microtubules, and intermediate filaments

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19
Q

what protein are microfilaments made up of

A

actin

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20
Q

what are the functions of microfilaments

A

provide protection and support for the cell (because actin filaments are resistant to both compression and fracture), provide force for movement by muscle contraction (by interacting with myosin), and play a role in cytokinesis by forming the cleavage furrow

21
Q

what is the structure of microtubules

A

hollow polymers of tubulin proteins

22
Q

what are the functions of microtubules

A

provide the primary pathways along with motor proteins like kinesin and dynein carry vesicles
also contribute to structure of motile structures like cilia and flagella

23
Q

compare the functions of cilia versus flagella

A

cilia are projections from a cell that are primarily involved in the movement of materials along the surface of the cell (example: cilia in the respiratory tract help move mucus down it)

flagella are structures involved in the movement of the cell itself through space

24
Q

what is the 9 + 2 structure

A

the arrangement of microtubules in eukaryotic organelles of motility (bacterial flagella have a different structure)
- nine pairs of microtubules form an outer ring with 2 microtubules in the center

25
what are centrioles
found in the centrosome (region of the cell involved in cell division) and are the organizing center for microtubules
26
how are microtubules involved in cell division
centrioles move to opposite poles of the cell to organize the mitotic spindle, microtubules emanating from the centrioles attach to the chromosomes via their kinetochores (structure in middle) and pull them apart
27
what are intermediate filaments and what are their functions
a diverse group of filamentous proteins (such as keratin, desmin, and lamins) that are involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton , also help anchor other organelles
28
what are the four tissue types
epithelial, connective, nervous, and muscle
29
what is the parenchyma versus the stroma
parenchyma: the functional tissue of an organ, usually made up of epithelial tissue stroma: structural tissue of an organ that provides support, usually made up of connective tissue
30
what is epithelial tissue
- they cover the body and line its cavities, protecting against pathogen invasion and desiccation - some absorb or secrete substances or participate in sensation - usually form the parenchyma
31
what does it mean that epithelial cells are often polarized
one side faces a lumen (hollow inside of organ) while the other side interacts with underlying blood vessels and structural cells
32
what are the different classifications of epithelial tissue (both by layers and shape)
layers: simple (one layer), stratified (multiple layers), pseudostratified (appear to have multiple layers but only have one) shape: cuboidal (cube), columnar (long and thin), and squamous (flat and scale-like)
33
what is connective tissue
supports the body and provides framework for epithelial cells to carry out their functions - contribute to the stroma - produce/secrete materials such as collagen and elastin to form the extracellular matrix examples: bone, cartilage, tendons, ligaments, blood
34
are bacteria prokaryotic or eukaryotic?
prokaryotic
35
where do prokaryotes keep their genetic material?
it is organized into a single circular molecule of DNA concentration in an area of the cell known as the nucleoid region
36
what are the three domains of life
Archaea (prokaryotic), Bacteria (prokaryotic), and Eukarya
37
describe some of the characteristics of Archaea
- were considered extremophiles bc they can live in extreme environments (but are found everywhere even in human body) - notable for their ability to use different sources of energy (chemosynthetic, can use sulfur and nitrogen) - hypothesized that they share the same origin as eukaryotes bc they share many characteristics
38
what are mutualistic symbiotes
both organisms in the relationship benefit (some bacteria are like this with humans, example: we have some bacteria in our gut that produce vitamin K)
39
what are the three shapes of bacteria
cocci - spherical bacilli - rod-shaped spirilli - spiral-shaped
40
what are obligate anaerobes vs. facultative anaerobes vs. aerotolerant anaerobes
obligate anaerobes: cannot survive in an oxygen-containing environment facultative anaerobes: can survive with oxygen, switch between aerobic and anaerobic function aerotolerant anaerobes: unable to use oxygen but can survive in its presence
41
what is the envelope of prokaryotes
the cell wall plus the cell/plasma membrane
42
what are gram-positive versus gram-negative bacteria
gram-positive (turn purple during gram staining process) : their cell walls consist of a thick layer of peptidoglycan and also contain lipoteichoic acid gram-negative (turn pink/red) : cell walls are very thin (with a little peptidoglycan), in addition to cell wall and cell membrane, also have outer membranes containing phospholipids and lipopolysaccharides
43
how does the antibiotic penicillin work?
targets the enzyme that catalyzes the cross-linking of peptidoglycan (no longer serves as an effective barrier)
44
what is chemotaxis
the ability of a cell to detect chemical stimuli and move toward or away from them
45
what are the three components of a bacterial flagella
a filament composed of flagellin, a basal body that anchors and rotates the flagellum, and a hook that connects the two
46
what are plasmids
small circular segments of DNA that can replicate independently, in bacteria they carry DNA that is not vital for survival - can be used in genetic modification
47
how do prokaryotes generate ATP
use their cell membrane for the electron transport chain
48
what are the prokaryotic and eukaryotic ribosome subunits?
prokaryotic - 30S and 50S eukaryotic - 40S and 60S 23

MCAT (13 decks)

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