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Biology Flashcards

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MCAT flashcards
1
Q

4 tenets of 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 can be passed on from parent to daughter cell
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2
Q

Contain a nucleus enclosed in a membrane

A

Eukaryotic cells

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3
Q

Do not contain a nucleus

A

Prokaryotic cells

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4
Q

Organelles of eukaryotic cells

A

Enclosed in semifluid cytosol

Membrane-bound, allowing for compartmentalization of functions

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5
Q

Cytosol

A

Allows for the diffusion of molecules throughout a eukaryotic cell

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6
Q

Nucleus

A

Contains all genetic material necessary for replication
Where genetic material is encoded
Surrounded by nuclear membrane/envelope

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7
Q

Nuclear membrane/envelope

A

Surrounds nucleus
Double membrane that maintains a nuclear environment separate and distinct from the cytoplasm
Contains nuclear pores

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8
Q

Nuclear pores

A

Located in the nuclear membrane/envelope

Allow selective two-way exchange of material between the cytoplasm and nucleus

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9
Q

Nucleolus

A

Located in the nucleus

Synthesizes ribosomal RNA (rRNA)

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10
Q

Mitochondria

A

Important metabolic functions, ATP production, and apoptosis
Contain inner and outer membranes
Contain their own genes and replicate independently of the nucleus via binary fission

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11
Q

Outer membrane of mitochondria

A

Serves as a barrier between the cytosol and the inner environment of the mitochondrion

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12
Q

Inner membrane of mitochondria

A

Arranged into numerous unfolding called cristae

Contains the molecules and enzymes of the electron transport chain

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13
Q

Cristae

A

Highly convoluted structures that increase the surface area available for electron transport chain enzymes

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14
Q

Intermembrane space

A

The space between the inner and outer membranes of the mitochondria

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15
Q

Mitochondrial matrix

A

The space inside the inner membrane of the mitochondria

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16
Q

Apoptosis

A

Programmed cell death due to release of enzymes

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17
Q

Lysosomes

A

Contain hydrolytic enzymes that are capable of breaking down substrates
Function in conjunction with endosomes
Sequesters enzymes to prevent damage to the cell but the enzymes can be released through autolysis which leads to apoptosis

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18
Q

Endosomes

A

Transport, package, and sort cell material traveling to and from the membrane

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19
Q

Endoplasmic reticulum

A

Series of interconnected membranes that are contiguous with the nuclear envelope
Smooth and rough

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20
Q

Rough ER

A

Studded with ribosomes which permit the translation of proteins destined for secretion directly into its lumen

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21
Q

Smooth ER

A

Lacks ribosomes
Utilized primarily for lipid synthesis, detoxification of drugs and poisons, and transportation of proteins from the rough ER to the Golgi apparatus

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22
Q

Golgi apparatus

A

Packages, modifies, and distributes cellular products

Cellular products are modified by adding a group (carbohydrate, sulfate, etc.) or a signal sequence

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23
Q

Peroxisomes

A

Contain hydrogen peroxide
Breakdown very long chains of fatty acids via B-oxidation
Participate in the synthesis of phospholipids and contain the enzymes involved in the pentose phosphate pathway

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24
Q

Cytoskeleton

A

Provides structure to the cell and helps to maintain its shape
Provides a conduit for the transport of materials around the cell
Components: microfilaments, microtubules, and intermediate filaments

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25
Q

Microfilaments

A

Composed of actin
Resistent to fracture and compression which provides protection for the cell
Play a role in cytokinesis

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26
Q

Cytokinesis

A

The division of materials between daughter cells
Microfilaments create cleavage furrow as a ring at the site of division, as the actin filaments contract, the ring gets smaller and pinches off the connection between the daughter cells

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27
Q

Microtubules

A

Composed of tubulin
Provide the primary pathway along which motor proteins carry vesicles
Make up cilia and flagella

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28
Q

Cilia

A

Composed of microtubules

Projections from a cell that are primarily involved in the movement of materials along the surface of the cell

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29
Q

Eukaryotic flagella

A

Composed of microtubules

Involved in the movement of the cell itself

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30
Q

How do the structures of eukaryotic and prokaryotic flagella differ?

A

Eukaryotic: 9 pairs of microtubules with 2 microtubules in the center (9+2 structure)
Prokaryotic: made of flagellin and consist of a filament, a basal body, and a hook

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31
Q

Centrioles

A

Found in the centrosome
The organizing center for microtubules
9 triplets of microtubules with a hollow center

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32
Q

Intermediate filaments

A

Primary protein depends on cel land tissue type but can be keratin, desmin, vimentin, or lamins
Involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton
Help anchor other organelles

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33
Q

Epithelial tissue

A

Covers the body and lines its cavities
Protects against pathogen invasion and desiccation
Can be involved in absorption, secretion, and sensation
Constitute the parenchyma

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34
Q

Parenchyma

A

The functional tissues of an organ

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35
Q

Simple epithelia

A

Epithelial tissue with one layer of cells

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36
Q

Stratified epithelia

A

Epithelial tissue composed of multiple layers

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37
Q

Pseudostratified epithelia

A

Epithelial tissue that appears to have multiple layers due to differences in cell height but only have one layer

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38
Q

Cuboidal cells

A

Epithelial cells that are cube-shaped

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39
Q

Columnar cells

A

Epithelial cells that are long and thin

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40
Q

Squamous cells

A

Epithelial cells that are flat and scale-like

41
Q

Connective tissue

A

Supports the body and provides a framework for the epithelial cells to carry out their functions
Main contributors to the stroma
Produce and secrete materials such as collagen and elastin to form the extracellular matrix

42
Q

Stroma

A

The support structure of the organ

43
Q

Archea

A

Single-called prokaryotes
Visually similar to bacteria but contain genes and several metabolic pathways that are more similar to eukaryotes
Able to use alternative sources of energy

44
Q

Bacteria

A

Single-called prokaryotes
Contain a cell membrane, cytoplasm, and flagella or fimbriae
Analogous structure to eukaryotes

45
Q

Mutalistic symbiotes

A

Bacteria in which both humans and the bacteria benefit from the relationship

46
Q

Pathogens/parasites

A

Bacteria that provide no advantage or benefit to the host, but rather cause disease

47
Q

Cocci

A

Spherical bacteria

48
Q

Bacilli

A

Rod-shaped bacteria

49
Q

Spirilli

A

Spiral-shaped bacteria

50
Q

Obligate aerobes

A

Bacteria that requires oxygen for metabolism

51
Q

Anaerobes

A

Bacteria that use fermentation or some other form of cellular metabolism that does not require oxygen

52
Q

Obligate anaerobes

A

Bacteria that cannot survive in an oxygen-containing environment

53
Q

Facultative anaerobes

A

Bacteria that use oxygen for aerobic metabolism when it is present and use anaerobic metabolism when it is not

54
Q

Aerotolerant anaerobes

A

Bacteria that are unable to use oxygen for metabolism but are not harmed but its presence in the environment

55
Q

Prokaryotic cell structure

A

Lack a nucleus and membrane-bound organelles

Single-celled

56
Q

Cell wall

A

Forms outer barrier of the cell
Provides structure send controls the movement of solutes into and out of the bacterium
Gram-positive and gram-negative

57
Q

Cell (plasma) membrane

A

Composed of phospholipids

58
Q

Gram-positive cell wall

A

Thick layer of peptidoglycan, a polymeric substance made from amino acids and sugars
Provides protection from a host organism’s immune system
Also contains lipoteichoic acid

59
Q

Gram-negative cell wall

A

Thin layer of peptidoglycan which is separated from the membrane by the periplasmic space
Outer membrane contains phospholipids and lipopolysaccharides
Lipopolysaccharides trigger an immune response in human beings much stronger than the response to lipoteichoic acid

60
Q

Prokaryotic flagella

A

Whip-like structures used for propulsion
Used to move toward food or away from toxins and immune cells
Composed of a filament, a basal body, and a hook

61
Q

Chemotaxis

A

The ability of a cell to detect chemical stimuli and move toward or away from them

62
Q

Plasmids

A

Carry DNA that is not necessary for the prokaryote’s survival
This DNA may confer some advantage even though it is not a part of the bacterium’s genome
Carry virulence factors

63
Q

Binary fission

A

A simple form of asexual prokaryotes

Proceeds more rapidly than mitosis

64
Q

Virulence factors

A

Traits that increase pathogenicity

Carried by plasmids

65
Q

Episomes

A

A subset of plasmids

Capable of integrating into the genome of the bacterium

66
Q

3 mechanisms of genetic recombination

A
  1. Transformation
  2. Conjugation
  3. Transduction
67
Q

Transformation

A

Results from the integration of foreign genetic material into the host genome
Gram-negative rods carry out this process

68
Q

Conjugation

A

Bacterial form of mating

Involves two cells forming a conjugation bridge that facilitates the transfer of genetic material

69
Q

Conjugation bridge

A

Facilities the transfer of genetic material from the donor male to the recipient female

70
Q

F+ cells vs. F- cells

A

F+ cells posses the F (fertility) factor plasmid

F- cells do not posses this sex factor plasmid

71
Q

High frequency of recombination cells

A

Hfr
The sex factor is a plasmid but, through transformation, can become integrated into the host genome. When conjugation occurs, the entire genome replicates and the donor cell will attempt to transfer an entire copy of its genome into the recipient. The conjugation bridge breaks before the whole DNA sequence is moved.

72
Q

Transduction

A

The only genetic recombination process that requires a vector
Bacteriophages incorporate a segment of host DNA during assembly. Transferred DNA integrates into the genome and gives the new host additional genes.

73
Q

Vector

A

A virus that carries genetic material from one bacterium to another

74
Q

Bacteriophages

A

Viruses that infect bacteria
Do not enter bacteria, but inject their genetic material
Composed of a capsid, a tail sheath, and tail fibers

75
Q

Transposons

A

Genetic elements capable of inserting and removing themselves from the genome

76
Q

4 phases of bacterial growth

A
  1. Lag phase
  2. Exponential/ log phase
  3. Stationary phase
  4. Death phase
77
Q

Lag Phase of bacterial growth

A

Bacteria adapt to the new, local conditions of their environment

78
Q

Exponential/log phase of bacterial growth

A

As bacteria adapt, the rate of division increases

79
Q

Stationary phase of bacterial growth

A

As the number of bacteria grows, resources are reduced which slows reproduction

80
Q

Death phase of bacterial growth

A

Bacteria have exceeded the ability of the environment to support the number of bacteria
Depletion of resources

81
Q

Capsid

A

The protein coat that is one part of what viruses are composed of
Surrounded by an envelope made of phospholipids and virus-specific proteins

82
Q

Virions

A

The viral progeny that viruses produce after replicating

Can be released to infect additional cells

83
Q

Tail sheath

A

One part of bacteriophages

Acts like a syringe to inject genetic material into the bacterium

84
Q

Tail fibers

A

One part of bacteriophages

Help the bacteriophages recognize and connect to the correct host cell

85
Q

Positive sense RNA viruses

A

The genome may be directly translated to functional proteins by the ribosomes of the host cell

86
Q

Negative sense RNA viruses

A

RNA strand acts as a template for synthesis of the complementary strand which can then be used as a template for protein synthesis
Carry an RNA replicase in the virion

87
Q

RNA replicase

A

Carried by negative sense RNA viruses

Ensures that the complementary strand is synthesized

88
Q

Retroviruses

A

Enveloped, single-stranded RNA viruses

Carry reverse transcriptase

89
Q

Reverse transcriptase

A

Carried by retroviruses

Synthesizes DNA from single-stranded RNA

90
Q

Types of progeny release

A
  1. Viral invasion may initiate cell death resulting in the spillage of viral progeny
  2. Host cell may lyse as a result of being filled with extremely large numbers of virions
  3. Extrusion
91
Q

Extrusion

A

Virus leases the cell by fusing with its plasma membrane

This process keeps the host cell alive and allows the virus to continue using it (productive cycle)

92
Q

Lytic cycle

A

Bacteriophages maximize the use of the cell’s machinery with little regard for the survival of the host cell. Once the host cell is swollen with new virions, the cell lyses, and other bacteria can be infected

93
Q

Virulent

A

Viruses in the lytic phase

94
Q

Lysogenic cycle

A

The virus is replicated as the bacterium reproduces because it is a part of the host’s genome

95
Q

Provirus/prophage

A

Viruses in the lysogenic phase

96
Q

Prions

A

Infectious proteins
Nonliving
Cause disease by triggering misfolding of other proteins, usually from an a-helical structure to a B-pleated sheet

97
Q

Viroids

A

Small pathogens consisting of a very short circular single-stranded RNA that infect plants
Bind to a large number of RNA sequences and can silence genes, preventing the synthesis of necessary proteins

98
Q

Why are viruses considered obligate intracellular parasites?

A

Viruses do not contain organelles such as ribosomes. Therefore, in order to reproduce and synthesis proteins, viruses ist infect cells and hijack their cellular machinery

MCAT Prep (8 decks)

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