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MCAT Biology > Chapter 1 > Flashcards

Chapter 1 Flashcards

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1
Q

Cell Theory

A
  • All living things are composed of cells
  • The cell is the basic funcitonal unit of life
  • Cells arise only from preexisting cells
  • Cells carry genetic information in the form of deoxyribonucleic acid (DNA) which is passed on from parent to daughter cell
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2
Q

Eukaryotic cells

A
  • Unicellular or multicellular
  • Contain nucleus enclosed in a membrane
  • Most organelles are membrane bound
  • Membrane is a phospholipid bilayer
  • Reproduce by mitosis leading to two identical daughter cells
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3
Q

Prokaryotic cells

A
  • Don’t contain a nucleus
  • Simplest
  • Include all bacteria
  • Don’t contain membrane-bound organelles
  • Genetic material is organized into one circular molecule found in nucleoid region
  • Each cell must be able to perform all life needed functions on its own
  • Cell membrane used for electron transport chain and ATP generation
  • Contain primitive cytoskeleton
  • Contain ribsomes that are different from eukaryotes
  • Reproduce through asexual reproduction by binary fission
  • Can take on and use genetic material from outside the cell
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4
Q

Phospholipid bilayer

A
  • Surfaces are hydrophilic (loves water)
  • Interior is hydrophobic (hates water)

Creates highly selective barrier between inside of cell and outside environment

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5
Q

Cytosol

A

Allows diffusion of molecules throughout cell

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6
Q

Nucleus

A

Where deoxyribonucleic acid (DNA) is encoded and organized into chromosomes
Site of transcription
* Contains all genetic material needed for replication
* Surrounded by nuclear membrane/envelope

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7
Q

Nuclear membrane/envelope

A

Keeps nuclear environment seperate and disticnt from cytoplasm

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8
Q

Nuclear pores

A

Holes in the nuclear membrane that allow for selective two-way exchange of material

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9
Q

Genes

A

Coding regions within DNA

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10
Q

Histones and Chromosomes

A

Linear DNA is wrapped around organizing proteins histones, and then wound into linear strands chromosomes

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11
Q

Nucleolus

A
  • Where ribosomal RNA (rRNA) is synthesized
  • Takes up 25% of nucleus volume
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12
Q

Mitochondria

A

Involved in ATP Production and apoptosis

  • Contains two layers, outer and inner membrane
  • Semi autonomous
  • Contain some unique genes and replicate independantly of nucleus (binary fission)

Outer membrane: barrier between cytosol and inner environment

Inner membrane: Thrown in numberous infoldings, AKA cristae, contains molecules and enzymes needed for electron transport chain

Intermembrane space: space between two membranes

Mitochondrial Matrix: space inside inner membrane

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13
Q

Cytoplasmic/Extranuclear Inheritance

A

Transmission of genetic material independant of nucleus

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14
Q

Lysosome

A
  • Membrane bound structures containing hydrolytic enzymes that can break down substrates (endocytosis and cellular waste)
  • Membrane keeps enzymes enclosed to prevent cell damage
  • Sometimes involved in apoptosis
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15
Q

Autolysis

A
  • Release of hydrolytic enzymes
  • Once released, results in apoptosis
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16
Q

Endoplasmic Reticulum (ER)

A
  • Series of connected membranes
  • Folded to create complex structure with central lumen
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17
Q

Rough ER

A
  • Covered with ribosomes
  • Synthesizes secretion proteins
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18
Q

Smooth ER

A
  • No ribosomes
  • Used for lipid synthesis (like phospholipids in cell membrane)
  • Detoxification of certain drugs and poisons
  • Transports protein from rough ER to golgi apparatus
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19
Q

Golgi Apparatus

A
  • Stacked membrane bound sacs
  • Materials are transferred from ER to golgia via vesicles
  • Modifies cellular products by adding various groups and introducing signal sequences (direct to specific place)
  • Repackages in vesicles and moved to correct place
    Packages, modifies, distributes
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20
Q

Exocytosis

A

Secretory vesicles merges with cell membrane and releases its contents

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21
Q

Peroxisomes

A
  • Contain hydrogen peroxide
  • Break down very long chain fatty acids via B-oxidation
  • Participate in synthesis of phospholipids
  • Contain some enzymes used in pentose phosphate pathway
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22
Q

Cytoskeleton

A
  • Provides structure to cell
  • Provides pathway for transport of material around cell

Three Components:
* Microfilaments
* Microtubules
* Intermediate filaments

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23
Q

Microfilaments

A
  • Made of solid polymerized rods of actin
  • Actin bundles and networks are resistant to compression and fracture providing protection
  • Actin filaments can use ATP to create force for movement through interaction with myosin (ex: muscle contraction)
  • Play a role in cytokinesis
  • Used to form clevage furrow during mitosis
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24
Q

Cytokinesis

A

Division of materials between daughter cells

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25
Q

Microtubules

A
  • Hollow polymers of tubulin proteins
  • Radiate throughout cell as main pathways for kinesis and dynein carrying vesicles
  • Compose cilia and flagella
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26
Q

Cilia

A
  • Projections from cell primarily involved in movement of materials along cell surface
  • Ex: line respiratory tract
  • Composed of 9 pairs of microtubules forming outer ring with two microtubules in center
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27
Q

Eukaryotic Flagella

A
  • Involved in movement of cell
  • Ex: sperm cells through reproductive tract
  • Composed of 9 pairs of microtubules forming outer ring with two microtubules in center
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28
Q

9 + 2 Structure

A
  • 9 pairs of microtubules forming outer ring with two microtubules in center
  • Only seen in eukaryotic organelles with movement
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29
Q

Centrioles

A
  • Found in centrosome
  • Organizing center for microtubules
  • Nine triplets of microtubules with hollow center
  • During mitosis, centrioles move to opposite ends of dividing cell and organize spindles
  • Kinetochores: Where centrioles attach to chromosomes
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30
Q

Intermediate Filaments

A
  • Group of filamentous proteins (keratin, desmin, vimentin, lamins)
  • Involved in cell-cell adhesion and maintenance of cytoskeleton
  • Can withstand lots of tension making more rigid
  • Anchor organelles, including nucleus
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31
Q

Epithelial Tissue

A
  • Cover body and line cavities
  • Protects against pathogen invasion and desiccation
  • Sometimes invovled in absorption, secretion, and sensation
  • Tightly joined to each other and underlying connective tissue basement membrane
  • In most organs constitute parenchyma (functional parts)
  • Often polarized
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32
Q

Polarized

A
  • One side faces a lumen (hollow inside) or outside world and other side interacts with bloods vessels and structural cells
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33
Q

Simple epithelia

A

One layer of cells

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34
Q

Stratified epithelia

A

multiple layers of cells

35
Q

Pseudostratified epithelia

A

Appear to have multiple layers due to differences in cell height, but truly only one layer

36
Q

Cuboidal

A

Cube-shaped cells

37
Q

Columnar

A

Long and thin cells

38
Q

Squamous

A

Flat and scalelike cells

39
Q

Connective Tissue

A
  • Supports and provides framework for epithelial cells
  • Main contributos of stroma (support structure)
  • Most produce and secrete materials like collagen and elastin to form extracellular matrix
  • Ex: Bone, cartilage, tendons, ligaments, adipose tisssue, and blood
40
Q

Prokaryotic Domains

A
  • Archaea
  • Bacteria
41
Q

Archaea

A
  • Single celled organisms visually similar to bacteria
  • Contain genes aand several metabolic pathways (more similar to eukaryotes vs bacteria)
  • Extremophiles: found in harsh environments (high temperature, high salinity, no light)
  • Can use alternative sources of energy (some photosyntehtic, many chemosynthetic)
  • Resistant to many antibiotics
42
Q

Bacteria

A
  • Contain cell membrane and cytoplasm
  • Some have flagella or fimbriae (like cilia)
  • Hard to develop medicines to target only bacteria
43
Q

Mutualistic Symbiotes

A

Both humans and bacteria benefit from relationship

44
Q

Pathogens/Parasites

A

Provide no advantage/benefit to host

45
Q

Cocci

A

spherical bacteria

46
Q

Bacilli

A

Rod-shaped bacteria

47
Q

Spirilli

A

Spiral-shaped bacteria

48
Q

Obligate aerobes

A

Bacteria that require oxygen for metabolism

49
Q

Anaerobes

A

Bacteria that use fermentation or another form of cellular metabolism that doesn’t require oxygen

50
Q

Obligate Anaerobes

A

Anaerobes that can’t survive in an environment containing oxygen

51
Q

Facultative Anaerobes

A

Bacteria that can use use oxygen if present for aerobic metabolism or can use anerobic metabolism if no oxygen is present

52
Q

Aerotolerant Anaerobes

A

Bacteria that is unable to use oxygen for metabolism, but not harmed by its presence.

53
Q

Cell Wall

A
  • Outer barrier of cell
  • Next layer is cell/plasma membrane (made of phospholipids)
  • Cell envelope = cell wall + membrane

Provides structure and controls movement of solutes in and out

54
Q

Gram positive

A

Envelope absorbs stain (purple)
* Have thick layer of peptidoglycan (polymeric substance of amino acids and sugars) and lipteichoic acid
* No outer membrane
* Aid pathogen by protecting from host’s immune system

55
Q

Gram negative

A

Envelope absorbs counterstain (pink/red)
* Very thin, but also contain a little peptidoglycan
* Have outer membranes with phospholipids and lipopolysaccharides (triggers immune response in humans)

56
Q

Prokaryotic Flagella

A
  • Long whiplike structures used for propulsion
  • Can have multiple
  • Filament: hollow helical structure made of flagellin
  • Basal body: complex structure anchoring flagellum and rotating
  • Hook: connects filament and basal body
  • Structure varies based on if gram-positive or gram-negative
57
Q

Chemotaxis

A

Cellular ability to detect chemical stimuli and move towards/away

58
Q

Plasmids

A
  • Small circular structures
  • Carry DNA not neccesary for prokaryote survival
  • Not considered part of genome but can have advantage (ex: antibiotic resistance)
    Episomes: can integrate in to the genome of bacteria
    Genetic recombination increases diversity and leads to evolution
59
Q

Archaea Bacteria Similarities

A
  • Single celled
  • No nucleus or membrane bound organelles
  • One circular chromsome
  • Divide by binary fission
  • Similar structure
60
Q

Archaea Eukaryote Similarities

A
  • Start translation with methionine
  • Have similar RNA polymerases
  • Associate DNA with histones
61
Q

Binary fission

A
  • Asexual reproduction in prokaryotes
  • Produces two identical daughter cells
  • Requires fewer events than mitosis, so faster
62
Q

Virulence factors

A

Traits that increase how pathogenic a bacteria is (toxin productions, projections, etc.)

63
Q

Genetic Recombination

A
  • Transformation
  • Conjugation
  • Transduction
64
Q

Transformation

A
  • Gaining foreign genetic matgerial from environment and integrating the foreign genetics into host genome
  • Usually foreign comes from other bacteria
  • Common in gram-negative rods
65
Q

Conjugation

A
  • Bacterial form of mating (sexual reproduction)
  • Two cells form conjugation bridge (made from sex pili on donor male)between allowing transfer of genetic material
  • Bacteria contain plasmids with sex factors that have needed genes
  • Unidirection transfer of plasmid from donor male (F+) to recipient female (F-)
  • Portion of genome transferred from cells that have undergone conjugation( high frequency recombination (Hfr)) to receipient
  • Leads to rapid antibiotic resistance or virulance factors in a colony
66
Q

Transduction

A
  • Transfer of genetic material from one bacteria to another using a bacteriophage as a vector
  • Only genetic recombination process requiring a vector
  • Obligate intracellular pathogens: Viruses don’t have ribosome to reproduce and synthesize protein so have to infect and use host cell machinery
  • Bacteriophages can accidentally trap some host DNA, so when infects another bacteria that host DNA is transferred
67
Q

Vector

A
  • Virus (Bacteriophages) carrying genetic material from one bacteria to another
68
Q

Transpoons

A
  • Genetic elements that can insert/remove themselves from a genome
  • Seen in prokaryotes and eukaryotes
  • Can disrupt gene if inserted within coding region
69
Q

Bacteria Growth

A
  1. Lag Phase: Bacteria adjust to environment, litle growth
  2. Exponential Phase: Bacteria use resources to multiply exponentially
  3. Stationary Phase: Bacteria multiplication stops as resources are all used
  4. Death Phase: Bacteria dies due to insuficent resources
70
Q

Virus

A
  • Made of genetic material, protein coat (capsid), and sometimes lipid envelope
  • Genetic information: circular/linear, single/double stranded, DNA/RNA
  • Obligate intracellular parasistes (can’t reproduce independently)
  • Must express and replicate genetic information in a host cell (because lack ribosomes, so can’t synthesize proteins)
71
Q

Capsid

A

Viral protein coat

72
Q

Envelope

A
  • If there is an envelope, it will surround the capsid
  • Made of phospholipids and virus-specific proteins
  • Sensitive to heat, detergents, and dessication
  • Envelope = easier to kill
  • No envelope = more resistant to sterilization and likely persistance on surfaces for a while
73
Q

Virions

A
  • Replicated virus using a host cell’s machinery
  • Released to infect other cells
74
Q

Bacteriophages

A
  • Viruses that specifically target bacteria
  • Don’t enter bacteria, but inject genetics
  • Have tail sheath and tail fibers
  • Tail sheath acts like syringe injecting genetic material into bacteria
  • Tail fibers help bacteriophage recognize and connect to correct host cell
75
Q

Positive sense

A

Single-stranded RNA virus where genome may be directly translated to functional proteins by ribosomes of host cell (like mRNA)

76
Q

Negative sense

A

Single-stranded RNA viruses that require synthesis of RNA strand complementary to negative-sense RNA strand
* This can than be used as template for protein synthesis
* Must carry RNA replicase in virion to make sure complementary strand is synthesized

77
Q

Retroviruses

A
  • Enveloped single-stranded RNA viruses
  • Usually virion contains two identical RNA molecules
  • Carry reverse transcriptase enzyme that synthesizes DNA from single-stranded RNA
  • DNA integrates into host cell genome where replicated and transcribed like host DNA
  • Allows for indefinite host cell infection
  • Ex: HIV
78
Q

Viral Life Cycle

A
  1. Infection
  2. Translation & Progeny Assembly
  3. Progeny Release
  4. Lytic and Lysogenic Cycles
79
Q

Infection

A
  • Infects specific cells (due to binding to specific receptors)
  • Virus binds to receptor bringing closer and fusing the enveloped virus with plasma membrane, allowing virions to enter
  • Sometimes misidentifies and brought in via endocytosis
  • Different portions of virion will insert
  • Enveloped viruses fuse with membrane and enter intact
  • Bacteriophages insert gentic material leaving capsids outside
80
Q

Translation & Progeny Assembly

A
  • Translation has to occur for reproduction
  • Requires translocation of genetics to correct area
  • Most DNA must go to nucleus to transcribe to mRNA which then goes to cytoplasm to translate into protein
  • Positive-sense RNA stay in cytoplasm for direct translation
  • Negative-sense RNA require sythenes of complementary strand using RNA replicase
  • Ribosomes, tRNA, amino acids, and enzymes transle viral RNA into protein
  • Many proteins are structural capsid
81
Q

Progeny Release

A
  1. Viral invasion may cause cell death leading to spilling of viral progeny
  2. Host cell can lyse due to too many viral progeny
    Lysis is disadvantage because can no longer use cell for life cycle
  3. Virus can leave by fusing with plasma membrane extrusion
    Extrusion allows host cell survival and continuous use (productive cycle)
82
Q

Lytic & Lysogenic Cycles

A

Lytic Cycle:
* Max use of cell’s machinery
* Don’t care about host cell survival
* Cell swells until lyses releasing virions to infect other
* Bacteria are virulent
* If virus doesn’t lyse, can integrate into host genome as a provirus or prophage

Lysogenic Cycle:
* Bacteriophage genome enters host genome and replicates with host cell as a provirus
* Environmental factors wil cause provirus to leave genome and restart lytic cycle
* Infenction with one strain of phage usually makes becteria less likely to superinfection (same infections with other phages)

83
Q

Prions

A
  • Infections nonliving proteins
  • Cause disease by triggering misfolding of proteins, usually conversion from a-helical to b-pleated sheet
  • Reduces solubility of protein and makes highlly resistant to degradation
  • Protein aggregates form and cell function is reduced
84
Q

Viroids

A
  • Small pathogens made of short circular single-stranded RNA that infect plants
  • Can bind to a lot of RNA sequences and silence genes in plant genome
  • Prevents needed protein synthesis and cause metabolic and structural dearangements
  • Few human viroids

MCAT Biology (8 decks)

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