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Biology > Chapter 1: The Cell > Flashcards

Chapter 1: The Cell Flashcards

1
Q

cell theory

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

membrane

A

Each cell has one that encloses cytosol.
Most eukaryotic organelles enclosed by membranes.
Eukaryotic membranes have phospholipid bilayer–hydrophobic interior, hydrophilic exterior

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3
Q

phospholipid bilayer

A

Hydrophilic exterior allows electrostatic interactions inside and outside of cell
Hydrophilic interior allows for selective permeability between interior of cell and environment

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4
Q

cytosol

A

Allows for diffusion of molecules throughout the cell

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5
Q

nucleus

A

Most heavily tested organelle on MCAT
Only present in eukaryotes
Surrounded by nuclear membrane/envelope (double membrane)
Contains all of genetic material necessary for replication (DNA), which is organized into chromosomes
Nuclear pores allow for selective two way exchange between cytoplasm and nucleus

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6
Q

nuclear envelope

A

Double membrane around nucleus
Allows for selective two way exchange between nucleus and cytoplasm via nuclear pores
Creates two distinct environments in the cell (nucleus and cytoplasm)
Allows for compartmentalization of transcription and translation

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7
Q

DNA

A

Contains coding regions called genes
Wound around organizing proteins called histones
Further wound into linear strands called chromosomes
Location in nucleus allows for compartmentalization of DNA transcription separate from RNA translation

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8
Q

nucleolus

A

Subsection of nucleus
Where rRNA is synthesized
25% of nucleic volume

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9
Q

mitochondria

A

Eukaryotic organelle
Powerhouse of the cell
Contains outer and inner membrane
Semi-autonomous (unlike other organelles)
Contain some of own genes and replicate independently of nucleus via binary fission
Thought to have come about when anaerobic prokaryote engulfed aerobic prokaryote
Capable of killing cell by release of enzymes from ETC

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10
Q

outer mitochondrial membrane

A

Barrier between cytosol and inner environment of mitochondria

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11
Q

inner mitochondrial membrane

A

Thrown into numerous infoldings (cristae)

Contains molecules and enzymes necessary for electron transport chain

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12
Q

cristae

A

Folds in inner mitochondrial membrane

Increases surface area available for electron transport chain enzymes

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13
Q

intermembrane space

A

Space between outer and inner mitochondrial membranes

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14
Q

matrix

A

Space inside inner mitochondrial membrane

Pumping of protons from matrix to intermembrane space establishes proton-motive force

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15
Q

proton-motive force

A

Pumping of protons from matrix to intermembrane space establishes proton-motive force
These protons flow through ATP synthase to generate ATP during oxidative phosphorylation

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16
Q

apoptosis

A

Programmed cell death
Kick started when mitochondria releases enzymes from ETC
Also can happen when lysosome release hydrolytic enzymes

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17
Q

lysosome

A

Membrane bound organelles that contain hydrolytic enzymes capable of breaking down substances like cellular waste and substances ingested during endocytosis

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18
Q

autolysis

A

When lysosome releases hydrolytic enzymes to result in apoptosis
Lead to degradation of cellular components

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19
Q

endoplasmic reticulum

A

Series of interconnected membranes that are contiguous with nuclear envelope
Surround nucleus
Single membrane is folded into multiple invaginations, which creates complex structures with central lumen
Two kinds: rough and smooth

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20
Q

rough ER

A

Studded with ribosomes

Permit translation of proteins destined for secretion directly in lumen

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21
Q

smooth ER

A

Lacks ribosomes
Utilized primarily for lipid synthesis and drug/poison detoxification
Transports proteins from rough ER to Golgi apparatus

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22
Q

Golgi apparatus

A

Consists of stacked membrane bound sacs
Right outside ER
Materials from ER to Golgi are transported in vesicles
Modifies ER products by addition of various groups, like carbohydrates, phosphates, and sulfates
Can add signal sequence to products that direct delivery of product to specific cellular location
Products are then repacked into vesicles and transferred to correct cellular destination

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23
Q

exocytosis

A

Release of secretory products

After release from Golgi apparatus, secretory storage vesicle merges with cell membrane and contents are released

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24
Q

vesicle

A

Materials created in RER are transported to Golgi apparatus (via SER) in vesicles
Vesicles also transport materials from Golgi to cellular destination
If product destined for secretion, vesicle will merge with cell membrane for exocytosis release

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25
Q

distribution of organelles

A

Different cells have different organelle amounts
Cells that require locomotion (i.e. sperm) have high concentration of mitochondria (energy!)
Cells involved in secretion (pancreatic/endocrine tissue) have high concentration of RER and Golgi apparatus
Transport cells (RBC’s) have no organelles at all

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26
Q

peroxisomes

A

Contain hydrogen peroxide
Allow for breakdown of very long fatty acid chains via beta-oxidation
Synthesis of phospholipids
Contain some pentose phosphate pathway enzymes

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27
Q

cytoskeleton

A

Maintain structure/shape of cell
Transport of materials around cell
Components: microfilaments, microtubules, and intermediate filaments

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28
Q

microfilaments

A

Made of rods of actin
Actin filaments organized into bundles & networks–resistant to breakage and compression
Cell protection
Filaments can also use ATP to generate force for movement by interacting with myosin (muscle contraction)
Play role in cytokinesis–division of materials between daughter cells
Pinch off connection between daughter cells

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29
Q

microtubules

A

Hollow polymers of tubulin
Primary pathways for vesicle carrying via motor proteins (kinesin and dynein)
Make up cilia and flagella

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30
Q

cilia

A

Projections from cell primarily involved in material movement along surface of cell
Mucus movement in respiratory tract
Composed of microtubules

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31
Q

eukaryotic flagella

A

Involved in movement of cell itself
Composed of microtubules made of tubilin
9+2 arrangement

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32
Q

9+2 structure

A

Cilia and flagella microtubule arrangement
9 pairs of microtubules in outer ring
2 microtubules at center
Only seen in eukaryotic cells of motility

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33
Q

centrioles

A

Found in centrosome
9 microtubules with hollow center
Organize mitotic spindle during mitosis when migrate to opposite poles of dividing cells
Attach to chromosomes via kinetochores and exert pulling apart force on sister chromatids

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34
Q

Intermediate filaments

A 
Diverse group of filamentous proteins (keratin and desmin)
Cell-to-cell adhesion
Maintenance of cytoskeleton integrity
Make cell more rigid
Anchor organelles like nucleus
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35
Q

epithelial tissue

A

Cover body and line cavities
Protection against pathogen invasion and desiccation
Absorption, secretion, sensation
Cells tightly joined together and to underlying basement membrane
Polarized: one side interacts with lumen/outside world, the other side interacts with blood vessels and structural cells

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36
Q

parenchyma

A

Functional part of an organ
Nephrons in kidney, hepatocytes in liver, acid producing cells in stomach
Consists of epithelial cells
Stroma is support structure (thanks to connective tissue)

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37
Q

simple epithelia

A

One layer of cells

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38
Q

stratified epithelia

A

Multiple layers of cells

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39
Q

psuedostratified epithelia

A

Appear to have multiple layers, really only has one

40
Q

connective tissue

A

Supports body and provides framework for epithelial cells to carry out functions
Main contributors of stroma (support structure) when epithelial cells contribute to parenchyma of organ
Bone, cartilage, tendons, ligaments, adipose tissue, blood
Most cells produce and secrete materials like collagen and elastin to form extracellular matrix

41
Q

prokaryotes

A

Simplest of all organisms
No membrane bound organelles
Single circular molecule of DNA concentrated in nucleoid region
DNA not coiled around histones
No membrane bound organelles, but may have plasmids
30S and 50S ribosomes

42
Q

nucleoid region

A

Where circular DNA molecule in prokaryotes is concentrated
This DNA not carried around histones
May have plasmids

43
Q

archaea

A

Single celled organisms that are visually similar to bacteria
Contain genes and metabolic pathways that are more similar to eukaryotes (start translation w/ methionine, contain similar RNA polymerases, associate DNA with histones)
Extremophiles
Resistant to many antibiotics
Divide by binary fission or budding

44
Q

bacteria

A

All contain cell membrane and cytoplasm
Some have flagella and fimbriae (analogous to cilia)
Outnumber human cells in the body 10:1
Do not form multicellular organisms, so responsible for protecting self from environment

45
Q

mutualistic symbiotes

A

Bacteria in the gut produce vitamin K (clotting) and biotin
Some bacteria prevent overgrowth of other bacteria
Babies are not colonized with bacteria yet, so given a vitamin K shot at birth to aid in clotting

46
Q

obligate aerobes

A

Require oxygen for metabolism

47
Q

anaerobes

A

Use fermentation or other metabolism that does not require oxygen

48
Q

obligate anaerobes

A

Cannot survive in oxygen containing environment

49
Q

facultative anaerobes

A

Can use oxygen for aerobic metabolism if present or can switch to anaerobic metabolism if no oxygen

50
Q

aerotolerant anaerobes

A

Unable to use oxygen but not harmed by it

51
Q

envelope

A

Cell wall + cell membrane in prokaryotes

52
Q

cell wall

A

In prokaryotes, forms outer barrier of cell
Provides structure and controls movement of solutes into and out of bacterium
Allows for maintenance of concentration gradient relative to environment
Two types of cell walls: (dependent on Gram staining process)
a) gram positive
b) gram negative

53
Q

gram positive bacteria

A 
Absorbs crystal violet stain
Appears deep purple
Consist of thick layer of peptidoglycan
Provides protection from host organisms immune system
Also contains lipoteichoic acid
No outer membrane
54
Q

peptidoglycan

A

Polymetric substance made from amino acids and sugars
Present in gram+ bacteria, and gram- (but in small amounts)
Penicillin targets the enzyme that catalyzes the cross-linking of peptidoglycan–if a gram+ cell can’t cross-link cell wall, it’s no longer an effective barrier

55
Q

lipoteichoic acid

A

Present in gram+ bacteria

Function unknown, but human immune system may be activated by exposure to this chemical

56
Q

gram negative bacteria

A

Do not absorb crystal violet stain
Absorb safranin counterstain, and appear pink-red
Thin layer of peptidoglycan
Contain lipopolysaccharides and phospholipids

57
Q

chemotaxis

A

Ability of a cell to detect chemical stimuli and move towards or away from them

58
Q

bacterial flagella

A

Made of flagellin

Composed of hook, filament, and basal body

59
Q

filament

A

Part of flagella

Hollow, helical structure composed of flagellin

60
Q

basal body

A

Complex structure that anchors the flagellum to the cytoplasmic membrane and is also the motor of the flagellum, rotating at rates of up to 300 hz

61
Q

hook

A

Connects filament and basal body so that, as basal body rotates, it exerts torque on the filament, which can thereby spin and exert the bacterium forward

62
Q

plasmids

A

Small circular structures on which DNA acquired from external sources may be carried
This DNA is not vital to survival of bacterium, but may carry advantage (like antibiotic resistance)
May contain virulence factors, which increase how pathogenic it is

63
Q

binary fission

A

Simple form of asexual reproduction seen in prokaryotes
Circular chromosome attaches to cell wall and replicates while cell continues to grow
Plasma membrane pinches towards midline to produce two identical daughter cells
Proceeds more rapidly than mitosis, because requires fewer events

64
Q

virulence factors

A

Traits that increase how pathogenic a bacterium is, like toxin production, projections that allow it to attach to cells, or evasion of immune system
Carried in plasmids

65
Q

episomes

A

Subset of plasmids
Capable of integrating into genome of bacterium
Help recombination and thus evolution of bacterial species over time

66
Q

transformation

A

Form of recombination process
Results from integration of foreign genetic material into host genome
Often from lysed bacteria that spill genetic contents into vicinity of bacteria capable of bacterium capable of transformation
Most gram- rods

67
Q

conjugation

A

Form of recombination process
Bacterial form of mating
Two cells form conjugation bridge that allows for the transfer of genetic material
Transfer is unidirectional (from donor male (+) to recipient female (-))
Bridge is made from appendages called sex pili found on donor male
Rapid acquisition of antibiotic of antibiotic resistance or virulence factors throughout a colony
F factor example:
Bacteria that possess F factor are called F+ cells; without are F-
F+ replicates F factor during conjugation and donates to F-
F- is now F+

68
Q

sex factor

A

Certain plasmids that are necessary for the formation of sex pili which creates the conjugation bridge
Relevant to conjugation
Best studied sex factor is the F (fertility) factor in E. coli

69
Q

F (fertility) factor

A

Best studied sex factor (in E. coli)
Type of plasmid
Bacteria that possess it are called F+ cells; without are F-
F+ replicates F factor during conjugation and donates to F-
F- is now F+

70
Q

transduction

A

Type of recombination process
Only recombination process that requires a vector–a virus that carries genetic material from one bacterium to another
Viruses can accidentally trap segment of host DNA during assembly inside host during reproduction, and when bacteriophage infects another bacterium, it can release this trapped DNA into new host cell.
This trapped DNA can integrate into genome, giving host additional genes.

71
Q

transposons

A

Genetic elements capable of inserting and removing selves from genome.
Observed in prokaryotes and eukaryotes

72
Q

lag phase

A

Bacteria adapt to local conditions

73
Q

exponential/log phase

A

Bacteria grow exponentially

Resources reduced

74
Q

stationary phase

A

Because resources were reduced in exponential phase, growth is slowed

75
Q

death phase

A

environment can no longer support amount of bacteria

76
Q

viruses

A

Are not living things; acellular
Lack organelles and a nucleus
Have genetic material, protein coat, sometimes an envelope containing lipids, tail sheath, tail fibers
Genetic material may be SS or DS, circular or linear, RNA or DNA
Lack ribosomes to carry out protein synthesis

77
Q

capsid

A

virus protein coat

78
Q

virus envelope

A

Surrounds capsid
Sensitive to heat, detergents, and desiccation
Easier to kill
Composed of phospholipids and virus-specific proteins

79
Q

virions

A

Viral progeny

Released to infect additional cells

80
Q

bacteriophages

A

Viruses that target bacteria

Do not enter bacteria, but inject genetic material

81
Q

tail sheath

A

Virus “syringe”, that can inject genetic material into bacterium

82
Q

tail fibers

A

help bacteriophage recognize and connect to correct host cell

83
Q

positive sense

A

Type of ssRNA virus

Implies the genome may be directly translated to functional proteins by the ribosomes by the host cells, just like mRNA

84
Q

negative sense

A

Type of ssRNA virus
Requires the synthesis of an RNA strand complementary to the negative sense RNA strand, which can then be used as a template for protein synthesis
Must carry an RNA replicase in the virion to ensure that the complementary strand is synthesized

85
Q

retroviruses

A

Enveloped, ssRNA viruses in the family Retroviridae
Virion usually carries 2 identical RNA molecules
Carry reverse transcriptase, which synthesizes DNA from ssRNA
The DNA then integrates into the host cell genome, where t is replicated and transcribed as if it were the host cell’s own DNA.
Only way to cure the infection is to kill the infected cell itself

86
Q

viral infection

A

Viruses can only bind to specific set of cells with proper receptors
Enveloped viruses, like HIV, (which enter the cell intact) fuse with plasma membrane of cell, allowing entry of virion into host cell
Bacteriophages only inset genetic material
Host cell may misinterpret binding of virus to membrane as nutrient, etc, and bring virus into cell via endocytosis

87
Q

DNA virus reproduction

A

Must go to the nucleus in order to be transcribed to mRNA

mRNA then goes to cytoplasm to be translated to protein

88
Q

positive sense virus reproduction

A

Genetic material stays in cytoplasm, where it’s directly translated to protein by host cell ribosomes

89
Q

negative sense virus reproduction

A

Requires synthesis of complementary RNA strand via RNA replicase, which can then be translated to form proteins

90
Q

retrovirus reproduction

A

Forms DNA through reverse transcription that travels to nucleus, where it can be integrated into host genome
Must transcribe new copies of ssRNA from DNA that entered host genome to reenter viral genome

91
Q

lytic cycle

A

Bacteriophage makes maximal use of cells machinery with little regard for survival of host cell
Once host cell is swollen with new virions, cell lyses, and other bacteria can be infected
Bacteria in the lytic phase are termed virulent

92
Q

virulent

A

Bacteria in the lytic phase

Swell with new virions and lyse

93
Q

lysogenic cycle

A

If virus does not lyse the bacterium, virus will be replicated as bacterium replicates because it is now part of host’s genome
Virus is known as provirus or prophage
May enter lytic cycle via variety of factors

94
Q

prion

A

Infectious proteins
Nonliving things
Cause disease by triggering misfolding of other proteins
Usually involves conversion of a protein from alpha-helical structure to beta-pleated sheet
Drastically reduces solubility of protein, as well as ability of cell to degrade misfolded protein
Eventually reduces function of cell
Known to cause mad cow, Creutzfeldt-Jakob, and familial fatal insomnia

95
Q

viriods

A

Small plant pathogens
Consists of very short circular ssRNA
Bind to RNA sequences and silence genes in the plant genome
Prevent synthesis of necessary proteins and can subsequently cause metabolic and structural derangement in the plant cell
Often plant pathogens, but some human pathogens, like Hepatitis D

Biology (4 decks)

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