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The Cell Flashcards

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1
Q

What are the four basic tenets of the cell theory

A
  • all living things are made of cells
  • the cell is the basis of all forms of life
  • cells can only come from pre-existing cells
  • cells carry genetic information in the form of DNA - this genetic information is passed from parent to daughter cell
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2
Q

Why are viruses not considered living things

A
  • acellular meaning they cannot replicate by themselves but must use a host cell to reproduces - they may also only use RNA as genetic information
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3
Q

What are the main differences between eukaryotic and prokaryotic cell

A
  • eukaryotes have a nucleus, prokaryotes do not have a true nucleus instead they have a nucleoid region
  • eukaryotes cells have membrane-bound organelles, prokaryotes do not have membrane-bound organelles
  • eukaryotes cells are multicellular or unicellular, prokaryotes are only unicellular
  • all prokaryotes have a cell wall, not all eukaryotes have a cell wall
  • ribosomes size is different - prokaryotic ribosomes are smaller than eukaryotic ribosomes
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4
Q

What are key features of the nucleus

A
  • contains DNA organized into chromosomes
  • surrounded by a nuclear membrane/envelope that allows for selective exchange through the nuclear pores via cytoplasm and nucleus
  • the nucleolus is inside of the nucleus (rRNA)
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5
Q

Where is rRNA synthesized

A

in the nucleolus - that is inside the nucleus - the dark spot you can see on imaging

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6
Q

What are the DNA coding regions called

A

genes

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7
Q

What protein is responsible for binding DNA together

A

Histones wind linear DNA together to form the double helix - they then wind further into linear strands called chromosomes

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8
Q

What are key features of the mitochondria

A
  • powerhouse of the cell
  • has and outer and inner membrane with an inter membrane space between
  • are semi-autonomous meaning they can divide independently via binary fission and contain their own genes - they have a circular dsDNA that is plasmid like
  • can trigger apoptosis by releasing mitochondrial (from electron transport chain) enzymes into their cytoplasm
  • only the maternal line is passes down
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9
Q

What is the role of the inner membrane of the mitochondria

A
  • foldings are called cristae
  • makes molecules/enzymes of the electron transport chain
  • cristae increase the surface area available for the electron transport chain
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10
Q

What is the role of the outer membrane of the mitochondria

A

barrier between cytosol and inner membrane

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11
Q

In what ways is the mitochondria different and similar from the eukaryotic cell

A
  • both have double stranded DNA
  • mitochondria have circular plasmid like and eukaryotic cell have linear DNA
  • mitochondria divide by binary fission
  • both contain their own genes
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12
Q

What are key features of lysosomes

A
  • contain hydrolytic enzymes that breakdown substances/autolysis
  • work with endosomes - to transport materials to trans golgi, cell membrane, or lysosomal pathway for degradation
  • membrane prevents enzymes from harming the cell
  • can release enzymes called autolysis - resulting in apoptosis and leads to direct degradation of the cell
  • single surrounding membrane
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13
Q

What are key features of the endoplasmic reticulum

A
  • smooth and rough ER
  • interconnected membranes that are continuous with the nuclear membrane
  • double membraned with central lumen
  • rough ER - studded with ribosomes to translate proteins that are then secreted into the lumen
  • smooth ER - no ribosomes - lipid synthesis and detoxification of certain drugs/poisons
  • RER to SER to Golgi apparatus
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14
Q

What are key features of the rough ER

A
  • RER

- translation of proteins secreted into the lumen - studded with ribosomes

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15
Q

What are key features of the smooth ER

A
  • SER
  • lipid synthesis and detoxification of certain drugs/poisons
  • synthesize phospholipids in cell membranes
  • no ribosomes
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16
Q

What are key features of the Golgi apparatus

A
  • stacked membrane-bond sacs in which cellular produces can be modified, packaged, and directed to specific cellular locations
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17
Q

What are key features of peroxisomes

A
  • contain hydrogen peroxide that can break down very long fatty acid chains via beta oxidation
  • can also participate in phospholipid synthesis and the pentose phosphate pathway
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18
Q

The cell membrane and organelle membranes contain _____ that arrange to form _____ interior and a _____ exterior with a

A
  • phospholipids
  • hydrophobic interior - tail
  • hydrophilic exterior - polar head
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19
Q

What are the key features of cytosol

A
  • suspends the organelles and allows for diffusion of molecules throughout the cell
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20
Q

What are the key features of cytoskeleton

A
  • provides structure to cell and helps maintain its shape

- provides a conduit for transport fo materials around the cell

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21
Q

What are the three main components of the cytoskeleton

A

microfilaments, microtubules, and intermediate filaments

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22
Q

What are key features of microfilaments

A
  • Microfilaments are solid polymerized rods of actin

Functions

  • structural protection of the cell
  • can cause muscle contraction though interaction with myosin using ATP
  • forms the cleavage furrow during cytokinesis in mitosis
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23
Q

What are the key features of microtubules

A
  • Microtubules are hollow polymers of tubulin

Functions

  • provide primary pathway for motor proteins (dynein and kinesin) to carry residues
  • compose cilia and flagella - organized in 9pair 2 structure
  • centrioles are in centrosomes and are involved in the organization of the mitotic spindle
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24
Q

What is a similarity and difference between cilia and flagella in eukaryotes

A
  • both composed of microtubules and have the same 9+2 structure (in eukaryotes only)
  • cilia move materials along cell surfaces
  • flagella move the cell itself
  • 9 pairs of microtubules make a circle
  • 2 microtubules in the center
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25
Q

What are key features of intermediate filaments

A
  • cell to cell adhesion
  • maintenance of the overall integrity of the cytoskeleton, increase structural integrity by withstanding tension
  • help anchor organelles
  • they type of intermediate filament protein within a cell is specific to the cell and tissue type
  • keratin,desmin,vimentin, lamin
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26
Q

What are the four different types of tissues

A
  • epithelial
  • connective
  • muscle
  • nervous
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27
Q

What are key features of prokaryotes

A
  • simplest of all organisms - always unicellular
  • no membrane bound organelles
  • genetic material is a single circular molecule of DNA that is concentrated in a nucleoid region
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28
Q

What are key features of Archaea

A
  • often extremophiles - living in harsh environments
  • uses chemosynthesis more than photosynthesis
  • more similar to eukaryotes than bacteria
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29
Q

How are eukaryotes similar to archaea

A
  • start translation with methionine (amino acid)
  • have histones
  • similar RNA polymerases
  • may share an origin
  • resistant to many antibiotics
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30
Q

How are archaea similar to bacteria

A
  • single circular chromosome
  • divide by binary fission or budding
  • similar overall structure
  • both prokaryotes
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31
Q

What are key features of bacteria

A
  • all have cell membrane and cytoplasm
  • some have a cell wall, flagellar or fimbriae ( cilia like)
  • similar structures to eukaryotes
  • mutualistic symbiosis with human
  • pathogenesis - cause diseases in humans
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32
Q

What are some examples of mutualistic symbiosis with humans and bacteria

A
  • vitamin K - bacteria break down
  • biotin B7 - bacteria can produce
  • outcompete bad bacteria
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33
Q

What are the three main shapes of bacteria

A
  • cocci - spherical bacteria
  • bacilli - rod shaped
  • spirilli - spiral shaped - not likely to be pathogens
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34
Q

What are the four types of bacteria metabolic processes

A
  • obligate aerobes
  • obligate anaerobes
  • facultative anaerobes
  • aerotolerant anaerobes
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35
Q

What is an obligate aerobes

A
  • bacteria requires oxygen

- cannot live in an environment without oxygen

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36
Q

What is an obligate anaerobes

A
  • bacteria cannot survive in an oxygen environment

- bacteria only carries out anaerobic metabolism

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37
Q

What is a facultative anaerobe

A
  • can survive with or without oxygen

- changes metabolic process depending on the environment

38
Q

What is an aerotolerant anaerobe

A
  • can survive in an oxygen environment

- cannot use oxygen for metabolism

39
Q

What is the bacterial envelope composed of

A
  • cell wall and the cell membrane

- controls the movement of solutes into and out of the cell

40
Q

How are bacteria classified using their cell wall

A
  • based on color
  • gram negative - thin cell wall - pink
  • gram positive - thicker cell wall - purple
41
Q

What are the difference between gram negative and gram positive cell walls

A
  • gram negative have thin cell wall composed of peptidoglycan and an outer membrane containing phospholipid and lipopolysaccharides - stain pink
  • gram positive have a thick cell wall composed of peptidoglycan and lipoteichoic acid - stain purple
42
Q

What is chemotaxis

A
  • moving in response to chemical stimuli
43
Q

How do prokaryotes carry out the electron transport chain

A
  • using the cell membrane
44
Q

What is the difference between prokaryotic and eukaryotic ribosomes

A
  • prokaryotic ribosomes are smaller - 30S and 50S

- eukaryotic ribosomes are larger - 40S and 60S

45
Q

What kind of bacteria have lipoteichoic acid in their cell wall

A

gram +

46
Q

What kind of bacteria have lipopolysaccharides in their cell wall

A

gram -

47
Q

How do prokaryotes multiply

A
  • through binary fission - the chromosomes replicates while the cell grows in size until the cell wall begins to grow inward along the midline of the cell and divides it into two identical daughter cells
48
Q

Where is extrachromosomal material found in prokaryote

A

in plasmids

49
Q

What are plasmids

A
  • store extrachromosomal material that is found in bacteria and archea (prokaryotes)
  • can contain antibiotics resistance genes or virulence factors
  • can integrate into the genome - called episomes
50
Q

What are episomes

A
  • plasmids that integrate into the genome
51
Q

What is the purpose of genetic recombination in bacteria

A
  • it increases bacterial diversity
52
Q

What is transformation in bacteria

A
  • occurs when genetic material from the surrounding environment is taken up by a cell and this material can incorporate into its genome
53
Q

What are the types of genetic recombination possible in bacteria

A
  • transformation
  • conduction
  • transduction
  • transposons
54
Q

What is conduction in bacteria

A
  • transfer of genetic material from one bacterium to another across a conjunction bridge
  • a plasmid can be transferred from from F+ cells to F- cells or a portion of the genome can be transferred from Hfr cell to a recipient
55
Q

What is transduction in bacteria

A
  • transfer of genetic material from one bacterium to another via a bacteriophage vector
56
Q

What are transposons

A
  • genetic elements that insert into or remove themselves from the genome
57
Q

What are the phases in detail of bacterial growth

A
  • lag phase - bacteria adapt to new local conditions
  • exponential/log phase - growth then increases exponentially
  • stationary phase - as resources are reduces - growth levels off
  • death phase - resources are depleted and bacteria being to die
58
Q

What are the components of a virus

A
  • genetic material
  • protein coat called capsid
  • lipid containing envelope - sometimes
59
Q

What are obligate intracellular parasites

A
  • cannot survive or replicate outside of a host cell

- viruses

60
Q

What is an example of obligate intracellular parasites

A
  • viruses

- certain types of bacteria

61
Q

What are virions

A
  • individual virus particles
62
Q

What are bacteriophages

A
  • viruses that target bacteria
  • have a tail sheath that injects its genetic material into a bacterium
  • tail fibers - allow the bacteriophage to attach to the host cell
63
Q

What is the role of the tail sheath and tail fibers in bacteriophages

A
  • have a tail sheath that injects its genetic material into a bacterium
  • tail fibers - allow the bacteriophage to attach to the host cell
64
Q

What are virus genomes composed of

A
  • ssRNA
  • dsRNA
  • ssDNA
  • dsDNA
65
Q

ssRNA viruses are either ____ or _____ sense

A
  • positive sense - can be translated by the host cell
  • negative sense - requires a complementary strand to be synthesized by RNA replicase forming a + sense before translation can occur
66
Q

How is negative ssRNA synthesized to positive sense before translation

A
  • RNA replicase
67
Q

Retroviruses contain a ___ genome from which a complementary ____ strand is made using _______ . Then the ____ strand can be integrated into the genome

A
  • ssRNA genome
  • DNA strand
  • reverse transcriptase
  • DNA strand
68
Q

How do viruses infect cells

A
  • attach to specific cell receptors and then enter the cell by fusing with plasma membrane, endocytosis or infecting the genomes into the cell then the virus reproduces
69
Q

What are the three ways viruses can enter into a cell

A
  • fusing with the plasma membrane
  • endocytosis
  • injecting genome into the cell
70
Q

How do viruses reproduce in cells

A
  • reproduces by replicating and translating genetic material using the host cell’s ribosome, tRNA, amino acids, and enzymes
71
Q

How are virus progeny release from the cell

A
  • cell death
  • cell lysis
  • extrusion
72
Q

What are the two life cycles of bacteriophages

A
  • lytic cycle

- lysogenic cycle

73
Q

What are prions

A
  • infectious proteins that trigger misfolding of other proteins, usually converting an alpha helical structure into a beta pleated sheet
  • this decreases the solubility of the protein and increases its resistance to degradation
74
Q

What are 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
75
Q

What is the lytic cycle

A
  • the bacteriophage produces massive numbers of new virions until the cell lyses
  • bacteria in the lytic phase are called virulent
76
Q

What is the lysogenic cycle

A
  • the virus integrates into the host genome as a provirus or prophase - which then can 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
77
Q

Hyperbaric oxygen may be used as a treatments for certain types of bacterial infections. In this therapy the partial pressure of oxygen is increased causing an increases in the partial pressure of oxygen in the tissues of the patient. This treatment is most likely used for infections with

  • obligate aerobic bateria
  • facultative anaerobic bacteria
  • aerotolerant anaerobic bacteria
  • obligate anaerobic bacteria
A
  • obligate anaerobic bacteria
78
Q

Which of the following does NOT describe connective tissue cells

  • they account for most cells in muscles, bones, and tissues
  • they secrete substances to form the extracellular matrix
  • in organs they tend to form the stoma
  • in organs they provide support for epithelial cells
A
  • they account for most of the cells in muscles, bones, and tissue cells
79
Q

Which of the following types of nucleic acid could form the genome of a virus
I. ssRNA
II. dsDNA
III. ssDNA

  • I
  • II
  • I and II
  • I, II, and III
A
  • I, II, and, III
80
Q

Which of the following activities occur in the golgi apparatus

  • synthesis of proteins
  • modification and distribution of proteins
  • breakdown of lipids and carbohydrates
  • production of ATP
A
  • modification and distribution of proteins
81
Q

Mitochondrial DNA is
I. circular
II. self-replicating
III. single-stranded

  • I
  • II
  • I and II
  • I, II, and III
A
  • I and II
82
Q

Which of the following is NOT a function of the SER

  • lipid synthesis
  • poison detoxification
  • protein synthesis
  • transport of proteins
A
  • protein synthesis
83
Q

What is the main function of the nucleolus

  • ribosomal RNA synthesis
  • DNA replication
  • cell division
  • chromosome assembly
A
  • ribosomal RNA synthesis
84
Q

Which of the following organelles is surround by a single membrane

  • lysosomes
  • mitochondria
  • ribosomes
  • nuclei
A
  • lysosomes
85
Q

Which of the following is NOT a difference that would allow one to distinguish a prokaryotic and eukaryotic cell

  • ribosomal subunit weight
  • presence of a nucleus
  • presence of a membrane on the outside surface of the cell
  • presence of a membrane-bound organelles
A
  • presence of a membrane on the outside surface of the cell
86
Q

Which of the following does not contain tubulin

  • cilia
  • flagella
  • microfilaments
  • centrioles
A
  • microfilaments
87
Q

Herpes simplex virus enters the human body and remains dormant in the nervous system until it produces an outbreak after exposure to heat, radiation, or other stimuli. Which of the following statements correctly describes HSV

  • while it remains dormant in the nervous system the virus is in the lytic cycle
  • during an outbreak the virus is in the lysogenic cycle
  • HSV adds it genetic information to the genetic information of the cell
  • the HSV contains a tail sheath and tail fibers
A
  • HSV adds its genetic information to the genetic information of the cell
88
Q

Resistance to antibiotics is a well recognized medical problem. Which mechanisms can account for a bacterium ability to increase its genetic variability and thus adapt itself to resist different antibiotics
I. binary fission
II. conduction
III. transduction

  • I and II
  • I and III
  • II and III
  • I, II, and III
A
  • II and III
89
Q

A bacterial cell is noted to be resistant to penicillin. The bacterium is transferred to a colony that lacks the fertility factor, and the rest of the colony does not become resistant to penicillin. However, the penicillin- resistant cell has also started to exhibit other phenotypic characteristics including secretion of a novel protein. Which of the following methods of bacterial recombination is NOT likely to account for this change

  • conjunction
  • transformation
  • transduction
  • infection with a bacteriophage
A
  • conjunction
90
Q

In Alzheimer’s disease, a protein called the amyloid precursor protein is cleaved to form a beta amyloid. This protein has beta sheet structure that precipitates to form plaques in the brain. This mechanism of disease is most similar to which of the following pathogens

  • bacteria
  • viruses
  • prions
  • viroids
A
  • prions
91
Q

After infection fo a cell, a viral particle must transport itself to the nucleus in order to produce viral proteins. What is likely genetic content of the virus

  • dsDNA
  • dsRNA
  • positive sense RNA
  • negative sense RNA
A
  • dsDNA
  • a virus that requires transport to the nucleus in order to produce viral proteins likely requires use of nuclear RNA polymerase in order to create mRNA that can be translated to protein. Therefore only DNA viruses need to be transported to the nucleus to produce viral proteins

Biology MCAT (3 decks)

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