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The Cell Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Theory of endosymbiosis

A

Eukaryotic cells emerged when mitochondria and choloroplasts, once free-living prokaryotes, took up permanent residence inside other large cells

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2
Q

Eukaryotic Cell

A

● Internal membrances that compartmentalized the cell so that complex chemical reactions can be carried out efficiently in separate regions of a cell
● Nucleus bound by a double membrane
● All cells of the human body are eukaryotic cells
● DNA wrapped with histone proteins into chromosomes
● Ribosomes are largerr
● Metabolism is aerobic
● Cytoskeleton present
● Mainly multicellular with differentiation of cell types
● Cells are larger

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3
Q

Cell thoery

A

● All organisms are composed of cells
● All celss arise from preexisting cells
● Cell is the basic component of life

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4
Q

Prokaryotic Cell

A 
● Simple cells containing no nuclei or other internal membrances
● All bacteria are prokayotic cells
● No nucleus -- they have a nucleoid region, which is a non-membrane-bound region where the chromosome is located
● Circular, naked DNA
● Ribosomes are very small
● Metabolism is anaerobic or aerobic
● Cytoskeleton absent
● Mainly unicellular
● Cells are very small
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5
Q

Nucleolus

A

● Inside the nucleus
● Where ribosomal RNA (rRNA) is synthesized according to instructions from the DNA
- Large and small subunits of ribosomes are also assembled there
● Combines proteins imported from the cytoplasm with rRNA made in the nucleolus
● Nucleoli are not membrane-bound structures but are actually a tangle of chromatin and unfinished riosomal precursors

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6
Q

Ribosomes

A

● Protein factories
● Can be found free in the cytoplasm or bound to the endoplasmic reticulum
● Free ribosomes are associated with protein produced for the cell’s own use, while ribosomes attached to the ER are meant for export out of the cell

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7
Q

Peroxisomes

A

● Found in both plant and animal cells
● Contain catalase, which converts hydrogen peroxide (H2O2), a waste product of respiration in the cell, into water with the release of oxygen atoms
● They also detoxify alcohol in liver cells

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8
Q

Endomembrane System

A

● Regulates protein traffic and performs metabolic functions in cells
● Includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane

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9
Q

Nucleus

A

● Contains chromosomes which are wrapped with special proteins into a chromatin network
● Surrounded by nuclear envelope

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10
Q

Nuclear envelope

A

● A selectively permeable membrane that separates the contents of the nucleus from the cyoplasm
● Contains pores to allow for the transport of molecules, like messenger RNA (mRNA), which are too large to diffuse directly through the envelope

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11
Q

Endoplasmic Reticulum

A

Membranous system of channels and flattened sacs that traverse the cytoplasm and account for more than half the total membranes in a eukaryotic cell

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12
Q

Rough Endoplasmic Reticulum

A

Studded with ribosomes and produces proteims

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13
Q

Smooth Endoplasmic Reticulum

A

● Assists in the synthesis of steroid hormones, like sex hormones, and of other lipids
● Stores Ca++ ions in muscle cells to facilitate normal muscle contractions
● Detoxifies drugs and poisons from the body

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14
Q

Golgi Apparatus

A

● Lies near the nucleus and consists of flattened membranous sacs stacked next to one another and surroundd by vesicles
● They process and package substances produced inthe rough ER and secrete hte substances to other parts of the cell or to the cell surface for export

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15
Q

Lysosomes

A

● Sacs of hydrolytic enzymes surrounded by a single membrane
● Principle site of intracellular digestion
● With the help of the lysosome, the cell continually performs autophagy
● Generally not found in plant cells

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16
Q

Hydrolytic enzymes

A

Digestive enzymes

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17
Q

Autophagy

A

The process of breaking down and recycling cell parts in a cell

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18
Q

Apoptosis

A

Programmed destruction of cells

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19
Q

Mitochondria

A

● Site of cellular respiration
● Have an outer double membrane and an inner series of membranes called cristae
● Contain their own DNA
● Constantly divide and fuse with each other in order to exchange DNA and compensate for one another’s defects

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20
Q

Vacuoles

A

● Membrane-bound structures used for storage
● Large vesicles derived from the ER and Glogi apparatus
● Mature plant cells generally have a single large central vacuole
● Many freshwater protists have contractile vacuoles

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21
Q

Contractile vacuoles

A

● Present in many freshwater protists

● Pump out excess water

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22
Q

Food vacuoles

A

Formed by the phagocytosis of foreign material

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23
Q

Chloroplast

A

● Contain the green pigment chlorophyll that abosrobs light energy and synthesizes sugar
● Found in plants and algae
● Double outer membrane and another inner membrane system called thylakoids

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24
Q

Cytoskeleton

A

● Complex mesh of protein filaments that extends throughout the cytoplasm
● Includes microtubules and microfilamnets

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25
Q

Microtubules

A

Hollow tubes made of the protein tubulin that make up the cilia, flagella, and spindle fibers

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26
Q

Cilia / Flagella

A

● Move cells from one place to another

● Consists of 9 pairs of microtubules organized around 2 singlest microtubules

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27
Q

Flagella

A

● Move cells from one place to another
● Consists of 9 pairs of microtubules organized around 2 singlest microtubules
● When present in prokaryotes, they are not made of microtubules

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28
Q

Spindle fibers

A

Help separate chromosomes during mitosis and meiosis and consist of microtubules organized into 9 triplets with no microtubules in the centre

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29
Q

Microfilaments

A

● Assembled from actin filaments

● Help support the shape of the cell

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30
Q

Centrioles, centrosomes, and the Microtubule Organizing Centers

A

● Nonmembranous structures that lie outside the nuclear membranes
● Organize spindle fibers and give rise to the spindle apparatus required for cell division
● Two centrioles oriented at right angles to each other make up one centrosome
● Plant cells lack centrosomes, but have MTOCs

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31
Q

Cell wall

A

● One cell structure not found in animal cells
● Plants and algae have cell walls made of cellulose
● Cell walls of fungi are usually made of chitin

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32
Q

Chitin

A

Prokaryotes conssit of other polysaccharides and complex polymers

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33
Q

Primary cell wall

A

Immediately outside the plasma membrane

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34
Q

Second cell wall

A

Underneath the primary cell wall

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35
Q

Middle lamella

A

The thin gluey layer formed between the two new cells when a plant cell divides

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36
Q

Plasma Membrane

A

● Selectively permeable membrane that regulates the steady traffic that enters and leaves the cell
● Eukaryotic membrane consists of a phospholipid bilayer with proteins dispersed throughout the layer

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37
Q

Fluid mosaid model

A

S. J. Singer’s description of the cell membrane

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38
Q

Integral proteins

A

Have nonpolar regions that completely span the hydrophobic interior of the cell membrane

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39
Q

Peripheral proteins

A

Loosely bound to hte surface of the cell membrane

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40
Q

Cholesterol molecules

A

Embedded in the interior of the bilayer to stabilize the cell membrane

41
Q

Glycolipids

A

● Carbohydrates covalently bonded to lipids
● Extend from the external surface of the plasma membrane
● Signal molecules that distinguish one cell type from another

42
Q

Glycoproteins

A

● Carbohydrates covalently bounded to protein
● Extend from the external surface of the plasma membrane
● Signal molecules that distinguish one cell type from another
- Glycoproteins on the surface of red blood cells are responsible fo ABO and Rh blood types

43
Q

Transport

A

● Movement of substances into and out of a cell

● Can be either active or passive

44
Q

Active transport

A

● Requires energy (ATP)
● Movement of molecules gainst a gradient
● Pumps or carriers, contractile vacuole, exocytosis, pinocytosis, phagocytosis, receptor-mediated endocytosis

45
Q

Passive transport

A

● Requires no energy
● Movement of molecules down a concentration gradient from a region of high concentration to a region of low concentration until equilibrium is reached
● Examples are diffusion and osmosis

46
Q

Diffusion

A

● Two types – simple and facilitated

● Random movement of molecules or other particles from a higher concentration to a lower concentration

47
Q

Simple difusion

A

● Does not involve protein channels
● Examples if found in the glomerulus of hte human kidney, where solutes dissolved in the blood diffuse into Bowman’s capsule of the nephron

48
Q

Facilitated diffusion

A

Requires a hydrophilic protein channel that will passively transport specific substances across the membrane

49
Q

Countercurrent exchange

A

● Special case of simple diffusion

● The flow of adjacent fluids in opposite directions that maximizes the rate of simples diffusion

50
Q

Osmosis

A

Specific type of diffusion of water across a membrane

51
Q

Solvent

A

The substance that does the dissolving

52
Q

Solute

A

The substance that dissolves

53
Q

Hypertonic

A

Having greater concentration of solute than another solution

54
Q

Hypotonic

A

Having lesser concentration of solute than another solution

55
Q

Isotonic

A

Two solutions containing equal concentration of solutes

56
Q

Osmotic potential

A

The tendency of water to move across a permeable membrane into a solution

57
Q

Water potential

A

● psi
● Results from two factors – solute concentration and pressure
● Water potential for pure water is zero
● the addition of solutes lowers water potential to a value less than zero
● Water will move across a membrane from the solution with the higher water potential to the solution with the lower water potential

58
Q

Turgid

A

The swelling of the plant cells when water flow into the cell

59
Q

Plasmolysis

A

Cell shrinking

60
Q

Aquaporins

A

● Special water channel proteins found in certain cells that facilitate the diffusion of massive amounts of water across a cell membrane
● They do not affect the water potential gradient or the idrection of water flowing
● They affect the rate at which water diffuses down its gradient

61
Q

Gated channels

A

Open and close in response to variables such as turgor pressure of a cell

62
Q

Pumps/Carriers

A

Carry particles across the membrane by active transport

63
Q

Sodium-potassium pump

A

Pumps Na+ and K+ ions across a nerve cell membrane to return the nerve to its resting state

64
Q

Electron transport chain

A

Consists of proteins htat pump protons across hte cristae membrane

65
Q

Contractile vacuoles

A

Pumps out excess water that has diffused inward because the cell lives in a hypotonic environment in freshwater Protista

66
Q

Exocytosis

A

Occurs as vesicles release neurotransmitters into a synapse in nerve cells

67
Q

Pinocytosis

A

● Cell drinking
● Uptake of large, dissolved, particles
● The plasma membrane invaginates around the particles and encloses them in a vesicle

68
Q

Phagocytosis

A

● Engulfing of large particles or small cells by pseudopods

● Cell membrane wraps around the particle and encloses it into a vacuole

69
Q

Receptor-mediated endocytosis

A

● Enables a cell to take up large quantities of very specific substances
● A process by which extracellular substances bind to receptors on the cell membrane
● Once the ligand binds to the receptors, endocytosis begins
● The receptors, carrying the ligand, migrate and cluster along the membrane, turn inward, and become a coated vesicle that enters the cell
● This is the way cells take in cholesterol from the blood

70
Q

Ligand

A

● The general name for any molecule that binds specifically to a receptor site of another molecule
● Never enters the cell

71
Q

Bulk flow

A

● Overall movement of a fluid in one direction in an organism
● always from source to sink

72
Q

Quorum sensing

A

● Simple bacterial cells respond to changes in population density
●Vibrio fisheri (bacteria) produces the bioluminsescne tsubstance luciferin that makes the bacteria glow
- By using quorum sensing, V. fischeri produces luciferin only when its population is large enough that its bioluminescence can really be noticed

73
Q

Gap junctions

A

● Permit the passage of materials directly from the cytoplasm of one cell to the cytoplasm of an adjacent cell
● In the muscle tissue of the heart, the flow of ions through the gap junctions coordinates the contractions of the cardiac cells

74
Q

Plasmodesmata

A

Connect one plant cell to the next

75
Q

Paracrine signaling

A

Release of local signals from one cell to nearby cells

76
Q

Synaptic signaling

A

A neuron releases neurotransmitter into a synapse to stimulate an adjacent neuron to fire or muscle to contract

77
Q

Long distance signaling

A

● Characteristic of the endocrine system in which hormones released by endocrine glands circulate in the blood to reach target organs or structures
● Three stages – reception, transduction and response

78
Q

Cell surface receptors

A

● Span the entire thickness of the membrane
● Are in contact with both the extracellular environment and hte cytoplasm
● ion channel receptors, G-protein-coupled receptors, protein kinase receptors

79
Q

Hydrophilic signaling molecules

A

● Cannot diffuse through the membrane
● Bind to the part of the recptor on the cell surface that changes the shape on the cytoplasmic side of the same receptor

80
Q

Second messenger

A

● Carried the signal from the hydrophilic signaling molecules
● The most common was cyclic AMP

81
Q

Inon-channel receptors

A

● Involve an allosteric recepor that opens and husts a gate in a membrane allowing an influx of ions
● Acetylcholine receptor located in the plasma membranes of skeletal muscle cells is an example
- Neurotransmitter acetylcholine binds to the allosteric receptor, which undergoes a conformational change that causes the opening of the channel

82
Q

G-protein coupled receptors (GPCR)

A

● Span the entire cell membrane
● When a ligand binds to the extracellular domain of the receptor, it changes the conformation of the cytoplasmic side of the receptor
- This then causes the G-protein in the alpha sub-unit to bind to and activate the enzyme adenylyl cyclase, activates mobile G protein to bind to GTP, which catalyzes the conversion of ATP to cAMP (second messenger)
● Cyclic-AMP activates other molecules inside a cell, which leads to a cellular response

83
Q

Receptor Throsine Kinases (RTKs)

A

● Characterized by having enzymatic activity
● Spans the entire membrane and the part of the receptor that extends into the cytoplasm functions as a tyrosine kinases, an enzyme that catalyzes the transfer of phosphate groups from ATP to the amino acid tyrosine
● Before the ligand binds, the receptors exist as individual units
- After binding, the individual units aggregate and activate the tyrosine kinase region which bonds to ATP
● Once fully activated, the receptor activates specific relay proteins which each lead to a cellular response

84
Q

Hydrophobic chemical messengers

A

● Readily diffuse into the cell and switch a gene on or off in the nucleus
● Include steroids, thyroid hormones, Nitric oxide, bisphenol A (estrogen disruptor)

85
Q

Transduction

A

● Once activated, the receptor converts a molecular signal into a cell response
● Often it requires a sequence of changes in a series of different molecules – a signal transduction pathway

86
Q

Signal transduction pathway

A

● Multi-step process in which a small number of extracellular signal molecules produce a major cellular response, a cascade effect
● It provides more oppotunities for coordination and regulation
● Exists in both yeast and animal cells and in bacteria and plants

87
Q

Response

A

Transduction lead to a multitude of responses, either in the cytoplasm or in the nucleus

88
Q

What are some characteristics that all cells share?

A

● They are all enclosed by a protective and selective barrier called a plasma membrance
● They all contain a semifluid substnace called cytosol in which subcellular components are suspended
● All cells contain ribosomes and genetic material in the form of DNA

89
Q

What are cells small?

A

● The surface area of the plasma membrane limits the amount of material that can enter and leave the call – diffusion rate
● Volume is proportional to how much energy the cell needs to survive
● SA : V = as big as possible
● When a cell grow larger, the SA does not keep up with the increase in volume
● Complex organisms consist of millionso f tiny cells carrying out different fucntions

90
Q

Why don’t cells look alike?

A

● Function dictates form and vice versa
● Different cell types have different overall appearances suited for each different function
- The nerve cell, whose purpose is to send electrical impulses, is long and spindly
- Fat cells are rounded, large, and istended
- Cells that make up a tough peach pit resemble square building blocks

91
Q

What are the roles of the cytoskeleton?

A

● Maintains the cell’s shape
● Controls the position of organelles within the cell by anchoring them to the plasma membrane
● Involved with the flow of the cytoplasms, known as cytoplasmic streaming
● Anchors the cell in place by interacting with extracellular elements

92
Q

What do microfilaments enable?

A

● Animal cells to form a cleavage furrow during cell division
● Ameoba to move by sending out pseudopods
● Skeletal muscle to contract as they slide along myosin filaments

93
Q

What are the functions of proteins in the plasma membrane?

A

● Transport – molecules, electrons, and ions are carried through channels, pumps, carriers, and electron trasnport chian, which manufacture ATP
● Enzymatic activity – one membrane-bound enzyme is adenylate cyclase, which synthesizes cyclic AMP (cAMP) from ATP
● Signal transduction – binding sites on protein receptors fit chemical messengers like hormones. Proteins changes shape and relays the message to the inside of the cell
● Cell to cell recognition – some glycoproteins serve as identification flags htat are recognized by other cells
● Cell to cell attachments – desmosomes, gap junctions, and tight junctions
● Attachment to the cytoskeleton and extracellular matrix – helps maintain cell shape and stabilizes hte location of certain membrane proteins

94
Q

What are some ways of communication between cells?

A

● Simple bacterial cells secrete molecules that enable them to respond to changes in their population density by a phenomenon called quorm sensing
● Multicellular organisms communicated through direct contact, gap junctions, paracrine signaling, long-distance signalling

95
Q

What are the two examples of direct contact?

A

● Gap junctions in animal cells

● Plasmodesmata in plant cells

96
Q

How do small, nonpolar ligands bind to receptors?

A

They diffuse directly through the plasma membrane and bind to an intracellular receptor in the cytoplasm

97
Q

Why is bisphenol A called estrogen disruptor?

A

● It mimics hormones like estrogen and sets up the estrogen signal pathway
● Believed to be responsible for problems in fetal development in humans

98
Q

What are the four things to remember about signal transduction pathways?

A

● They are characterized by a signal, a transduction, and a response
● They are highly specific and regulated
● One signal molecule can cause a cascade effect, releasing thousands of molecules inside a cell
● These pathways evolved milions of years ago in a common ancestor

AP Biology (15 decks)

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