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BIOL 213 > Chapter 5 > Flashcards

Chapter 5 Flashcards

1
Q

Robert Hooke (1665)

A

-an early microscopist, gave us the word cell
-used a compound microscope
-Looked at slices of cork

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2
Q

Antoni van Leeuwenhoek (1683)

A

-an early microbiologist
-discovered the microbial world using a simple lens
-Reported seeing animalcules which were bacteria and protozoa

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3
Q

what is cell theory?

A

-A cell is the smallest living thing
-all cells come from other cells (at least one exception)
-organisms are made of 1+ cells
-Diverse forms of life range from single-celled organisms like paramecium to more complex multi-cellular organisms like plants and animals
-cells are very small/microscopic
-Schleiden and Schwann

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4
Q

Three features of all cells

A

-cell membrane
-DNA region
-cytoplasm

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5
Q

Prokaryotic

A

-very efficient
-replicate very quickly
-no membrane-bound organelles
-smaller cells

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6
Q

Eukaryotic

A

-complex cells
-sub-cellular organelles
-complicated

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7
Q

What features make cells the fundamental units of life?

A

-cells are small because a high surface area to volume ration is essential
-Volume determines the amount of chemical activity in the cell per unit time
-Surface area determines the amount of substances that can pass the cell boundary per unit of time

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8
Q

Magnification

A

Increases apparent size

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9
Q

resolution

A

Clarity of the magnified object-minimum distance two objects can be apart and still be seen as two objects

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10
Q

Light microscope

A

Use glass lenses and light. Resolution=0.2um
-cheaper and can be used to see live cells

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11
Q

Electron microscope

A

Electromagnets focus an electron bean. Resolution=0.2nm
-more powerful magnification

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12
Q

what features characterize Eukaryotic cells

A

-Membrane-bound organelles
-Each organelle has a specific role in cell functioning
-this has allowed diversification of functions in eukaryotic cells, and their specialization into tissues

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13
Q

How do we study cells

A

-Cell fractionation: separates organelles for study by chemical methods
-Microscopy: Electron, fluorescent and confocal microscopy allow visualization of the location and movement of specific, tagged molecules

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14
Q

Cell fractionation

A

-Takes cells apart and separates the major organelles from one another
-Ultracentrifuges fractionate cells into their component parts
-cell fractionation enables scientists to determine the functions of organelles
-Biochemistry and cytology help correlate cell structure with function

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15
Q

Eukaryotic nucleus

A

-Some cells may have more than one or none at all
-contains nuclear DNA
-Site of DNA replication
-site of gene transcription
-assembly of ribosomes begins in a region called the nucleolus
-surrounded by a double membrane -the nuclear envelope
-Nuclear pores in the envelope control movement of molecules between nucleus and cytoplasm

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16
Q

DNA in the nucleus

A

-combines with proteins to form chromatin in long thin threads called chromosomes
-before cell division, chromatin condenses and individual chromosomes are visible in the light microscope

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17
Q

entire sum of genetic material

A

genome

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18
Q

Necleoplasm

A

surrounds the chromatin and a network of structural proteins helps organize the chromatin

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19
Q

Nuclear lamina

A

attaches to both the chromatin and the nuclear envelope and maintains nuclear shape

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20
Q

endomembrane system

A

-includes the plasma membrane, nuclear envelope, endoplasmic reticulum, golgi apparatus and lysosomes
-tiny membrane-surrounded vescicles shuttle substances between the various components

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21
Q

Endoplasmic reticulum

A

network of interconnected membranes in the cytoplasm; has a large surface area

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22
Q

rough endoplasmic reticulum

A

ribosomes are attached
-Newly made proteins enter the RER lumen where they are modified with carbohydrate, folded, and transported to other regions

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23
Q

Ribosomes

A

sites of protein synthesis
-occur in both prokaryotic and eukaryotic cells and have similar structure
-consist of ribosomal RNA (rRNA) and more than 50 different protein molecules

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24
Q

Ribosomes in Eukaryotes

A

-free in the cytoplasm -attached to the endoplasmic reticulum or inside mitochondria and chloroplasts

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25
Q

Eukaryotic proteins

A

-may have intrinsic localization signals
-Nuclear localization sequence (NLS)
-RER localization

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26
Q

Smooth endoplasmic reticulum (SER)

A

-More tubular, no ribosomes
-chemically modifies small molecules such as drugs, alcohol, and pesticides
-Hydrolysis of glycogen in animal cells
-synthesis of lipids and steroids
-Calcium (Ca++) storage especially in muscle tissue

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27
Q

xenobiotic

A

anything that is foreign to the cell
-drugs, trans fats, alcohol, etc

28
Q

Golgi apparatus

A

composed of flattened sacs (cisternae) and small membrane-enclosed vesicles
-receive proteins from the RER-can further modify them
-concentrates, packages, sorts proteins
-in plant cells, polysaccharides for cell walls are synthesized here

29
Q

Cis region

A

receives vesicles (a piece of the ER that “buds” off) from the ER

30
Q

Trans region

A

vesicles bud off from the golgi apparatus and are moved to the plasma membrane or other organelles

31
Q

Lysosomes

A

originate from the golgi apparatus
-they contain digestive enzymes- macromolecules are hydrolyzed into monomers

32
Q

phagocytosis

A

how foreign molecules enter the cell, a phagosome is formed

33
Q

Phagosome

A

fuse with primary lysosome to form secondary lysosome (phagolysosome)
-enzymes in the secondary lysosome hydrolyze the food molecules

34
Q

autophagy

A

lysosomes digest cell materials
-cell components are frequently destroyed and replaced by new ones

35
Q

Lysosomal storage disorders

A

-a genetic deficiency in a lysosomal enzyme
-over 40 such diseases/syndromes
-unhydrolyzed materials accumulate in lysosomes
-1 in every 8000 newborns affected

36
Q

Tay-Sachs disease

A

-mental retardation
-blindness
-death by age 3

37
Q

Proteasome

A

-a protein degrading machine
-proteolytic cleavage of denatured proteins
-a hollow protein structure similar to a chaperone
-found in nucleus and cytosol
-found in prokaryotes and eukaryotes

38
Q

Peroxisomes

A

Collect and break down toxic byproducts of metabolism such as H2)2 using specialized enzymes

39
Q

Glyoxysomes

A

only in plants-lipids are converted to carbohydrates for growth

40
Q

Plasma membrane

A

-the outer surface of every cell and has more or less the same structure in all cells
-It is made of a phospholipid bilayer with proteins and other molecules embedded
-It is not rigid but more like an oily fluid in which proteins are in constant motion
-Selectively permeable
-allows cells to. maintain a constant internal environment
-is important in communication and receiving signals
-Often has proteins for binding and adhering to adjacent cells

41
Q

cytoplasm

A

-area enclosed by the plasma membrane excluding the contents of the nucleus
-many important biochemical pathways such as glycolysis
-non-membrane bound ribosomes and translation
-filled with cytosol-aqueous solution rich in biological molecules and ions

42
Q

mitochondria

A

-energy in fuel molecules is transformed to the bonds of energy-rich ATP
-Cells may have up to hundreds of mitochondria or none at all
-Cells that require a lot of energy have a lot of mitochondria
-contain two membranes
-inner membrane folds inward to form cristae. This forms a large surface area for proteins involved in cellular respiration reactions
-Mitochondrial matrix contains enzymes, DNA and ribosomes
-replicated by binary fission (once the mitochondria increases to a certain size, it divides in two)

43
Q

apoptosis

A

programmed cell death
-mitochondria are responsible for this pathway

44
Q

Plastids

A

(a class of organelles) occur only in plants and some protists

45
Q

Chloroplasts

A

Site of photosynthesis-light energy is converted to the energy of chemical bonds
-have their own DNA and produce 50-200 gene products
-Most of the 2500 proteins found in chloroplasts are imported
-Replicate by binary fission
-Demonstrate a great deal of diversity-many types of plastids have lost photosynthetic ability and have other functions

46
Q

Grana

A

Stacks of thylakoids
-made of circular compartments of the inner membrane

47
Q

Stroma

A

fluid in which grana are suspended
the stroma contains DNA and ribosomes

48
Q

Vacuole

A

-Store waste products and toxic compounds; some may deter herbivores
-Provide structure for plant cells-water enters the vacuole by osmosis creating turgor pressure
-Store anthocyanins (pink and blue pigments in flowers and fruits the colors attract polliinators
-Vacuoles in seeds have digestive enzymes to hydrolyze stored food for early growth

49
Q

Contractile Vacuoles

A

Expel excess water
-Vacuoles take in excess water that enters the cell by osmosis; then expel it by contracting, forcing water out through a pore

50
Q

Cytoskeleton

A

-Supports and maintains cell shape
-Holds organelles in position
-Moves organelles
-Moves the organism
-Moves materials outside the cell
-Involved in cytoplasmic streaming
-Interacts with extracellular structures to hold cell in place

51
Q

Microfilaments

A

-Help a cell or parts of a cell to move
-Determine cell shape
-Made from the protein actin
-Actin has + and - ends and polymerizes to form long helical chains (reversible)
-involved in the formation of pseudopodia (false feet)
-In some cells, form a meshwork just inside the plasma membrane

52
Q

Intermediate filaments

A

-Many different kinds in six molecular classes
-tough ropelike protein assemblages
-anchor cell structures in place
-Resist tension

53
Q

Microtubules

A

Form rigid internal skeleton in some cells
-Act as a framework for motor proteins
-made from the protein tubulin-a dimer
-Have + and - ends
-can change length rapidly by adding or losing dimers

54
Q

Cilia

A

short, usually many present, move with stiff power stroke and flexible recovery stroke

55
Q

Flagella

A

longer, usually one or two present, movement is snakelike

56
Q

Centrioles

A

identical to basal bodies
-involved in formation of the mitotic spindle to which chromosomes attach during cell division

57
Q

Motor Proteins

A

undergo reversible shape changes powered by ATP hydrolysis

58
Q

Dynein

A

binds to microtubule doublets and allows them to slide past each other

59
Q

Nexin

A

can cross-link the doublets and prevent them from sliding, and the cilium bends

60
Q

Kinesin

A

motor protein, binds to a vesicle and walks it along by changing shape

61
Q

Categories of experiments that determine the function of cellular components

A

Inhibition and Mutation

62
Q

Extracellular structures

A

Cell wall: In plants, cellulose fibers are embedded in other complex polysaccharides and proteins

Adjacent plant cells are connected by plasma membrane-lined channels called plasmodesmata

63
Q

Extracellular matrix composed of

A

fibrous proteins such as collagen, gel-like proteoglycans and other proteins

64
Q

Extracellular matrix functions

A

*Holds cells together in tissues
*Contributes to properties of bone,
cartilage, skin, etc.
*Filters materials passing between
different tissues
*Orients cell movements in development
and tissue repair
*Plays a role in chemical signaling

65
Q

Prokayotic cells

A

-Are enclosed by a plasma membrane
* The DNA is contained in the nucleoid region
* Cytoplasm consists of cytosol (water and
dissolved material) and suspended particles
* No organelles–photosynthesis and respiration (if
present) occur in association with plasma
membrane
* No endomembrane system
* Simple cytoskeleton (if any present at all)

66
Q

Eukaryotic cell evolution

A

may have originated from the inward folds of plasma membrane of prokaryotes

enclosed compartments would have allowed chemicals to be concentrated and chemical reactions to proceed more efficiently

67
Q

Endosymbiosis Theory

A

proposes that mitochondria and plastids arose when one cell engulfed another cell

Mitochondrial DNA most closely related to that of Rickettsia bacteria

BIOL 213 (13 decks)

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