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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
Eukaryotic proteins
-may have intrinsic localization signals -Nuclear localization sequence (NLS) -RER localization
26
Smooth endoplasmic reticulum (SER)
-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
27
xenobiotic
anything that is foreign to the cell -drugs, trans fats, alcohol, etc
28
Golgi apparatus
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
Cis region
receives vesicles (a piece of the ER that "buds" off) from the ER
30
Trans region
vesicles bud off from the golgi apparatus and are moved to the plasma membrane or other organelles
31
Lysosomes
originate from the golgi apparatus -they contain digestive enzymes- macromolecules are hydrolyzed into monomers
32
phagocytosis
how foreign molecules enter the cell, a phagosome is formed
33
Phagosome
fuse with primary lysosome to form secondary lysosome (phagolysosome) -enzymes in the secondary lysosome hydrolyze the food molecules
34
autophagy
lysosomes digest cell materials -cell components are frequently destroyed and replaced by new ones
35
Lysosomal storage disorders
-a genetic deficiency in a lysosomal enzyme -over 40 such diseases/syndromes -unhydrolyzed materials accumulate in lysosomes -1 in every 8000 newborns affected
36
Tay-Sachs disease
-mental retardation -blindness -death by age 3
37
Proteasome
-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
Peroxisomes
Collect and break down toxic byproducts of metabolism such as H2)2 using specialized enzymes
39
Glyoxysomes
only in plants-lipids are converted to carbohydrates for growth
40
Plasma membrane
-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
cytoplasm
-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
mitochondria
-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
apoptosis
programmed cell death -mitochondria are responsible for this pathway
44
Plastids
(a class of organelles) occur only in plants and some protists
45
Chloroplasts
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
Grana
Stacks of thylakoids -made of circular compartments of the inner membrane
47
Stroma
fluid in which grana are suspended the stroma contains DNA and ribosomes
48
Vacuole
-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
Contractile Vacuoles
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
Cytoskeleton
-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
Microfilaments
-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
Intermediate filaments
-Many different kinds in six molecular classes -tough ropelike protein assemblages -anchor cell structures in place -Resist tension
53
Microtubules
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
Cilia
short, usually many present, move with stiff power stroke and flexible recovery stroke
55
Flagella
longer, usually one or two present, movement is snakelike
56
Centrioles
identical to basal bodies -involved in formation of the mitotic spindle to which chromosomes attach during cell division
57
Motor Proteins
undergo reversible shape changes powered by ATP hydrolysis
58
Dynein
binds to microtubule doublets and allows them to slide past each other
59
Nexin
can cross-link the doublets and prevent them from sliding, and the cilium bends
60
Kinesin
motor protein, binds to a vesicle and walks it along by changing shape
61
Categories of experiments that determine the function of cellular components
Inhibition and Mutation
62
Extracellular structures
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
Extracellular matrix composed of
fibrous proteins such as collagen, gel-like proteoglycans and other proteins
64
Extracellular matrix functions
*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
Prokayotic cells
-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
Eukaryotic cell evolution
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
Endosymbiosis Theory
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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