Chapter 4: Cell Structure and Function Flashcards

1
Q

What are the parts of the cell theory?

A
  • all living things are made of cells
  • cells are the basic unit of structure and function
  • cells come from existing cells
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2
Q

Why can only some cells be seen with a light microscope?

A

there is a minimum resolution, which is around the size of small bacteria (~200 nm) to see the cell

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3
Q

What parts of cells can be seen with a light microscope?

A

nucleus/chromosomes in dividing cells/central vacuole/NOT other organelles

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4
Q

Why is an electron microscope helpful to us?

A
  • electromagnets focus beam of electrons
  • better resolution than light microscope
  • can only observe organelles in DEAD cells
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5
Q

How does a transmission electron microscope work, and why is it helpful?

A
  • thin sections of specimens are stained with heavy metals
  • can see cell organelles
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6
Q

How does a scanning electron microscope work, and why is it helpful to us?

A
  • sample surface is covered with a thin gold film
  • study surface structures of cells
  • image looks 3D
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7
Q

Cell Fractionation

A

uses an ultracentrifuge to separate major organelles to study

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8
Q

What are characteristics of all cells?

A
  • surrounded by a cell membrane
  • contain semifluid substance within membrane (cytosol)
  • have organelles suspended in semi-fluid substance called the cytoplasm
  • contain chromosomes (DNA)
  • have ribosomes
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9
Q

Characteristics and examples of prokaryotes

A
  • bacteria
  • no nuclear membrane
  • no membrane bound organelles
  • DNA is in nucleoid region
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10
Q

Characteristics and examples of eukaryotes

A
  • plants, animals, fungi, protists
  • DNA surrounded by nuclear envelope
  • contains membrane bound organelles
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11
Q

How big are most bacteria?

A

1-10 um (mirons)

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12
Q

How big are most eukaryotic cells?

A

10-100 um (microns)

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13
Q

Why is there a size limit on cells?

A
  • need an upper limit due to metabolic requirements
  • if a cell is too big it cannot transport food, oxygen, and waste fast enough for its needs
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14
Q

Relationship between surface area and volume of a cell

A

as cells increase in size, volume increases faster than the surface area (SA / volume ration decreases)

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15
Q

How do large organisms adapt to their large size?

A
  • have more cells, not bigger cells
  • have microvilli on cells to increase surface area
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16
Q

Structure and function of internal membranes in eukaryotes

A
  • mainly made of phospholipids and proteins
  • divide cell into various compartments
  • take part in metabolism
  • membrane surfaces compartmentalize
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17
Q

Structure and function of plasma membrane

A
  • phospholipid bilayer (polar/hydrophilic heads face out and nonpolar/hydrophobic tails face in)
  • selectively permeable because of the hydrophobic tails (some molecules can go through, others cannot)
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18
Q

Structure and function of the nuclear envelope

A
  • contains genes in eukaryotes
  • surrounded by a double membrane
  • has nuclear pores lined by proteins to regulate passage of molecules
  • nuclear side of envelope is lined with protein filaments (nuclear lamina) to maintain shape
  • contains chromatin fibers = DNA + histone proteins
  • chromatin wraps into chromosomes during cell division
  • has nucleolus, which is the site of ribosome (rRNA) production
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19
Q

Structure and function of ribosomes

A
  • made of proteins and rRNA
  • synthesize proteins
  • free ribosomes = make cytosol proteins
  • bound ribosomes on ER or nuclear envelope = make proteins for cell membranes or export
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20
Q

Structure and function of endomembrane system

A
  • continuous or connect with transfer of membrane sacs (vesicles)
  • includes nuclear envelope, ER, Golgi body, lysosomes, vacuoles, plasma membrane
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21
Q

Structure and function of endoplasmic reticulum

A
  • membranous tubules filled with internal fluid filled spaces (cisternae)
  • continuous with nuclear envelope
22
Q

Structure and function of rough ER

A
  • ribosomes are attached
  • many of them in cells that secrete proteins
  • proteins synthesized on ribosomes, and folded into 3D shape in cisternal space
  • secretory proteins are put into vesicles and sent to Golgi body
  • makes membranes/phospholipids
  • as ER grows, vesicles move membranes
23
Q

Structure and function of smooth ER

A
  • does not have ribosomes
  • has many enzymes to help synthesize oils, steroids, and phospholipids (sex hormones, adrenal steroids)
  • in liver: helps break down toxins
  • in muscle: stores Ca+ ions to regulate muscle contraction
  • frequent drug use leads to increase of SER & why it can lead to liver damage (CIRRHOSIS)
24
Q

Structure and function of golgi apparatus

A
  • flattened membranous sacs = cisternae
  • cell “UPS” - manufacture, warehouse, sort, ship
  • has direction
    - cis face facing ER = receiving side
    - trans side = shipping side where
    transport vesicle buds off
  • extensive in secretory cells
  • can manufacture own macromolecules (amylopectin)
  • phosphate groups act as zip codes and can help identify product’s destination
25
Structure and function of lysosomes
- found in animal cells - membrane bound sac of hydrolytic enzymes --> can hydrolyze food, whole cells, damaged cell parts - example of compartmentalization - enzymes work best at pH of 5 - H+ ions are pumped from cytosol to lysosome - massive rupture of lysosomes can destroy a cell by "
26
Structure and function of lysosomes
- found in animal cells - membrane bound sac of hydrolytic enzymes --> can hydrolyze food, whole cells, damaged cell parts - example of compartmentalization - enzymes work best at pH of 5 - H+ ions are pumped from cytosol to lysosome - massive rupture of lysosomes can destroy a cell by "
27
Structure of lysosomes and how they work
- found in animal cells - membrane bound sac of hydrolytic enzymes --> can hydrolyze food, whole cells, damaged cell parts - example of compartmentalization - enzymes work best at pH of 5 - H+ ions are pumped from cytosol to lysosome - massive rupture of lysosomes can destroy a cell by "self-digestion" (autophagy)
28
Function/purpose of lysosomes
- digestion of food in unicellular organisms - recycle cell's organelles and macromolecules - programmed cell death (apoptosis) - embryonic development (form fingers, lose tail) - cells that are damaged get signal to self- destruct
29
What can a malfunction of lysosomes lead to?
- Tay-Sacs = genetic disorder - don't have lysosomal enzymes to break down lipids - accumulation of lipids in the brain may lead to seizures, death, blindness, etc
30
Structure and formation of vacuoles
- vesicles and vacuoles (larger) = membrane-bound sacs - food vacuoles form by phagocytosis and fuse with lysosomes - surrounded by membrane = tonoplast
31
Function of vacuoles
- contractile vacuoles in freshwater protists = pump out excess water to maintain balance - large central vacuole in many plant cells - stockpile proteins/inorganic compounds - dispose of metabolic byproducts - contain pigments - store defensive compounds to defend plants against herbivores - large vacuole reduces area of cytosol --> SA/volume ratio increases - water storage makes plants turgid
32
Structure and function of peroxisomes
- single membrane around it - made of proteins and lipids in cytosol - breaks down fatty acids and transports them to mitochondria, then mito uses it them for ceullular respiration - detoxifies alcohol - peroxisomes in seeds (glyoxysomes) convert fatty acids into sugars - have enzymes that transfer hydrogen from substrates to oxygen - makes hydrogen peroxide - contains catalase to convert H2O2 --> H20 + O2
33
Structure of mitochondria
- not part of endomembrane system - membrane proteins are made by free ribosomes and ribosomes in mitochondria - semi-autonomous = grow/reproduce on their own - mobile; move on cytoskeleton tracks - double membrane makes internal compartments - smooth outer membrane/inner membrane separated by intermembrane space - folded inner membrane (cristae) increases surface area for chemical reactions - fluid filled space enclosed by inner membrane (matrix) - has DNA, ribosomes, enzymes
34
Function of mitochondria
- site of cellular respiration - breaks down sugars, fats, fuels in presence of oxygen - generates ATP - cells with high energy needs have many mito
35
Structure of chloroplasts
- not in endomembrane system - plastid found in leaves/green organs - membrane proteins made by ribosomes and those in chloroplasts - semi-autonomous = grow/reproduce on their own - mobile; move on cytoskeleton tracks - double-membrane creates internal compartments - fluid filled space inside = stroma (has DNA, ribosomes, etc) - granum = stacks of thylakoid sacs (trap light energy)
36
Function of chloroplasts
- site of photosynthesis - convert solar energy to chemical energy - synthesize new organic compounds like sugars from CO2 and H2O
37
Examples of plastids
- amyloplast = colorless plastid that store starch in roots and tubers - chromoplast = store color pigments for fruits and flowers
38
What is the endosymbiosis theory?
- engulfed prokaryotes shared symbiotic relationship with the host cell - one gives energy, one gives raw materials/protection - origin of mitochondria and chloroplasts
39
What evidence shows that chloroplasts and mitochondria correlate with the endosymbiosis theory?
- only organelles besides nucleus with own DNA and double membranes - have single, circular naked (no histones) DNA - inner membranes have enzymes and transport systems like bacterial plasma membranes - replicate independently of nucleus - binary fission - ribosome size, nucleotide sequence, sensitivity to some antibiotics is similar to bacterial ribosomes
40
Structure and function of centrioles
- only in dividing animal cells - made of microtubules in pattern of 9 triplets - found inside centrosome, move to poles during cell division
41
Structure and function of the cytoskeleton
- network of fibers that extend throughout the cytoplasm - provides support and maintains cell shape - anchorage for many organelles and cytosolic enzymes - dismantled in one part and reassembled in another part - helps with cell motility
42
Tubulin microtubules (type of cytoskeleton fiber)
- thickest - hollow tube = dimer, made of protein subunits; change length by add/remove dimer - make tracks for motor proteins to go to organelles/vesicles - separate chromosomes during cell division - centrosomes = microtubule organizing region in many cells - in animal cells it contains centrioles
43
Actin microfilaments (type of cytoskeleton fiber)
- thinnest - made of protein actin in double twisted chain - support network inside membrane - support cell shape - interact with myosin filaments for muscle contraction - cleavage furrow in cell division: amoeboid movement (pseudopodia) & cytoplasmic streaming (plant cells)
44
Intermediate filaments (type of cytoskeleton fiber)
- middle size - more permanent framework/anchor cell organelles in place - made of keratin proteins
45
What are motor proteins?
- require ATP - go along cytoskeleton tracks to move to organelles, vesicles, chromosomes - myosin heads interact with actin for muscle contraction - dynein arms interact with tubulin to move cilia and flagella
46
Structure and function of eukaryotic cilia and flagella
- extend from cell surface - surrounded by plasma membrane sheath - anchored in cell by basal body (like centriole) - made of microtubules in a 9+2 pattern - 9 doublets in a ring around pair in center - flexible protein wheels connect microtubule doublets and center - motor proteins connect outer doublets - movement of dynein arms causes bending and moving
47
Differences between cilia and flagella
- differ in length, size, beating pattern cilia: - short (2-20 um), long, large numbers - in windpipe to sweep mucus flagella: - long (10-200 um), one or few - single protein filament (not 9+2), no outer membrane sheath
48
Structure and function of cell wall
- found in plants, some prokaryotes, fungi, protists - protect, support, keep shape - microfibrils of cellulose are embedded in a matrix of proteins and polysaccharides - middle lamella/polysaccharides hold cells/secondary cell walls together - plasmodesmata (channels btwn adjacent cells) which connect cytosol --> water/small solutes/proteins can pass freely from cell to cell
49
Structure and function of animal cell's extraceullular matrix
- outside of plasma membrane - made of glycoproteins secreted by the cell - strengthens tissues - cell signaling, can turn on genes, modify biochemical activity, coordinate behavior of cells in a tissue
50
Tight junctions (intercellular links)
- membranes are fused - form continuous seal - prevents leakage of extracellular fluids
51
Desmosomes (intercellular links; anchoring junctions)
- fasten cells together in strong sheets - keratin protein anchors to cytoplasm
52
Gap junctions (intercellular links; communication junctions)
- similar to plasmodesmata in plants - cytoplasmic channels between adjacent cells - special proteins surround these pores --> allow ions, sugars, amino acids, etc, to go through - help facilitate chemical communication in embryos during developmental stage