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AP Biology > Chapter 4: Cell Structure and Function > Flashcards

Chapter 4: Cell Structure and Function Flashcards

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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
Q

Structure and function of lysosomes

A
  • 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
Q

Structure and function of lysosomes

A
  • 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
Q

Structure of lysosomes and how they work

A
  • 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
Q

Function/purpose of lysosomes

A
  • 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
Q

What can a malfunction of lysosomes lead to?

A
  • 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
Q

Structure and formation of vacuoles

A
  • vesicles and vacuoles (larger) = membrane-bound sacs
  • food vacuoles form by phagocytosis and fuse with lysosomes
  • surrounded by membrane = tonoplast
31
Q

Function of vacuoles

A
  • 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
Q

Structure and function of peroxisomes

A
  • 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
Q

Structure of mitochondria

A
  • 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
Q

Function of mitochondria

A
  • site of cellular respiration
  • breaks down sugars, fats, fuels in presence of oxygen
  • generates ATP
  • cells with high energy needs have many mito
35
Q

Structure of chloroplasts

A
  • 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
Q

Function of chloroplasts

A
  • site of photosynthesis
  • convert solar energy to chemical energy
  • synthesize new organic compounds like sugars from CO2 and H2O
37
Q

Examples of plastids

A
  • amyloplast = colorless plastid that store starch in roots and tubers
  • chromoplast = store color pigments for fruits and flowers
38
Q

What is the endosymbiosis theory?

A
  • engulfed prokaryotes shared symbiotic relationship with the host cell
    - one gives energy, one gives raw
    materials/protection
  • origin of mitochondria and chloroplasts
39
Q

What evidence shows that chloroplasts and mitochondria correlate with the endosymbiosis theory?

A
  • 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
Q

Structure and function of centrioles

A
  • only in dividing animal cells
  • made of microtubules in pattern of 9 triplets
  • found inside centrosome, move to poles during cell division
41
Q

Structure and function of the cytoskeleton

A
  • 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
Q

Tubulin microtubules (type of cytoskeleton fiber)

A
  • 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
Q

Actin microfilaments (type of cytoskeleton fiber)

A
  • 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
Q

Intermediate filaments (type of cytoskeleton fiber)

A
  • middle size
  • more permanent framework/anchor cell organelles in place
  • made of keratin proteins
45
Q

What are motor proteins?

A
  • 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
Q

Structure and function of eukaryotic cilia and flagella

A
  • 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
Q

Differences between cilia and flagella

A
  • 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
Q

Structure and function of cell wall

A
  • 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
Q

Structure and function of animal cell’s extraceullular matrix

A
  • 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
Q

Tight junctions (intercellular links)

A
  • membranes are fused
  • form continuous seal
  • prevents leakage of extracellular fluids
51
Q

Desmosomes (intercellular links; anchoring junctions)

A
  • fasten cells together in strong sheets
  • keratin protein anchors to cytoplasm
52
Q

Gap junctions (intercellular links; communication junctions)

A
  • 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

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