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Bio 1 > Organelles > Flashcards

Organelles Flashcards

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Biology 101 flashcards
1
Q

Nucleus

A
  • Contains most genes of the cell
  • Contains nucleolus
  • Membrane bound organelle (nuclear envelope: phospholipid bilayer)
  • Helps direct protein synthesis (synthesis of mRNA)
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2
Q

Functions of nucleus

A
  • Control cellular structure/ activities
  • site of DNA replication/ mRNA production
  • Produces ribosomes (nucleolus)
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3
Q

Nuclear envelope

A
  • Double membrane (lipid bilayer with an inner & outer membrane)
  • Contains pores (due to fusion of 2 membranes /To regulate entry & exit of the cell)
  • On nuclear side: Nuclear lamina (network of proteins that help maintain the shape of the nucleus)
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4
Q

Function of nuclear membrane

A

Separate nucleus from cytoplasm

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5
Q

Nucleolus

A

Site of rRNA synthesis

- Assembles rRNA + proteins into ribosomal subunits (large & small)

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6
Q

Function of Ribosomes

A

Site of protein synthesis

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7
Q

Ribosomes

A
  • Made rRNA + proteins
  • Composed of 2 subunits
  • 2 types:
    Free;
  • in cytosol
  • make proteins functionning in cytosol
    Bound;
  • attached to endoplasmic reticulum or nuclear envelope
  • make proteins for membranes (aquaporin) and for secretion (insulin)
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8
Q

Endomembrane system

A 
Transport system of proteins
- Nuclear envelope
- Endoplasmic reticulum 
- Golgi apparatus 
- Vacuoles
- Lysosomes
- Plasma membrane
connected directly through physical contact (Nucleus-ER) or indirectly by transport vesicles
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9
Q

Smooth ER

A

lacks ribosomes

  • Synthesizes lipids (like hormones)
  • Metabolizes carbohydrates
  • Detoxifies drugs and poisons (liver)
  • Stores calcium ions (muscle)
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10
Q

Rough ER

A

attached to ribosomes

  • membrane production (membrane bound proteins)
  • protein synthesis (secretory proteins; glycoprotein)
  • Distributes transport vesicle (protein surrounded by membranes)
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11
Q

Endoplasmic Reticulum

A
  • Network of tubules and sacs (cisternae)
  • continuous with nuclear envelope
  • 2 regions : Rough & smooth
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12
Q

Golgi apparatus

A
  • flattened membranous sacs = cisternae

- contains cis (receiving) and trans (shipping) sides

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13
Q

Functions of Golgi Apparatus

A
  • Modifies, sorts and packages glycoproteins from rough ER
  • Receives vesicles from rough ER (cis)
  • Ships vesicle to other end (trans)
  • Produces polysaccharides
  • Makes lysosomes
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14
Q

Lysosomes

A
  • Membrane enclosed sacs of hydrolytic enzymes
  • has an acidic environment (pH=5)
  • enzymes (proteins) synthesized in RER; processed by Golgi
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15
Q

Functions of Lysosomes

A

1) Intracellular digestion:
- Lyosomes fuse with food vacuole produced by phagocytosis (cell engulating another cell or food particle)
2) Recycles old/damaged organelles:
- called autophagy
- components released into cytosol for re-use

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16
Q

Vacuoles

A
  • membrane bound sacs

- perform different functions in different cels

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17
Q

Food vacuoles

A

formed by phagocytosis

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18
Q

Contractile vacuole

A

pumps excess of water out of cells (paramecium)

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19
Q

Central vacuole

A
  • For plants cells
  • found in mature plant cells
  • stores organic compound, inorganic ions, metabolic by-products; offers protection
20
Q

Functions of mitochondria

A
  • Energy metabolism

- site of cellular respiration (ie.: ATP production)

21
Q

Mitochondria

A
  • Found in eukaryotic cells including plants
  • Number of mitochondria varies with level of metabollic activity
    Surrounded by a double membrane (lipid bilayer)
    Outer:
    -smooth
  • highly permeable to small molecules & ions
    Inner:
  • extensively folded into cristae (increase surface area)
  • contains enzymes for cellular respiration
    2 compartments:
  • intermembrane space
  • mitochondrial matrix: filled with DNA, ribosomes (free), enzymes
22
Q

Chloroplasts

A 
Found in plants & algae
Surrounded by a double membrane:
- both membrane are smooth
- inner membrane surrounds stroma
2 compartments:
- intermembrane space
- Stroma: DNA, ribosomes and enzymes photsynthesis as well as Thylakoids
23
Q

Function of chloroplast

A

Site of photosynthesis (converts light energy to chemical energy)

24
Q

Thylakoids

A
  • membranous sacs
  • contain chlorophyll (green pigment)
  • involved in photosynthesis
  • stacked into grana (granum)
25
Q

Peroxisome

A
  • Found in both plants (glyoxysomes) and animal cells
  • single lipid bilayer
  • no ribosomes or DNA
26
Q

Functions of peroxisomes

A
  • Breakdown of fatty acids (also fuel for cellular respiration
  • Detoxification alcohol/ harmful substances
27
Q

Cytoskeleton

A
  • network of protein fibers
  • found in cytoplasm
  • Dynamic = dismantled in one part of the cell and reassembles in another part
  • 3 types of fibers:
    Microtubules, Microfilaments and Intermediate filaments
28
Q

Functions of cytoskeleton

A
  • Mechanical support & maintains cell shape
  • Organelle movement
  • Cell movement
29
Q

Microtubules

A
  • Thickest
  • Hollow rods
  • Constructed from the protein tubulin
  • Controlled by the centrosome (MT organizing center)
30
Q

Function of microtubules

A
  • Cell division : Chromosomes movement (ie: mitotic spindle)

- Cell movement: Cilia or flagella

31
Q

Cillia & Flagella

A
  • locomotive projection of cells
  • move material across a surface (Ex. Cillia: Mucus in resp tract; egg in fallopian tube) otr move cell (ex. Flagella sperm)
  • Differences:
    Cilia: Short, large number on cell
    Flagella: Long, one or few per cell
32
Q

Microfilaments

A
  • Thinnest
  • Solid rods
  • Constructed from the protein actin
33
Q

Functions of microfilaments

A
  • Cell division: by separating the cytoplasm (cytokinesis)
  • Cell movement: by pseudopodia
  • Muscle contraction
    Cytoplasmic streaming: circular flow of cytoplasm within cell
34
Q

Pseudopodia

A

Cellular arm-like extensions

35
Q

Intermediate filaments

A
  • intermediate in size

- diverse: differ in size and composition depending on cell type (ex: keratin)

36
Q

Functions of intermediate filaments

A
  • Anchors nucleus and organelles

- Forms nuclear lamina (maintains nucleus shape)

37
Q

Extracellular components

A
  • Cells synthesize and secerte materials that are external to the plasma membrane
  • Cell walls, the extracellular matrix (ECM), cell junctions
38
Q

Cell walls

A
  • Found in prokaryotes, fungi, some protists, plants but NOT animals
  • Composition varies from species to species
39
Q

Functions of cell walls

A
  • protects cell
  • maintains cell shape
  • Prevent excessive uptake of water
40
Q

Extracellular Matrix (ECM)

A
  • Found in animal cells
  • Network of macromolecules secreted by cells
  • contains:
    Glycoproteins (collagen most abundant)
    Proteoglycans (small protein rich in sugar)
    Fibronectin
    Integrins: Transmembrane protein, Bind ECM (fibronectin) on one side; Cytoskeleton (microfilaments) on the other side, connect ECM to cytoskeleton
41
Q

Functions of ECM

A
  • Anchorage of cells in tissues

- Cell movement

42
Q

Cellular junctions

A

Neighboring cells adhere, interact and communicate through direct physical contact via cellular junctions

  • Plasmodesmata (Plants)
  • Tight junction
  • Desmosomes
  • Gap junctions
43
Q

Plasmodesmata

A
  • Communicating channels in plants
  • Perforate plant cell walls
  • Allow movement of H2O, small solutes etc from cell to cell
44
Q

Tight junctions

A
  • Membrane of neighboring cells are fused
  • prevents leakage of fluid
    Ex: intestinal epithelium (stomach ph= 2; intestine ph=7), kidneys (seperate blood & urine)
45
Q

Desmosomes

A
  • Anchoring junctions
  • Fasten cells together into strong sheets
  • Withstand mechanical stress
    Ex: muscle,skin
46
Q

Gap junctions

A
  • Communicating junctions in animal cells
  • cytoplasmic channels between adjacent cells
  • Small molecule may pass( salts, sugar, amino acids etc)

Bio 1 (8 decks)

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