Cell Organelle

Question 1

Vesicles

Answer 1

membrane sacs used to transport materials within, into, or out of the cell

• vacuoles, transport vesicles, lysosomes, and secretory vesicles
• found in both plant and animal cells

Question 2

Cilia

Answer 2

propel organisms through water and move fluid over the surface of the tissue

• generate a force perpendicular to the axis and occur in large numbers on the cell surface
• anchored in the cell by a basal body, dynein are responsible for bending movements
• found mostly in animal cells

Question 3

Lysosome

Answer 3

membrane-enclosed sac with hydrolytic enzymes used to digest macromolecules and recycle intracellular materials

• digestion products (ie simple sugars, amino acids, and other monomers) pass into the cytosol and become nutrients for the cell
• found in animal cells

Question 4

Nucleolus

Answer 4

structure within the nucleus comprised of various chromosomes that synthesizes ribosomal RNA and assembles proteins into large and small ribosomal subunits
-found in both plant and animal cells

Question 5

Rough Endoplasmic Reticulum

Answer 5

bound ribosomes attached to rough ER produce secretory proteins (mostly glycoproteins) and membranes, which are distributed from the ER by transport vesicles

• also makes hydrolytic enzymes and lysosomal membrane
• found in both plant and animal cells

Question 6

Cell Wall

Answer 6

protects the cell, maintains cell shape, holds plants upright against gravity, and prevents excessive uptake of water

• comprised of polysaccharides, cellulose, and protein
• found in plant cells

Question 7

Cytoskeleton

Answer 7

a network of microtubules, microfilaments, and intermediate filaments that functions in structural support, maintenance of cell shape, cell motility, regulation of biochemical activities in the cell through signal transmission, and anchorage of organelles
-found in both plant and animal cells

Question 8

Microfilaments

Answer 8

• maintenance of and changes in cell shape through tension-bearing elements
• muscle contraction through interactions with myosin
• cleavage furrow formation in cell division
• amoeboid movement through pseudopodia
• cytoplasmic streaming in plant cells
• support for microvilli
• found in both plant and animal cells

Question 9

Nucleus

Answer 9

contains most of the genes in the eukaryotic cell, directs protein synthesis by synthesizing messenger RNA that will exit through nuclear pores and be translated

• regulates cellular metabolism, growth, and division through gene expression
• found in both plant and animal cells

Question 10

Smooth Endoplasmic Reticulum

Answer 10

network of membranous tubules and sacs called cisternae involved in lipid synthesis of oils, phospholipids, and steroids, -metabolism of carbohydrates, storage of calcium ions, and detoxification of poisons and drugs
-found in both plant and animal cells

Question 11

Centriole

Answer 11

located within the centrosome, region where microtubules initiate and replicate before a cell divides and also help organize microtubule assembly
-found in animal cells

Question 12

Flagella

Answer 12

propel organisms through water (ex. sperm) and move fluid over tissue surface; longer than cilia and usually limited to one/two per cell

• generate force parallel to axis
• anchored in the cell by a basal body, dynein are responsible for bending movements
• found in mostly animal cells and some plant sperm

Question 13

Microtubule

Answer 13

• maintain cell shape through compression-resisting girders, cell motility (cilia and flagella), chromosome movement in cell division, and serve as tracks for organelle movement through motor proteins
• found in both plant and animal cells

Question 14

Plastids

Answer 14

• a family of closely related plant organelles:
  
  • amyloplasts store starch (amylose) in roots and tubers
  • chromoplasts have pigments that give fruits and flowers their orange and yellow hues
  • chloroplasts contain chlorophyll, enzymes, and other molecules that function in photosynthesis
• found in plant cells

Question 15

Vacuoles

Answer 15

carry out hydrolysis

• food vacuoles are formed by phagocytosis and fuse with lysosomes so hydrolytic enzymes can digest food particles
• contractile vacuoles only in protists pump excess water out of cells to maintain appropriate concentrations of salts and other molecules
• central vacuole in plant cells functions in digestion, storage of organic compounds (proteins) and inorganic ions (ex. potassium, chloride), waste disposal, cell growth, protection, and maintenance of turgor pressure
• found in both plant and animal cells

Question 16

Chloroplast

Answer 16

contain chlorophyll, enzymes, and other molecules that function in photosynthesis (which converts light energy to chemical energy - glucose)
-found in plant cells

Question 17

Golgi Body

Answer 17

modifies, stores, sorted, and routes products of the endoplasmic reticulum to other parts of the cell through transport vesicles. After transport vesicles coalesce to form new cis golgi cisternae, the cisternae progress forward during cisternal maturation, carrying and modifying products until transport vesicles depart from the trans face with molecular identification tags
-found in both plant and animal cells

Question 18

Mitochondria

Answer 18

contains mitochondrial DNA, ribosomes, and enzymes that catalyze metabolic steps of cellular respiration in the mitochondrial matrix
-bound in both plant and animal cells

Question 19

Ribosome

Answer 19

• carry out protein synthesis
• free ribosomes in the cytosol mostly make enzymes that function in the cytosol
• bound ribosomes attached to the ER and nuclear envelope make enzymes for insertion into membranes, packaging within certain organelles, or for export from the cell
• sites of DNA translation by facilitating the orderly linking of amino acids into polypeptide chains
• found in both plant and animal cells

Question 20

Cell Membrane

Answer 20

exhibits selective permeability to regulate the transport of substances into and out of the cell, provides a physical barrier that separates cell’s environment from the surroundings, controls endocytosis and exocytosis, cell signaling and communication

• enzymatic pathways, cell-to-cell recognition, intercellular joining, signal transduction attachment to ECM and cytoskeleton
• found in both plant and animal cells

Question 21

Organelles with double membrane

Answer 21

mitochondria, plastids, nucleus

Question 22

Cell Theory

Answer 22

1. All living organisms are composed of one or more cells
2. Cells are the basic unit of structure and organization in organisms.
3. Cells arise from pre-existing cells

Question 23

Who is credited with the cell theory?

Answer 23

Schleiden, Schwann, and Virchow

Question 24

Prokaryotic vs. Eukaryotic Cells

Answer 24

Prokaryotic: pili, capsule, DNA in nucleotide region
Both prokaryotic and eukaryotic: ribosomes, plasma membrane, chromosomes, flagella, cell walls
Eukaryotic: cytoskeleton, endomembrane system, mitochondria, membrane-bound organelles, DNA located in the nucleus

Question 25

Endomembrane System

Answer 25

responsible for metabolism and movement of lipids, detoxification of poisons, and protein synthesis and protein transport to membranes, organelles, or out of the cell - membranes are related either through direct physical continuity or by the transfer of vesicles - nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, and the plasma membrane

Question 26

What challenges does a cell face that undergoes as it increases in size?

Answer 26

volume increases at a greater rate than surface area. A greater surface area to volume ratio is desirable to sustain metabolic requirement and maintain efficient transport of substances across the membrane and within the cell

Question 27

How can cell overcome challenges related to surface area to volume as it increases in size?

Answer 27

divide into smaller cells, become multinucleated, cytoplasmic streaming

Question 28

Endosymbiotic Theory of Eukaryotic Cell Origin

Answer 28

- the prokaryotic ancestors of mitochondria and plastids entered a heterotrophic host cell, became endosymbioants, and developed a mutually beneficial symbiosis over time - some of the genes originally present in mitochondria and plastids were transferred to the nucleus - eventually evolved to the modern eukaryotic cell

Question 29

What structural evidence supports the Endosymbiotic Theory of Eukaryotic Cell Origin?

Answer 29

presence of mitochondria or genetic remnants of the organelle, in all eukaryotes - enzymes and transport systems of inner membranes of both mitochondria and plastids are homologous to those found in the plasma membranes of living prokaryotes - replication process of both organelles is similar to binary fission in certain prokaryotes - each organelle has a singular, circular DNA molecule that is not associated with histones or other proteins (like bacteria) - the ribosomes of mitochondria and plastids are more similar to prokaryotic ribosomes than to cytoplasmic ribosomes of eukaryotic cells in size, nucleotide, sequence, and sensitivity to certain antibiotics

Question 30

lysosomes & vacuoles

Answer 30

food vacuoles are formed by phagocytosis and then fuse with a lysosome, whose hydrolytic enzymes digest food particles

Question 31

endoplasmic reticulum & golgi apparatus

Answer 31

secretory proteins and membrane synthesized by the rough endoplasmic reticulum are transferred to the cis face by transport vesicles → cisternal maturation → golgi products leave at the trans face in transport vesicles to other locations in the cell, or to be transported backwards to newer golgi cisternae, or the endoplasmic reticulum

Question 32

centrioles & cilia

Answer 32

centrioles form the basal body required for the formation of cilia that anchors the cilia in the cell -in many animals, the basal body of fertilizing sperm's flagellum enters the egg and becomes a centriole

Question 33

ribosomes & endoplasmic reticulum

Answer 33

bound ribosomes attached to the ER synthesize proteins and membranes - as the polypeptide chain produced by ribosomes are threaded into the ER lumen through pores in the ER membrane, it folds into its native conformation. The ER membrane keeps the secretory protein separate and the secretory protein will depart in the membranes of vesicles at the transitional ER. - bound ribosomes can also form polypeptides that will form membrane proteins as the polypeptides are inserted into the ER membrane and anchored by hydrophobic regions

Question 34

golgi apparatus & vesicles

Answer 34

transport vesicles carrying ER products are transferred to the cis face of the golgi apparatus from the ER. Vesicles depart from the golgi body and carry specific proteins to other locations within the cell or to the plasma membrane for secretion at the trans face.

Question 35

nucleolus & ribosomes

Answer 35

``` ribosomal RNA (rRNA) is synthesized from instructions in DNA proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes, which can be assembled into a ribosome once the subunits exit the nucleus through nuclear pores ```

Question 36

mitochondria & flagella of a sperm tail

Answer 36

The midpiece of sperm contains a large amount of mitochondria for ATP production in order to power the conformational changes in dynein for flagellar locomotion.

Question 37

smooth ER & cell membranes

Answer 37

enzymes in the smooth ER synthesize lipids, including cholesterol and phospholipids, which are essential to the production of new cellular membrane