Eukaryotic Cell Structure

Question 1

organelle

Answer 1

• specialized compartments within the cell, surrounded by their own membrane(s)
• permit many incompatible reactions to occur simultaneously within a cell
• quantity and distribution varies with cell type

Question 2

chromatin

Answer 2

condensed DNA

• DNA is condensed by wrapping it around histones
• make up chromosomes

Question 3

nucleus

Answer 3

• contains genetic material
• site of RNA synthesis
• site where ribosomal subunits are made
• surrounded by double membrane called the nuclear envelope
• filled with nucleoplasm

Question 4

how do eukaryotic cells differ from prokaryotes?

Answer 4

-higher degree of organization/possess organelles
-DNA chromosomes reside in the double-membraned nucleus
(also generally a bit larger in size)

Question 5

ribosome

Answer 5

• synthesize protein from amino acids
• contain two subunits (complexes of rRNA and ribosomal proteins)
• exported separately from the nucleolus
• one in the cytosol, one big and one small subunit assemble with mRNA molecule
• bound ribosomes (on rough er) are part of the endomembrane system while free ribosomes make soluble proteins that function within the cytosol

Question 6

nuclear pore

Answer 6

protein complex that crosses both membranes of the nuclear envelope
-allows movement of molecules between nucleoplasm and cytosol

Question 7

cytoskeleton

Answer 7

• network of cytoplasmic proteins in eukaryotes (microtubules, microfilaments, intermediate filaments)
• maintains cell shape
• anchors organelles in place
• involved in movement of cells, movement of organelles and vesicles inside cells (with help of motor proteins-cytoskeleton is the highway)
• receives regulatory signals from outside cell and carries them to the nucleus

Question 8

nucleolus

Answer 8

dense region within the cell where rRNA is synthesized and ribosomal subunits are formed from rRNA and ribosomal protein

Question 9

centrosome

Answer 9

made of two centrioles at right angles

• the MTOC (microtubule organizing centre of animal cells)
• resides near nucleus
• all MTs grow outward from here

Question 10

centriole

Answer 10

9 microtubule triplets in a ring

Question 11

golgi apparatus

Answer 11

vesicles pinched off er fuse with cis face of golgi apparatus

• cisterna containing protein goes through cisternal maturation, becoming medial then trans cisterna, protein is further glycosylated
• trans side sorts the proteins and sends them off to their next destination (lysosomes, plasma membrane or secretion)

Question 12

procession of endomembrane system organelles

Answer 12

nuclear envelope
rough er
lysosomes
golgi bodies
vacuoles
plasma membrane

Question 13

lysosome

Answer 13

membrane bound sacs containing hydrolytic enzymes

• digestive organelles (most common in animals) involved in phagocytosis and autophagy
• catalyze hydrolysis of macromolecular polymers
• proton pumps in their membranes maintain an acidic environment to optimize enzyme function

Question 14

vacuole

Answer 14

membrane bound sacs derived from golgi apparatus

• larger but less numerous than vesicles
• food vacuoles formed in phagocytosis
• contractile vacuoles pump excess water out of the cell
• central vacuole in plants fills cytosol as the cell grows

Question 15

peroxisome

Answer 15

(not part of endomembrane system)

• single membrane bound sac
• detoxifies alcohols and posions
• oxidizes fatty acids into smaller molecules
• contains enzymes that produce H2O2 while detoxifying, other enzymes then break down that biproduct

Question 16

mitochondria

Answer 16

(not part of endomembrane system)

• double membraned
• site of cellular respiration
• oxidizes energy-storage monomers
• require abundant O2 and sugars to make ATP (and CO2 biproduct)
• infoldings called cristae increase surface area

Question 17

chloroplast

Answer 17

(not part of endomembrane system)

• three membranes (inner, outer, thylakoid)
• site of photosynthesis (convert light energy and CO2 to glucose (C6H12O6) and O2)

Question 18

mitochondria

Answer 18

(not part of endomembrane system)

• double membraned
• site of cellular respiration
• oxidizes energy-storage monomers
• require abundant O2 and sugars to make ATP (and CO2 biproduct)
• infoldings called cristae increase surface area
• internal membrane contains enzymes
• matrix contains ribosomes, DNA (and also respiration enzymes?)

Question 19

vacuole

Answer 19

membrane bound sacs derived from golgi apparatus

• larger but less numerous than vesicles
• food vacuoles formed in phagocytosis
• contractile vacuoles pump excess water out of the cell
• central vacuole in plants fills cytosol as the cell grows

Question 20

endosymbiont hypothesis

Answer 20

small bacteria were engulfed by and began living within larger cells
mutually beneficial relationship develops (smaller cell gets protection from predators and larger cell gets the benefit of oxygen based metabolism)
two organisms become dependent and eventually become a single organism

Question 21

microtubule

Answer 21

• support cell shape by resisting compression
• pathway for organelle and vesicle movement
• separate chromosomes during mitosis
• form eukaryotic flagella and cilia
• made of 9+2 long strands of tubulin