Intro. to Eukaryotic Cells

Question 1

Label the parts of a eukaryotic cell and describe the function of each part.

Answer 1

Nucleus: houses DNA, carries out cellular activities

ER: essential roles in protein and lipid production

rough ER: modifies proteins

smooth ER: lipid production/detoxifies

Vesicles: lipid bilayer sacs (transport and secratory)

Golgi: coordinates with ER/ modifies cellular proteins, builds lipids, sorts and distributes

Lysosomes: contain hydrolytic enzymes that break down substances engulfed by the cell

Mitochondria: makes ATP, carries out programmed death (apoptosis), regulates cell division, makes amino acids and vitamins

Chloroplasts: allows cells to harvest energy from sunlight using light collecting pigments

Peroxisomes: contain enzymes that break down fats and amino acids by oxidaton

Question 2

What is endosymbiosis?

Answer 2

endo: inside
symbiotic: collaboration between organisms
- series of sequential cell merging events between ancient eukaryotic ancestors and certain prokaryotes

Question 3

Mitosis

Answer 3

• generates two genetically identical offspring from one parent cell
• offspring cells maintain the same number of chromosomes as the parent cell

Question 4

Meiosis

Answer 4

• involved in sexual reproduction
• two cell division stages
• one parent cell produces four gametes
• gametes are haploid
• crossing over allows for genetic recombination

Question 5

Binary Fission

Answer 5

• mitochondria and chloroplasts use this process that resmebles binary fission
• asexual reproduction
• makes 2 genetically identical cells
• same number of chromosomes as parent

Question 6

Endocytosis

Answer 6

• substances from the extracellular environment enter the cell in membranous endcoytic vesicles that form as the cell’s plasma membrane folds inward and pinches off
• pinocytosis (cell drinking) : nonspecific mass transport important for cell survival
• phagocytosis (cell eating)

Question 7

Exocytosis

Answer 7

• involves vesicles delivering their contents to the plasma membrane
• exocytic vesicles are formed inside the cell-often budding from cellular organelles like the Golgi apparatus
• vesicles transported to plasma membrane where they can fuse in order to expel their contents

Question 8

Receptor Mediated Endocytosis

Answer 8

• Ligands bind to specific cell surface receptors
• Inner sruface of the plasma membrane is coated with clathrin
• Clathrin polymerizes forming a pit
• Clathrin coated pit pinches off
• Forms a clathrin-coated vesicle
• Sheds the clathrin coat
• Fuses with an endosome
• Altered pH seperates ligand and receptor
• Ligand and receptor are sorted and delivered

Question 9

Eukaryotic versus Prokaryotic Cells

Answer 9