The Eukaryotic Cell

Question 1

Describe Nuclear Envelope (membrane)

Answer 1

• double phospholipid bilayer that surrounds the nucleus

Question 2

RNA exits the nucleus through what?

Answer 2

• nuclear pores

- DNA is trapped in the nucleus

Question 3

What is the nucleolus

Answer 3

• part of the nucleus where rRNA is transcribed and ribosomal subunits are assembled.

Question 4

Describe various types of Endocytosis…

Answer 4

• Phagocytosis (to eat)
• Pinocytosis (to drink)
• Receptor mediated Endocytosis

Question 5

Describe Phagocytosis:

Answer 5

(to eat)
- cell membrane protrudes outward to envelope and engulf particulate matter.

• binding of proteins on the particulate matter to protein receptors on the phagocytotic cell.

Question 6

Describe Pinocytosis:

Answer 6

• to drink
• extracellular fluid is engulfed by small invaginations of the cell membrane.
• nonselective process

Question 7

Describe Receptor Mediated Endocytosis:

Answer 7

• specific uptake of macromolecules such as hormones and nutrients.
• ligand binds to a receptor protein on the plasma membrane and then is moved into the clathrin coated pit.

Question 8

The reverse of endocytosis is_________?

Answer 8

Exocytosis

Question 9

What is clathrin?

Answer 9

• protein that forms a polymer adding structure to the underside of the coated pit.
• absorbs ligands
• becomes a coated vesicle

Question 10

Describe Rough Endoplasmic Reticulum

Answer 10

• contiguous with the cell membrane and nuclear membrane in many places
• has ribosomes attached to the cytosol side
• synthesizes almost all proteins not used in the cytosol
  
  • proteins are pushed into the ER lumen as they are created, and then sent to the Golgi

Question 11

Describe the Smooth Endoplasmic Reticulum

Answer 11

• site of lipid synthesis including steroids
• also helps detoxify some drugs(pesticides, toxins, pollutants)
• triglycerides are produced here and stored as fat droplets

Question 12

Describe the Golgi apparatus

Answer 12

• modifies and packages proteins
• flattened, membrane-bound sacs
• releases protein filled vesicles or lysosomes

Question 13

Describe Lysosomes

Answer 13

• contain hydrolytic enzymes to digest substances taken in by endocytosis
• come from the Golgi
• generally interior pH of 5
• material not degraded is ejected from cell

Question 14

Describe Secretory Vesicles

Answer 14

• protein filled vesicles released from Golgi to be expelled from cell.
• may contain enzymes, growth factors, or extracellular matrix components
• supply membrane with its integral proteins and lipids

Question 15

What is autolysis

Answer 15

• can occur when a lysosome ruptures releasing contents into the cytosol killing the cell.
• useful in the formation of certain organs and tissues ( webs fingers and toes of fetus)

Question 16

Describe Peroxisomes

Answer 16

• production and breakdown of Hydrogen Peroxide
• vesicles in the cytosol
• grow by incorporating lipids and proteins from the cytosol
• inactivate toxic substances
• regulate O2 concentration
• play role in synthesis and breakdown of lipids
• metabolism of nitrogenous bases and carbohydrates
• self replicate

Question 17

Desccribe the Cytoskeleton

Answer 17

Fx: cell shape, organelle movement, motility
- anchors some membrane proteins and other cellular components, moves components within the cell, moves the cell itself

1. Intermediate filaments = mechanical strength
2. Microtubules(tubulin) = LARGE= determine organell position and direct intracell transport
3. Microfilaments ( actin) = small = cell shape and locomotion.

Question 18

Describe Intermediate Filaments

Answer 18

• Mechanocal Strength
• tough ( can survive cell death…hair, fur, nails, claw, skin)
• controls breakdown and reassemble of nuclear envelope in Mitosis

Question 19

Describe Microtubles

Answer 19

• Large - determine organelle position & direct intracell transport
• flagella & cilia formation
• spindle apparatus
• made from tubulin
• (-) end is anchored to MTOC (+)end grows and shrinks

Question 20

Describe Microfilaments

Answer 20

• Actin
• Small
• cell Shape and Locomotion
• contractile force in microvilli and muscle
• squeez membrane in phagocytosis and cytokinesis.

Question 21

Microtubles are made of the protein ____?

Answer 21

Tublin

- a globular protein that can polymerise into a straight filament.

Question 22

Describe Flagella and Cilia

Answer 22

• 9+2 ( 9 pairs plus 2 single in the center of Microtubules)

Question 23

The only cell in the in the body with flagella is _____.

Answer 23

Sperm

Question 24

In the human body ciliated cells are only found in ____ and ______.

Answer 24

• Fallopian tube and Respiratory tract.

my balls your mouth =>cilia like Sx found in testes, and cilia in trachea

Question 25

What is Dynein

Answer 25

- protein that makes cross bridges connecting MTs | - slides MTs past each other using ATP casing it to bend = whiplike movement

Question 26

Whats the difference between eukaryotic flagella and prokaryotic flagella?

Answer 26

Eukaryotic - 9+2 MT - whip like motion Prokaryotic - single thin strand of protein Flagellin - Flagellin rotates

Question 27

What is the significance of the MTOC?

Answer 27

- Microtubule Organizing Center (aka centrosome) - the MT grows away from the MTOC at is + end - GTP bound = growth - GDP bound = shrinkage

Question 28

Describe Basal Bodies

Answer 28

- 9 triplets of MTs in a circle | - Anchor flagella and cilia

Question 29

What are the three types of culluar jumctions ni eularyotes?

Answer 29

1. Tight Junctions 2. Desmosomes 3. Gap Junctions

Question 30

Describe Tight Junctions:

Answer 30

- Fluid Barrier around cell - ex: Epithelial tissue like bladder, intestines, kidney --> prevents waste from leaking - prevent protein movement between apical and basolateral serface.

Question 31

What the difference between basolateral and apical surface.

Answer 31

Apical- part of cell facing the lumen ofa cavity Basolateral- the opposite side of the cell

Question 32

Describe Desmosomes

Answer 32

- holds cells together at a single point - attach directly to cytoskeleton - normally found in tissues that experience stress( skin, intestinal epithelium)

Question 33

Describe Gap Junctions:

Answer 33

- Tunnels between cells allowing small molecules and ions to pass through - In cardiac muscle , allows for spread of action potential

Question 34

Describe Mitondria

Answer 34

- Powerhouse of the cell | - (she get it from her mamma)