lecture 3

Question 1

cytoskeleton function

Answer 1

Cell Shape – provides mechanical strength and helps support microvilli (finger-like extensions of the cell membrane that increase surface area).
Internal Organization – stabilize the positions of organelles.
Intracellular Transport – transports materials within the cytoplasm by serving as an intracellular “railroad track”.
Assembly of Cells into Tissues – Protein fibers allow the linking of cells to one another.
Movement – Allows some cells to elongate or form cilia and flagella for additional movement.

Question 2

Microfilament Function - Microvilli

Answer 2

Microvilli increase the cell surface area tremendously and are most often found on the surface of absorptive cells such as intestinal cells.

Question 3

Microtubule Function - Centrioles

Answer 3

Microtubules are the largest cytoplasmic protein fibers that create the complex structures of centrioles, cilia, and flagella.
The centrosome is the cell’s microtubule-organizing center. Assembles tubulin monomers into microtubules
The centrosome contains 2 centrioles that function during cell division to direct the movement of DNA strands.
made of tubulin
3 triplekets 9 of em

Question 4

Microtubule Function – Cilia

Answer 4

Cilia – short, hairlike structures projecting from the cell which beat to create currents that sweep fluids or secretions across the cell surface
base is centriole.9 plus two arrange of microtubules

Question 5

Microtubule Function – Flagella

Answer 5

A long, sheathed structure used to propel the organism through a fluid environment.
Also made of Microtubules in a 9+2 arrangement
Also covered by the cell membrane
Whips back and forth for cell motility

Question 6

what uses microtubules as railways

Answer 6

motor protiens use microtubules as railways to move things in cell like vesicles

Question 7

ribosome

Answer 7

Small, dense granules of RNA and protein
Function in protein synthesis under the direction of the cell’s DNA
Fixed or Bound Ribosomes are attached to the cytosolic surface of organelles
Free Ribosomes are suspended free in the cytosol
Polyribosomes are free ribosomes that form groups of 10-20

Question 8

mitochondria

Answer 8

Mitochondria are spherical to elliptical organelles with a double membrane that creates two separate compartments within the organelle.

The inner matrix is surrounded by an inner membrane that folds into
leaflets called cristae.

The intermembrane space, which lies between the two membranes, plays an important role in ATP
production.

Mitochondria are the site of most ATP synthesis in the cell.

Called powerhouse or energy generator of the cells

has ciricular dna and ribosomes. same size has bacteria ribosomes 70s

Question 9

Nucleus

Answer 9

Contains DNA, the genetic material that ultimately controls all cell processes.
Nuclear Envelope – composed of 2 parallel membranes connected by small nuclear pores.
Nuclear Pores – serve as selective passageways in and out.
Nucleolus – dark staining region that is site for ribosomal RNA synthesis
Chromatin – scattered granules composed of DNA and associated proteins

Question 10

rough er

Answer 10

A series of tunnels originating from the outer membrane of the nuclear envelope.
Appears rough due to ribosomes attached to surface
Ribosomes synthesize proteins into the RER cisternae (hollow sacs)
Involved in protein synthesis, modification, and packaging

Question 11

smooth er

Answer 11

Have no ribosomes attached
Also connected to RER and Nuclear Envelope
Function in synthesis, storage, and transport of lipids
Storage of Calcium Ions: important for cell signaling

Question 12

golgi apparaatus

Answer 12

Consists of a series of hollow curved sacs called cisternae.
Cisternae are stacked on top of one another and surrounded by vesicles.
Functions in modification, maturation, sorting, and transport of proteins.
Commonly referred to as the “post office” of the cell
Pinches off Vesicles: small sacs of membrane containing various components.
receive proteins from er or stuff from all over cell
cis face: loaidng or receiving side of golgi
trans face: shipping side

Question 13

lysosome

Answer 13

Lysosomes are small, spherical storage vesicles that contain powerful digestive enzymes.
Involved in digestion of food particles that enter the cell, breaking down old organelles, and degrading bacteria
Lysosomes activate their enzymes once their internal pH drops to 4.8-5.0
inside of phagocytes.
have speical pumps that have protons. when acidity dorps it activeates enzymes to digest things.

Question 14

peroxisomes

Answer 14

Peroxisomes are storage vesicles that are even smaller than lysosomes
They contain a different set of enzymes that break down long-chain fatty acids and potentially toxic foreign molecules
Peroxisomes got their name from their internal production of hydrogen peroxide, a toxic molecule
Peroxisomes rapidly convert this peroxide to oxygen and water using the enzyme catalase

Question 15

chemical formula of hydrogen peroxide

Answer 15

h2o2

Question 16

gap junctions

Answer 16

The simplest cell-to-cell junctions
Allow rapid and direct cell-to-cell communication through hollow cylinders called connexons, composed of cylindrical proteins called connexins
The channels are able to open and close, regulating the movement of small molecules and ions through them
Example: in heart muscle, gap junctions allow chemical and electrical signals to pass through rapidly from one cell to the next

Question 17

tight junction

Answer 17

Tight barriers that restrict movement of material between the cells they link
Cell membranes of adjacent cells partly fuse together with the help of interlocking junctional proteins called claudins and occludins
Found in gastrointestinal tract and kidneys
Example: form the Blood-Brain Barrier that prevents many potential harmful substances in the blood from reaching the ECF of the brain

Question 18

anchoring junctions

Answer 18

Attach cells to one another or to the extracellular matrix
Cell-to-cell anchoring junctions are created by Cell Adhesion Molecules (CAMs) called: cadherins
Desmosomes
Adherens junctions
Cell-matrix junctions are created by CAMs: integrins. anchor them to Ecm
Hemidesmosomes
Focal Adhesions

Question 19

tissue remodeling

Answer 19

Attach cells to one another or to the extracellular matrix
Cell-to-cell anchoring junctions are created by Cell Adhesion Molecules (CAMs) called: cadherins
Desmosomes
Adherens junctions
Cell-matrix junctions are created by CAMs: integrins
Hemidesmosomes
Focal Adhesions

Question 20

tissue remodeling apoptosis

Answer 20

1. Apoptosis (Cont’d)
   - During fetal development, apoptosis removes unneeded cells (e.g. finger and toe webbing in human fetuses)
   - In adults, cells are continuously undergoing apoptosis, especially those subject to normal wear and tear from outside environment (e.g. intestinal epithelium is completely replaced every 2-5 days)

Question 21

tissue remodeling necrosis

Answer 21

2. Necrosis (Traumatic Cell Death): Cell homicide; cell death from physical trauma, toxins or lack of oxygen when blood supply is cut off.
   
   • Necrotic cells swell and rupture, spewing their contents, including digestive enzymes, to neighboring cells.
   • Ruptured cells lead to tissue damage and inflammation

Question 22

stem cells

Answer 22

As cells in tissue die, they are replaced by new cells created from stem cells.
Stem cells are immature cells that have the ability to produce daughter cells that can differentiate.
Undifferentiated stem cells in a tissue that retain the ability to divide and develop into the cell types of that tissue are said to be multipotent. (adult stem cells)
Additional terminology:
Totipotent – earliest cells formed from a zygote which have the ability to develop into any and all types of specialized cells. Each has the potential to become a functioning organism.
Pluripotent – cells that now have a narrowed potential fate and develop into specific cell types. These cells cannot develop into an organism.
zygotes turn from totiotent to pluripotent.