Block 1 - Building Blocks (L1-2)

Question 1

Which organelles are membrane-bound?

Answer 1

nucleus, mitochondria, lysosome, and endoplasmic reticulum

Question 2

What 4 elements are we primarily made of?

Answer 2

oxygen, carbon, hydrogen, and nitrogen

Question 3

How many cells and cell types make up a human?

Answer 3

3.7 x 10^13 cells, 200 different types

Question 4

What is homeostasis? What are some examples?

Answer 4

self-regulating process by which biological systems maintain stability while adjusting to external conditions (constant internal conditions)

ex: body temp, blood pH, tissue oxygenation, cell size, and cytoplasmic composition

Question 5

Cells contain macromolecules that can’t pass through the membrane. Because of this, cells have a tendency to —– due to…..

Answer 5

swell due to the osmotic effect (water moves in to lower the concentration inside vs. outside)

Question 5

To form multicellular structures, individual cells must c—— and c——-.

Answer 5

coordinate and cooperate

Question 6

What are the 6 modern tenets of cell theory?

Answer 6

1. all living things are made of cells
2. the cell is the structural and functional unit of all living things
3. all cells come from preexisting cells by division (there is no spontaneous generation)
4. cells contain hereditary information that is passed from cell to cell during division
5. all cells are basically the same chemical composition
6. all energy flow of life occurs within cells

Question 7

What is the general size of cells? Which are some of the largest and the smallest?

Answer 7

in micrometers/microns, ranging from 20-120 roughly

adipocytes are large, around 120 micrometers, while pancreatic beta cells are very small, around 25 micrometers

*exceptions for some, such as the length of a neuron in the sciatic nerve

Question 8

What are the most abundant cell in the human body?

Answer 8

red blood cells, 83% of the total cells in the body

Question 9

Because of the communication between cells, complex tissues can…

Answer 9

sense and respond to other cells, coordinate actions, and develop specialized functions

Question 10

What is the difference between endocrine, paracrine, and autocrine signaling?

Answer 10

Endocrine - travel through the bloodstream from one cell to a target cell
Paracrine - travel to a nearby target cell
Autocrine - target cell is the same cell that released the signal

Question 11

Describe the composition of the phospholipid bilayer

Answer 11

polar hydrophilic head groups face out, nonpolar hydrophobic tails face in toward each other and away from water

Question 12

Integral membrane proteins are located ——- so they must have ——-

Answer 12

through the entire membrane, so they must have hydrophobic and hydrophilic parts (must be amphipathic)

Question 12

Proteins that sit on the outside of the membrane are called…

Answer 12

peripheral membrane proteins

Question 13

What are the three main components of the phospholipid bilayer?

Answer 13

glycerophospholipids, sphingolipids, and cholesterol

Question 13

Describe glycerophospholipids

Answer 13

amphipathic, main component of the plasma membrane

glycerol backbone and 2 fatty acid tails in an ester linkage with a polar head group (phosphate ester of another alcohol, like choline, ethanolamine, serine, or inositol)

Question 14

Describe sphingolipids

Answer 14

amphipathic

sphingosine backbone (1 tail) and 1 fatty acid tail in amide linkage and a polar head group (either a carbohydrate or a phosphate ester of another alcohol)
glycosphingolipids or phosphosphingolipids

Question 15

What is the general size of a phospholipid bilayer? What contributes to this size?

Answer 15

5-6 nm (50-60 A)

the dimension of the lipid constituents determines the thickness

Question 16

Describe cholesterol

Answer 16

amphipathic, a sterol, essential membrane component

wedges into the bilayer and has effect on fluidity by interacting with first few hydrocarbon groups on phospholipid tails (make the tails less hydrophobic)

Question 17

What is the difference between saturated and unsaturated fatty acids in the bilayer?

Answer 17

unsaturated fatty acids have one or more double bonds that make the tails “crooked”

Question 18

What factors effect membrane fluidity?

Answer 18

• lipid composition
• fatty acid chain length (longer means tighter packing and less fluidity)
• number of double bonds in the fatty acid chains (more double bonds means looser packing and more fluidity)
• cholesterol (increases fluidity)

Question 19

Membranes are dynamic because…

Answer 19

proteins can move through them relatively quickly

if you fuse two cells, the proteins will spread throughout pretty fast

Question 20

Sometimes proteins do not move easily throughout the membrane because…

Answer 20

they can link to other structures inside or outside the cell, such as intracellular proteins or the cell matrix/cytoskeleton

Question 21

What are the relative concentrations of Na and K inside and outside the cell? How are those concentrations maintained?
Why do the concentrations need to be maintained?

Answer 21

low Na+ inside the cell and high Na+ outside the cell

high K+ inside the cell and low K+ outside the cell

maintained by Na+/K+ pumps powered by ATP

maintaining these concentrations keeps the gradient and prevents swelling of the cell