A&P1_HW04

Question 1

What events can result in a protein misfolding?

Answer 1

• a mutation in a gene that changes an amino acid in a protein
• a protein adopts a stable but nonfunctional tertiary structure
• contact with a misfolded protein with the same amino acid sequence

Question 2

Name __ types of motor proteins

Answer 2

• myosin

* dynein

Question 3

Plasma membranes are selectively permeable, or semipermeable, meaning that

Answer 3

the membrane regulates what enters and leaves the cell.

Question 4

Describe diffusion

Answer 4

The movement of a substance from a region where it is more concentrated to a region where it is less concentrated, down its concentration gradient.

Question 5

Define the cell membrane’s role in homeostasis

Answer 5

If there is an excess of carbon dioxide inside the cell, some of the carbon dioxide molecules permeate the membrane and leave the cell.

Passive forms of transport move molecules such as water across the cell membrane with no energy added.

Question 6

Describe a Simple diffusion

Answer 6

movement of solute out of the cell directly through the plasma membrane

Question 7

Describe a Facilitated diffusion

Answer 7

movement of solutes out of the cell down their concentration gradient using membrane proteins

Question 8

Describe a Active transport

Answer 8

movement of solute out of the cell against their concentration gradient using membrane proteins

Question 9

Describe a Bulk transport

Answer 9

movement of contents of transport vesicles out of the cell by exocytosis

Question 10

Substances that move easily through the lipid bilayer of the plasma membrane

Answer 10

Small, uncharged molecules, such as oxygen can pass easily between the phospholipids in a plasma membrane because they do not interact with the hydrophobic fatty acid tails of the phospholipid molecules

Question 11

Substances that need help from a protein to cross the membrane because they are repelled by the lipid bilayer

Answer 11

• large polar molecules, such as the simple sugars frutose and glucose, are not only too big to squeeze easily between the phospholipids, they are repelled by the hydrophobic fatty acid tails of the the phospholipid that make the middle of the lipid bilayer.Likewise, many of the amino acids are charged or polar, and they have difficulty passing between the phospholipid tails. Protein channels allow these molecules to cross the membrane.
• charged substances are repelled by the hydrophobic fatty acid tails of the phospholipid molecules and connot cross through the membrane without the help of a protein carrier. Ions, such as calsium ions, are very small, but they have troble moving across cell membranes with the help of protiens because it dissociates into two ions when in water

Question 12

Describe passive transport

Answer 12

• does not require energy

* moves substances down a concentration gradient

Question 13

Describe active transport

Answer 13

• requires energy

* moves substances against a concentration gradient

Question 14

Describe simple diffusion

Answer 14

movement of solutes out of the cell directly through the plasma membrane

Question 15

Describe facilitated diffusion

Answer 15

movement of solutes out of the cell down their concentration gradient using membrane proteins

Question 16

Describe primary active transport

Answer 16

movement of solutes into the cell against their concentration gradient using ATP-powered membrane pumps

Question 17

Describe secondary active transport

Answer 17

movement of one solute out of the cell, against its concentration gradient, via a cotransporter driven by another solute’s gradient

Question 18

Define facilitated diffusion

Answer 18

a protien-faciliated movement of solutes across a membrane from an area of higher concentration to an area of lower concentration

Question 19

Passive transport best describes

Answer 19

facilitated diffusion

Question 20

What is an aquaporin?

Answer 20

membrane protein that contains a channel for water movement

Question 21

Examples of facilitated diffusion

Answer 21

*an inner ear hair cell allows potassium ions to flow down their concentration gradient after sound waves stimulate a membrane protein
*a kidney cell absorbs water molecules down their concentration gradient using a membrane protein
A neuron allows potassium ions to leave the cell down their concentration gradient using a membrane channel

Question 22

When a muscle contracts, calcium ions are forced into an extracellular space against their concentration gradient

Answer 22

An influx of ATP provides the energy needed for an ion pump

Question 23

Example of symporter

Answer 23

A protein moves one H+ ion and one K+ ion out of the cell

Question 24

Example of uniporter

Answer 24

A protein allows glucose to flow into a cell down its concentration gradient

Question 25

Example of antiporter

Answer 25

A protein moves one Ca2+ out of the cell and three Na+ into the cell

Question 26

Define exocytosis

Answer 26

one of the processes living organisms use to move molecules

Question 27

Examples of exocytosis

Answer 27

• Pancreatic cells release digestive enzymes into the small intestine
• A never cell releases peptides used as messengers into the extracellular space
• A single-celled eukaryotic organism excretes digestive waste into the surrounding water.

Question 28

Define Phagocytosis

Answer 28

a method of cellular ingestion that engulfs specific, targeted matter.

Question 29

Define pinocytosis

Answer 29

ingesting solutes in the aqueous environment and enclosing them in intracellular vesicles

Question 30

What is clathrin?

Answer 30

peripheral membrane protein that mediates endocytosis

Question 31

Describe pinocytosis

Answer 31

• it is referred to as cellular drinking

* tiny vesicles are formed

Question 32

Describe phagocytosis

Answer 32

• it is referred to as cellular eatting
• large vesicles are formed
• pseudopodia are used