Chapter 3/4: The Living Units

Question 1

What changes the function of a cell?

Answer 1

the shape

Question 2

What does the plasma membrane do?

Answer 2

• physical barrier
• selective permeability
• communication
• cell-to-cell recognition

Question 3

What is the plasma membrane made of?

Answer 3

phospholipids

Question 4

True or False: phospholipid heads are hydrophilic

Answer 4

True

Question 5

What is hydrophilic?

Answer 5

polar molecule attracted to water

Question 6

Is the lipid tail hydrophobic or hydrophilic?

Answer 6

hydrophobic

Question 7

How many layers does the plasma membrane have?

Answer 7

2 (bilayer)

Question 8

Which type of heads (hydrophobic or hydrophilic) face out?

Answer 8

hydrophilic

Question 9

What are plasma membranes made of?

Answer 9

lipids, proteins, and carbohydrates

Question 10

What are the functions of integral proteins?

Answer 10

transport, signal transduction, enzymatic activity, and cell-to-cell interactions

Question 11

What do carriers and channels do?

Answer 11

transport small molecules across membranes

Question 12

What do receptors do?

Answer 12

sense interior and exterior environment

Question 13

What do enzymes do?

Answer 13

perform chemical reactions

Question 14

What are the functions of membrane carbohydrates?

Answer 14

• lubricate, cushion and protect cell
• reinforce membrane integrity
• can act as recognition factors (cell-to-cell interactions and pathogen recognition)

Question 15

What can chains of sugars attach to?

Answer 15

• lipids (glycolipids)
• proteins (glycoproteins)

Question 16

What are lipid rafts?

Answer 16

many kinds of phospholipids with different properties
- some form stiffer or more flexible membranes
- some form thicker or thinner membranes

Question 17

What is selectively (referring to plasma membrane)?

Answer 17

permits free passage of some materials and restricts passage of others

Question 18

What is passive transport?

Answer 18

move substance without using cellular energy

Question 19

Can passive transport use a protein channel?

Answer 19

yes

Question 20

What is active transport?

Answer 20

move substance using cellular energy (ATP)

Question 21

What is diffusion?

Answer 21

material moves from high to low concentration; down concentration gradient

Question 22

What is simple diffusion?

Answer 22

non-polar and lipids voluble substances defuse directly through the lipid bilayer

Question 23

What are some example of molecules that can diffuse through simple diffusion?

Answer 23

oxygen, carbon dioxide, fat-soluble vitamins, some water

Question 24

True or false: lipiphobic can pass using facilitated diffusion

Answer 24

false

Question 25

What is channel-mediated?

Answer 25

acts as a pore in the plasma membrane

Question 26

What is an example of channel-mediated?

Answer 26

leak and gated channels

Question 27

What is carrier-mediated?

Answer 27

changes shape as it binds substrate, envelops it, and releases

Question 28

What is osmosis?

Answer 28

defined specifically as movement of water across a selectively permeable membrane

Question 29

How does water diffuses through plasma membrane?

Answer 29

Simple diffusion channel-mediated facilitated diffusion

Question 30

What causes water to have a change in net movement across the plasma membrane?

Answer 30

solute concentration

Question 31

Water moves to dilute or concentrate the solute?

Answer 31

dilute the solute

Question 32

What is osmolarity?

Answer 32

measure of solute concentration in water

Question 33

What will happen if the membrane is permeable to the solute and water?

Answer 33

diffusion

Question 34

What will happen of the membrane is impermeable to the solute and permeable to water?

Answer 34

osmosis

Question 35

Tonic

Answer 35

concentration

Question 36

Two types of active transport

Answer 36

active transport vestibular transport

Question 37

What do the two active transports have in common?

Answer 37

both use ATP to move solutes across a cell membrane

Question 38

Why do these processes need to use energy?

Answer 38

to go against the concentration gradient

Question 39

How does it differ from passive processes?

Answer 39

needs ATP

Question 40

What does active transport require?

Answer 40

carrier proteins (solute pumps)

Question 41

What does primary use as energy?

Answer 41

hydrolysis of ATP

Question 42

What is hydrolysis of ATP?

Answer 42

using energy to break down; decomposition

Question 43

What does primary transport cause?

Answer 43

shape change in transport protien

Question 44

What is the function of primary transport?

Answer 44

“pumps” solutes (ions) across membrane against gradient

Question 45

What is Na+/K+ pump?

Answer 45

- in all plasma membranes - primary & secondary active transport -maintains electrochemical gradient - neuron and muscle cell function

Question 46

What does secondary transport depend on?

Answer 46

an ion gradient created by primary active transport

Question 47

What is secondary transport?

Answer 47

energy stored in ionic gradients is used indirectly to drive cotransport of the other solute

Question 48

How else can cells move materials in and out of the cell?

Answer 48

endocytosis & exocytosis

Question 49

endo

Answer 49

enter

Question 50

exo

Answer 50

exit

Question 51

True or false: endocytosis and exocytosis is a form of active transport

Answer 51

true

Question 52

What are some of the larger cellular items that get transported?

Answer 52

extracellular solutes, cellular debris, pathogens, cellular waste products

Question 53

What does endocytosis do?

Answer 53

bringing materials into the cell

Question 54

What are the major forms of endocytosis?

Answer 54

phagocytosis, pinocytosis, receptor-mediated endocytosis

Question 55

What does phagocytosis do?

Answer 55

eat bacteria, cellular debris, and foreign material

Question 56

Is pinocytosis selective about what enters the cell?

Answer 56

yes

Question 57

Tru or false: receptor-mediated endocytosis is not selective

Answer 57

false

Question 58

What are the receptors binding to in receptor-mediated endocytosis?

Answer 58

enzymes and insulin

Question 59

What does exocytosis do?

Answer 59

releases cellular products and waste out of the cell

Question 60

What gets released during exocytosis?

Answer 60

proteins and carbohydrates, hormones, neurotransmitters, muscles, and wastes

Question 61

What is the function of the smooth ER?

Answer 61

the site of steroid and lipid synthesis, lipid metabolism, drug detoxification, and Ca+ storage

Question 62

What makes up the cytoskeleton?

Answer 62

microfilaments, intermediate filaments, and microtubules

Question 63

What are microfilaments?

Answer 63

strands made up of spherical protein subunits called actin

Question 64

What are intermediate filaments?

Answer 64

tough, insoluble protein fibers constructed like woven ropes composed of tetramer fibrils

Question 65

What are microtubules?

Answer 65

hollow tubes of spherical proteins subunits called tubulin

Question 66

How do lysosomes work?

Answer 66

use hydraulic enzymes to digest substances

Question 67

Where are lysosomes most abundant?

Answer 67

in phagocytes

Question 68

How do peroxisomes work?

Answer 68

use molecular oxygen to detoxify harmful substances

Question 69

Where are peroxisomes most numerous?

Answer 69

in the kidneys and liver

Question 70

What do centrioles do?

Answer 70

aid in organizing microtubules network, form spindles and asters during cell division