Chapter 2 - Cells and Organelles

Question 1

cell membranes contain three main things:

Answer 1

phospholipids, proteins, cholesterol

Question 2

Membrane proteins come in two types:

Answer 2

integral (transmembrane) and peripheral

Question 3

True or false: peripheral membrane proteins extend throughout the entire bilayer

Answer 3

False - only on the periphery, generally hydrophilic

Question 4

Transmembrane protein function

Answer 4

1. transport proteins

2. receptor proteins

Question 5

transport proteins

Answer 5

move large, polar molecules across the cell membrane since they cannot freely diffuse by themselves

Question 6

examples of peripheral membrane proteins

Answer 6

adhesion proteins, cellular recognition proteins, receptor proteins

Question 7

adhesion protein function

Answer 7

attach adjacent cells to other things (like other cells) and they also act as anchors for the cytoskeleton

Question 8

cellular recognition proteins

Answer 8

peripheral membrane proteins that help cells recognize each other; usuallyt interact with receptor protein; attach to glycoproteins

Question 9

receptor proteins

Answer 9

receive chemical signals from the extracellular environment that do not need to be transmitted inside the cell

Question 10

agonist

Answer 10

ligands that bind to a receptor and activate its response

Question 11

antagonist

Answer 11

ligands that bind to a receptor and prevent it from activating

Question 12

what kind of molecules can travel directly across the phospholipid bilayer?

Answer 12

small, uncharged nonpolar molecules. ex co2 and o2

Question 13

simple diffusion

Answer 13

flow of substances down their concentration gradient, does not consume energy. does not use proteins to help particles across membrane

Question 14

what kind of molecules cannot travel directly across the bilayer?

Answer 14

large hydrophilic molecules

Question 15

facilitated transport

Answer 15

describes how large, hydrophilic molecules travel across the bilayer through transmembrane proteins (usually uniport, moving in 1 direction)

Question 16

symport

Answer 16

transmembrane protein that helps several molecules moving in 1 direction

Question 17

antiport

Answer 17

several molecules moving in opposite directions

Question 18

symport and antiport are examples of :

Answer 18

secondary active transport

Question 19

channel proteins

Answer 19

face extra and intracellular of the cell at the same time, usually allow the passage of many small, polar molecules and ions

Question 20

carrier proteins

Answer 20

change their shape to facilitate the movement of molecules through the protein

Question 21

porins

Answer 21

channel protein used in passive diffusion because they are usually not specific for just one type of molecule

Question 22

porins usually allow any ____ molecule that fits to pass through

Answer 22

hydrophilic

Question 23

aquaporin

Answer 23

type of porin found in kidney and plant roots, allow water to flow more rapidly than is possible through simple diffusion alone

Question 24

active transport

Answer 24

occurs when particles travel against their concentration gradient and requires energy input

Question 25

primary active transport

Answer 25

uses the energy released from ATP hydrolysis to pump molecules against their concentration gradient.

Question 26

example of primary active transport

Answer 26

sodium-potassium (Na+/K+) pump (hydrolyzes ATP)

Question 27

The sodium potassium pump consumes _ ATP to pump (out/in) _ Na+ and pump (out/in) _ K+

Answer 27

1 ATP; 3 out Na+; 2 in K+

Question 28

Na+/K+ pump is known as:

Answer 28

an ATPase since it hydrolyzes ATP to pump Na⁺ and K⁺ against their concentration gradients by primary active transport.

Question 29

secondary active transport

Answer 29

uses energy obtained from a source other than ATP; usually comes from free energy released as other molecules spontaneously flow down their concentration gradients

Question 30

cytosis

Answer 30

facilitates bulk transport of large, polar (hydrophilic) molecules

Question 31

2 main types of cytosis

Answer 31

endocytosis; exocytosis

Question 32

true or false: endocytosis and exocytosis require energy input

Answer 32

true - they are active transport mechanisms

Question 33

phagocytosis

Answer 33

cell engulfs undissolved materials

Question 34

pinocytosis

Answer 34

"cellular drinking" - cell will invaginate to engulf dissolved materials (liquids)

Question 35

receptor-mediated endocytosis

Answer 35

occurs when specific ligand binds to peripheral membrane receptor protein, recruits clathrin

Question 36

exocytosis is an essential part of ___ ___ from the ____ ____

Answer 36

vesicle secretion; golgi apparatus

Question 37

nuclear envelope

Answer 37

sets the borders of a eukaryotic nucleus

Question 38

true or false: nuclear envelope has 1 membrane

Answer 38

false - 2 membranes. 2 phospholipid bilayers (one inner, one outer)

Question 39

area between outer and inner membrane of nuclear envelope

Answer 39

perinuclear space

Question 40

nuclear pores

Answer 40

holes in the nuclear envelope; mRNA exits through nuclear pores

Question 41

what is the nuclear lamina

Answer 41

dense and fibrous network of proteins associated with the inner membrane of the nuclear envelope

Question 42

nuclear lamina function

Answer 42

provides structural support to the nucleus, also regulated DNA organization, DNA replication, and cell division

Question 43

nucleolus

Answer 43

dense region within the nucleus where rRNA is produced, site of production of ribosomal subunits

Question 44

ribosomal subunits contain:

Answer 44

proteins and rRNA

Question 45

when do ribosomal subunits assemble?

Answer 45

when they are floating in nucleoplasm (exited nucleolus)

Question 46

when do ribosomal subunits assemble into a complete ribosome?

Answer 46

once in the cytosol

Question 47

true or false: ribosomes are organelles

Answer 47

false (do not contain a membrane)

Question 48

eukaryotic ribosome subunits

Answer 48

40S and 60S (assemble into 80S)

Question 49

typical manipulation to proteins in the rough ER

Answer 49

glycosylation

Question 50

role of smooth ER

Answer 50

synthesize lipids, steroid hormones, detoxify cells, store ions in some cases

Question 51

example of cells that contain lot of smooth ER

Answer 51

human liver cells (heavily involved with detoxification)

Question 52

glycoproteins from the rough ER can undergo ____ in the golgi complex

Answer 52

phosphorylation