FINAL: unit 1

Question 1

what part of the phospholipid bilayer is hydrophilic?

Answer 1

the phosphate polar heads

Question 2

what stabilizes the polar heads?

Answer 2

hydrogen bonds with water and each other

Question 3

what is the hydrophilic part of the phospholipid bilayer?

Answer 3

the nonpolar fatty acid tail

Question 4

what stabilizes the nonpolar tail?

Answer 4

van der waal bonds with each other

Question 5

what is the purpose of the phospholipid bilayer?

Answer 5

creates a barrier between the inside of the cell and the outside environment
- only allows certain molecules through

Question 6

what can pass through the phospholipid bilayer?

Answer 6

• small nonpolar molecules like gas
• small uncharged polar molecules like water

Question 7

how do small nonpolar and polar molecules get through the phospholipid bilayer?

Answer 7

they diffuse directly through the hydrophobic area

Question 8

what cannot pass through the phospholipid bilayer?

Answer 8

large polar molecules and ions

Question 9

how do large polar molecules and ions get through the phospholipid bilayer?

Answer 9

through transport proteins
- channel and carrier proteins

Question 10

channel proteins

Answer 10

open pores that allow many molecules through at once
- needs a signal to be opened

Question 11

are channel proteins active or passive transport?

Answer 11

passive

Question 12

carrier proteins

Answer 12

bind to specific molecules and undergoes a shape change to allow molecules through

Question 13

are carrier proteins active or passive transport?

Answer 13

both

Question 14

why is different transport necessary for different molecules?

Answer 14

the hydrophobic barrier does not allow charged or polar molecules through

Question 15

where are proteins found in a cell?

Answer 15

cell membrane, cytoplasm, extracellular matrix and organelles (nucleus, mitochondria, chloroplast, rough ER, golgi apparatus, and vesicles)

Question 16

what is the polar region of proteins?

Answer 16

• the backbone containing COOH and NH2
• charged amino acid side chains that can hydrogen bond with water

Question 17

what is nonpolar region of a protein?

Answer 17

hydrocarbon side chains
- cannot hydrogen bond with water

Question 18

why do proteins need hydrophilic and hydrophobic parts?

Answer 18

in water, proteins fold so that hydrophilic parts face outwards and hydrophobic parts are clustered inwards to stabilize the structure

Question 19

where are carbohydrates found in the cell?

Answer 19

cell membrane, cell walls, and cytoplasm

Question 20

what are polar and nonpolar parts of carbohydrates?

Answer 20

carbohydrates contain many OH groups that can form hydrogen bonds with water therefore it is always polar

Question 21

why do carbohydrates need to be polar?

Answer 21

hydorgen bonding is important because carbohydrates store energy and provide structural support

Question 22

where are lipids found in the cell?

Answer 22

smooth ER and cell membrane

Question 23

why are polar and nonpolar parts of a lipid important?

Answer 23

lipids form the phospholipid bilayer with their polar heads and nonpolar tails

Question 24

where are nucleic acids found in the cell?

Answer 24

nucleus as DNA
cytoplasm as RNA
mitochondria as DNA

Question 25

what is the polar part of nucleic acids?

Answer 25

sugar-phosphate backbone

Question 26

what is the nonpolar part of nucleic acids?

Answer 26

nitrogenous bases (A,T,C,G)

Question 27

why are polar and nonpolar parts of nucleic acids important?

Answer 27

the polar backbone is important to form the double helix of DNA while the nonpolar bases form van der waals with each other to stabilize the DNA helix

Question 28

what is a transmembrane protein?

Answer 28

proteins that are permanently embedded in the cell membrane and they span the entire the membrane

Question 29

what do transmembrane proteins do?

Answer 29

facilitate transport of molecules across membrane, transmit signals, act as receptors, and cell-cell adhesion

Question 30

what is the polar region of a transmembrane protein?

Answer 30

the sides of the protein that are exposed to the cytoplasm which allow it to hydrogen bond

Question 31

what is the nonpolar region of a transmembrane protein?

Answer 31

the hydrophobic alpha helices that interact with the hydrophobic interior of the cell membrane - helps anchor the protein

Question 32

what are the different phospholipid bilayers in an eukaryotic cell?

Answer 32

plasma membrane, nuclear membrane and organelle membranes

Question 33

plasma membrane

Answer 33

single bilayer made of proteins and lipids that attach to carbohydrates and acts as a barrier to regulate the passage of substances in and out of the cell

Question 34

nuclear membrane

Answer 34

double layer membrane that forms the nuclear envelope and surrounds the nucleus - regulates movement of substance between nucleus and cytoplasm using nuclear pores - protects DNA

Question 35

organelle membranes

Answer 35

surround organelles and are specialized for organelle function

Question 36

nucleus

Answer 36

contains DNA and is the site of transcription

Question 37

rough ER

Answer 37

site of protein synthesis

Question 38

smooth ER

Answer 38

site of lipid synthesis

Question 39

golgi apparatus

Answer 39

modifies, stores, and packages proteins and lipids for transport

Question 40

vesicles

Answer 40

take proteins to external cellular membrane

Question 41

lysosomes

Answer 41

digestive enzymes that break down waster and old organelles - needs acidic environment

Question 42

peroxisomes

Answer 42

- detoxifies cells of lipids and alcohols - carries out redox reactions

Question 43

ribosomes

Answer 43

determines where a protein functions depending on if it was made by a cytoplasmic ribosome or rough ER ribosome

Question 44

cytoskeleton

Answer 44

provides structural support and intracellular transport

Question 45

mitochondria

Answer 45

site of chemical reactions of cellular respiration that supply most cellular energy