Chapter 4: Cell Structure

Question 1

cell wall

Answer 1

• plants: made out of cellulose (polysaccharide)
• fungi: made out of chitin (polysaccharide)
• bacteria: made of peptidoglycan (protein and sugar)
• forms outer layer

Question 2

cell membrane

Answer 2

• selectively permeable
• composed of lipids and proteins
• forms oily layer between the inside of the cell and the outside so hydrophilic substances cannot cross the hydrophobic barrier

Question 3

simple diffusion

Answer 3

• movement of a hydrophobic substance (like oxygen, carbon dioxide, and cholesterol) down a concentration gradient from an area of high concentration to low concentration until dynamic equilibrium is reached
• only works when the substance is lipid soluble (hydrophobic) and can interact with the oily barrier
• passive

Question 4

facilitated diffusion

Answer 4

• hydrophillic particles (like ions and glucose) diffuse across the membrane with the use of membrane proteins that form specialized channels
• passive
• some proteins act as carrier molecules that bind to a substance and “pull” it through a membrane

Question 5

active transport

Answer 5

• can go against the concentration gradient
• use energy to move something across the membrane
• relies on membrane proteins to transport hydrophobic and hydrophillic particles

Question 6

bulk transport

Answer 6

-movement of large, bulky items across the membrane through endocytosis or exocytosis

Question 7

endocytosis

Answer 7

• cell takes in a particle by surrounding and engulfing it into a vesicle
• phagocytosis: cell eating
• pinocytosis: cell drinking

Question 8

exocytosis

Answer 8

-particle in a vesicle is released to the outside by fusing the vesicle with the cell membrane

Question 9

osmosis

Answer 9

• diffusion of water across a membrane down the water concentration gradient
• water’s concentration gradient is opposite of the solute’s concentration gradient
• must cross through facilitated diffusion (with aquaporins)

Question 10

hypertonic solution

Answer 10

• concentrated solution

- causes cell to shrivel or become flaccid

Question 11

hypotonic solution

Answer 11

• dilute solution

- cell will lyse or become turgid for plants

Question 12

isotonic solution

Answer 12

• same concentration as cell

- cell will be normal (plant will be shriveled)

Question 13

cytoplasm

Answer 13

• contains eukaryotic cell’s organelles

- some prokaryotic cells do not have organelles

Question 14

ribosome

Answer 14

• no membrane

- site of protein synthesis

Question 15

nucleus

Answer 15

• double membrane bound
• contains genetic material (chromosomes and DNA)
• control center of cell

Question 16

mitochondria

Answer 16

• functions in cellular respiration (produces ATP for the cell)
• bound by double membrane

Question 17

vacuole

Answer 17

-storage of wastes and other materials

Question 18

smooth ER

Answer 18

• transports substances around the cell

- creates lipids

Question 19

rough ER

Answer 19

-has ribosomes that synthesizes membrane (protein channels) and secreted proteins

Question 20

golgi body

Answer 20

-sorts and packages proteins made by ribosomes on the ER

Question 21

lysosomes

Answer 21

-digest foreign substances and worn-out organelles

Question 22

nucleolus

Answer 22

• small, dense structure in the nucleus

- site of ribosome synthesis

Question 23

enzyme

Answer 23

• protein (organic molecule) that acts as a catalyst (a molecule that speeds up chemical reactions) in cells
• reusable (not used up)
• induced-fit or lock-and-key model (an enzyme has a specific shape catered to certain reactions bc active site is specific to certain reactants)
• reactants are called substrates
• determines which reactions occur inside a cell

Question 24

denaturation

Answer 24

• degradation of enzyme (often through heat or change in pH)

- no longer useful because they lose their shape

Question 25

coenzymes

Answer 25

• molecules that help enzymes work faster (or work at all)

- ex: vitamins

Question 26

centriole

Answer 26

-help form the mitotic spindle during mitosis (cell division)