Intro to Membranes + Bacterial Cell Structure

Question 1

What kind of movement is common in the phospholipid bilayer and why

Answer 1

Lateral movement, provides fluidity and flexibility. Flip-flop movement is rare because polar head is not stable in hydrophobic core

Question 2

In high temperatures, there is _____ (more/less) room between phospholipids and the membrane permeability _______ (increases/decreases)

Answer 2

more, increases

Question 3

In low temperatures, there is _____ (more/less) room between phospholipids and the membrane permeability _______ (increases/decreases)

Answer 3

less, decreases

Question 4

How do membranes adapt to high & low temperatures

Answer 4

High: increase hydrocarbon tail length (increase hydrophobicity), decrease C=C bonds (they cause kinks, increase cholesterol content (stiffens/thickens membrane, increases hydrophobicity)
Low: Increase C=C bonds (“kick” apart), decrease tail length, increase cholesterol (acts as a spacer)

Question 5

Non-polar amino acids are

Answer 5

hydrophobic

Question 6

List substances from most permeable to least permeable

Answer 6

hydrophobic (np) molecules (O2, CO2, N2) -> small uncharged polar molecules (H2O, Glycerol, Ethanol) -> large uncharged polar molecules (glucose, sucrose) -> ions (Na+, K+, H+, Cl-)

Question 7

How does passive transport work

Answer 7

Molecules flow from an area of high concentration to low concentration (water follows solute). Water undergoes passive transport by osmosis.

Question 8

What is a risk when water rushes into the cell in animal cells

Answer 8

cells can burst (osmotic lysis)

Question 9

What is a risk when water rushes out of the cell in animal cells

Answer 9

cells can shrink

Question 10

Does facilitated diffusion require energy

Answer 10

no

Question 11

Name the two forms of facilitated diffusion

Answer 11

Channel “tunnel” protein and carrier “revolving door” protein

Question 12

Is facilitated diffusion specific

Answer 12

yes

Question 13

Why perform active transport?

Answer 13

expel waste, concentrate nutrients in cell

Question 14

Describe the sodium potassium pump

Answer 14

Sodium
Out
Potassium
In

Positive
Out
Negative
In
3Na+ out 2K+ in

Question 15

Define coupled transport, give an example

Answer 15

Energy released by one gradient is used to establish another gradient.
Sodium/Potassium pump is used to pull glucose up its gradient into the cell.

Question 16

Explain exocytosis

Answer 16

Bulk transport out of the cell, proteins from golgi transported in vesicle that fuses with plasma membrane to secrete proteins

Question 17

Explain Endocytosis/Phagocytosis

Answer 17

Bulk transport into the cell, non specific, vesicle forms from plasma membrane, transports to lysosome (digestive organelle)

Question 18

Explain Receptor mediated endocytosis

Answer 18

Endocytosis of a specific ligand (anything that binds a receptor) placed in vesicle, receptors recycled, ligand goes to lysosome to be digested/recycled.

Question 19

Bacteria HAVE:

Answer 19

fimbriae, cell membrane, cell wall, cytoplasm, flagella, ribosomes, DNA in nucleoid region

Question 20

Bacteria DO NOT have:

Answer 20

Membrane bound organelles (eg. Golgi, ER, chloroplasts)

Question 21

What is the motile structure of Bacteria, explain it

Answer 21

Bacteria flagellum: rotates like a corkscrew to allow movement, powered by H+ gradient
Basal apparatus anchors filaments into cell wall/membrane

Question 22

What is peptidoglycan

Answer 22

structural polysaccharide

Question 23

What is lipoteichoic acids role

Answer 23

link cell wall to membrane

Question 24

Explain the differences between Gram negative and Gram positive bacterial cell walls

Answer 24

Positive: thick layer of peptidoglycan
Negative: thin layer of peptidoglycan, but has an outer membrane (but not a major permeability layer)

Question 25

What are Fimbriae and Biofilm

Answer 25

Forms of attachment in prokaryotes

Question 26

How does the antibiotic penicillin work

Answer 26

Disrupts transpeptidation step (works well on Gram positive bc more PG)

Question 27

How does colonization begin at birth

Answer 27

“Good” skin bacteria in birth canal so that baby is bathed in it before bad bacteria can reach it, around 600 species of bacteria in breast milk

Question 28

What is humans only source of vitamin K

Answer 28

E Coli

Question 29

Bacteria can aid in….

Answer 29

development of gut, digesting complex carbs, train immune system to distinguish harmful & helpful