The Cell

Question 1

Cell membrane

Answer 1

• semi-permeable
• phospholipid bilayer
• passive diffusion
  1. phospholipids
  2. cholesterol
  3. proteins
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Question 2

Phospholipid bilayer (3 parts)

Answer 2

1. Phosphate head (polar/hydrophilic)
2. Glycerol backbone
3. Fatty acid tails (nonpolar/hydrophobic)
   Amphipathic!!!!!
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Question 3

Passive Diffusion

Answer 3

Allows small, nonpolar molecules to pass through membrane such as gases but also water and ethanol (polar, pass slowly) and benzene (large, nonpolar, pass slowly)
Does not allow charged or large, polar molecules through (such as amino acids or glucose)

Question 4

Cholesterol

Answer 4

Acts as a buffer

• Increases fluidity in lower temperatures
• Decreases fluidity in higher temperatures

Question 5

Membrane Fluidity

temp

Answer 5

Low T = Low fluidity (think crystallized state tight together)
High T = High fluidity (loose state)

Question 6

Membrane Fluidity

cholesterol

Answer 6

At High T, cholesterol reduces fluidity

At Low T, cholesterol increases fluidity

Question 7

Membrane Fluidity

Saturation of FAs

Answer 7

Saturation decreases fluidity
Unsaturated FAs increase fluidity
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Question 8

Uncatalyzed Membrane Dynamics (w/ Proteins)

Answer 8

Transbilayer Diffusion: slow

Lateral Diffusion: fast

Question 9

Catalyzed Membrane Dynamics (w/ Proteins)

Answer 9

Flippase (fast): outer to inner membrane
Floppase (fast): inner to outer membrane
Scramblase (fast): both directions
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Question 10

Channel Proteins

Answer 10

• no energy needed
• moves with concentration gradient
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Question 11

Carrier Proteins

Answer 11

• some energy needed
• can move against concentration gradient
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Question 12

Glycoproteins

Answer 12

Proteins with carbs attached, used for signaling

Question 13

Types of Proteins in phospholipid bilayers

Answer 13

Proteins act as receptors and for transport of molecules

• peripheral proteins sit inside or outside of bilayer
• integral/transmembrane proteins extend across the bilayer
• lipid-bound proteins sit in the middle of the bilayer and are rare

Question 14

Cell Theory

Answer 14

1. All living things are composed of cells (Von Leeuwenhoek and Hooke in 1600s)
2. The cell is the basic functional unit of life (Schleiden and Schwann in early 1800s)
3. Cells arise only from pre-existing cells
4. Cells carry genetic info in the form of DNA and this DNA is passed on from to parent to daughter cell

Question 15

Abiogenesis

Answer 15

Spontaneous generation. Disproven in 1860s by Pasteur.

Question 16

Exceptions to cell theory

Answer 16

Viruses require intermediate to replicate DNA.

Mitochondria have own DNA.

Question 17

Nucleoid Region

Answer 17

DNA region in prokaryotes

Question 18

Nucleolus

Answer 18

Makes ribosomes, sits in the nucleus, no membrane

Question 19

Peroxisomes

Answer 19

• Collect and break down material

- Peroxides reduced into non-toxic forms (into H2O and 1/2 O2) via catalase enzyme

Question 20

Rough ER

Answer 20

Accept mRNA to make proteins

Proteins secreted in extracellular space become integral proteins or end up in ER, golgi body, or lysosomes

Question 21

Smooth ER

Answer 21

Detox, make lipids, make steroid hormones, metabolism of carbs

Question 22

Golgi Apparatus

Answer 22

Posttranslational protein modification and distribute proteins. Synthesized molecules for secretion. Only in eukaryotes.
Cis stack-closest to ER; Medial stack; Trans stack-farthest from ER

Question 23

Centrioles

Answer 23

9 groups of microtubules; pull chromosomes apart

Question 24

Lysosomes

Answer 24

• Demo and recycling center
• Autophagy-digest cell parts
• Crinophagy- digest excess secretory products
• pH of 5

Question 25

Plasmids

Answer 25

In prokaryotes, Carry DNA not necessary for survival

Question 26

Cytoplasm pH

Answer 26

~7.4

Question 27

Mitochondria

Answer 27

Site for CAC, ETC, Oxidative Phosphorylation, pyruvate dehydrogenase, B-Oxidation, some of gluconeogenesis, and urea cycle Site of ATP production Have their own genome, self-replicating

Question 28

Nucleus

Answer 28

Contains all genetic material for replications | Contains nucleolus

Question 29

Eukaryotes Vs. Prokaryotes: | Size, reproduction, organelles, DNA region, and site for ETC

Answer 29

Euks larger than Proks Euks reproduce via mitosis, Proks via binary fission Euks contain membrane-bound organelles (compartmentalization) Euks have nucleus, Proks have nucleoid region Euks ETC in mitochondria, Proks ETC in cell membrane

Question 30

Cytoskeleton

Answer 30

Microfilaments, Microtubules, Intermediate Filaments

Question 31

Intermediate Filaments

Answer 31

Resist mechanical stress and provide structural support | Keratin = vimentin; Desmin = lamin

Question 32

Microtubules

Answer 32

Transport within a cell TUBULIN: hollow protein polymers CENTRIOLES: 9 triplets of microtubules with a hollow center Also cilia and flagella

Question 33

Microfilaments

Answer 33

Movement of entire cell from within cytoplasm | ACTIN: solid polymerized rods resistant to compression and fracture