1 Cell Biology

Question 1

What is the composition of the cell membrane?

Answer 1

Lipid bilayer with protein channels, enzymes, receptors

Question 2

What is the role of cholesterol in the cell membrane?

Answer 2

Increases membrane fluidity

Question 3

What is the charge of the inside of the cell versus outside? What maintains this gradient?

Answer 3

Negative inside versus outside
Due to Na/K ATPase transporter
3 Na+ out/2 K+ in

Question 4

How are glucose, proteins and other molecules transported across the cell membrane?

Answer 4

Via co-transport supported by the Na+ gradient

Question 5

Components of extracellular fluid?

Answer 5

CATIONS:
Sodium - 140
Potassium - 4
Calcium - 5
Magnesium - 2
ANIONS:
Chloride - 103
Bicarb - 24
So4-2 - 1
HPO3-3 - 2
Protein - 16
Organic anion - 5

Question 6

Component of intracellular fluid

Answer 6

CATIONS:
Sodium - 12
Potassium - 150
Calcium - 10-7
Magnesium - 7
ANIONS:
Chloride - 3
Bicarb - 10
So4-2 - -
HPO3-3 - 116
Protein - 40
Organic anion - -

Question 7

Define desmosomes/hemidesmosomes

Answer 7

Adhesion molecules, which anchor cells

Cell-cell and cell-extracellular matrix

Question 8

Define tight junctions

Answer 8

Cell-cell occluding junctions - form and impermeable barrier

Question 9

Define gap junctions

Answer 9

Connexin subunits

Allow communication between cells

Question 10

Define osmotic equilibrium

Answer 10

Water will move from an area of low solute concentration of higher solute concentration and approach osmotic equilibrium

Question 11

What are the cell cycles - what occurs during them?

Answer 11

G1 (cell increases in size, checkpoint)
S (protein synthesis, chromosomal duplications)
G2 (cell increases in size, checkpoint)
M (mitosis, nucleus divides)

Question 12

What is the most variable stage in the cell cycle?

Answer 12

G1 - affected by growth factors

Determines cell cycle length

Question 13

What are the stages of mitosis?

Answer 13

Prophase - centromere attachment, spindle formation, nucleus disapears
Metaphase - chromosome alignment
Anaphase - chromosome pulled apart
Telophase - seperate nucleus reforms around each set of chromosomes

Question 14

What is the composition of the nucleus?

Answer 14

Double membrane - outer membrane is continuous with the rough endoplasmic reticulum
Contains DNA

Question 15

What is the composition of the nucleolus?

Answer 15

Inside the nucleus
No membrane
Ribosomes are made here

Question 16

Define transciption

Answer 16

DNA stand is used as a template by RNA polyermase for the synthesis of a mRNA strand

Question 17

What are the purines?

Answer 17

Guanine, Adenine

Question 18

What are the pyrimidines?

Answer 18

Cytosine, thymidine (DNA), uracil (RNA)

Question 19

How do purines and pyrimidines bind?

Answer 19

Guanine forms 3 H-bonds with cytosine
Adenine forms 2 H-bonds with thymidine/uracil

AT CoG (for RNA switch a vowel with a vowel)

Question 20

Define translation

Answer 20

mRNA acts as template for ribosomes in the synthesis of protein

Question 21

Glycolysis - cost/outcome

Answer 21

2 glucose

2 ATP and 2 pyruvate molecules

Question 22

What is the composition of the mitochondria?

Answer 22

2 membrances
Krebs cycle on the inner matrix
Create NADH/FADH2

Question 23

Krebs cycle/ETC - cost/outcome

Answer 23

2 pyruvate molecules (from 1 glucose)
Multiple NADH, FADH2
ETC creates 36 ATP

Question 24

How does gluconeogensis work?

Answer 24

Lactic acid (via cori cycle) and amino acids are converted to glucose
Stress/starvation
Glycolysis in reverse

Question 25

Why can fat/lipids not used on gluconeogensis?

Answer 25

``` Acetyl CoA (breakdown product of fat metabolism) Cannot be converted back to pyruvate ```

Question 26

What is the cori cycle?

Answer 26

Occurs in liver | Converts muscle lactate into glucose via pyruvate

Question 27

Rough endoplasmic reticulum

Answer 27

Synthesizes proteins for export | Prominent in pancreatic acinar cells

Question 28

Smooth endoplasmic reticulum

Answer 28

Synthesis lipid/steroids Detoxifies drugs (Prominent in liver and adrenal cortex)

Question 29

Golgi apparatus

Answer 29

Modifies proteins with carbohydrates | Allows for transport to the cellular membrane, secreted, or target to lysosomes

Question 30

Lysosomes

Answer 30

Contain digestive enzymes that degrade engulfed particles and worn-out organelles

Question 31

Phagosomes

Answer 31

Engulfed large particle that fuses with a lysosome

Question 32

Endosome

Answer 32

Engulfed small particle that fuses with a lysosome

Question 33

Protein kinase C

Answer 33

Activated by calcium and diacylglycerol (DAG) | Phosphorylates other enzymes and proteins

Question 34

Protein kinase A

Answer 34

Activated by cAMP | Phosphorylates other enzymes and proteins

Question 35

Define myosin

Answer 35

Thick filament | Uses ATP to slide along actin and cause muscle contraction

Question 36

Define actin

Answer 36

Thin filament | Provides the scaffold for myosin to move along in muscle contraction

Question 37

What are some intermediate filaments? Where are they found?

Answer 37

Keratin (hair, nails) Desmin (muscle) Vimentin (fibroblasts)