Biochem-Cell Bio Lecture I And Ii, Lipids

Front 1

What are five strategies for regulating enzymes?

Back 1

1. Controlling number of enzyme molecules

2.Regulated proteolysis

3.Covalent modifications

4.Feedback inhibition

5. Controlling enzyme
concentration

Front 2

Describe two general mechanisms by which phosphorylation can alter the function of a protein.

Back 2

causing conformational change or creating a new binding site

Front 3

What does a protein kinase do?
A protein phosphatase?

Does phosphorylation always increase the activity of an enzyme?

Back 3

Protein Kinase removes a phosphate group from ATP

protein phosphatase removes a phosphate group from its substrate by hydrolyzing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group

it can decrease activity

Front 4

Name four ways in which prokaryotic cells differ from eukaryotic cells. Why are some of these differences therapeutically important?

Back 4

bacteria have a cell wall

ribosomes are slightly different

haploid

lack internal compartments

important because of the action of antibiotics

Front 5

What classes of molecules can pass through lipid bilayers? What classes cannot?

Back 5

hyd

Front 6

****All cells:

Back 6

solutions of proteins enclosed by a membrane, use nucleic acids to store/transmit hereditary information, and use energy

Front 7

****4 major mechanisms of antibiotic action

Back 7

1.Inhibition of nucleic acid synthesis,
2.Inhibition of protein synthesis,
3.Disruption of cell wall, and
4.Antimetabolite

Front 8

What is the difference between an integral and a peripheral membrane protein?

Back 8

Integral-have ampithatic helices that pass through membrane

periphial-held to membrane by electrostatic interactions

Front 9

Actin:
function:
dynamic:
major constituent:

Back 9

dense network underlying the plasma membrane, cell shape and motility, and substrate for myosin motor proteins

very dynamic

actin

Front 10

Tubulin filaments (microtubules)

Back 10

important for: establishing cell polarity, positioning organelles, and forming the spindle during mitosis

Front 11

Intermediate Filaments

Back 11

give mechanical strength to cells, not present in all euk, composed of various different proteins

Front 12

What is the cytosol? Name three important processes that occur in the cytosol of a eukaryotic cell.

Back 12

half of total cell volume, varies between cell types

1. protein synthesis/degradation

2. location of enzymes for glycolysis-interm. metabolism

3. packed with macromolecules

Front 13

What is a nuclear pore?

Back 13

aqueous pore-diffusion of small molecules less than 5 kD

larger molecules require active process and protein folding

Front 14

mRNA and nuclear pore?

Back 14

requires proper splicing and exportins

Front 15

What is a miRNA? A shRNA

Back 15

miRNA-small, non-coding, role in translational inhibition, RNA stability, and formation of heterochromatin

shRNA-exploit the miRNA mechanism to decrease or abolish the expression of a target protein

Front 16

What determines whether a protein is synthesized in the cytosol or in the endoplasmic reticulum?

Back 16

sorting signal

Front 17

What types of proteins need to be synthesized into the ER?

Back 17

integral membrane, secreted proteins, and lysosomal proteins

Front 18

What, physically, is a sorting signal? How does it work? How does a signal sequence differ from a signal patch?

Back 18

Sorting signals are brief stretches of amino acids that are recognized by complimentary sorting receptors. The signal can be linear in the primary amino acid sequence or amino acids from different regions brought together by tertiary structure can form a patch on the cell surface after the protein folding comprised of amino acids from different regions

Front 19

Proteins are transported between intracellular compartments by one of three processes:

Back 19

gated transport
transmembrane transport
vesicular transport

Front 20

Name six important cellular functions of the endoplasmic reticulum.

Back 20

1. Protein synthesis – integral membrane proteins, secreted proteins and lysosomal proteins
2. Disulfide bonds are formed
3. N-linked glycosylation
**4-6 are non-protein-making thingies…..
4. Major site of phospholipid synthesis- takes place in the cytoplasmic face of the ER membrane
5. Detoxification of lipid-soluble compounds -Cytochrome P450 enzymes
6. Calcium store – calcium is an important signaling molecule

Front 21

What, specifically, happens to proteins that fail to fold correctly in the ER?

Back 21

exported from ER to cytosol where they are degraded

Front 22

Name three functions of the Golgi apparatus. What are common destinations for vesicles leaving the Golgi?

Back 22

Trims N-linked sugars and may add further oligosaccharide modifications

O-linked glycosylation on some serine or threonine residues

Final sorting of protein to their appropriate destinations> transport to the lysosome > Secretion

lysosome, secretory vesicles, plasma membrane

Front 23

What is the difference between constitutive and regulated secretion?

Back 23

Constitutive Secretion – vesicles constantly transported to plasma membrane
Regulated Secretion – vesicles are stored and then only released after a signal
Examples: Neurotransmitter release and release of insulin

Front 24

What is an endosome, and what is its major function?

Back 24

Endosome is a membrane-bounded organelle in animal cells that carries materials ingested by endocytosis and passes them on to lysosomes for degradation.

Front 25

Fatty acids are amphipathic – what does this mean, and what parts of the fatty acid molecule contribute to this property? What does “C20” indicate?

Back 25

Amphipathic molecules contain both hydrophilic (polar head) and hydrophobic (nonpolar tail) portions. Molecules need to be amphipathic to form a lipid bilayer. C20 indicates a fatty acid/hydrocarbon chain with 20 carbons in it. Most common fatty acids are even numbered chains of 12-24 C’s.

Front 26

2. The hydrocarbon tails of fatty acids can be saturated or unsaturated - what does this mean, and how does this affect the shape of the molecule? In human fatty acids double bonds occur predominantly in which configuration?

Back 26

Hydrocarbon chains that are saturatedsaturated w/hydrogen’s (contain no double bonds). Chains that are unsaturatedfew hydrogen’s (contain double bonds).
Saturated fatty acids can pack tightly together and share a very stable van der Waals interaction with their neighbor along the length of the tail. Cis double bonds introduce a rigid kind into the HC tail, fatty acids pack less tightly, and the membrane is MORE FLUID.

Front 27

Lipids can be used to store energy. What molecule forms the fat droplets found in adipocytes? How is this molecule synthesized? Is it amphipathic? Where in the cell are fat droplets formed, and what is special about their outer membrane?

Back 27

Triglycerides form the fat droplets in adipocytes. Adipocytes contain lipases to break triglycerides into fatty acids when energy is needed. These molecules are amphipathic in order to form a lipid bilayer.

Front 28

Name two reasons why lipids are a more efficient way to store energy than carbohydrates.

Back 28

Triglycerides yield twice as much energy, and lipids have “no water of hydration”

Front 29

Glycerophospholipids:

What forms backbone:
How many fatty acid chains attached:

What constituent is the molecule named for:

Back 29

Glycerol

2

the head group

Front 30

What type of lipid helps determine ABO blood type?

Back 30

Glycosphingolipids

Front 31

Where are phospholipids degraded? Which type of phospholipase initiates the degradation? Where does it cut the phospholipid?

Back 31

Degraded in the lysosome. Type A phospholipases attack ester linkages to remove a fatty acid.

Front 32

Where are sphingolipids degraded?

Back 32

lysosome

Front 33

Derivatives of phosphatidylinostol are important for what cellular process?

Back 33

Intracellular signaling

Front 34

The active form of vitamin D, 1,25-dihydroxyvitamin D3 , is involved in what physiological process?

Back 34

Involved in Calcium homeostasis

Front 35

What is the physiological function of Vitamin E? Vitamin K?

Back 35

Vitamin E is an antioxidant that destroys antioxidants.

Vitamin K is a blood clotting factor that facilitates the activation of thrombin

Front 36

What is the major function of a peroxisome?

Back 36

major site of BETA oxidation of very long chain fatty acids

Front 37

What molecule is defective in X-linked adrenoleukodystrophy, and what cellular process does this compromise?

Back 37

mutation in the ABCD1 transporter

affects beta oxidation