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Biochem 1 > Module 5 > Flashcards

Module 5 Flashcards

1
Q

What are sucrose, lactose, and maltose composed of?

A

All three are made up of glucose. Specifically:
Sucrose= Glucose (C1)+Fructose(C2)– linked via 1,2 linkages– both are non-reducing
Lactose= Galactose (non reducing end)+Glucose (reducing end) linked by Beta-1,4 linkages
Maltose= 2 glucoses linked by Beta-1,4 linkages

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2
Q

For animals that must react with sudden action that requires rapid energy, what two things are needed in terms of glucose?

A

..???? (many non reducing ends and alpha-1,4 linkages between glucoses)

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3
Q

How is cellulose different from glycogen?

A

Glycogen has ALPHA-1,4 linkages while cellulose has BETA-1,4 linkages

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4
Q

Under what conditions do the melting temperature of fatty acids increase?

A

The melting temperatures of fatty acids increase when there is more saturated/ non-kinked FA’s present and increase in length

  • decreases when there is an increase in unsaturated length and double bonds
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5
Q

Outline the different ways molecules are transported across a membrane. – just list for now

A
  1. Non-mediated
  2. Mediated
  3. Passive mediated
  4. Active
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6
Q

What is non-mediated transport?

A

Non-mediated transport is simple diffusion driven by chemical potential gradients across membrane.

  • non-polar molecules diffuses in the direction that eliminates the gradient
  • the rate will depend on the solubility in the membrane’s nonpolar core
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7
Q

What is mediated transport?

A

Mediated transport via permeases, channels, ionophores, and transporters

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8
Q

What is passive mediated transport?

A

Passive-mediated transport from high to low concentration

- this form of transport eliminates the gradient

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9
Q

What is active transport?

A

Active transport is from low to high concentration/ against the gradient, coupled to an exergonic process (i.e. ATP hydrolysis)

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10
Q

What is the difference between D-Glucose and D-Fructose?

A

D-glucose is an aldose where C1 is an aldehyde
D-fructose is a ketose where C2 is a ketone
-Both have and OH to the right at C5

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11
Q

How do monosaccharides form cyclic rings?

A

The C5 OH attacks the C1 carbonyl to form the ring. This carbon carbonyl now becomes an anomeric carbon

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12
Q

What is the difference between cyclic glucose, mannose, and galactose?
- Note: these are all monosaccharides

A

Mannose and galactose are all EPIMERS of glucose. So the only difference between them is the positions of their OH groups where (from C1-C4):

  • Glucose: up, down, up, down
  • Mannose: up, up, down, up
  • Galactose: down, up, up, up
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13
Q

What is considered the reducing ends and non-reducing ends of a sugar?

A

Reducing end= the anomeric carbon with no OR group attached to it
- it is called the reducing end b/c it can reduce copper
Non-reducing end= the end that can form a glycosidic bond

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14
Q

Name the 4 major polysaccharides that we discussed in class?

A
  1. Cellulose
  2. Amylose
  3. Chitin
  4. Glycogen
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15
Q

What is cellulose?

A

Cellulose is a polymer made up of 50,000 glucoses linked by B-1,4 glycosidic linkages

  • insoluble in H2O
  • linkages position each glucose in alternating positions to prevent H-bonding with H2O
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16
Q

What is amylose?

A

Amylose is a component of starch that unlike cellulose IS H2O soluble.

  • has alpha-1,4 linkages
  • Amylose dissolves in water because its alpha 1,4 glycosidic bond causes the formation of a helical structure that does not form inter-strand hydrogen bonds like cellulose
17
Q

What is chitin?

A

Chitin is made up of GLUNAc (aka glucose-N-acetyl or N-acetylglucosamine) where the N-acetyl group is on C2

  • this is a linear unbranched polysaccharide
  • chitin is found in insect exoskeleton, shell of shrimps and crabs
18
Q

What is glycogen?

A

Glycogen is a branched energy storage carbohydrate found in animals with many non-reducing ends (branched every 7-11 sugars)
- has ALPHA-1,4 linkages

19
Q

Why does amylose and cellulose have differences in linkages?

A

This differences arise in a change in chirality (i.e. celulose= Beta-1,4; while amylose= Alpha-1,4)

20
Q

What is amylopectin and how does it differ from glycogen?

A

Amylopectin is the storage carbohydrate for PLANTS and forms ALPHA-1,6 linkage, branching every 30-50 sugars

  • this differs from glycogen because it has less reducing ends that can be cleaved for release of glucose
  • Also, glycogen has ALPHA- 1,4 linkages and branches more frequently (every 7-11 sugars) than amylopectin.
  • However, they BOTH have alpha 1,6 linkages at their branch points!*
21
Q

What enzyme is used to cleave glycogen and where does the cleaving occur in the molecule?

A

Glycogen phosphorylase breaks down glycogen by cleaving at the non reducing ends of glucose monomers

22
Q

What makes fats similar to lipids?

A

both fats and lipids have aliphatic hydrocarbon tails and polar head groups

23
Q

What are fatty acids?

A

FA’s are what make up fats and considered stored energy

  • they include a carboxylic acid head group and hydrocarbon tail that can be either:
    1. Saturated
    2. Unsaturated
24
Q

What is the difference between unsaturated and saturated fatty acids?

A

Unsaturated= contains 30 degree cis double bonds/ “kinks”
- considered unsaturated b/c they have less hydrogens present
Saturated= contain only single bonds in hydrocarbon tail; therefore, having more hydrogen molecules

  • I mention hydrogen here b/c saturation deals with being saturated or filled with hydrogen in the tail, the more H’s the more saturated
25
Q

How do you name fats?

A

delta naming= count from C1 carbonyl carbon
omega naming= count from opposite end of carbonyl

Naming- C(number of carbons): number of double bonds, delta/omega (location of double bonds)

  • Ex: C18:3delta3,6,9
  • note double bonds will occur every 3 carbons b/c their structure will not allow double bonds to be direct neighbors (every 2 carbons)
26
Q

What are triacylglycerides?

A

These are fats that are made up of 3 acyglycerides formed via ester linkages between glycerol and FA at their carbonyl carbons
Note: glycerol comes from fructose and glucose breakdown

27
Q

What is a membrane lipid?

A

Mmebrane lipid is similar to fat except there is a phosphate group on C3 of glycerol backbone instead of another acylglyceride
- lipid is known as phosphotidic acid

28
Q

What are the types of phospholipids? (know structures)

A
  1. Phosphatidyl-choline
  2. Phosphatidyl-serine
  3. Phosphatidyl- ethanolamine
  4. Phosphatidyl- linositol-4,5 phosphate
29
Q

What is cholesterol and how does it affect the bilayer?

A

Cholesterol is considered a sterol, but is sometimes considered a lipid since it plays an integral part of the membrane as it embeds in the hydrophobic core, INCREASING rigidity of the bilayer.

-It is able to do this b/c at high temperatures, it stabilizes the membrane and raises its melting point, whereas at low temperatures it help to retain fluidity and prevent it from stiffening.

30
Q

What is the difference between lateral and transverse diffusion in lipid membranes?

A

Lateral diffusion: individual lipid molecuels are allowed to move quicker in membrane (does not require crossing hydrophobic barrier)
Transverse diffusion- is much slower since it involves moving the polar head group across this barrier (not favorable)

31
Q

What are some ways proteins interact with membrane?

A
  1. transmembrane/integral proteins- can span entire lipid bilayer, some will allow polar molecules to cross the barrier
  2. Peripheral proteins- are partially embedded or associate with the lipid head groups, some are modified with hydrophobic tails for anchoring
32
Q

What are ionophore?

A

Ionophores are small membrane soluble molecules/peptides that bind and transport specific ions or molecules across a membrane

33
Q

What is GLUT 4 and how does it allow transport in the lipid membrane?

A

GLUT 4 is a glucose transporter that transport glucose and 6 carbon sugars across the plasma membrane 10x faster than normal diffusion.

  • allows transport by conformational change in the protein structure.
  • when glucose binds to GLUT 4, GLUT 4 will flip to allow glucose to the inside of the cell
34
Q

What is an aquaporin and how is water transported through this?

A

Aquaporins transport H2O across the membrane allowing it to pass in a single file

  • it has polar and basic residues that orient water
  • it can regulate the amount of H2O in cell.
  • due to repulsion between positive charges on the residue of the channels, H3O+ will not be able to enter
35
Q

What is Valinomycin?

A

Valinomycin consists of 3 repeat tetra peptides, each with 3 valines
- the structure positions hydrophobic side chains outward to be membrane soluble and the polar backbone carbonyl will form a channel that can bring in K+

36
Q

How does valinomycin only allow K+ and not Na+ into the cell?

A
  • K+ that will bind will have a similar energy as solvated K+ ions, so the free energy bound by valinomycin is the same as water
  • Free energy of Na+ ions is much higher than its solvated form, so it remains in more energetically stable aqueous environment,so it will not be transported (i.e Na+ would rather remain solvated than be transported)
37
Q

How does ATP dependent active transporter work?

A

ATP dependent active transporters transport ions and molecules against the gradient, requiring ATP hydrolysis to DRIVE the reaction.

  • it will pump 3 Na+ ions out and 2 K+ ions into the cell
  • this form of transport is essential for energy neurons and muscle contractions
38
Q

What are the functions of carbohydrates?

A

Carbohydrates function as:

  1. chemical energy
  2. barrier on cell surface
  3. for cell interactions
  4. stabilizing plant structure
  5. signaling molecules

Biochem 1 (5 decks)

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