Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 2020 > Macromolecules And Membrane Structure > Flashcards

Macromolecules And Membrane Structure Flashcards

1
Q

Polymers

A
  • polymers formed from monomers via condensation/dehydration reactions
  • water made as byproduct
  • for 2 monomers to join, they are usually coupled to a carrier molecule
  • once coupled to a carrier molecule, the monomer is activated
  • enzymes and ATP required to activate monomers

-hydrolysis reactions break polymers into monomers and water is required for the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Lysosome

A
  • intracellular digestion

- hydrolytic enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Carbohydrates

A
  • (CH2O)n
  • molar ratio of 1:2:1
  • n=number of carbons
  • monosaccharides are the monomer for carbohydrates
  • 2 monosaccharides = disaccharide
  • glycosidic bond between monomers
    • lactose has beta-glycosidic bonds
    • sucrose has alpha-glycosidic bonds
  • oligosaccharides = small chains 3-10
    • always covalently attached to lipids or proteins
  • polysaccharides = hundreds/thousands monosaccharides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Starch

A
  • polysaccharide
  • stores chemical energy in plants
  • amylose and amylopectin
  • alpha glycosidic bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Glycogen

A
  • polysaccharide
  • stores chemical energy in animals
  • linked by alpha glycosidic bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cellulose

A
  • structural polysaccharide

- beta glycosidic linkage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Lipids

A
  • fats (triglycerides)
  • phospholipids
  • steroids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Fatty acid

A
  • hydrocarbon chain with a carboxy group on the end
  • building block for some classes of lipids
  • saturated: no double bonds
  • unsaturated: has at least one double bond
    • causes kink in 3D shape
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Triacyglycerols

A
  • function is to store energy
  • sometimes for insulation against the cold
  • 1 glycerol + 3 fatty acids joined via condensation rxn
  • connected by ester linkage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Saturated triacylglycerols

A
  • usually called fats
  • no double bonds
  • solid at room temperature because of linearity
  • pack together tightly
  • most animal fats are saturated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Unsaturated triacylglycerols

A
  • oils (fish and plants)
  • liquid at room temp due to kinks that create gaps in structure
  • has double bonds
  • can be cis or trans
  • cis (same side) will form a bend
  • trans (opposite side) has no bend… so similar to saturated FA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Hydrogenated veg oil

A
  • artificially making saturated or trans fats from cis fats
  • shoot hydrogen atoms at molecule (hydrogenation)
  • trans fats will taste better and last forever
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Phospholipids

A
  • phosphoglycerides

- sphingolipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Phosphoglyceride

A
  • found in cell membranes
  • has a polar head group, glycerol backbone, 2 FA tails
  • amphipathic (hydrophobic and hydrophilic regions)
  • form a lipid bilayer in membranes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Steroids

A
  • derived from 4-ringed hydrocarbon skeleton
  • cholesterol precursor for all steroids
  • amphipathic due to OH group
  • examples: estradiol, testosterone, cortisol, aldosterone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Proteins

A
  • monomers are amino acids
  • amino acids contain: an amino group, carboxyl group, H, and R group attached to a carbon
  • amino acids classified by R groups
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Amino acids

A
  • non-polar: side chains are hydrophobic
    • associate via van der waals forces and hydrophobic interactions
    • always on inside
  • polar, uncharged: at physiological pH, side chains have partial charge
    • will form hydrogen bonds with other molecules, including water
  • polar, charged: at physiological pH, side chains will have a full charge
    • will form ionic bonds with other charged species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

UNIQUE amino acids

A
  • Cysteine: will form a covalent bond with another cysteine to form a DISULFIDE BOND
  • proline: will form a disruptive kink in a polypeptide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Peptide bonds

A

-amino acids join via condensation reactions to form peptide bonds between carboxy group and amino group

  • N terminus: amino group
  • C terminus: carboxyl group
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Protein structure

A

-if a protein doesn’t fold correctly it can cause functional problems including diseases

  • primary structure: order of amino acids
    • peptide = 20-30 aa
    • polypeptide = 30-400 aa
  • secondary: 3D shape in a localized area
    • alpha helix or beta pleated sheets (proteins under a lot of pressure like silk)
    • stabilized by H bonds
  • tertiary structure: overall 3D shape
    • due to interactions between side chains
    • stabilized by disulfide bonds, H bonds, ionic bonds, van der waals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Fibrous proteins

A
  • often outside of cell
  • elongated
  • structural
  • filamentous

-examples: fibroin, keratin, collagen, elastin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Globular proteins

A
  • most proteins
  • compact shape
  • folding unique to specific function
  • consists of a number of domains

-examples: most enzymes, many cell structure proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Protein domains

A
  • protein segments with a distinct structure and predictable function
  • each domain functions in a semi-independent manner
  • can mix and match different domains to create custom protein with multiple functions
24
Q

Quaternary structure

A
  • not possessed by all proteins
  • multiple polypeptides associate to work as one functional protein
  • eg. Hemoglobin
  • some multiple functional proteins come together to make a multi protein complex or molecular machine
    • pyruvate dehydrogenase
25
Q

Protein folding

A
  • Christian anfinsen (1956)
  • destabilized disulfide bonds using urea and mercaptoethanol
  • then used dialysis to remove urea and mercaptoethanol
  • protein refolded all on its own
  • demonstrated that all the information needed for correct folding is contained within the amino acid sequence
26
Q

Molecular chaperones

A
  • also called heat shock proteins
  • prevent inappropriate interactions by binding to the nascent polypeptide to give it time to fold
  • role is to assist folding and assemble
  • as proteins come out of the ribosome, chaperones stick mostly to hydrophobia AA exposed in non-native proteins but buried in proteins with a native conformation
  • during increased heat, proteins unfold and hydrophobic sites become exposed
    • heat shock response: altered gene expression when cell exposed to high temps

-chaperoning has a barrel shape and provides a space where the new protein can fold properly without disturbances from other proteins

27
Q

Hsp70/BiP

A

-sticks to hydrophobic AAs to allow nascent polypeptide to fold into Native conformation

28
Q

Membrane facts and functions

A

-5-10nm thick

  • functions:
    1. Boundary and permeability barrier (separates activities and reactions)
    2. Sites for specific proteins
    3. Regulate solute transport (gate keepers)
    4. Signal transduction (receptor molecules)
    5. Cell-to-cell interaction
29
Q

Membrane composition

A
  • lipids
    • phospholipids
    • glycolipids
    • steroids
  • protein
    • often outweigh lipid composition
  • carbohydrates
    • found in glycolipids and glycoproteins
    • never found alone, always attached to lipid or carbo
30
Q

Phosphoglycerides

A
  • type of phospholipid
  • contains a polar head group
  • glycerol backbone
  • 2 fatty acid tails
  • can have different polar head groups (eg. Choline)
31
Q

Head groups of phosphoglycerides

A
  1. Choline = phosphotidylcholine
  2. Serine = phosphotidylserine
  3. Ethanolamine = phosphotidylethanolamine
  4. Inositol = phosphotidylinositol
  • different membranes have different distributions of phosphoglycerides
  • inner leaflet vs outer layer have very different compositions
    • ASYMMETRIC DISTRIBUTION
32
Q

Asymmetric distribution

A

-different competitions of outer layer of membrane vs inner layer

33
Q

Sphingolipids

A
  • similar to phosphoglycerides, but sphingosine backbone instead of glycerol
  • fatty acid tails are usually longer
  • due to L shape of sphingosine, only one additional FA tail attached
  • cerebrosides and gangliosides
    • prominent in membranes of brain and nerve cells
34
Q

Gorter and Grendel

A
  • 1952
  • phospholipid bilayer experiment using red blood cells
  • isolated phospholipids and put them on water
  • the phospholipids arranged themselves to that only hydrophilic areas on water
  • discovered that the cells covered 2x as much water as they had calculated it should have -> discovered bilayer
35
Q

Phospholipid bilayer

A
  • will spontaneously form in water

- contains a cytoplasmic (inner) leaflet and an exoplasmic (outer) leaflet

36
Q

Movement of lipids

A
  • rotation (rotate in one place)
  • lateral diffusion (move laterally throughout one side of membrane)
  • transverse diffusion (flip flop to other side of membrane)
    • thermodynamically unfavourable so rarely occurs
    • requires flipases
37
Q

FRAP

A
  • fluorescence recovery after photo bleaching
  • a technique to study lipid mobility
  • must label cell surface molecules with fluorescent dye
  • bleach an area of cell surface with laser beam
  • watch fluorescent labeled molecules diffuse into bleached area
38
Q

Membrane fluidity

A
  • critical to membrane function
  • transport of solutes across membrane depend on membrane fluidity
  • too fluid can cause problems (ions leaking in and out)
  • at high temps membrane is MORE FLUID
  • at low temps membrane is LESS FLUID
    • movement of molecules slows down
39
Q

Fatty acid saturation and membrane fluidity

A
  • UNSATURATED fatty acids = INCREASED FLUIDITY
    • more kinks creates less compact structure
  • SATURATED fatty acids = DECREASED FLUIDITY
    • more organized structure/compact arrangement
40
Q

Homeoviscous adaption

A
  • ability for cell to change lipid content to adapt for temperature
  • can increase or decrease the amount of saturation
  • can change the length of fatty acid chains
41
Q

Fatty acid length and membrane fluidity

A
  • LONGER hydrocarbon chains = LESS FLUID
  • SHORTER hydrocarbon chains = MORE FLUID
  • think of spaghetti analogy
42
Q

Cholesterol and membrane fluidity

A
  • at WARM temps = DECREASE FLUIDITY
    • Acts as walls to prevent movement making it rigid
  • at COLD temps = INCREASE FLUIDITY
    • bumpy shape makes gaps and prevents tight packing

-cholesterol usually evenly distributed between two leaflets

43
Q

Fluid mosaic model

A

-proposed by singer and Nicholson (1972)

  • described a fluid bilayer of lipids
  • containing mosaic of proteins within it
44
Q

Freeze fracture

A
  • technique to demonstrate existence of proteins in membranes
  • freeze membrane and cut with diamond to separate leaflets
  • examine layer under microscope
45
Q

Types of membrane proteins

A
  • integral
  • peripheral
  • lipid-anchored
46
Q

Integral proteins

A
  • penetrate into the hydrophobic region of the bilayer
  • securely positioned… dont move
  • they are:
    1. Asymmetric
    2. Amphipathic
    3. Alpha-helices (usually)

-transmembrane domains contain AAs with hydrophobic chains

47
Q

Peripheral membrane proteins

A
  • loosely attached to surface through electrostatic bonds
  • they are dynamic and move around
  • asymmetric distribution across leaflets
48
Q

Lipid-anchored proteins

A
  • on the surface of the membrane
  • covalently attached to lipid (strong bond)
  • in the EXOPLASMIC leaflet, usually attached to GPI
  • in CYTOPLASMIC leaflet, usually attached to fatty acid
49
Q

GPI

A
  • glycosylphosphatidylinositol

- protein is attached to a sugar that is attached to a phosphotidylinositol

50
Q

Lipid rafts

A

-localized areas with unique lipid composition that sequester signalling proteins

  • 4 features:
    1. Tightly packed (many saturated FAs)
    2. Sphingolipids (higher % than rest of membrane)
    3. Cholesterol
    4. GPI proteins
51
Q

Membrane carbohydrates

A
  • ALWAYS on exoplasmic leaflet
  • important in cell-cell interactions and sorting proteins to different compartments
  • always attached to something
  • attached to lipid = GLYCOLIPID
  • attached to proteins = GLYCOPROTEIN
52
Q

Glycoproteins

A
  1. N-linked: carbohydrate attached to asparagine amino acid

2. O-linked: carbohydrate attached to a serine or threonine AA

53
Q

Glycolipids

A
  • glycolipids in red blood cell membranes determine blood type
  • antigens
54
Q

Glycocalyx

A
  • sugar coat
  • carbohydrates from glycolipids and glycoproteins stick out from the cell surface and make a sticky surface coat
  • important for
    1. Cell to cell adhesion
    2. Adhesion
    3. Protection
    • body doesnt recognize some bacteria due to glycocalyx surrounding it/hiding it
55
Q

Membrane protein movement

A
  • Larry Frye and Michael Edidin
  • 1970
  • “Classic experiment”
  • fusion of human and mouse cells that contain different proteins
  • exposed to fluorescent antibodies
  • after 5 mins the proteins began to mix
  • within 40 mins they were evenly distributed
56
Q

Proteins don’t ALWAYS move in membrane

A
  • reasons why a protein might not move:
    1. May be anchored to cytoskeleton below
    2. May be wedged between other immobile proteins
    2. May be attached to something in extracellular matrix

BIOL 2020 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions