Week 4 learning goals Flashcards

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1
Q

Describe Lactose intolerance

A

caused by missing/ defective lactase enzymes

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2
Q

Management options for lactose intolerance

A
  1. avoid dairy products 2. lactase supplements 3. treat dairy products with lactose
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3
Q

Explain the importance of alpha and beta linkages in polysaccharides

A

Only alpha linkages (starches - amalyases) in polysaccharises can be digested by humans Beta linkages (humans) cannot be digested by humans - enzyme needed is not produced

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4
Q

How does cellulose pass in the human

A

through the digestive tract as fiber

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5
Q

How does cellulose pass through the digestive tracrt

A

Many herbivores and microorganisma have symbiotic relationships to produce enzyme in hydrolyaze b linkages

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6
Q

Function of : Enzymes

A

selective catalysis

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7
Q

Function of : structural proteins

A

support of cellular structures

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8
Q

Function of : motlility proteins

A

movement of cells and cell parts

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9
Q

Function of : regulatory proteins

A

regulation of cellular fxns

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10
Q

Function of : transport proteins

A

transport of substances across membranes

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11
Q

Function of : hormonal proteins

A

communication between distant parts of an organism

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12
Q

Function of : receptor proteins

A

response of cells to chemical stimuli

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13
Q

Function of : defensive proteins

A

protection against disease

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14
Q

Function of : storage proteins

A

storage and release of amino acids

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15
Q

Describe in detail the peptide bond formation

A

Product of condesation - peptides are formed based on structural polarity utlizinf the N and C terminuses

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16
Q

Peptide backbone of a polypeptide

A

repeating sequence of atoms along polypeptide chain Cα, carbonyl, amino, Cα, carbonyl, amino…

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17
Q

How are the ‘R’ groups oriented along the peptide backbone of a polypeptide?

A

held together by peptide bond btwn aa’s ‘R’ groups spead out from the back bone

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18
Q

Define Polypeptide

A

polymer of aa - not neccesarily a functional protein

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19
Q

Define Protein

A

a functional polypeptide or group of polypeptides

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20
Q

True or False: All proteins are polypeptides but not all polypeptides are considered proteins.

A

False

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21
Q

N- terminus

A

End that results in NH3 5’ end

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22
Q

C- terminus

A

End that results in COO- 3’ end

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23
Q

Primary Structure

A

Sequence aa’s linked together by peptide bind forming a polypeptide

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24
Q

Secondary structure

A

local regions of the resulting polypeptide can be then coiled into and helix, one form of secondary structure

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25
Q

Teritary structure

A

associate w/ each other in a specific manner to form the 3’ structure, which describes the final folding of a polypeptide

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26
Q

What interactions are responsible for stabilizing 3 structure

A

Covalent bonds H bonds Ionic Bonds Hydrophobic interactions

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27
Q

How do the Interactions occir in a 3 structure

A

Covalent bonds- occurs btwn SH groups of cysteine Hbonds - polar groups may H bond with one another, or turn outward + H bond w/ the surrounding water moles Ionic bonds - positively + negativeky charged groups may form ionic bonds Hydrophobic interactions - Nonpolar R groups cluster on the inside of the protein, away from aq. enviroment of the cell/ organelles

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28
Q

What interactions are responsible for stabilizing 4 structure

A

Same as 3 structure However covalent bonds are less likely

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29
Q

What interactions are responsible for stabilizing 2 structures

A

Hydrogen bonds

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30
Q

Redox rxn

A

involves a change in oxidation numver

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31
Q

Oxidation indicates

A

a loss of H

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32
Q

Reduction indicates

A

a gain of H

33
Q

Homomeric

A

all the same subunits in quaternary structure

34
Q

Hetermeric

A

different subunits EX: heterotrimer = 3 diff subunits

35
Q

Multimeric

A

many subunits can be used to describe a protein w/ more than 1 subunit - subunits may be identical or different

36
Q

What is a protein domain? Recogonize different structural/ functional regions of a polypeptide as independent domains.

A

Domains: Portions of the polypeptide chains can fold into compact, semi indepdent units - These are discrete structural function unit within the polypeptide - Domains form their own 3D conformation within the polypeptide - Domains are not sepearate subunit - just parts of polypeptides that are folded differently based on their fxn

37
Q

Cofactor

A

non protein components of proteins - can be organic or in organic

38
Q

Coenzyme

A

an in organic cofactor EX: some vitamins

39
Q

Are cofactors necessary for all proteins ?

A

No

40
Q

Localization pathways for a polypeptide synthesized from mRNA exported from the nucleus into the cytoplasm

A

Cytosolic (default) - all ribosomes begin translation in the cytoplasm Endomembrane System 3. Mitochondria/ Chloroplast/ Nucleus/ Peroxisome via Nuclear Locaization Sequence (NLS) - have their own specific tag

41
Q

Define Signal Peptide

A

A particular streech of aa’s within a protein. Avg. length 15-30 aa’s - Functions as an address for proteins final destination

42
Q

Describe the events incvolved in properly targeting a protein to the endomembrane system

A

Co translation import 1. SRP binds to ER signal sequence and blocks translation 2. SRP binds to SRP receptor ribosome docks on membrane 3. Signal sequence is cleaved by signal peptidase as polypeptide elongates and translocates into ER lumen 4. Completed polypeptide is released into ER lumen, ribosome is released, and translocon pore closes RESULT : BOTH TERMINUS ARE IN LUMEN

43
Q

SRP

A

Signal recognition particles

44
Q

what needs to happen for the N-terminus to be cytoplasmically localized and the C-terminus to be localized in the lumen of the ER?

A
  1. Internal start sequence begins in the middle of the polypeptide 2. Protein continues translocation until the C terminus moves through translocon 3. Protein is released laterally into ER membrane
45
Q

what needs to happen for the C-terminus to be cytoplasmically localized and the N-terminus to be localized in the lumen of the ER?

A
  1. Signal sequence targets polypeptide to translocon. 2. Stop transfer sequence halts translocation; signal sequence removed. 3. Protein released laterally into ER membrane.
46
Q

How would multiple membrane-spanning domains be achieved?

A

Multiple membrane-spanning domains - have alternating start and stop sequences

47
Q

Conformation

A

overall, 3D shape of a polypeptide after it’s fully folded.

48
Q

Native Conformation

A

conformation that represents the most stable statefor a particular polypeptide

49
Q

Denaturation

A

loss of conformation, usually resulting in loss of fxn. caused by changes in cellular enviroment (eg. pH)

50
Q

Renaturation

A

Return of denatured polypeptide to its native conformation, usually w/ restoration function

51
Q

Which of the 4 structures doe conformation alter

A

tertiary

52
Q

Factors that could influence protein conformation

A

Spontaneous self assembly via polarity

Polar R groups will interact with polar soln where as nonpolar will turn inward

Enviroment

53
Q

How does the enviroment influence the folding of proteins

A

Native conformation –> Denaturation conditions –> renaturing conditions –> renatured molecule may or may not be the same as previous native conformation

54
Q

Influences of Enviromental Protein conformation

A

pH

Temperature

Solvent

Solute concentrations (Especially ions)

Redox status

Mechanical stress

Space

55
Q

Which structures would be altered in enviromental protein conformation? not altered ?

A

2 3 4 would be alrered

primary would not because hydrolysis has not occured

56
Q

Molecular chaperones

A

protein molecules that assist in the folding of other proteins that cannot fold sponaneously

57
Q

How does HSP 60 behave

A

a partially misfolded protein enters one end of the complex

ATP hydrolysis leads to a shape change of the subunit

Creates a hydrophilic enviroment for correct folding of the protein

Correctly folded protein is released

* Different from cytoplasm - Unique enviroment that overrides polarity

58
Q

How does HSP 70 behave

A

bound to ATP can associate w/ polypeptides that are still being processed; prevents folding. Chaperone for post- traditionally imported proteins

59
Q

Post translational import refers to…

A

proteins that are imported into the organelle after translation

60
Q

Post translational import is used for what organelles

A

Mitochondria

Chloroplast

Peroxisome

Nucleus

61
Q

Describe the events involved in post-translational import of proteins

A
  1. HSP 70 binds to polypeptide
  2. Transit sequence binds to TOM receptor
  3. HSP70 molecules detach as polypeptide passes through membranes
  4. Transit sequence cleaved
  5. Mitochondrial HSP70 molecules bind and release polypeptide as it enters matric
  6. Polypeptide folds aided by HSP60.

Transit and Signal is used interchangably

62
Q

Describe the various modifications discussed in class that can occur to a protein during post-translational modification

(6)

A

Chaperone assisted folding

Acetylation / Deacetylation

Protein phosphorylation

Glycosylation

Lipidation

Proteolytic cleavage

63
Q

Acetylation/ Deacetylation

A

histones regulating gene expression

64
Q

Protein phosphorylation

A

adds a phosphate group via ATP

65
Q

Glycosylation

A

adding small carbohydrates –> glycoproteins

66
Q

lipidation

A

adding lipid groups

67
Q

Proteolytic cleavage

A

cleaving or breaking down the protein

EX: insulin taking out the C chain

68
Q

Describe Cystic FIbrosis

A

A defect in transport functions include:

A genetic disease

Affects secretory cells ex: glands, mucus producing cells

Symptoms include: thick, dehydrated mucus, incessant coughing, lung damage

Lungs become colonized by microorganisms - usually lead to death - pneumonia

No cure; avg life span ~ 35

69
Q

Structure of cystic fibrosis

A

spans of 6 transmembrane proteins

70
Q

Explain why protein structure is so important for protein function

A

Protein structure is important because if altered the function of the protein changes which typically results in terrible diseases

71
Q

Sickle Cell Anemia

A

Sickle Cell anemia → happens due to clumped hemoglobin which typically are free flowing

Sickle cell anemia prevents rbc from flowing freely

This occurs due to an altered primary structure; Glutamine to Valine (Acidic → nonpolar aa)

72
Q

Describe the basic details of the RBC structure and function.

A

RBC: Hemoglobin: function to carry O2 around the body via blood flow

Typically free flowing throughout the blood

73
Q

Define a ‘prion’.

A

Prion: infectious disease - causing proteins

  • result from misfolded PrP proteins
  • No change in corresponding PrP disease
74
Q

Describe prion diseases

A

Prion diseases cause neurological breakdown which is rare, has no cure and fatal

EX: Mad cow disease or BSE / Creutzfeldt - Jakob disease (humans)

Explanation:

Normal Prion Protein, PrPC

2 structure is rich in alpha helices and Soluble

Disruption results in 2 structure with misfolded pathogenic protein, PrPSC

PrPSC is rich in beta sheets → which drastically changes the 3d structure

PrPSC is highly insoluble and protease resistant

Promotes conversion of PrPC to PrPSC

Aggregates disrupt cellular fxn

75
Q

Can prion diseases be seen based off primary structure

A

Primary Structure of PrPC and PrPSC are identical so issues will begin to be shown in secondary structure due to beta sheets occuring instead of alpha

76
Q

In terms of disease transmission, explain why prion diseases are unlike any other type of disease that is bacterial- or viral-based.

A

Prions are caused by an infection of proteins

77
Q

Different Variants of transmission

A

Familial (increased risk in certain families)

Spontaneous

Health facilities due to sanitary issues

BSE acquired ( eating tainted meat products)

78
Q
A