Brainscape's Knowledge GenomeTM

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


See full index

Year 1 - Semester 1 > Week 4 - Cell Signalling > Flashcards

Week 4 - Cell Signalling Flashcards

1
Q

What are the four parts of an amino acid?

A

Carboxyl group, amino group, alpha carbon (between carboxyl and amino groups) and a side chain

Give protons to become COO-

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

What bonds are the carboxyl and amino groups available for?

A

Hydrogen bonding

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

What is a non polar amino acid and give examples

A

Repelled by water so involved in hydrophobic interactions e.g. interior of soluble proteins and outside surface of proteins associated with the middle of membranes

Alanine, glycine

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

What is a polar amino acid and give examples

A

Unequal distribution of charge

Serine, threonine and tyrosine form hydrogen bond with -OH groups

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

What is a acidic amino acid and give examples

A

-COOH groups in aspartic acid and glutamic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a basic amino acid and give examples

A

-NH2 groups in lysine and arginine

Accept protons to become NH3+

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

What is special about cysteine?

A

Has a sulphydryl group -SH

Can form a covalent cross-link S-S between two cysteines called a disulphide bridge to form a dimer called cystine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is special about proline?

A

Side chain and amino group form a rigid five member ring structure. Interrupts alpha helices in globular proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is primary structure?

A

The sequence of amino acids in the protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do you name peptides?

A

With free amino - N terminus - valine become valyl

Amino is named first - A comes before C

With free carboxyl - C terminus - stays the same

Carboxyl is named second C comes after A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is secondary structure? Give examples

A

Local folding in the polypeptide chain

Alpha helix - 3.6 amino acids per turn
Right handed spira - non polar amino acids towards center and polar towards surface
Bulky side chains can interfere
Proline doesn't have a free amino group
Charged AAs can disrupt

Beta pleated sheets
Can be parallel or antiparallel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is tertiary structure?

A

Determines if a protein is globular or fibrous
Chaperones assist correct folding
S-S bonds, hydrophobic or hydrophilic interactions can stabilise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is quaternary structure?

A

More than one polypeptide

Sometimes have a prosthetic group such as haemoglobin

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

Describe myoglobin

A

Present in heart and skeletal muscle
Reservoir and carrier of oxygen
Single polypeptide with 8 stretches of alpha-helices
Each is partially terminated by a proline to form kinks
Loops are stabilised with hydrogen and ionic bonds
Does not show cooperativity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe haemoglobin

A

In RBCs
Transports oxygen from lungs to capillaries and H+ and CO2 in the other direction
Composed of 2 identical dimers - 2 alpha, 2 beta subunits
Can bind 4 oxygen molecules - 4 heme prosthetic groups - each has one iron that can bind oxygen
Tight binding between dimers in deoxygenated state
Some weak bonds between dimers break giving relaxed structure in oxygenated state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe collagen

A

Long rigid structure of three polypeptides called alpha chains are wound around one another in a triple helix every three amino acids is glycine
Contains proline

Found in skin, connective tissue, blood vessels, sclera and cornea

Fibril forming - 1 tendon, 2 carTWOlage, 3 blood vessels, 4 rhymes with floor - basement membrane
Fibril associative
Other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe elastin

A

Found in lungs, ligaments and arteries return to normal length when stretching is removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe enzymes

A

Protein catalysts

Increase chemical reaction time by 10^3 to 10^8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a holoenzyme

A

An active enzyme including its non-protein component

20
Q

What is an apoenzyme?

A

An inactive enzyme without its non-protein component

21
Q

What are the types of non protein component?

A

Cofactor - metal

Coenzyme - organic

             - transiently associated - co-substrate
             - permanently bound     - prosthetic group
22
Q

How can an enzyme reaction velocity be affected

A

Temp - more chance for molecules to meet and not energy to overcome activation energy - too much and enzyme denatures

pH - extremes can denature proteins - some enzymes work at high or low pHs

Enzyme activity depends on substrate concentration

23
Q

What is feedback inhibition?

A

The first reaction unique to a pathway is catalysed by an allosteric enzyme regulated by the concentration of the end-product

24
Q

What is allosteric regulation?

A

Positive or negative effector molecules bind non-covalently to a non-active site - non competitive inhibition due to conformational change, altering the enzymes affinity to its substrate

25
Q

What is covalent modification?

A

Addition or removal of phosphate groups from certain residues in the enzyme. Kinases and phosphatases. Conformational change which activate or inhibit enzyme activity

26
Q

What is the adjustment of enzyme synthesis or degradation?

A

Increasing or decreasing enzyme production or destruction will change number of active sites available and hence overall enzyme activity. Takes hours or days.
Insulin regulation of glucose metabolism is an example

27
Q

What are the four types of signalling

A

Endocrine - hormones through the blood from glands

Paracrine - signals are released locally and affect neighbouring cells

Autocrine - signal molecules affect the cell that produces them

Neuronal - transmitted along axons to neighbouring and target cells

28
Q

Two types of receptor

A

Surface - large and hydrophilic signalling molecules

Intracellular - small, hydrophobic diffuse across membrane - STEROID HORMONES - affect transcription

29
Q

What is signal transduction?

A

Binding of a ligand to an external receptor to bring about an internal response

30
Q

Describe GPCRs

A

Polypeptides which span the membrane 7 times

When ligand binds, changes conformational shape and allows it to bind to the alpha subunit of the G-protein. This binding decreases the affinity for GDP and so GTP binds. This activates the alpha subunit and it dissociates from the other two, which activates them to allow them to activate other molecules. The alpha subunit activates a target protein and then hydrolyses GTP to GDP and dissociates from the target protein. Inactive alpha subunit associates with the other two subunits to reform the inactive G-protein. This prevents constant activation of the target protein. The target protein is often an enzyme which produced product- secondary messenger molecules which act on intracellular signalling proteins

31
Q

Explain the phospholipase C pathway

A

GPCR activates G-protein which activates phospholipase C. This produces DAG and IP3 which binds to calcium channels on the ER. The calcium and DAG then activate protein kinase C which phosphorylates target proteins

32
Q

Explain the Adenylyl Cyclase pathway

A

Adrenaline binds to GPCR. Alpha unit binds to adenylyl cyclase which catalyses the production of cyclic AMP. cAMP activates protein kinase A which activates glycogen phosphorylase which catalyses the breakdown of glycogen into glucose - fight or flight

33
Q

Explain receptor tyrosine kinase

A

Inactive RTK made up of two monomers

Binding of ligand brings monomers together - dimerisation.

34
Q

Explain Ras pathway

A

Ligand binds to RTK
Adaptor molecule binds to activated RTK and activated Ras-activating protein
Activates Ras
Activates MAP kinase kinase kinase
Activates MAP kinase kinase
Activates MAP kinase
Activates a number of possible mitogen activated proteins which control gene expression

If on permanent causes uncontrolled cell proliferation

35
Q

Describe the phospholipid bilayer

A

cholesterol - fits in gaps between phospholipids to stiffen membranes
glycolipids - carbohydrate facing out
Phosphatidylcholine most common phospholipid - has choline attached to phosphate group

Asymmetrical - some phospholipids face extracellular space and some inwards

36
Q

What are the three types of transporter

A

Uniport - carries one solute in one direction

Symport - carries two solutes in the same direction

Antiport - carries two solutes in different directions

37
Q

Types of association with plasma membrane

A

Transmembrane

Peripheral - lipid linked or protein linked

Integral - integrated into the membrane

37
Q

Types of association with plasma membrane

A

Transmembrane

Peripheral - lipid linked or protein linked

Integral - integrated into the membrane

38
Q

Types of association with plasma membrane

A

Transmembrane

Peripheral - lipid linked or protein linked

Integral - integrated into the membrane

39
Q

Types of association with plasma membrane

A

Transmembrane

Peripheral - lipid linked or protein linked

Integral - integrated into the membrane

39
Q

Types of association with plasma membrane

A

Transmembrane

Peripheral - lipid linked or protein linked

Integral - integrated into the membrane

40
Q

What is the electrochemical gradient?

A

The concentration gradient and the voltage gradient

41
Q

Describe the sodium potassium ATPase

A

Sodium binds to the pump
Phosphorylates itself using ATP
Triggers conformational change - sodium ejected out of cell
Potassium binds
The pump is dephosphorylated
Pump returns to original conformation - K released into cell

42
Q

Sodium glucose symport

A

Passive transport of sodium provides energy for transport of glucose against concentration gradient
Sodium at high concentration out of cell due to na/k pump

43
Q

What are ABCs

A

ATP-binding-cassettes
Have to ATP-binding sites on the inside of the membrane and two transmembrane domains that form a passage for transported molecules

Active transport of ions, drugs and xenobiotics (not usually found in the cell)

Implicated in multidrug resistance - responsible for extruding chemotherapeutic drugs from cancer cells

Year 1 - Semester 1 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions