Brainscape's Knowledge GenomeTM

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


See full index

Y1S1- Fundamentals of Medicine > Cells, Components and Communication > Flashcards

Cells, Components and Communication Flashcards

1
Q

amino acid structure

A

Central Carbon with 4 groups attached:

  • Amino group
  • Carboxyl group
  • Hydrogen group
  • R group- side chain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

physiological pH

A

7.4

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

what are amino acids dissociated into at 7.4 pH?

A
  • Carboxyl group- carboxylate ion (negatively charged so acidic)
  • Amino group is protonated by a hydrogen ion (positively charged so basic)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

non polar amino acids

A
  • Have side chains involved in hydrophobic interactions and tend to cluster in the centre of proteins
  • Examples: glycine, alanine, valine, proline etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

proline special structure

A

due to cyclic structure- disrupts secondary structure of proteins (eg. alpha helices, beta sheets), allows formation of fibres in collagen so is important in connective tissue

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

polar amino acids

A
  • Side chains involved in hydrophilic interactions and tend to be found on surface of proteins
  • Examples: serine, threonine, tyrosine, cysteine etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

basic amino acids

A
  • R groups accept protons at 7.4 pH
  • Nitrogen in R groups
  • Examples: lysine, histidine, arginine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

acidic amino acids

A
  • R groups are acidic at 7.4 pH so they have a negative charge
  • Have carboxyl group in R gorup
  • Examples: aspartic acid and glutamic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

special case amino acids

A

Glycine- simplest amino acid, R group is just a hydrogen
Alanine- R group is a methyl group
Proline
Cysteine- sulfhydryl group allows for formation of disulphide bridges, important in quaternary structure of proteins

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

protein bonds

A
  • peptide bonds form between amino acids between the carboxylate ion of one amino acid and the protonated amino group of the next
  • strong covalent bonds, not affected by mild conditions like heat or ph
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

primary structure

A

sequence of amino acids, polypeptide chain

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

secondary structure

A

local folding in the polypeptide chain caused by interactions between atoms of the amino acids that aren’t involved in R groups

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

alpha helix

A
  • Right-handed spiral of tightly packed coiled backbone of amino acids
  • Amino acids with bulky side chains wont fit in the spiral eg. proline
  • 3.6 amino acids per turn
  • Found in keratin, myoglobin etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

beta sheets

A
  • parallel or antiparallel

Polypeptide chains line up next to each other and hydrogen bonds are formed between the opposing O- and NH+

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

tertiary structure

A

further folding assisted by chaperone proteins, determines whether protein is globular or fibrous, by the end of this process functional areas of the protein will be configured

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

quartenary structure

A

when proteins is made up for more than one polypeptide chain, sometimes with prosthetic group- inorganic group eg. haemoglobin

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

haemoglobin structure

A
  • globular
  • 4 polypeptide chains (2 alpha helices, 2 beta sheets)- each alpha group binds ot a beta group via strong hydrophobic bonds to form a dimer (2 dimers in a haemoglobin molecule), each dimer binds to the other via weak ionic and hydrogen bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

states of haemoglobin

A
  • Deoxyhaemoglobin (no oxygen)- tight binding between dimers

- Oxyhaemoglobin (oxygen-bound)- some weak bonds between dimer break, giving a relaxed structure

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

cooperatively of haemoglobin

A

If one of the 4 haemoglobins subunits bonds to oxygen, the others have increased affinity for oxygen. If one subunit releases oxygen, others have decreased affinity. Due to conformational changes in the protein structure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

myoglobin

A
  • globular
  • Found in skeletal and cardiac muscle
  • One polypeptide- with many alpha helices that are partially terminated by prolines
  • Oxygen carrier
  • Does not show cooperativity- 1 unit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

collagen general structure

A
  • 3 alpha polypeptide chains that wind around eachother

- Important amino acids: glycine, proline

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

fibril forming collagen

A
  • 1= skin, bone, tendon, blood vessels, cornea
  • 2= cartilage, intervertebral discs
  • 3= blood vessels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

fibril associative collagen

A

bind to collagen fibres and link them to form ECM

  • 9= cartilage
  • 12= tendons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

other types of collagen

A
  • 4= basement membrane

- 7= underneath stratified squamous epithelia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

elastin

A
  • fibrous
  • Synthesised from tropoelestin- secreted in ECM onto fibrillin scaffold
  • Tropoelastin molecules crosslinked between lysine side chains
  • Found in lungs, arteries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

enzyme active sites

A

pocket containing amino acids that participate in substrate binding and catalysis i.e substrate binds, and product is released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

apoenzyme

A

inactive enzyme without non protein component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

holoenzyme

A

= active enzyme including non-protein component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

cofactor

A

metal molecules that help enzymes to function

30
Q

coenzymes

A

organic molecule that helps enzymes to function

31
Q

cosubstrate

A

coenzymes that transiently (for a short time) associate with the enzyme

32
Q

prosthetic group

A

coenzymes that are permanently associated with the enzyme

33
Q

reaction velocity

A

number of substrate molecules converted to product/ unit of time

34
Q

transition state

A

has the highest associated energy in any part of the reaction: to complete the reaction there must be sufficient energy to form this state, transition state is lowered in enzyme catalysed reactions

35
Q

effect of substrate concentration on reaction velocity

A

Increased concentration of substrate increases the rate of reaction until all the active sites available are saturated and further increases have no effect

36
Q

Effect of Temperature on Reaction Velocity

A
  • Increase in temp= increased number of molecules have sufficient energy to reach transition state
  • Velocity therefore increases but only until 37C, further increase will break weak bonds holding secondary and tertiary structure and denature enzyme so reaction velocity will decrease
37
Q

Effect of pH on Reaction Velocity

A
  • Optimum pH is specific for each enzyme and reflects its function
    Eg. Pepsin’s optimum ph 2 is reflected in the acidic nature of the gastric lining where it helps with digestion
  • Extreme pH denatures enzymes
38
Q

allosteric regulation

A
  • Bind non covalently and non-competitively to allosteric site and can positively or negatively modulate the enzymes
  • Causes conformational changes in the activity site, altering the affinity of the enzyme for its substrate or modifying maximum catalytic activity
39
Q

feedback inhibition

A

allosteric enzyme is regulated by the concentration of the end product of the reaction pathway.

  • Inhibition only when there is too much end product
  • End product binds to allosteric site of enzyme that catalyses regular rate limiting step of series to change its conformation
  • Reaction pathway carries on when there is no end product (or v little)
40
Q

covalent modification

A
  • Addition or removal of phosphate groups from specific serine, threonine or tyrosine residues in enzyme
  • Either addition or removal can act as an activator or inhibitor depending on the specific situation
41
Q

adjusting enzyme synthesis/degradation to regulate enzymes

A
  • Usually affects enzymes that are active at a particular physiological or developmental stage
  • Alters the number of active sites available and hence the overall enzyme activity
  • Slow process that involves blocking of RNA
  • Eg. Insulin regulation of glucose mechanism
42
Q

signal transduction

A

binding of a ligand to an external receptor to bring about an internal cellular response

43
Q

types of signalling

A
  • Endocrine- hormones (ligands). Secreted from endocrine glands transported in blood and act on distant target cells
  • Paracrine- paracrine factors (ligands) secreted and targets nearby cells over a short range
  • Autocrine- ligands secreted that acts on the same cell eg. In immune cells
  • Neuronal- electrical signals travel along the cell and neurotransmitters (ligands) are released through the synapse to the target cells
44
Q

Membrane receptors- target receptors and mechanism

A

hydrophilic ligands as they are unable to cross the hydrophobic plasma membrane

45
Q

Intracellular receptors- target molecules

A

small and hydrophobic eg. Steroid hormones (cortisol, testosterone ect.)

46
Q

molecular switches

A

protein molecules that can either be activated (switching the pathway on) or inactivated by:

  • GTP binding
  • Phosphorylation
47
Q

G protein coupled receptors (GPCRs) and similar receptors to it

A

proteins that span the membrane 7 times and are attached to G proteins, GTP acts on GPCRs
Similar receptors are steroid hormone receptors and enzyme coupled receptors

48
Q

G proteins structure

A

usually made of 3 subunits (alpha, beta, gamma) but can be monomers, the alpha subunit binds to either GDP/GTP and has intrinsic GTPase activity

49
Q

activation of GPCR

A
  1. Ligand binds to GCPR
  2. Alpha subunit separates from the rest of the G protein
  3. The activated alpha binds and activates the target enzyme
  4. This hydrolyses GTP to GDP so the alpha subunit dissociates from target enzyme and reassembles with the rest of G proteins
  5. Activated enzymes then act on downstream proteins
50
Q

Adenynyl Cyclase (cAMP- dependant) Pathway

A

Ligand= variable but adrenaline is an example in the fight or flight response
1. Adrenaline binds to GPCR: GTP binds to alpha unit, activating it
2. Alpha unit binds to adenylyl cyclase (a membrane enzyme)
3. Adenylyl cyclase catalyses the production of cyclic AMP from ATP
4. Protein kinase A activates glycogen phosphorylase which catalyses the breakdown of glycogen to glucose
Glucose is imp for energy in a fight or flight response.

51
Q

Phospholipase C pathway

A
  1. Ligand activates alpha unit of a G protein via GCPR
  2. Alpha subunit activates phospholipase C enzymes
  3. These enzymes catalyse the breakdown of inositol phospholipid (associated with the plasma membrane) into diagcylglycerol (DAG) (also membrane associated) and inositol-1,4,5-triphosphate (IP3)
  4. Calcium molecules move down the concentration gradient from the ER to the cytoplasm
  5. The DAG and the calcium molecules activate the protein kinase C which will phosphorylate target proteins
52
Q

Receptor Tyrosine Kinase (RTK) Structure

A

Ligand= form of a dimer
Inactive RTK- made up of two monomers, intracellular components are tyrosine kinase domains and extracellular components are ligand binding domains

53
Q

RTK Activation

A
  1. Binding of ligand dimer brings the two monomers together= dimerization
  2. Kinase activity is stimulated
  3. A tyrosine in the cytoplasmic portion of each monomer is phosphorylated by its partner
  4. Binding sites are created for intracellular signalling proteins that lead to the initiation of signal transduction pathways
54
Q

RAS Pathway

A
  1. RTK activated by signal molecule
  2. Adaptor molecule binds to activated RTK and Ras activation protein
  3. Ras activated which then activates mitogen activated protein (MAP) kinase kinase kinase
  4. This phosphorylates MAP kinase kinase
  5. This phosphorylates MAP kinase
  6. This phosphorylates a number of possible mitogen activated proteins bringing about changes in protein activity and gene expression to facilitate cell proliferation
55
Q

issue with Ras being permanently switched on

A

leads to uncontrolled cell proliferation- cancer

56
Q

plasma membrane

A
  • Selectively permeable barrier that separates and protects the interior of all eukaryotic cells from external environment
  • Main components: phospholipids and proteins
  • Phospholipid bilayer with embedded and associated proteins
57
Q

endomembranes

A

plasma membranes that surround organelles inside the cell, have same basic components as plasma membrane, ratio of lipids to proteins in a membrane changes based on what the membrane encloses

58
Q

lipids

A
  • Most abundant macromolecule in membranes + plays structural and regulatory roles eg. IP3 and DAG from phospholipase C
  • Have a hydrophilic head and two hydrophobic portions
  • Lipids are amphiphilic and amphiphobic- have both hydrophobic and hydrophilic portions
59
Q

glycolipid

A
  • Hydrophilic head: glycerol-sugar molecule

* Hydrophobic tail: fatty acid, one with a kink cause by C=C double bond which increase membrane flexibility

60
Q

phospholipid

A
  • Hydrophilic head: phosphate-glycerol molecule
  • Phosphatidylcholine (most imp phospholipid)- choline-phosphate glycerol molecule
  • Hydrophobic tail: fatty acid, one with a kink cause by C=C double bond which increase membrane flexibility
61
Q

sterol (eg. cholesterol)

A
  • Hydrophilic head is attached to a planar steroid ring and a non-polar g=hydrocarbon tail
  • Cholesterol fits into the gaps between the phospholipids of the membranes and stiffens the membrane
  • The ratio of cholesterol to phospholipids in a membrane varies with the flexibility of the membrane- most cholesterol means stiffer membrane
62
Q

types of transport proteins

A
  • Uniport= carries one solute in one direction across membrane
  • Symport= carries two solutes at the same time in the same direction across the membrane
  • Antiport= carries two solutes at the same time in the opposite direction across the membrane
63
Q

types of association with the membrane that transport proteins have

A
  • Transmembrane (integral): high no. of amino acids in these proteins to associate in the hydrophobic bilayer
  • Peripheral: can be monolayer associates, lipid linked or protein linked
64
Q

simple diffusion across the membrane is done by which molecules?

A
  • Small hydrophobic molecules- oxygen, CO2, nitrogen, benzene
  • Small uncharged polar molecules- water, glycerol, ethanol
65
Q

channel mediated passive transport

A
  • Ions pass through the membrane via channel along a concentration gradient
  • Channel provides a hydrophilic environment within the lipid bilayer
  • Size of channel confers degree of selectivity onto a channel protein
66
Q

transporter mediated passive transport

A
  • Solute binds to specific binding site on transporter bringing about a conformational change
  • Solute is transported and released
  • Increasing solute concentration will increase rate of transport up to a threshold where rate will plateau as a result of a limited number of binding sites
67
Q

transporter mediated active transport

A
  • Active transport transports molecules again their electrochemical gradient- concentration gradient and voltage gradient ions move from an area of positive charge to negative
  • Requires energy in the form of ATP or by coupling active transport with passive transport of molecules along concentration gradient (cotransport)
68
Q

Sodium/Potassium ATPase process

A
  1. Sodium binds to pump
  2. Pump phosphorylates itself via ATP which triggers a conformation change in pump that causes Na+ to be ejected outside cell
  3. K+ bind
  4. The pump is dephosphorylated so it returns to original conformation and K+ is ejected inside cell
69
Q

Sodium/ Glucose Symportprocess

A
  • Passive transport of sodium= active transport of glucose, important in gut epithelial cells for food absorption
    1. Passive transport of sodium provides energy for transport of glucose against concentration gradient
    2. Sodium is constantly actively excreted by the Na/K ATPase to maintain higher concentration outside the cell
70
Q

ATP Binding Cassettes

A
  • 2 cytostolic ATP binding sites + 2 transmembrane transporter domains
  • ABC hydrolyses ATP and induces a conformational change in the membrane spanning domain causing the transport of substrates
  • Important in multidrug resistance- the transporter export ions, drugs and xenobiotics from cells- can include anti-cancer, anti-viral and immunosuppressive agents
71
Q

Haem groups

A

Fe2+ oxygen binding sites

Y1S1- Fundamentals of Medicine (11 decks)

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