Brainscape's Knowledge GenomeTM

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


See full index

Membranes and Receptors > Lecture 1.1: Overview of Biological Membranes > Flashcards

Lecture 1.1: Overview of Biological Membranes Flashcards

1
Q

What are the Functions of Biological Membranes? (5)

A
  • Form continuous and highly selective permeability
    barrier
  • Control enclosed chemical environment
  • Facilitate communication between organelle/cell and
    environment
  • Allow recognition through the presence of signalling
    molecules, adhesion proteins and allow immune
    surveillance
  • Generate signals in response to stimuli (electrical,
    chemical)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Composition of Biological Membranes and Percentages (Dry Weight)

A
  • 60% protein
  • 40% lipid
  • 1-10 % carbohydrate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What percentage of total membrane weight is water?

A

20 %

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

Phospholipid Structure

A
  • Hydrophilic Group (choline, amines or sugars,
    phosphate)
  • Glycerol (NOTE: sphingomyelin contains sphingosine)
  • Hydrophobic Group (two fatty acids of varied length,
    C16 and C18 are most common, and degree of
    saturation- cis double bond introduces a kink)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What allows phospholipids to be less packed in the lipid bilayer?

A
  • Unsaturated fatty acids introduce a kink in
    the hydrophilic part of the phospholipid
  • This allows them to be less packed/rigid and
    more flexible
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cholesterol Structure

A

Contains hydroxyl group and rigid steroid ring
and hydrocarbon side chain

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

How does cholesterol fit in-between phospholipids?

A

It fits into spaces created by the kinks of
unsaturated fatty acids in phospholipids

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

What are the 2 types of carbohydrate found in Glycolipds?

A
  • Cerebrosides: head group with monosaccharide
  • Gangliosides: head group with oligosaccharide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 3 Types of Membrane Proteins?‡

A
  • (Integral) Transmembrane Proteins
  • (Integral) Lipid Anchored Proteins
  • Peripheral Proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where are Transmembrane Proteins found?

A

Deeply embedded in the lipid bilayer of membrane

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

Examples of Transmembrane Proteins (4)

A
  • Adhesion Proteins
  • Ion Channels
  • Transporters
  • Receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where are Lipid Anchored Proteins found?

A
  • Attached covalently to lipids without entering
    core portion of lipid bilayer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Examples of Lipid Anchored Proteins (1)

A

G-coupled proteins

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

Where are Peripheral Proteins found?

A
  • Associated with the surface of membrane
  • Electrostatic and hydrogen bond interactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What denatures Peripheral Proteins?

A
  • pH change
  • Temperature change
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Examples of Peripheral Proteins (1)

A

Cytoskeletal proteins (e.g. actin)

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

Functions of Membrane Proteins by Function?

A
  • Transporters (control movement across membrane)
  • Anchors (act as attachment points to membrane)
  • Recognition (markers for cell-cell interactions)
  • Glue (junctions connecting cells)
  • Enzymes (localising metabolic pathways)
  • Transduction (receptors carry signals into the cell)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the Fluid Mosaic Model of Membranes?

A
  • Biological membranes are fluid structures as
    lipids and proteins
  • Are not placed rigidly in particular location
  • Despite their fluidity they are stable
  • As in mosaic, proteins are scattered throughout
    membranes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Mobility of Phospholipid Bilayer (4 Types of Movement)

A
  • Flexion
  • Rotation
  • Flip-flop
  • Lateral Diffusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Examples of Hydrophobic Molecules (4)

A
  • O2
  • CO2
  • N2
  • Benzene
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Examples of Small Uncharged
Polar Molecules (3)

A
  • H2O
  • Urea
  • Glycerol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Examples of Large Uncharged
Polar Molecules (2)

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

Why do we want to transport things across the membrane? (6)

A
  • Maintenance of ionic composition
  • Maintenance of intracellular pH
  • Regulation of cell volume
  • Control concentration of metabolic fuels and building
    blocks
  • Extrusion of waste products of metabolism and toxic
    substances
  • Generation of ion gradients necessary for the
    electrical excitability of nerve and muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is Passive Transport?

A

Diffusion of hydrophobic molecules across the membrane with their concentration gradient (from higher concentration to lower concentration)

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

What is Passive Facilitated Transport?

A

Diffusion of hydrophilic substances through specific membrane proteins:
‡* Carrier proteins (ping-pong)
‡* Protein pores (channels)
‡* Protein flip-flop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the Types of Channels (6)

A
  • Gap Junction
  • Uniporter
  • Ligand Gated
  • Antiporter
  • Voltage Gated
  • Symporter
27
Q

Types of Channels: Gap Junction

A

Pore between cells for electric and chemical continuity

28
Q

Types of Channels: Uniporter

A

Transports 1 molecule across a membrane

29
Q

Types of Channels: Ligand Gated

A

Opens when chemical binds to a receptor

30
Q

Types of Channels: Antiporter

A

Transports 2 molecules in opposite directions

31
Q

Types of Channels: Voltage Gated

A

Opens when potential difference across membrane change

32
Q

Types of Channels: Symporter

A

Transports 2 different molecules across membranes in the same direction

33
Q

Primary ATP-Powered Pumps: P-class
What does it transport? (4) Across what membrane?

A
  • H+
  • Na+
  • K+
  • Ca2+
  • Across several different membranes
34
Q

Primary ATP-Powered Pumps: F-class
What does it transport? Across what membrane?

A
  • H+ ions
  • Across inner mitochondrial membrane
35
Q

Primary ATP-Powered Pumps: V-class
What ion does it transport? Across what membrane?

A
  • H+ ions
  • Across lysosomal membrane
36
Q

Primary ATP-Powered Pumps: ATP-Binding Cassette (ABC)-class
What does it transport? Across what membrane?

A
  • Ions
  • Drugs
  • Xenobiotics
  • Across various cell membranes
37
Q

What is Primary Active Transport?

A
  • ATP-powered pumps that have ATPase
    activity
  • They use energy from hydrolysis of ATP
38
Q

What is Secondary Active Transport?

A
  • Transport proteins do not have ATPase activity
  • Their function depends indirectly on ATP hydrolysis by
    ATPases (sodium pump)
  • They use the ion gradient generated by ATPases
  • This is co-transport
39
Q

What is co-transport?

A

The movement of one substrate depends on the movement of another substrate

40
Q

When is pH controlled by the activity of
cell membrane transporters?

A

When cellular buffering capacity is exceeded

41
Q

How is pH controlled by cell membrane transporters ?

A

Most of them use H+ gradient generated by Na+-K+-ATPase

42
Q

What cell membrane transporters cause Alkalinisation? (3)

A
  • Na+/H+ antiporter
  • Na+/HCO3- symporter
  • Na+/Cl-/HCO3-/H+ antiporter
43
Q

What cell membrane transporter causes Acidification?

A

Cl-/HCO3- antiporter

44
Q

How is Cellular Volume regulated?

A
  • Regulated by transport of osmotically active ions
  • Na+, K+, Cl- or organic osmolytes (amino acids)
  • Water follows them affecting cell volume
  • Most of cell membrane transporters use H+
    gradient generated by Na+-K+-ATPase
45
Q

Mechanisms to Resist Cell Swelling (3)

A
  • Conductive Systems
  • Efflux of osmotically active ions in response to
    cell swelling
  • Co-transport Systems
46
Q

Mechanisms to Resist Cell Shrinking (4)

A
  • Conductive Systems
  • Influx of osmotically active ions in response to
    cell shrinking
  • Co-transport Systems
  • Organic Osmolytes
47
Q

Types of Transport across the Placenta (4)

A
  • Simple Diffusion
  • Facilitated Diffusion
  • Active Transport
  • Pinocytosis
48
Q

What is transported via simple diffusion across the placenta? (5)

A
  • Water
  • Sodium
  • Chloride
  • Gases
  • Drugs (midazolam & paracetamol)
49
Q

What is transported via facilitated diffusion across the placenta? (3)

A
  • Glucose
  • Fatty Acids
  • Drugs (cephalosporins, glucocorticoids)
50
Q

What is transported via active transport across the placenta? (5)

A
  • Amino Acids
  • Iron
  • Calcium
  • Vitamins
  • Drugs (norepinephrine, dopamine)
51
Q

What is Neonatal Abstinence Syndrome (NAS)?

A
  • Foetus is exposed to drugs (e.g. opioids) via placental
    transfer
  • Mother and foetus/baby with dependency to a drug
  • Withdrawal symptoms after birth
    ‡
52
Q

Complications of NAS (4)

A
  • Preterm Birth
  • Intrauterine Growth Restriction
  • Withdrawal symptoms after Birth
  • Death
53
Q

What is Coeliac Disease?

A
  • It is a lifelong autoimmune disease caused by an
    abnormal immune system reaction to gluten
  • The damage (atrophy of the villi), and inflammation to
    the lining of small intestine reduces body’s ability to
    digest and absorb nutrients from food
54
Q

What are the Symptoms of Coeliac Disease? (8)

A
  • Bloating
  • Diarrhoea
  • Nausea
  • Wind
  • Constipation
  • Tiredness
  • Weight Loss
  • Anaemia
55
Q

What is the Placenta?

A

It is a disc-shaped organ which forms the physical barrier between mother and foetus

56
Q

What are the Functions of the Placenta? (4)

A
  • Gas Exchange
  • Metabolic Transfer
  • Hormone Secretion
  • Foetal Protection
57
Q

What is is the primary barrier limiting nutrient transfer
across the placenta?

A

Syncytiotrophoblast

58
Q

What is the Structure of the Syncytiotrophoblast?

A
  • Maternal-facing microvillous plasma membrane
    (MVM)
  • Basal plasma membrane (BM) oriented towards foetal
    circulation
59
Q

How does nutrient and drug transfer across the placenta occur? (4)

A
  • Simple Diffusion
  • Facilitated Diffusion
  • Active Transport
  • Pinocytosis (type of endocytosis)
60
Q

Villus of Small Intestine Important Structures

A
  • Lacteals (dilated lymphatic vessels) are
    important in the absorption of fat
  • Smooth muscle produces local rhythmic
    movements to improve the efficiency of
    absorption
  • Simple columnar epithelium:
  • Enterocytes (absorptive cells)
  • Goblet cells (mucus- secreting cells)
  • Enteroendocrine cells (gastric inhibitory
    peptide hormone- producing cells)
  • Paneth cells (enzymes and anti-microbial
    compounds- secreting cells)
61
Q

Small Intestine: protein networks between cells and microvilli. What are they? Why are they important/What is their role?

A
  • Specific connections formed by protein-protein
    complexes link adjacent cells in a controlled way
  • This allows for paracellular transport of substances
62
Q

What useful substances are transported across the Placenta?

A
  • Nutrients
  • Hormones
  • Gases
63
Q

What harmful substances are transported across the Placenta?

A
  • Drugs
  • Alcohol
  • CO

Membranes and Receptors (19 decks)

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