Brainscape's Knowledge GenomeTM

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


See full index

Molecules and cells > Cells and membranes > Flashcards

Cells and membranes Flashcards

You may prefer our related Brainscape-certified flashcards:
Organic Chemistry 101 flashcards
1
Q

Why are membrane compartments important?

A

Cell function an in disease

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

Plasma membrane

A

Maintains cell contents, semi-permeable battier only some molecules can pass

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

Nuclear membranes

A

Contain and organise genome

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

Mitochondria and chloroplasts

A

Localise and facilitate ATP synthesis

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

ER and golgi apparatus

A

Organise glysosylation or proteins, protein modification and sorting

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

Lysosomes

A

Degradation of unwanted contents - intracellular digestion

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

Convex lens

A

Converges parallel beams to focal point

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

What does focal length depend on?

A

Curvature of lens - long and less curved = less magnifiying

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

Concave lens

A

Diverges parallel beams

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

Single lens

A

Enlarged visual image if object is closer than focal point

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

Decreasing focal length…

A

Increases magnification as fatter lens

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

Object further from focal length

A

Real image is formed

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

Objective lens

A

Magnified real image, eye piece lens produces magnified virtual image of real image

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

Bright field microscope

A

Light through specimen - image magnification and focussed on retina

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

Phase contrast

A

Can amplify refractive index differences in cell composition - live cells

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

Fluorescence microscopy

A

Different parts if cell specifically stained using spec dyes of antibodies to individual proteins, attached to fluorescent molecules. These are excited by a wavelength of light which emits light of another wavelength - image magnification focussed on retina/detector. Compare by immunofluorecese - secondary antibody - GFP

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

Confocal microscopy

A

Physical filter e.g. pin-hole prevents out of focus light reacting detector

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

Deconvolution

A

Remove out of focus light in silico

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

Resolution of EM vs LM

A

0.1nm vs 200nm

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

TEM

A

2D projection image of thin specimen. Focuses e- onto specimen, focuses and magnification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

SEM

A

Surface image of specimen of unlimited thickness - e- emitted or reflected from surfaces - detection = image

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

Resolution

A

The closest 2 objects can be and still be distinguishable - depends on wavelength

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

Non-polar molecules with water

A

No interaction - order on water molecules (thermodynamically unfavourable)
Entropy decreases, but aggregation releases water molecules, increasing entropy = favoured - reduced number of water molecules affected - SA reduced
Cages around non-polar to reduce H bonding = stronger and more stabled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Amphipathic molecule

A

No interaction with water - affects H bonds, therefore forced together to reduce water contact

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

Aggregation of lipids

A

Reduces water order - more aggregation = less water molecules involved per lipid, therefore water n a system is less ordered overall.

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

How can you prove that membrane lipids are highly mobile?

A

Fluorescent molecules bleach with laser beam, fast recovery as bleached diffuse out and outside bleached area move in

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

Monoglyceride

A

Fatty acid and C1 on glycerol - mediated by CoA –> di/triglyceride

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

Phosphatidate

A

Phosphate to C3 (simplest head group) - alcohols may be added

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

How does shape affect reactions?

A

Different alcohol head groups added with different chem and phys properties. Affects reactions with other molecules, affecting packing in bilayer - fluidity, affects other physical properties e.g. curvature

30
Q

How are kinks formed in fatty acids?

A

Double bonds - less flexibility

31
Q

How can lipids be more/less packed?

A

Saturated = less fluid (closer packed) than unsaturated

32
Q

What affects the mpt of FAs?

A

Saturated = higher mpt as more van der waals and need to disrupt order. Longer = higher mpt and more van der waals stabilising

33
Q

Sphringolipids

A

Long chain amino alcohol, 2nd HC tail held by amide bond. Fit into membrane like phospholipids but usually saturated strong van der waals - tend to partition.

34
Q

Cholesterol

A

Amphipathic, small head group, too hydrophobic to form own bilayers, can insert into membrane, interaction with FA tail - heads form “umbrella” stiffens FA tails and thickens membrane - less fluid, introduces order into tail, increasing tight packing but maintaining fluidity

35
Q

Micro domains - lipid rafts

A

Concentration thicker domains rich in sphingomyelin and cholesterol - rafts thicker than rest of the membrane, proteins long and transmembrane domains partition to rafts, short domains partition to phospholipid contain domains. Recruit proteins with lipid anchors or long TM domains.

36
Q

Single pass transmembrane proteins

A

Alpha helix most common structural motif
H bonds in backbone stable in membrane - lack of competing water
Side chains mostly uncharged, non-polar
Unusual number of glycine - flexibility
Hydropathy measure of energy need to pass a segment of pp into water from solvent - hydrophobic = energy - measures hydrophobicity

37
Q

Multi-pass transmembrane proteins

A

Light driven proton pump, H bonding to alpha helix, Gly is rate in alpha helices of soluble proteins, common in alpha helices of trans-membrane domains. Gly allows chain flexibility as it is small - tight packing in multi-pass proteins

38
Q

Functions of integral membrane proteins

A

Transporters, anchors, receptors, enzymes

39
Q

How to study trans-membrane proteins

A

Solublisiation - use detergents
Isolation - column chromatography
Characterisation - gel electrophoresis to determine Mr
Functional/structural incorporation into artificial membrane - clone genes/isolate proteins

40
Q

Detergents

A

Amphipathic - incorporate into membranes at high doc to displace phospholipids. Extract P and lipids. Mild non-ionic maintain functions, ionic detergents denature proteins –> gel electrophoresis. Form micelles at critical micelle conc

41
Q

Simple diffusion

A

Only gases and small uncharged molecules high –> low. Rate depends in diffusion gradient and hydrophobicity of molecule

42
Q

Osmosis

A

Semi-permeable membrane allows water, not solutes
Water molecules to equalise water concentration - dilute solute, osmotic pressure = pressure to prevent water flow. Channels also allow flow if water in plasma membrane - isotonic no net flow, hypnotic water in and cell swells, hypertonic water out and shrinks.

43
Q

Uniporter

A

High –> low e.g. glucose. Faster than diffusion but saturable. Conformational change

44
Q

Symporter

A

Co-transporter. One against and one with conc grad - energy provided (facilitated) by conformational changes

45
Q

Antiporters

A

Co-transporter. One against, one with in opposite directions

46
Q

Active transport

A

Movement against gradient driven by ATP hydrolysis

47
Q

Secreted proteins

A

Synthesised by ribosomes on ER - mediated by signal sequence at N-terminus, proteins into ER lumen, modified, passed to golgi, further modified, transport

48
Q

Protein synthesis

A

RNA out of nuclear envelope => ER => golgi => membrane. Chaperones mediate protein folding, disulphide bonds added and oligomerisation occurs

49
Q

Docked ribosomes

A

Synthesise integral membrane proteins or lumenal proteins. Dock to translocation channel, mediated by signal peptide

50
Q

Type I integral protein

A

LDL receptor, insulin receptor etc. Single pass, C-terminus on cytosolic side, N-terminus of lumenal side

51
Q

Type II/III synthesis

A

If internal signal preceded by positive aa side chains. N-terminus of cytosolic side if positive side chains after pos side chains = type 3, C-terminus cytosol

52
Q

Where are proteins glycosylated?

A

In ER - add polysaccharide => N linked, more Philic, stops aggregation and aids folding, protects from degradation

53
Q

Function of RER

A

Membrane and secretory protein synth, folds protein in lumen, glycosylates proteins,makes disulphide bridges, checks protein quality, ca2+ store

54
Q

SER

A

Connects to RER, exit sites for transport vesicles, synthesis of lipids and steroids, abundant in lipid metabolising cells

55
Q

Golgi apparatus

A

Further glycosylation and protein sorting. Incoming cis-face towards nucleus, outgoing trains-face towards plasma membrane. Flat sac like cisternae, distinct compartments. Secretory proteins move on cis to trans direction. Further glycosylation in each Golgi stack - complex specific polysaccharide

56
Q

Forward traffic

A

ER => Golgi => plasma memb

57
Q

Retrograde transport

A

Golgi => Golgi; golgi => ER

58
Q

Endocytosis

A

Used to internalise certain molecules e.g. nutrients. Used to control cell surface proteins e.g. receptors mediated by clathrin and adapters e.g. LDL particle internalisation, dietary lipids and cholesterol transport in LDL particle => binds LDL receptor => formation of clathrin coat => coated pit/vesicle => endosome => lysosome => mutation LDL causes familial hypercholesterolemia.

59
Q

Cathrin cage

A

Assembly drives membrane curvature. Vesicle formation involves coating. Endocytosis => clathrin coats - attaches to membrane via adaptor. Drives membrane deformation by assembling into curved cages - form multiple hexametric complexes - triskelions.

60
Q

Intra-cellular vesicle transportation

A

ER => golgi = COPII; Golgi => ER = COPI Golgi => golgi = COPI

61
Q

Protein through golgi

A

Cisternal progression
Each golgi stack has a cis-golgi network formed by a fusion of COPII vesicles from ER. Cis-golgi formed when COPI vesicles from cis-golgi stack fuse with cis-golgi networks. Medial-golgi formed COPI fuse cis-golgi network. Trans-golgi => COPI vesicles fuse medial goggle network,
COPII ER => golgi vesicle formation (forward)
COP I golgi => ER vesicle formation (retrograde transportation)

62
Q

+ SNARES (target) and V-SNARES (vesicle)

A

Target correct compartment and membrane fusion. SNARES also in fusion of vesicle target. V-SNARES to + SNARE tight complex. SNARES unstructured until bound - 4 helix bundle. Z membranes close - fusion

63
Q

Nuclear envelope

A

Double membrane separating nucleus and cytoplasmic compartments. Nuclear pores mediate - move nuclear proteins => nucleus and mRNA to cytoplasm => transport and transport separation. Nuclear transport receptor mediation - uses internal non-cleaved signal sequences.

64
Q

Purpose of cell cycle

A

To produce 2 new separate daughter cells from 1 mother cell

65
Q

Phases of cell cycle

A

G1: Gap 1 - each chromosome has a single chromatid, cell gets ready for DNA replication, varies in time from 0-several years
S-Phase: DNA replication - each duplicated to contain 2 joined chromatids
G2: ago 2 - two chromatids, cell prepares for metaphase and cell division
Mitosis
G0: exit phase - cell leaves cell cycle, needs external signals to re-enter

66
Q

Stages of mitosis

A

Prophase: centrosomes separate, chromosome condenses, nuclear envelope disassembles, spindle forms, chromosomes attach to spindle
Metaphase: Chromosomes align on spindle equator
Anaphase: Sister chromatids separate and move to poles, organised central spindle disassembles, poles separate, cleavage furrow assembles
Telophase: Cleavage furrow contracts, nuclear envelope reassembles
Cytokinesis: New membrane inserted, acth-myosin contractile ring forms, chromatin condenses, nuclear substructures for,

67
Q

Check points of cell cycle check for…

A

DNA damage to prevent replication of incorrect sequences
Incomplete replication to ensure only whole chromosomes are pass on
Spindle attachment to ensure correct chromatid separation into daughter cells

68
Q

How are checkpoints controlled?

A

Controlled by kinases which phosphorylate proteins. - Cyclin dependent kinases (CDKs) are activated by cyclins.

69
Q

G1/S cyclins

A

Activate CDKs during G1, destroyed at end. Phosphorylate and inactivate proteins that block progression through restriction point, activate synthesis of S-cyclins, S-cyclins activate S-CKDs, S-cyclin/S-CDKs phosphorylate and activate DNA replication proteins, so allow entry to S-phase

70
Q

What level are CDK proteins at throughout the cell cycle?

A

Constant. Cyclin only present at specific times. CDK only active when appropriate once is present.

71
Q

S-cyclin

A

Synthesised in G1, destroyed during mitosis.

72
Q

M-cyclin

A

Synthesised in G2, activated M-CDK phosphorylation of may proteins and triggers massive reorganisation of cell for division. M-cyclin rapidly destroyed at end of metaphase, destruction via unquitination by APC/C with target protein to proteasome, reverses mitotic changes.

Molecules and cells (6 decks)

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