Brainscape's Knowledge GenomeTM

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


See full index

Cell Biology > Anitas Content > Flashcards

Anitas Content Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Definition of a cell

A

Small aqueous solution of chemicals enclosed in a selective barrier that can make a copy of itself

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

What do compartments allow a cell to do

A

Enclose reactions
Create gradients

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

Steps in scientific research

A

Observations leads to questions
Focused, clear hypothesis
Pitch ideas to get funding
Design experiment
Replicabaility
Analyse data
Conclude
peer review

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

How to isolate parts of animal tissue to analyse

A

Use laser beam to cut around tissue and second laser to catapult region into container
Break up tissue using enzymes, culture in a plate, flask, bioscaffold
Coat the culture surface in ECM components to mimic cells natura environment

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

How to isolate specific cells and organelles to analyse

A

Centrifuge to separate by density

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

General principles of eukaryotic cell culture

A

Easy to contaminate with yeast and bacteria as culture medium is nutrient rich
Sterile technique needed

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

What are primary cells

A

Straight from living organism
Haven’t been manipulated for too long
Harder to isolate and culture
Isolate with enzyme treatment
Hayflick limit- number of times they will divide before senescence
Senescence- metabolic rate goes down

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

What are cell lines

A

Immortalised cells as they have changes in key genes, genetically different to primary cells

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

Fluorochromes

A

Sticks to a part of a cell
Absorbs light and emits it at specific wavelengths that are detected

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

Specific antibodies

A

Can be used to isolate specific cells
Bind to specific proteins

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

Fluorescently labelled antibodies

A

Can bind to specific proteins so they can be identified
Can label a gene and its protein with a tag
Stronger signal when using an unlabelled primary antibody that binds to a group of labelled secondary antibodies

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

FRAP (fluorescence recovery after photobleaching)

A

Used to investigate plasma membrane
Area bleached with intense light
If proteins are free to move then area will be filled again by fluorescent proteins
Can monitor kinetics
Make sure fluorescent tag doesnt inactivate protein

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

FRET (Forster resonance energy transfer)

A

To see if two proteins interact
Label 2 different proteins with 2 different labels and excite with laser
1 emits energy that can only excite label 2 if within 10nm
Efficiency is proportional to distance between then

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

What are cell membranes made of

A

Phospholipid bilayer
Protein molecules
Cholesterol

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

What are membranes used for

A

Create ion gradients
Signalling
Protects against pathogens
Maintains internal environment
Proteins sense and respond to changes in environment
Create compartments inside cell
Selectively permeable

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

What is an amphipathic lipid

A

Hydrophilic end and hydrophobic end
Creates bilayer
Saturated tails are straight chains so pack closer
Forms and heals spontaneously
Hydration cell of water around heads stops 2 cell membranes fusing

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

Roles of water in cell membrane function

A

Hydration shell
Membranes fluid as lipids move to avoid water

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

How can membrane lipids move

A

Lateral diffusion
Rotate
Tails flex
Enzymes can be used to move lipids to outer membrane

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

Why would lipid composition of a membrane change with temperature of environment

A

Colder- more unsaturated tails so lipids can’t pack as close, keeps membrane fluid
Colder- shorter hydrocarbon tails as reduces tendency to interact with each other
Hotter- fewer unsaturated lipids

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

How can a cell use membrane lipid asymmetry

A

Signalling a cell has died by apoptosis
Create docking sites fr proteins
Convert extracellular signals to intracellular

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

What is glycosylation

A

Sugars attached to lipids of proteins
Interact with signalling molecules
Can be important in fertilisation

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

Nucleus

A

Protects genome
Outer membrane continuous with ER
Held together by lamina (mesh of proteins)
Specific, gated nuclear pores

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

ER

A

RER for protein modification, amount of ribosomes fluid, can drop off after job done
SER for lipid synthesis, calcium storage and carbohydrate metabolism
Can grow and shrink as needed and can be moved around the cell by microtubules

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

Golgi

A

Smooth stacks of flattened cisternae
Continues protein modification after ER
Leave ER in vesicles ad join golgi at cis face, leave at trans
Sorts proteins and packs into vesicles

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

Lysosomes

A

Number can change
Spherical
Full of enzymes
Lower pH inside than in cytoplasm, enzymes work at this pH
Digest waste biomolecules

26
Q

endosomes

A

Some bring in material from plasma membrane
Help sort and target material that enters cell
Many near plasma membrane
Several types
Early endosomes - sort molecules that enter cell
Recycling endosomes- return molecules to plasma mebrane for reuse
Late endosomes- carry material to lysosomes for degradation

27
Q

Mitochondria

A

Generate ATP
Some can store ATP
Sometimes broken down by lysosomes as they can leak ROS

28
Q

Peroxisomes

A

Single membrane bound
No genome or ribosomes
Full of enzymes
Have to import proteins through membrane
Made from bits of ER that pinch off and by splitting of existing peroxisomes

29
Q

Functions and clinical importance of peroxisomes

A

Oxidation of amino acids or fatty acids
Uses O2 to oxidise organic substrates to produce H2O2
Catalase uses H2O2 to oxidise phenols, formic acid, formaldehyde and alcohol
Clinical importance: build up of long chain (c>20) fatty acids can be toxic, if not all H2O2 removed from cell it can increase amount of ROS which causes oxidative stress as it damages DNA and organelles.

30
Q

How do cell signals and receptors differ

A

Types of signal includes proteins, amino acids, nucleotides, steroids, fatty acid derivatives
Receptors bind to low concentrations of signal with high affinity
If signal hydrophilic, receptor on cell surface
If small and hydrophobic, receptor may be inside cell
Ligand binds to receptors and induces conformational change, activates protein so intracellular signalling path activated

31
Q

Steps in typical cell signalling pathway

A

Ion-channel coupled- when ligand binds the channel opens
G-protein coupled- G protein active when bound to GTP, when GTP hydrolysed to GDP it switches off
Enzyme coupled- ligand binding draws 2 monomers together so intracellular components can interact
Extracellular signal molecule binds to receptor protein in plasma membrane, causes release of intracellular signalling proteins as it activates intracellular signalling pathway

32
Q

General principles of nuclear receptor and cell surface receptor signalling

A

Small hydrophobic ligands- steroids, retinoids, vitamin D
Bind to intracellular receptors in cytosol and move to nucleus or bind to regulatory regions
Alter gene transcription

33
Q

Examples of molecular signalling switch action

A

Phosphorylation - via kinases (to add phosphate) and phosphatases (cleave phosphate groups) to switch receptor on or off
GTP binding proteins-
GTP high in cell, protein on if GTP bound, changes conformation and activates other signalling proteins
Can switch itself off as has GTPase activity
Off if GDP bound
GAPs (GTPase activating proteins) turn off
Gets (guanine exchange factors) turn on, add GTP

34
Q

Definition of endocytosis

A

Process by which material enters a cell
Active process
Can be quick

35
Q

Pinocytosis

A

Taking in fluid and solutes from extracellular environment
Small pinocytotic vesicles
Can remove damaged membrane
Clathrin coated vesicles
Shed coat and fuse with early endosomes
Some Pinocytosis involves caveolae
Caveolae form from lipid rafts, can pitch off from membrane as dynamin protein wraps around neck of vesicle so bilayer can fuse, don’t shed coat

36
Q

Phagocytosis

A

Cell engulfing larger material
Macrophages and neutrophils are specialised phagocytes
Macrophages engulf senescent cells
Phagosomes fuse with lysosomes
Any residues exocytosed
A signalled process e.g. triggered by antibodies
Involves cytoskeleton remodelling

37
Q

Receptor mediated endocytosis

A

Ligand binding to receptor triggers process
Specific macromolecules
Can concentrate ligands without taking up lots of extracellular fluid
Involved in uptake of cholesterol in the form of low density lipoprotein (LDL)
Clathrin coated pits and vesicles

38
Q

Functions of endocytosis

A

Can bring molecules into cell
Can remove damaged parts of cell membrane
Allows engulfing of senescent cells

39
Q

Clinical relevance of endocytosis

A

Pathogens hijack it to enter cells, e.g. anthrax, tetanus, rabies, HPV

40
Q

Definition of exocytosis

A

Transport of proteins, carbohydrates and lipids that have been made in the cell from the trans golgi network to the plasma membrane or extracellular space

41
Q

Constitutive exocytosis

A

Doesnt need a trigger
Supplies newly synthesised plasma membrane proteins and lipids that span ER membrane, pass through golgi then fuse with plasma membrane

42
Q

Regulated exocytosis

A

Ca2+ dependent, Ca2+ helps vesicles fuse and interact with snare proteins
Secretory vesicles wait near plasma membrane for signal
Especially in specialised secretory cells for releasing hormones, neurotransmitters, digestive enzymes
Synaptic vesicles can be primed so fast vesicle fusion
Ca2+ changes conformation of snare proteins so full fusion can occur
Reform synaptic vesicles rapidly, not via trans golgi
Can deliver biomolecules to specific regions of cell due to polarised cell structure

43
Q

How do exocytotic vesicles form

A

Cargo starts to concentrate in trans golgi
Clathrin coat used to fuse vesicle, as much membrane is recycled to golgi as possible, cargo highly concentrated

44
Q

Functions of exocytosis

A

Releasing material
Increasing plasma membrane

45
Q

Clinical relevance of exocytosis

A

Antibody secretion
Neurotransmitter control or stimulation
Digestive enzymes
Insulin secretion

46
Q

What is cell adhesion

A

Attachments that form using a variety of proteins between a cell and another cell or a cell and the extracellular matrix

47
Q

What can cells use cell adhesion for

A

Communication
Tissue and organ formation
Channels linked to adhesion for direct communication between cells so cells in a tissue can cooperate
Decrease in cell adhesion can trigger cell division
Allows cells to form barrier to prevent entry of pathogens
Changes in cell adhesion can change gene expression
Pathways from adhesion complexes in membrane to signalling cascades
Can affect polarisation of cell

48
Q

4 functional types of cell to cell and cell to ECM junctions

A

Anchoring junctions
Occluding junctions
Channel-forming junctions
Signal-relaying junctions

49
Q

Cell adhesion in epithelia

A

Cell-cell anchoring junctions
Occluding junctions
Channel forming junction
Cell-matrix anchoring junction

50
Q

Structure of cadherins

A

700-750aa
5 extracellular cadherin domains
Short cytoplasmic domain
Glycoprotein
String cell-cell adhesion

51
Q

What can cadherins interact with

A

Binding is homophilic- specific type of cadherin will bind to same type on another cell
Joins to next cadherin by a hinge
Ca2+ ions bind to sites near the hinge to prevent it from flexing, without Ca2+ it becomes floppy and weak
Binding occurs at N terminus
Terminal domains form knob shape and pocket
Knob do one cadherin inserts into pocket of another

52
Q

Functions of cadherins

A

Highly selective recognition that allows cells of same type to stick together
Allows formation of tissues as they segregate different types of cells
Involved in cell shape regulation
Interact with signalling pathways

53
Q

Structure of integrins

A

Heterodimer, alpha and beta glycoprotein subunits
Transmembrane
Can bind Ca2+ and Mg2+
Bind RGD

54
Q

Function of integrins

A

Has extracellular ligand and intracellular and transmembrane parts
Beta chain exposes high affinity talon binding site, then actin can assemble
Intracellular signal can induce talin to bind strongly to beta chain of integrin
2 chains of integrin spring apart
Extracellular part extends and is active so can bind to specific amino acid sequences in ECM proteins

55
Q

Ig-superfamily cell adhesion molecules

A

Immunoglobulin domains
100aas folded into disulphide bonded beta strands
Often glycosylated
Some bind to integrins, others to same Ig-cam
Don’t need Ca2+ to be active
Heterophilic or homophilic binding
Weaker adhesion than cadherin
Adhesion between blood cells
Roles in bone marrow cells and blood cell generation

56
Q

Selectins

A

Cell surface carbohydrate binding proteins
Cell-cell adhesion in blood stream
Transmembrane proteins
Bind to endothelial cells
Heterophilic adhesions
Allow white blood cells to enter and leave blood stream
Low affinity binding allows white blood cell to adhere reversibly and roll along surface of blood vessel, propelled by blood
Lectin domain binds to specific sugar on another cell
Transient interactions, needs Ca2+
L-selectin, white blood cells
P-selectin, platelets and activated endothelial cells
E-selectin, activated endothelial cells

57
Q

Describe the ECM

A

Mesh of proteins and polysaccharides
Secreted and organised by cells
Diverse e.g. bone, teeth, tendon, cornea
Can be passive or actively influence cell behaviour
Not static
Sometimes has to be broken down
Can affect cell behaviour with matrix receptors- mainly integrins

58
Q

Glycosaminoglycans (GAGs) in ECM

A

Highly -ve charged polysaccharide
Attract water and swell and fill space with gel
Often covalently linked to proteins
Stiff, can’t fold
Absorb compression forces or create space
Proteoglycan- GAG linked to tetrasaccharide linked to serine or protein

59
Q

Fibrous proteins in ECM

A

Often collagen
Typical collagen is 300nm long, stiff, triple alpha chains
Gly.X.Y X often proline and Y often hydroxyproline
Resist tensile forces
Some assemble into fibrils, then fibres, bundles, sheets
elastin molecules, stretch and recoil, probably loose random coil structure, cross-linked network

60
Q

Non collagen glycoproteins

A

E.g. classical laminin
3 chains
Disulfide bonds
Self assemble into mesh
Held by integrins and other receptors in basal plasma membrane
Diverse

61
Q

Basal lamina

A

Supports, attaches, polarises, separates, organises membrane proteins, can filter, promotes cell survival, division, differentiation, migration routes
Located under epithelia, round muscle, fat, Schwann cells
Major components are laminin and type IV collagen

Cell Biology (6 decks)

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