Cells Flashcards
1
Q
What does the permeability of the membrane depend on
A
the nature of the molecule (polar , non polar)
size
2
Q
What can polar molecules easily form
A
hydrogen bonds
3
Q
What are polar molecules often called
A
hydrophilic
4
Q
What are hydrophobic molecules
A
non- polar molecules that are unable to form hydrogen bonds
5
Q
What molecules are lipids
A
hydrophobic
6
Q
What three things do membranes consist of
A
lipids
proteins
glycolipids / glycoproteins
7
Q
What does amphipathic mean
A
molecules with both hydrophobic and hydrophilic regions
8
Q
what are the three major classes of lipids
A
phospholipids
glycolipids
sterols
9
Q
what phospholipids are the most abundant
A
membrane
10
Q
What does a phospholipids backbone composed mostly of
A
glycerol and a three carbon alcohol
11
Q
What else is attached to the backbone
A
• negatively charged phosphate molecule forming polar hydrophilic head group
• two non -polar fatty acid chains forming the hydrophobic tails
12
Q
What are the two fatty acids
A
unsaturated
saturate
13
Q
what do the unsaturated fatty acids result in
A
kinks
14
Q
Why can’t ions and lipid soluble molecules (polar) pass through the membrane
A
the interior of the bilayer is hydrophobic (non-polar)
15
Q
Why can’t uncharged polar molecules like glucose pass through
A
they are hydrophilic
16
Q
What can pass through the bilayer
A
small uncharged non polar lipid soluble molecules
17
Q
example of large uncharged polar molecules that will be mostly impermeable to the bilayer
A
glucose
sucrose
18
Q
Examples of small uncharged polar molecules that will be mostly permeable to the bilayer
A
water
urea
ethanol
glycerol
19
Q
Examples of non polar lipid
molecules that will be permeable
A
Oxygen , Co2 , N2 , steroids
20
Q
Where does oxygen diffuse from
A
air in the alveoli (high conc of oxygen) to blood in the capillaries (low conc of oxygen)
21
Q
Where does carbon dioxide diffuse from in tissues
A
from cells (conc higher) to blood (conc is lower)
22
Q
Where does the carbon dioxide diffuse from in the LUNGS
A
from the blood to the alveoli
23
Q
What is a transmembrane protein
A
A protein that transfers molecules across the membrane
24
Q
What are aquaporins
A
They are transmembrane proteins that allow water molecules to flow down their channels. From a region of higher concentration to lower
25
What are the two types of membrane proteins
integral
peripheral
26
What are integral proteins
embedded in the lips bilayer
difficult to isolate
amphipathic molecules
27
How are integral proteins embedded into the bilayer
The hydrophobic regions of the integral proteins interact with the hydrophobic interior of the lipid bilayer
28
What are peripheral proteins
•Hydrophilic
• found on the surface of the membrane
•interact only with the hydrophilic regions of the integral proteins
29
List the 4 functions of membrane (TRRE)proteins
- Transport
- Recognition
- Receptors
- Enzymes
30
Explain how membrane proteins help transport proteins
facilitate the movement of molecules in and out of the cell
channel and carrier proteins
31
What are channel proteins
Transmembrane proteins form channels for the passage of molecules
32
What are Carrier proteins
Undergo a conformational change to transfer the molecules from one side of the membrane to the other
33
Explain how membrane proteins help recognition
help in cell-cell recognition
34
Explain how membrane proteins act as receptors
for chemical signals and are burning sites for molecules like hormones and neurotransmitters
35
Explain how membrane proteins act as enzymes
catalyse reactions
36
Define osmosis
The diffusion of water across a selectively permeable membrane from lower to higher solute concentrations
37
How does water move in osmosis
From a region of lower water concentration to a region of higher water concentration
38
What are the factors that make facilitated diffusion
• molecules move down the conc gradient
• the movement is facilitated by transport proteins
39
What are channel proteins
transmembrane proteins that assemble to form channels for the passage of polar molecules
40
What is the selectivity of the ion channels due to
• the binding sites of hydrophilic amino acid side chains lining the channel
• the size of the pore
41
What are some reasons the channels open or close:
- changes in voltage across a membrane
- binding of small molecules to the channel proteins
- mechanical forces
42
What are carrier protiens
transmembrane transport proteins
43
What is the mechanism of carrier proteins
the carrier protein binds to the solute molecules, it undergoes a conformational change and transfers the molecules to the other side of the membrane
44
Define Active transport
the net movement of particles through a cell membrane from a region of lower conc to a region of higher suing energy
45
What are 3 things active transport helps to:
• takes up essential nutrients
• removes secretory
• maintain the right concentrations of ions in the cells
46
What are the two types of active transport
Indirect
Direct
47
Explain direct active transport
The energy released by an exergonic reaction is used to directly transport molecules across the membrane
48
Explain Indirect transport
The movement of one solute down its gradient drives the movement of the second solute against its concentration gradient
49
What factors are based on the movement of molecules by simple diffusion
• the size of the molecules
• hydrophobic or hydrophilic nature
50
What are the carbohydrates linked to creating what
lipids and proteins
forming glycolipids and glycoproteins
51
What forms glycolipids
covalent bonding of carbohydrates to lipids
52
What are the two factors of glycolipids
- amphipathic molecules
- external surface of the cell membrane
53
What are the carbohydrates and lipids like in glycolipids
carbs are polar and extend to the extra cellular environment
lipids are non polar and embedded into the bilayer
54
How do glycolipids contribute to membrane stability
They form hydrogen bonds with the water molecules surrounding the cell
55
What are the 4 (triple c g) functions of glycolipids and proteins
Cell recognition
cell adhesion
cell signalling
glycocalyx
56
Explain cell recognition in glycolipids and glycoproteins
They act as markers and help cells of the body recognise eachother.
They help immune systems recognise foreign cells
57
Explain cell adhesion
they help cells to attach and bind to other cells to form tissues
58
Explain cell signalling
They act as receptors for enzymes
59
What is glycocalyx
A sticky layer formed by the carbohydrate groups of the glycolipids and protiens that protrude form the cell surface .
60
Who proposed the fluid mosaic model and what year
Singer and Nicholson 1972
61
What does the fluid mosaic describe
the arrangement of the lipids and proteins
62
What 2 things does the Fluid Mosaic Model state:
• The lipid bilayer is fluid
• The proteins are embedded in the fluid bilayer which resembles a mosaic
63
What is the benefit of the fluid nature of the membrane
That most lipids and proteins are able to move laterally , parallel to the membrane surface
64
What are organelles
discrete structures in cells adapted to perform specific functions
65
what 5 organelles have no membranes
ribosomes
centrioles
microtubules
proteasomes
nucleoli
66
what organelles have a single membrane
smooth er
rough er
golgi
vesicles / vacuoles
lysosomes
67
what organelle has a double membrane (5)
nuclei
mitochondria
chloroplasts
68
what does compartmentalisations allow
it allows the development of specialised cell structures
69
where are membrane bound organelles found
eukaryotic
70
what is an advantage of compartmentalisation in cells
the cell can separate chemical reactions and other cellular processes, this allows the cell to increase rate of chemical reactions
71
What two factors should you have to be an organelle
enclosed by a membrane
have a specific function
72
what is a disadvantage of compartmentalisation
it can delay a cells ability to respond to the environment
73
What are the 4 types of stem cell
Totipotent
Pluripotent
Multipotent
Unipotent
74
What are the differentiated cells produced in totipotent cells
• Can differentiate into any type of cell
• Can give rise to a complete organism
75
What are the differentiated cells produced in pluripotent t cells
Can differentiate into all body cells , cannot give rise to a whole organism
76
What are the differentiated cells produced in multipotent cells
Can differentiate into a few closely related type of body cell
77
What can unipotent cells differentiate into
Can only differentiate into their associated cell type
78
What are the stem cells at the morula stage
Totipotent
79
Are stem cells specialised or unspecialised
unspecialised
80
What is the morula
solid ball of totipotnet cells formed soon after fertilisation
81
What’s the function of the stem cell niche
The micro environment in which stem cells reside and receive their instructions
82
What is a micelle
formed when phospholipids are shaken with water
83
What are the two main components of animal cell plasma membranes
Phospholipids
Cholesterol
84
What makes Cholesterol (lipid) amphipathic
• majority hydrophobic
• the hydroxyl group of cholesterol molecule is hydrophilic
85
What does cholesterol help with
regulation of membrane fluidity and permeability
86
What happens in the interaction between cholesterol and phospholipids tails (temperature)
stabilises the plasma membrane at higher temperatures by stopping the membrane from becoming too fluid
87
What does cholesterol do at cold temperatures
increases fluidity of membrane, stopping it crystallising
88
What type of proteins are plasma membrane
globular proteins
89
What is cholesterol
lipid
90
As a whole what is the job of a transport protein
creates hydrophilic channels to allow ions and polar molecules to travel through the membrane
91
What is cell adhesion
allows tight junctions to form between cells
92
What organ and organ system do epithelial cells make up
Organ: Stomach
Organ system : digestive
93
What organ and organ system do muscle cells make up
Organ : bladder
Organ system : Urinary system
94
What organ and organ system do nerve cells make up
Organ : Brain
Organ system: CNS
95
What organ and organ system do rod and cone ells make up
Organ : Eye
Organ system : Visual system
96
What do structural adaptations include
shape of cell
the organelles the cell contains
97
What is a stem cell
a cell that can divide by mitosis an unlimited number of times
98
What is potency
the ability of stem cells to differentiate into more specialised cell types
99
What are the 4 types of potency
Totipotency
Pluripotentcy
Multipotentcy
Uni potency
100
Explain totipotency
stem cell that can differentiate into any cell type found in an embryo
101
Explain pluripotentcy
Embryonic Stem cells that can differentiate into any cell type found in an embryo but are not able to differentiate into any extra - embryonic cells
102
Explain multipotentcy
Adult stem cells that can differentiate into closely related cell types
103
Explain unipotency
adult cells that can only differentiate into their own lineage
104
What embryonic stem cell would it be if taken 3-4 days after fertilisation
Totipotent
105
What embryonic stem cell would it be if taken 3-4 days after fertilisation
Totipotent
106
What embryonic stem cell would it be if taken 3-4 days after fertilisation
Totipotent
107
What embryonic stem cell would it be if taken 5days after fertilisation
pluripotent
108
What is one treatment of Stargardts disease
Injection of retina cells derived from embryonic stem cells into patients eyes
109
Ethics : Arguments for Embryonic stem cells
• Totipotent and pluripotent can differentiate into any cell type thus giving patient a higher chance of living a healthy life
• Embryonic stem cells are not differentiated therefore less chance of genetic damage due to accumulation of mutations
110
Arguments against embryonic stem cells
• cells have a higher risk of developing tumours
• process involves the creation and destruction of embryos
111
Arguments for cord blood stem cells
• can be easily obtained and stored
• fully compatible either tissues of adult - reduce risk of rejection
112
Arguments against Cord blood stem cells
• The cells are multipotent and therefore have a limited capacity to differentiate into different cell types
113
Arguments for Adult stem cells
- donor able to give permission - less controversial
- lower chance of rejection patients own adult stem cells are being used to treat them
- lower chance of developing tumours
- can be removed without any long lasting side effects ffecfs
114
Arguments against adult stem cells
- difficult to obtain painful to extract
- are multi potent limited capacity to differentiate into different cell types
