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IB BIOLOGY > Cells > Flashcards

Cells Flashcards

1
Q

What does the permeability of the membrane depend on

A

the nature of the molecule (polar , non polar)
size

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2
Q

What can polar molecules easily form

A

hydrogen bonds

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3
Q

What are polar molecules often called

A

hydrophilic

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4
Q

What are hydrophobic molecules

A

non- polar molecules that are unable to form hydrogen bonds

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5
Q

What molecules are lipids

A

hydrophobic

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6
Q

What three things do membranes consist of

A

lipids
proteins
glycolipids / glycoproteins

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7
Q

What does amphipathic mean

A

molecules with both hydrophobic and hydrophilic regions

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8
Q

what are the three major classes of lipids

A

phospholipids
glycolipids
sterols

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9
Q

what phospholipids are the most abundant

A

membrane

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10
Q

What does a phospholipids backbone composed mostly of

A

glycerol and a three carbon alcohol

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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

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12
Q

What are the two fatty acids

A

unsaturated
saturate

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13
Q

what do the unsaturated fatty acids result in

A

kinks

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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)

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15
Q

Why can’t uncharged polar molecules like glucose pass through

A

they are hydrophilic

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16
Q

What can pass through the bilayer

A

small uncharged non polar lipid soluble molecules

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17
Q

example of large uncharged polar molecules that will be mostly impermeable to the bilayer

A

glucose
sucrose

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18
Q

Examples of small uncharged polar molecules that will be mostly permeable to the bilayer

A

water
urea
ethanol
glycerol

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19
Q

Examples of non polar lipid
molecules that will be permeable

A

Oxygen , Co2 , N2 , steroids

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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)

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21
Q

Where does carbon dioxide diffuse from in tissues

A

from cells (conc higher) to blood (conc is lower)

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22
Q

Where does the carbon dioxide diffuse from in the LUNGS

A

from the blood to the alveoli

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23
Q

What is a transmembrane protein

A

A protein that transfers molecules across the membrane

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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

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25
Q

What are the two types of membrane proteins

A

integral
peripheral

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26
Q

What are integral proteins

A

embedded in the lips bilayer
difficult to isolate
amphipathic molecules

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27
Q

How are integral proteins embedded into the bilayer

A

The hydrophobic regions of the integral proteins interact with the hydrophobic interior of the lipid bilayer

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28
Q

What are peripheral proteins

A

•Hydrophilic
• found on the surface of the membrane
•interact only with the hydrophilic regions of the integral proteins

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29
Q

List the 4 functions of membrane (TRRE)proteins

A
  • Transport
  • Recognition
  • Receptors
  • Enzymes
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30
Q

Explain how membrane proteins help transport proteins

A

facilitate the movement of molecules in and out of the cell

channel and carrier proteins

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31
Q

What are channel proteins

A

Transmembrane proteins form channels for the passage of molecules

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32
Q

What are Carrier proteins

A

Undergo a conformational change to transfer the molecules from one side of the membrane to the other

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33
Q

Explain how membrane proteins help recognition

A

help in cell-cell recognition

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34
Q

Explain how membrane proteins act as receptors

A

for chemical signals and are burning sites for molecules like hormones and neurotransmitters

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35
Q

Explain how membrane proteins act as enzymes

A

catalyse reactions

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36
Q

Define osmosis

A

The diffusion of water across a selectively permeable membrane from lower to higher solute concentrations

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37
Q

How does water move in osmosis

A

From a region of lower water concentration to a region of higher water concentration

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38
Q

What are the factors that make facilitated diffusion

A

• molecules move down the conc gradient
• the movement is facilitated by transport proteins

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39
Q

What are channel proteins

A

transmembrane proteins that assemble to form channels for the passage of polar molecules

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40
Q

What is the selectivity of the ion channels due to

A

• the binding sites of hydrophilic amino acid side chains lining the channel

• the size of the pore

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41
Q

What are some reasons the channels open or close:

A
  • changes in voltage across a membrane
  • binding of small molecules to the channel proteins
  • mechanical forces
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42
Q

What are carrier protiens

A

transmembrane transport proteins

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43
Q

What is the mechanism of carrier proteins

A

the carrier protein binds to the solute molecules, it undergoes a conformational change and transfers the molecules to the other side of the membrane

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44
Q

Define Active transport

A

the net movement of particles through a cell membrane from a region of lower conc to a region of higher suing energy

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45
Q

What are 3 things active transport helps to:

A

• takes up essential nutrients
• removes secretory
• maintain the right concentrations of ions in the cells

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46
Q

What are the two types of active transport

A

Indirect
Direct

47
Q

Explain direct active transport

A

The energy released by an exergonic reaction is used to directly transport molecules across the membrane

48
Q

Explain Indirect transport

A

The movement of one solute down its gradient drives the movement of the second solute against its concentration gradient

49
Q

What factors are based on the movement of molecules by simple diffusion

A

• the size of the molecules
• hydrophobic or hydrophilic nature

50
Q

What are the carbohydrates linked to creating what

A

lipids and proteins
forming glycolipids and glycoproteins

51
Q

What forms glycolipids

A

covalent bonding of carbohydrates to lipids

52
Q

What are the two factors of glycolipids

A
  • amphipathic molecules
  • external surface of the cell membrane
53
Q

What are the carbohydrates and lipids like in glycolipids

A

carbs are polar and extend to the extra cellular environment

lipids are non polar and embedded into the bilayer

54
Q

How do glycolipids contribute to membrane stability

A

They form hydrogen bonds with the water molecules surrounding the cell

55
Q

What are the 4 (triple c g) functions of glycolipids and proteins

A

Cell recognition
cell adhesion
cell signalling
glycocalyx

56
Q

Explain cell recognition in glycolipids and glycoproteins

A

They act as markers and help cells of the body recognise eachother.

They help immune systems recognise foreign cells

57
Q

Explain cell adhesion

A

they help cells to attach and bind to other cells to form tissues

58
Q

Explain cell signalling

A

They act as receptors for enzymes

59
Q

What is glycocalyx

A

A sticky layer formed by the carbohydrate groups of the glycolipids and protiens that protrude form the cell surface .

60
Q

Who proposed the fluid mosaic model and what year

A

Singer and Nicholson 1972

61
Q

What does the fluid mosaic describe

A

the arrangement of the lipids and proteins

62
Q

What 2 things does the Fluid Mosaic Model state:

A

• The lipid bilayer is fluid
• The proteins are embedded in the fluid bilayer which resembles a mosaic

63
Q

What is the benefit of the fluid nature of the membrane

A

That most lipids and proteins are able to move laterally , parallel to the membrane surface

64
Q

What are organelles

A

discrete structures in cells adapted to perform specific functions

65
Q

what 5 organelles have no membranes

A

ribosomes
centrioles
microtubules
proteasomes
nucleoli

66
Q

what organelles have a single membrane

A

smooth er
rough er
golgi
vesicles / vacuoles
lysosomes

67
Q

what organelle has a double membrane (5)

A

nuclei
mitochondria
chloroplasts

68
Q

what does compartmentalisations allow

A

it allows the development of specialised cell structures

69
Q

where are membrane bound organelles found

A

eukaryotic

70
Q

what is an advantage of compartmentalisation in cells

A

the cell can separate chemical reactions and other cellular processes, this allows the cell to increase rate of chemical reactions

71
Q

What two factors should you have to be an organelle

A

enclosed by a membrane
have a specific function

72
Q

what is a disadvantage of compartmentalisation

A

it can delay a cells ability to respond to the environment

73
Q

What are the 4 types of stem cell

A

Totipotent
Pluripotent
Multipotent
Unipotent

74
Q

What are the differentiated cells produced in totipotent cells

A

• Can differentiate into any type of cell
• Can give rise to a complete organism

75
Q

What are the differentiated cells produced in pluripotent t cells

A

Can differentiate into all body cells , cannot give rise to a whole organism

76
Q

What are the differentiated cells produced in multipotent cells

A

Can differentiate into a few closely related type of body cell

77
Q

What can unipotent cells differentiate into

A

Can only differentiate into their associated cell type

78
Q

What are the stem cells at the morula stage

A

Totipotent

79
Q

Are stem cells specialised or unspecialised

A

unspecialised

80
Q

What is the morula

A

solid ball of totipotnet cells formed soon after fertilisation

81
Q

What’s the function of the stem cell niche

A

The micro environment in which stem cells reside and receive their instructions

82
Q

What is a micelle

A

formed when phospholipids are shaken with water

83
Q

What are the two main components of animal cell plasma membranes

A

Phospholipids
Cholesterol

84
Q

What makes Cholesterol (lipid) amphipathic

A

• majority hydrophobic
• the hydroxyl group of cholesterol molecule is hydrophilic

85
Q

What does cholesterol help with

A

regulation of membrane fluidity and permeability

86
Q

What happens in the interaction between cholesterol and phospholipids tails (temperature)

A

stabilises the plasma membrane at higher temperatures by stopping the membrane from becoming too fluid

87
Q

What does cholesterol do at cold temperatures

A

increases fluidity of membrane, stopping it crystallising

88
Q

What type of proteins are plasma membrane

A

globular proteins

89
Q

What is cholesterol

A

lipid

90
Q

As a whole what is the job of a transport protein

A

creates hydrophilic channels to allow ions and polar molecules to travel through the membrane

91
Q

What is cell adhesion

A

allows tight junctions to form between cells

92
Q

What organ and organ system do epithelial cells make up

A

Organ: Stomach
Organ system : digestive

93
Q

What organ and organ system do muscle cells make up

A

Organ : bladder
Organ system : Urinary system

94
Q

What organ and organ system do nerve cells make up

A

Organ : Brain
Organ system: CNS

95
Q

What organ and organ system do rod and cone ells make up

A

Organ : Eye
Organ system : Visual system

96
Q

What do structural adaptations include

A

shape of cell
the organelles the cell contains

97
Q

What is a stem cell

A

a cell that can divide by mitosis an unlimited number of times

98
Q

What is potency

A

the ability of stem cells to differentiate into more specialised cell types

99
Q

What are the 4 types of potency

A

Totipotency
Pluripotentcy
Multipotentcy
Uni potency

100
Q

Explain totipotency

A

stem cell that can differentiate into any cell type found in an embryo

101
Q

Explain pluripotentcy

A

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
Q

Explain multipotentcy

A

Adult stem cells that can differentiate into closely related cell types

103
Q

Explain unipotency

A

adult cells that can only differentiate into their own lineage

104
Q

What embryonic stem cell would it be if taken 3-4 days after fertilisation

A

Totipotent

105
Q

What embryonic stem cell would it be if taken 3-4 days after fertilisation

A

Totipotent

106
Q

What embryonic stem cell would it be if taken 3-4 days after fertilisation

A

Totipotent

107
Q

What embryonic stem cell would it be if taken 5days after fertilisation

A

pluripotent

108
Q

What is one treatment of Stargardts disease

A

Injection of retina cells derived from embryonic stem cells into patients eyes

109
Q

Ethics : Arguments for Embryonic stem cells

A

• 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
Q

Arguments against embryonic stem cells

A

• cells have a higher risk of developing tumours
• process involves the creation and destruction of embryos

111
Q

Arguments for cord blood stem cells

A

• can be easily obtained and stored
• fully compatible either tissues of adult - reduce risk of rejection

112
Q

Arguments against Cord blood stem cells

A

• The cells are multipotent and therefore have a limited capacity to differentiate into different cell types

113
Q

Arguments for Adult stem cells

A
  • 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
Q

Arguments against adult stem cells

A
  • difficult to obtain painful to extract
  • are multi potent limited capacity to differentiate into different cell types

IB BIOLOGY (10 decks)

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