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Biology > Chapter 5- Membranes > Flashcards

Chapter 5- Membranes Flashcards

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1
Q

Arrangement + function of phospholipids in CSM?

A
  • forms phospholipid bilayer w hydrophilic heads pointing out + hydrophobic tails pointing in
  • only allows small/ non polar molecules to pass through
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2
Q

Arrangement + function of proteins in CSM?

A
  • proteins form channel proteins + carrier proteins

- for facilitated diffusion + active transport

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3
Q

Arrangement + function of cholesterol in CSM?

A
  • fit between phospholipids

- stabilise membranes + regulate fluidity

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4
Q

Arrangement + function of glycoproteins in CSM?

A
  • stick out from surface of CSM

- receptor sites for chemical signals/ cell signalling

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5
Q

Arrangement + function of glycolipids in CSM?

A
  • stick out from surface of CSM

- antigens used for recognition

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6
Q

Describe effects of high temperature on structure of membrane

A
  • phospholipids have more KE
  • increases size of gaps between phospholipids
  • bilayer becomes fluid
  • glycoproteins denature
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7
Q

Functions of membranes within cells?

A
  • forms vesicles
  • separate contents of organelles from cytoplasm (compartmentalisation)
  • controls what substances enter + leave organelles
  • provides surface for attachment
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8
Q

Describe structure of CSM

A
  • phospholipid bilayer with hydrophilic heads pointing outwards+ hydrophobic tails pointing inwards
  • contains intrinsic + extrinsic proteins
  • glycoproteins + glycolipids stick out of membrane
  • cholesterol molecules between phospholipids
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9
Q

Added alkaline NH3 to sample with acidic cells. No colour change.
What can you conclude about permeability of CM?

A

-not permeable to NH3

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10
Q

State the term to describe a membrane through which some substances can pass freely but others cannot.

A

Partially permeable

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11
Q

The model of cell membrane structure is called?

A

Fluid mosaic model

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12
Q

What molecules does the bilayer allow to diffuse through it?

A
  • oxygen
  • CO2
  • fats
  • fat soluble vitamins
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13
Q

One function of membranes is cell signalling. What is this?

A

Communication between cells

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14
Q

Explain how cell surface membranes contribute to the process of cell signalling

A
  • release of signal molecules by exocytosis
  • glycoproteins acts as receptor
  • receptors are specific
  • shape of receptor + signal are complementary
  • attachment of signal causes change inside cell
  • CSM allows entry of some signal molecules
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15
Q

Describe how vesicles are moved from one organelle to another

A

-move along microfilaments + microtubules using ATP

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16
Q

Suggest how the proteins embedded in CSM of vesicles ensure the vesicle is transported to correct target organelle

A
  • receptor found only on target organelle
  • protein has a specific shape
  • shape of receptor and protein are complementary
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17
Q

Describe how extracellular enzymes are secreted from cells

A
  • exocytosis

- vesicles fuses with CSM releasing enzymes

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18
Q

List 3 components of CSM

A
  • phospholipids
  • cholesterol
  • proteins

Do not say phospholipid bilayer

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19
Q

What is active transport?

A

Mov meant of substances against a conc. gradient using ATP

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20
Q

2 examples of active transport in cells?

A
  • mineral ions into root hair cells

- H+ ions out of companion cells

21
Q

What is the mechanism for a plant cell taking up water?

A

Osmosis

22
Q

What is the mechanism for oxygen entering a RBC?

A

Diffusion

23
Q

What is the mechanism for calcium ions entering a nerve cell down a concentration gradient?

A

Facilitated diffusion

24
Q

Describe the route water molecules take through CSM

A

Through phospholipid bilayer through channel proteins

25
Q

Why plant cells don’t burst when left in pure water?

A

Have cell walls that provide strength and withstand pressure

26
Q

Membranes allow recognition by other cells. Why is this important in relation to the immune system?

A
  • glyclipids allow identification of the cell as own cell so white blood cells don’t attack
  • allows identification of foreign cells via antigens on CSM
27
Q

Functions of membranes?

A
  • cell communication: chemical detection via receptors

- barrier between internal + external environment: maintains the 2 environments

28
Q

Identify organelles w a membrane + state why presence of membranes important in its function

A
  • mitochondria : increases SA for reactions
  • nucleus: protects DNA
  • lysosomes: keeps hydrolysis enzymes separate from cell interior
  • RER: allows ribosomes to attach for protein synthesis
29
Q

Describe structure of membrane using ‘phospholipid bilayer’ + ‘fluid mosaic model’

A
  • membrane is a bilayer of phospholipid molecules
  • phospholipid is a glycerol molecule attached to phosphate group + 2 fatty acids tails
  • arranged so hydrophilic heads point onwards towards interior+ exterior environments of cell
  • hydrophobic tails point inwards
  • membrane surface called mosaic because embedded w proteins
  • called fluid as phospholipids are flexible + move to allow movement of substances across membrane
30
Q

Why is it key that there isn’t too much or too little cholesterol in membrane?

A
  • too much will make membrane too rigid + exchange less efficient
  • too little will make membrane too fluid +break up
31
Q

How the membrane acts as a barrier to water soluble molecules?

A
  • Arrangement of phospholipids makes it difficult for water soluble molecules to pass through
  • Hydrophilic heads face out
  • Hydrophobic tails face in
32
Q

How could temp below 0c affect membrane permeability?

A
  • initially membrane becomes more rigid so permeability decreases
  • proteins could be denatured so increased permeability
  • ice crystals could pierce membrane further increasing permeability
33
Q

What happens to CSM when temp v high?

A
  • proteins denature
  • phospholipid bilayer more fluid
  • membrane more permeable
34
Q

Why stained cells lost colour at high temperatures?

A

-membrane permeable to stain so stain leaked out of cell

35
Q

Functions of glycoproteins (inc. glycolipids)

A
  • act as antigens as allow identification of cells as self
  • cell signalling: receptor binding site for chemical signals
  • attach to water molecules to stabilise membrane
36
Q

What is cell signalling?

A
  • communication between cells

- allows cells to work together

37
Q

how glycoprotein acts as a receptor?

A

-has specific shape complementary to molecule

38
Q

How to improve beetroot experiment?

A
  • pieces blotted after cutting
  • more intermediate temperatures
  • same part of beetroot used
  • same vol of water in water bath
  • all samples same size
39
Q

why no transmission of light after beetroot placed in water at 100c

A

-CSM damaged so pigment leaks out

40
Q

What happens to plant cell when placed in sugar solution?

A
  • water moves out of cell by osmosis
  • cell has higher water potential than surrounding solution
  • water moves down water potential gradient
41
Q

How small/ non polar molecules enter CSM?

A

Diffuse through phospholipid bilayer

42
Q

How polar substances enter CSM?

A

Facilitated diffusion through channel proteins

43
Q

How large substances enter CSM?

A

Though carrier proteins

44
Q

Routes that water molecules take through CSM?

A

-through phospholipid bio aye through aquaporins

45
Q

How student could use graph to get better estimate of water potential?

A
  • plot sucrose conc on x axis
  • % plasmolysed on y axis
  • read down from 50% plasmolysed to sucrose conc and look up equivalent water potential
46
Q

How to make results more results more reliable?

A
  • count more cells
  • identify anomalous results
  • calculate mean
47
Q

How to make results more accurate?

A
  • use more intermediate conc

- take photographs and mark cells as counting

48
Q

Histamines make capillary walls more permeable. What effect does this have in surrounding tissues?

A
  • more tissue fluid formed
  • inflammation
  • larger molecules pass into tissue fluid
49
Q

Roles of Membanes inside cells?

A
  • compartmentalisation
  • site of attachment for enzymes
  • provides selective permeability

Biology (26 decks)

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