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Biology HL 11 > Cell Membranes > Flashcards

Cell Membranes Flashcards

Unit 1, Cell Biology

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1
Q

What are lipids?

A

They are a class of biomolecule that contain glycerol and chains called fatty acids.

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2
Q

What are phospholipids

A

They are a type of lipid molecule that have two fatty acid chains, hydrocarbon tails and a glycerol molecule, phosphate head

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3
Q

Difference between fatty acid end and phosphate head?

A

Phosphate head is hydrophilic, and fatty acid tail is non polar, hydrophobic.

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4
Q

What does amphipathic mean?

A

Having two different affinities, polar end that is attracted to water and a nonpolar end that is repelled by it.

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5
Q

Why is cell membrane a bilayer?

A

They occur in bilayers becuase of the amphipathic property, and the fact that water is present in both inside and out of a cell

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6
Q

What are fatty acids?

A

Fatty acids tails are long chains that are mostly made up of hydrogen and carbon, called hydrocarbon

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7
Q

What are phosphate groups (heads) made of?

A

They consists of phosphorus molecule with four oxygen molecules

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8
Q

What to make note when sketching phospholipid structures?

A
  • Two fatty acids (Saturated and unsaturated tails)
  • Phosphate group (head)
  • Connected via glycerol
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9
Q

What are biological membranes composed of?

A

They are composed of a bilayer of phospholipids and other amphipathic molecules

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10
Q

Advantages of biological membrane’s structure?

A

They allow the control of internal conditions within the cell and the maintenance of homeostasis

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11
Q

What are two key features of cell membranes?

A
  1. Semi-permeability, only certain materials are able to freely cross the cell membrane
  2. Selectivity, the cell can control the passage of any material that can’t freely cross the membrane.
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12
Q

Define Permeability

A

Ability of a molecule to pass through a membrane

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13
Q

What affects the rate of diffusion across a membrane?

A

Size and charge

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14
Q

What molecules are allowed in and what are not allowed across a membrane

A
  1. Hydrophobic molecules are allowed in (i.e o2, Co2)
  2. Small, uncharged polar molecules are allowed in (i.e h20)
  3. Large, uncharged polar molecules are not allowed in (i.e glucose, sucrose)
  4. Ions are not allowed in (i.e Cl, K, Na)
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15
Q

What does bilayer’s create?

A

They creat a barrier between the inside and outside of a cell

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16
Q

What are integral proteins?

A

They are hydrophobic proteins, permanently embedded within a membrane

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17
Q

What are peripheral proteins?

A

Hydrophilic, not embedded and are mostly attached to integral protein. Attached to either the inside or outside surface

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18
Q

What are glycoprotein?

A

They are proteins with an attached carbonhydrate

19
Q

Difference between non polar amino acids (hydrophobic) and polar amino acids (hydrophilic)?

A

Non polar amino acids will associate with the lipid bilayer, while polar amino acids will face the aqueous solutions.

20
Q

Functions of protein channel?

A

The inner surface will be lined with polar amino acids to allow the passing of specific polar and charged molecules

21
Q

Where are glycoprotein found?

A

They are found in cell membranes with the protein part embedded and the carb part extending into extracellular environment

22
Q

What are glycolipids?

A

They are carbonhydrates, linked to lipids, the lipid part fitting into the bilayer

23
Q

What are the roles of glycoprotein and glycolipid?

A

They both have roles in cell recognition
ex) Helps immune ssytem distinguish cellst hat belong and those that don’t

24
Q

What does glycoproteins and glycolipids form?

A

They form a carb rich layer on the outer surface of animal cells with aqueous solution in between the carbs.

25
Q

What are glycocalyx?

A

carb rich layer formed by glycoproteins and glycolipids. The glycocalyx of near cells can sometimes fuse, binding the cells together

26
Q

What are functions of membrane proteins? (TRACIE)

A

T - Transport, channels and pumps
R - Receptors, i.e connections for hormones
A - Anchorage, attach to extracellular matrix or cytoskeleton
C - Cell recognition, ie. immune system
I - Intercelluar joinings
E - Enzyme activity

27
Q

What are the tails of the cell membrane made of?

A

They are made of a molecule called a fatty acid

28
Q

What are the two types of fatty acids?

A
  1. Saturated fatty acids, they have hydrocarbon chains connected by single bonds only
  2. Unsaturated fatty acids, have on or more double bonds, causing the molecule to bend.
29
Q

Function of saturated fatty acids?

A

They pack tightly, giving high density and reducing fluidity/flexibility of the membrane and its permeability.

30
Q

What do fatty acids need to maintain?

A

They need to maintain a balance of being fluid and permeable but maintain integrity/strength (Determined greatly by temperature of the environment)

31
Q

Characteristics of cholesterol

A

They are a steroid and is hydrophobic, attracted to phospholipid tails in the middle

32
Q

Characteristics of hydroxyl cholestrol group

A

One end with a hydroxyl (-OH) group, hydrophilic and is attracted to the phosphate heads.

33
Q

What are the roles of cholesterol?

A

They help maintain the balance needed in the membrane properties, stabilizes the membrane at high temperature and prevents it from solidifying/stiffening at low temperatures.

34
Q

Define cell adhesion

A

It is the binding of outside of a cell to another cell or a cell

35
Q

What is a CAM-cell adhesion molecule?

A

Typically a protein with a part embedded in the plasma membrane and a protruding (sticking out) part.

36
Q

Necessary parts needed to be labelled in fluid mosaic model of membrane structure

A
  1. Periperal proteins
  2. Integral proteins
  3. Glycoproteins
  4. Phospholipids (Including hydrophobic and hydrophilic regions)
  5. Cholesterol
37
Q

Youtube Videooo (So much better than teachers)

A

https://www.youtube.com/watch?v=qBCVVszQQNs

38
Q

Define receptor?

A

A receptor that binds to chemical messengers such as hormones sent by other cells

39
Q

Define Enzyme

A

An enzyme that breaks down a chemical messenger and terminates its effect

40
Q

Define Ion Channel

A

A channel protein that is constantly open and allows ions to pass into adn out of the cell

41
Q

Define Gated Ion Channel

A

A gated channel that opens and closes to allow ions through only at certain times

42
Q

Define cell-identity marker

A

A glycoprotein acting as a cell-identity marker distinguishing the body’s own cells from foreign cells

43
Q

Defein Cell-Adhesion Molecule (CAM)

A

A cell-adhesion molecule that binds one cell to another

Biology HL 11 (13 decks)

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