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Biology 3.1 > 3.1.3: Cells and Movement in and out of them > Flashcards

3.1.3: Cells and Movement in and out of them Flashcards

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0
Q

What is the appearance of the object viewed under a microscope called?

A

The image.

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1
Q

What is the material beneath the microscope called?

A

Object.

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2
Q

What is the magnification of an object?

A

How many times bigger the image is compared to the object.

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3
Q

What is the formula for magnification?

A

Magnification: size of image/ size of object

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4
Q

Unit table:

A 
Unit: Symbol: Equivalent in metres 
Kilometre: km: 10^3
Metre: m: 1
Millimetre: mm: 10^-3
Micrometre: um: 10^-6
Nanometre: nm: 10^-9
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5
Q

What is the resolution/ resolving power?

A

The minimum distance apart that two objects can be in order for them to appear as separate items under a microscope.
Greater resolution means greater clarity.

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6
Q

What is cell fractionation?

A

The process where cells are broken up and the different organelles they contain are separated out.

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7
Q

What needs to be done before cell fractionation can begin and why?

A

Tissue is placed in a cold, isotonic, buffered solution:
Cold- reduce enzyme activity which would break down the organelle.
Isotonic- prevent organelles from bursting or shrinking as a result of osmotic gain or water loss. Isotonic solution has same wp as original tissue.
Buffered- to maintain constant pH.

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8
Q

What are the stages to cell fractionation?

A

Homogenation

Ultracentrifugation

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9
Q

What is homogenation?

A

Cells are broken up by a homogeniser releasing organelles from the cell. Resultant fluid is the homogenate, which is filtered to remove any large pieces of debris and complete cells.

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10
Q

What is ultracentrifugation?

A

Fragments in homogenate are separated in a machine called the ultracentrifuge. Steps:

1) tube of filtrate is placed in machine and spun at low speed.
2) heaviest organelle(nuclei) sinks to bottom forming a thin sediment/pellet.
3) fluid at the top (supernatent) is removed, leaving sediment of nuclei.
4) supernatent transferred to another tube and spun at a faster speed.
5) process continues till each organelle is separate.

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11
Q

From lowest speed to highest speed, which organelle is released first from cell fractionation?

A

Nuclei
Mitochondria
Lysosomes
Ribosomes

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12
Q

What is a light microscope?

A

Long wavelength of light rays so poor resolution, can only distinguish two objects 0.2um or further apart. Colour can be seen, mobile, cheap, living tissue can be estimated.

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13
Q

What is an electron microscope?

A

Beams of electrons with shorter wavelengths. Can distinguish two objects as close as 0.1nm. Higher resolving power. Beam can be focused using electromagnets as electrons are negatively charged. Image has to be formed on a fluorescent screen.

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14
Q

TEM and SEM are both types of…?

A

Electron microscopes.

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15
Q

What are the disadvantages of the TEM?

A

1) whole system must be in a vacuum so live specimens cannot be observed.
2) image is produced in black and white.
3) specimen must be extremely thin to allow electrons to penetrate.
4) flat 2D image is created.

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16
Q

Epithelial cells are…?

A

Eukaryotic cells- cell which has a membrane bound nucleus and chromosomes.

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17
Q

What is the function of epithelial cells?

A

To absorb and secrete.

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18
Q

What does the nucleus do?

A

1) Contains hereditary material in the form of DNA or chromosomes.
2) Control centre of the cell through production of mRNA and hence protein synthesis.
3) Manufactures ribosomal RNA and ribosomes.

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19
Q

NUCLEUS: What is the nuclear envelope?

A

Double membranes surrounding nucleus. Controls entry and exit of materials in and out of the nucleus and contains reactions taking place within it.

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20
Q

NUCLEUS: What are nuclear pores?

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A

Allow passage of large molecules EG. Messenger RNA.

21
Q

NUCLEUS: What is the nucleoplasm?

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A

Jelly like material making up bulk of nucleus.

22
Q

NUCLEUS: What is chromatin?

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A

DNA found within the nucleoplasm.

23
Q

NUCLEUS: What is the nucleolus?

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A

Manufactures ribosomal RNA and assembles ribosomes.

24
What is the role of the mitochondrion?
Sites of respiration. Produce energy carrier molecule ATP from carbohydrates.
25
MITOCHONDRIA: What is a double membrane?
Surrounds organelle, outer one controls entry and exit of material, nine one is folded to form extensions "cristae"
26
MITOCHONDRIA: What is cristae?
Extensions of the inner membrane, provide large surface area for the attachment of enzymes involved in respiration.
27
MITOCHONDRIA: What is the matrix?
Material containing protein, lipids, traces of DNA allowing mitochondria to control production of their own proteins.
28
What is the rough endoplasmic reticulum? (RER)
Sheets of membrane with ribosomes present on the outer surface of the membrane. Function: 1) provide large surface area for synthesis of proteins and glycoproteins. 2) provide a pathway for the transport of material.
29
What is the smooth endoplasmic reticulum? (SER)
Sheets of membrane. Functions: 1) synthesise, store and transport lipids 2) synthesise, store and transport carbohydrates.
30
What is the Golgi apparatus?
Receives substances from ER and then: - adds carbohydrates to proteins forming glycoproteins - produce secretory enzymes - transport (in vesicles), modify and store lipids - form lysosomes
31
What is a lysosomes?
Breaks down material ingested by phagocytic cells | Complete breakdown of cells after they have died (autolysis)
32
What are ribosomes?
80s type- eukaryotic cells 70s- prokaryotic cells Important for proteinsynthsis.
33
What is the microvilli?
Finger like projections of the epithelial cell which increase surface area to allow more efficient absorption.
34
What characteristic do lipids have?
Contain carbon, hydrogen and oxygen | Insoluble in water
35
What is the role of lipids?
In plasma membranes- make it flexible 1) an energy source 2) waterproofing (as they are insoluble) 3) insulation 4) protection
36
Triglycerides have...?
1 glycerine 3 fatty acids EACH FATTY ACID FORMS A BON WITH GLYCEROL IN A CONDENSATION REACTION. HYDROLYSIS OF TRIGLYCERIDE PRODUCED GLYCEROL AND 3 FATTY ACIDS.
37
What is saturated, monounsaturated and polyunsaturated?
If the hydrocarbon chain has no carbon- carbon double bonds, the fatty acid is then SATURATED. If the hydrocarbon chain has 1 carbon-carbon double bond, it is MONO-UNSATURATED. If the hydrocarbon chain has more than 1 carbon-carbon double bond, the fatty acid is POLYUNSATURATED.
38
What is a phospholipid?
2 fatty acids 1 glycerol 1 phosphate group Hydrophilic head- attracted to water but not fat Hydrophobic tail- not attracted to water (repels) but mixes with fat. POLAR molecule
39
What is the test for lipids?
Emulsion test: 1) take a dry and grease-free test tube 2) add 5cm3 of ethanol to the 2cm3 of sample being tested 3) shake test tube to dissolve any lipid in sample 4) add 5cm3 of water and shake 5) cloudy- white indicates there is a lipid AS A CONTROL: repeat procedures using water instead of sample- final solution should be clear.
40
What structure do cells and cell organelles have around them?
Plasma membrane- boundary between cell cytoplasm and the environment. Controls movement of substances in and out of the cell.
41
What molecule forms the plasma membrane?
Phospholipids- bilayer sheet formed. One layer= hydrophilic heads pointing inwards (interacting with water in cell cytoplasm) One layer= hydrophilic head pointing outwards (interacting with water in cell cytoplasm) Hydrophobic rails of both layers point into the centre of the membrane. Function of phospholipids in membrane: Allow lipid soluble substances to enter and leave the cell Prevent water soluble substances entering and leaving the cell Make the membrane flexible
42
What is also embedded into the phospholipid bilayer?
PROTEINS: functions: Structural support, carriers for transporting water soluble substances across membrane, allow active transport by forming ion channels, act as receptors Extrinsic proteins: surface of bilayer or partly embedded in it, give mechanical support Intrinsic proteins: carriers to transport plane
43
Why is the arrangement of cell surface membrane called the fluid mosaic model?
Fluid- phospholipid molecules move relative to one another giving membrane a flexible structure Mosaic- proteins are embedded in the phospholipid bilayer which are different shape, sizes etc
44
What is diffusion?
The net movement of molecules or ions from a region of high concentration to low concentration (down a concentration gradient) - passive transport (does not require metabolic energy)
45
What does passive transport mean?
Energy comes from natural motion of particles rather from an external source. Particles are in motion due to kinetic energy Motion is random Particles collide with one another as well as the walls
46
When particles have diffused completely, it is in a state of...? When particles are just changing positions, it is called...?
Equilibrium. | Particles still move but just change positions, this is called dynamic equilibrium.
47
What affects the rate of molecule and ion diffusion?
Concentration gradient- greater the concentration on one side of an exchange surface, the faster the diffusion. Area over which diffusion takes place- larger the area of an exchange surface, faster the diffusion. Thickness of exchange surface- thinner an exchange surface, the faster the rate of diffusion.
48
What is the equation of diffusion?
Surface area x Difference in concentration/ Length of diffusion path
49
What is facilitated diffusion?
Passive process, relies on kinetic energy of molecules. Down a concentration gradient (higher to lower).

Biology 3.1 (3 decks)

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