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Biology > Cells as a Basis of Life > Flashcards

Cells as a Basis of Life Flashcards

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1
Q

Give examples of prokaryotic and eukaryotic cells.

A

Prokaryotic: bacteria
Eukaryotic: fungi, animal and plant cells (everything else)

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2
Q

What are the similarities of Eukaryotic and Prokaryotic cells?

A

They both have a cell membrane, cytoplasm, genetic material and a mitochondria.

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3
Q

What are the differences between eukaryotic and prokaryotic cells?

A

Eukaryotic:

  • Has a nucleus and an enclosed membrane (cell wall and membrane) organelles
  • Multicellular

Prokaryotic

  • without an enclosed membrane organelles
  • Unicellular
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4
Q

What is the structure and function of a cell wall?

A

It is a non-living cellulose structure outside the plasma membrane. It provides support, prevents cell expansion, and allows water and dissolved substances to pass freely through.

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5
Q

What is the function of the Centrioles?

A

They are involved in the separation of chromosomes during cell division in animal cells and protists.

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6
Q

What is the structure and function of the Chloroplast?

A

It stores a green pigment called the chloroplast. The chloroplasts convert sunlight into chemical energy (photosynthesis)

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7
Q

What is the function of the Cytoplasm?

A

It contains all organelles except the nucleus. It acts as a storage for substances.

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8
Q

What is the function of Cytoskeleton?

A

It determines cell shape, participating in cell division, growth and differentiation and allowing cells to move. It also provides a track-like system that directs the movement of organelles and other substances within cells.

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9
Q

What is the structure and function of the Endoplasmic Reticulum (ER)?

A

A continuous 3-D membrane system that permeates the entire cytosol. It helps process molecules created by the cell - protein synthesis. It transports these molecules to their specific destinations either inside or outside the cell.

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10
Q

What is the function of the Golgi Apparatus?

A

Packages molecules processed by the endoplasmic reticulum to be transported out of the cell.

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11
Q

What is the function of the Lysosomes?

A

It is the recycling centre of the cell. they digest foreign bacteria that invade the cell, rid the cell of toxic substances, and recycle worn-out cell components.

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12
Q

What is the function of the Mitochondria?

A

It converts energy from food into a form that the cell can use - cellular respiration.

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13
Q

What is the function of the Nucleus?

A

It is the cell’s command centre, sending directions to the cell to grow, mature, divide or die. It also houses DNA.

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14
Q

What is the function of the Plasma Membrane?

A

It separates the cell from its environment and allows materials to enter and leave the cell.

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15
Q

What is the function of the Ribosomes?

A

It processes the cell’s genetic instructions to create proteins.

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16
Q

What is the structure and function of Tonoplast?

A

It is the vacuole membrane in plant cells. It regulates the movement of substances into the vacuole.

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17
Q

What is the structure and function of the Vacuole?

A

It is surrounded by a single membrane (tonoplast), it may take up most of the cell volume. It stores nutrients and other.

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18
Q

What are some advantages and disadvantages of a light microscope?

A

Advantages: The staining allows us to be able to differentiate the different parts of the specimen.
Disadvantages: in the process of staining, it kills the organism. You can’t see past 200nm clearly.

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19
Q

What is a Phospholipid?

A

It is an amphipathic molecule meaning that it has both a hydrophilic region and a hydrophobic region.

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20
Q

What does the Proteins and Phospholipids help with?

A

To control the exchange of materials between the external and internal environments.

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21
Q

What does Cholesterol help with the cell?

A

It enables the membrane to be flexible and repairable. This allows cells to grow and change shape.

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22
Q

Where are proteins found in the cell?

A

Lipid biayer.

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23
Q

Define the words “hydrophobic” and “hydrophilic” as they relate to the parts of a phospholipid molecule.

A

Hydrophobic in relation to the head of a phospholipid molecule means that it is unable to dissolve in water. Hydrophilic in relation to the phospholipid molecule means that it is able to absorb or dissolve in water. Therefore this is why the head is on the outside and the tail on the inside of the cell membrane.

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24
Q

What materials or substances are needed by cells?

A
  • Gases (Oxygen and Carbon Dioxide)
  • Nutrients (sugars, amino acids. glycerol and fatty acids)
  • Water (the main solvent)
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25
Q

What substances must leave a cell?

A
  • Wastes (urea, uric acid and excess Carbon Dioxide)
  • Mucous coatings
  • Hormones
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26
Q

Define the term Selectively Permeable cell membrane?

A

Its ability to differentiate between different types of molecules, only allowing some molecules through while blocking others.
It is found in the cell membrane of animal cells.

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27
Q

What determines the permeability of a cell membrane?

A
  • Size
  • Electrical charge
  • Lipid solubility
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28
Q

When do cells have to really rely on carrier proteins?

A

When the molecules that are trying to cross the membrane and into the cell have low permeability.

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29
Q

Define Passive movement?

A

The movement of materials across a cell membrane, down a concentration gradient without the need for energy.

30
Q

Define Diffusion?

A

The net movement of any molecules from a region of high concentration to a region of low concentration of that substance, until equilibrium, is reached.

31
Q

What does it mean when molecules move down the concentration gradient?

A

Require no energy input. (Passive movement)

32
Q

Define Osmosis?

A

The movement of a solvent from an area where it is highly concentrated to an area of lower concentration through a semipermeable membrane.

33
Q

Define an Isotonic solution.

A

A solution that has the same concentration of solutes on both sides of a membrane.

34
Q

Define a Hypotonic solution on the outside of the cell?

A

A solution that has a lower concentration of solutes outside the membrane than inside the membrane. This causes water to move into the membrane.

35
Q

Define a Hypertonic solution on the outside of the cell?

A

A solution that has a high concentration of solutes outside the membrane than inside the membrane. This causes water to move out of the membrane.

36
Q

What can happen to a Hypotonic solution in a cell?

A

The cell can become Ruptured.

37
Q

What can happen in a Hypertonic solution

A

The cell can become shrivelled.

38
Q

How does temperature affect the rate of diffusion?

A

It increases the rate of diffusion which increases the average kinetic energy of the particles.

39
Q

How does the concentration gradient affect the rate of diffusion?

A

The higher the gradient the faster the rate of diffusion to enable equilibration with the cell and its environment making it isotonic.

40
Q

How does particle size affect the rate of diffusion?

A

The smaller the particle size, the faster the rate of diffusion due to the higher surface area to volume ratio.

41
Q

How does the distance to travel affect the rate of diffusion?

A

The thinner the membrane, the faster the rate of diffusion.

42
Q

How does the surface area affect the rate of diffusion?

A

The greater the surface area the faster the rate of diffusion.

43
Q

What is the name for the pressure created by water moving across a semipermeable membrane?

A

Osmotic pressure.

44
Q

The more water that moves across into the membrane…

A

The higher the osmotic pressure created.

45
Q

Cells in most animals are not directly exposed to the external environment and are bathed in isotonic extracellular fluid. What does this mean for the cell.

A

This means that the cell can function efficiently because water is diffused equally in both directions, resulting in no net movement of water into or out of the cell.

46
Q

What is meant by Turgid?

A

When the cell membrane of a plant cell is pushed by the vacuole to the cell wall due to osmosis.

47
Q

What is meant by Plasmolysis?

A

When the cell membrane of a plant cell is moved away from the cell wall due to the vacuole shrinking from osmosis.

48
Q

Define active transport?

A

The movement of molecules from a region low concentration to a region of high concentration, and requires the input of energy. (This movement is against the concentration gradient)

49
Q

What does a carrier protein do in a cell?

A

To actively move chemicals from a low to a high concentration, using cellular energy.

50
Q

Define endocytosis.

A

When a large particle has to be moved into a cell, the cell membrane can change its shape to surround the particle and engulf it.

51
Q

What is phagocytosis?

A

When a solid particle is engulfed.

52
Q

Define exocytosis?

A

The process by which these substances are transported to the external environment of the cell.

53
Q

What are some factors that affect the exchange of materials across a membrane?

A
  • Chemical factors
  • Physical factors
  • Concentration gradient
  • Surface area to volume ratio
54
Q

How can physical factors (of the substance) affect the exchange of materials across a membrane?

A

Small molecules are able to diffuse easily between the phospholipids. Although, large molecules use carrier proteins to move through the cell membrane. Very large molecules that need to be transported into or out of the cell are moved by the process of endocytosis or exocytosis.

55
Q

How can concentration gradient affect the exchange of materials across a membrane?

A

If the concentration gradient is high (that is, there is a large difference between the concentrations on either side on the membrane), then the substance will diffuse rapidly. As the concentration gradient decreases, the rate of diffusion will be slower.

56
Q

How can surface area to volume affect the exchange of materials across a membrane?

A

A smaller size cell (higher surface area to volume ratio) allows a faster movement of substances between the centre and the surface of the cell (into and out of the cell).

57
Q

Why are enzymes so important?

A

Enzymes are protein molecules that catalyse specific reactions. They control all metabolic reactions in living cells. They do this by reducing the activation energy of the reaction.

58
Q

Define metabolism.

A

The sum of all chemical reactions occurring within a living organisms.

59
Q

Define Anabolic reactions.

A

Involves building up large molecules from smaller ones.

60
Q

Define Catabolic reactions.

A

Involve breaking down larger molecules into smaller parts.

61
Q

What are the reactants also known as?

A

Substrate.

62
Q

What is it called when an enzyme binds to a substrate?

A

Enzyme-substrate complex.

63
Q

Sometimes enzymes need assistance from other molecules to function correctly, such as…

A

Coenzymes, vitamins, cofactors or minerals

64
Q

Define the 2 models of enzyme activity and explain what the model states.

A

The Lock and key model: The substrate is specific to its enzyme. It will only react if the substrate matches its active site, like a lock and key works.

The Induced-Fit Model: The substrate determines the final shape of the enzyme-substrate complex. The active site is more flexible and aligns with the substrate to fit more tightly around it.

(the substrate goes “into” the enzyme)

65
Q

What are the factors that affect enzyme activity?

A

Temperature, pH and Substrate Concentration.

66
Q

How does Substrate concentration affect enzyme activity?

A

The higher the substrate concentration, the greater the rate of enzyme reaction, until all available enzymes are being used to catalyse reactions (reaching saturation point).

67
Q

What are the 2 major biochemical processes that cells carry out?

A

Photosynthesis and Cellular Respiration.

68
Q

How does ATP help with cell function?

A

ATP provides energy to all cell functions.

69
Q

Define anaerobic cellular respiration.

A

Anaerobic respiration is a type of respiration where oxygen is not used.

70
Q

Define Aerobic cellular respiration.

A

A chain of many biochemical reactions that occur in the cells of the organism in the presence of oxygen.

Biology (1 decks)

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