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Biology PMT > 1.1 Cell Biology > Flashcards

1.1 Cell Biology Flashcards

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1
Q

What are the two types of cells?

A

Prokaryotic (Bacteria) & Eukaryotic (Plant and animals)

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2
Q

What are the differences between eukaryotic and prokaryotic cells?

A

Prokaryotic cells are much smaller that eukaryotic cells.

Eukaryotic cells contain membrane bound-organelles and a nucleus containing genetic material, while prokaryotes do not.

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3
Q

What is the prokaryotic cell composed of?

A

Peptidoglycan

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4
Q

How is genetic information stored in a prokaryotic cells?

A

Found Free withing the cytoplasm as:
- Chromosomal DNA
- Plasmid DNA

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5
Q

What are plasmids?

A

Small, circular loops of DNA found free in the cytoplasm and separate from the main DNA

Carry genes that provide genetic advantages e.g antibiotic resistance

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6
Q

What is the order of magnitude?

A

A power to the base 10 used to quantify and compare size

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7
Q

What is a centimetre (cm)

A

1 x 10(-2)

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8
Q

What is a millimetre (mm)

A

1 x 10(-3) metres

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9
Q

What is a micrometre

A

1 x 10 (-6)

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10
Q

What is a nanometre (nm)?

A

1 x 10(-9)

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11
Q

List the components of bath plant and animal cells? (5)

A
  • Nucleus
    -Cytoplasm
  • Cell Membrane
  • Mitochondria
  • Ribosomes
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12
Q

List the additional cell components found in plant cells (£)

A
  • Chloroplasts
  • Permanent Vacuole
  • Cell Wall
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13
Q

Other than storing genetic information, what is the function of the nucleus?

A

Controls cellular activities

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14
Q

Describe the structure of the cytoplasm?

A
  • Fluid Component of the cell
  • Contains organelles, enzymes and dissolved ion and nutrients
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15
Q

What is the function of the cytoplasm?

A

Site of the cellular reactions e.g first stage of respiration.

Transport Medium

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16
Q

What is the function of the cell membrane?

A

Controls the entry and exit of materials into and out of the cell.

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17
Q

What is the function of mitochondria?

A

Site of later stages of aerobic respiration in which ATP is produced.

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18
Q

What is the function of the ribosomes?

A

Joins amino acids in a specific order during translation for the synthesis of proteins.

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19
Q

What is the plant cell wall made of?

A

Cellulose

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20
Q

What is the function of the plant cell wall?

A
  • Provides Strength
  • Prevents the cell bursting when water enter by osmosis
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21
Q

What does the permanent vacuole contain?

A

Cell sap (A solution of salts, sugars and organic acids).

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22
Q

What is the function of the permanent vacuole?

A

Supports the cell, maintaining it turgidity.

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23
Q

What is the function of chloroplasts

A

Site of photosynthesis.

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24
Q

Describe how sperm cells in animals are adapted to their function

A
  • Haploid Nucleus: Contains genetic information.
  • Tail: Enables movements
  • Mitochondria: provides energy for tail movement
  • Acrosome: Contains enzymes that digest the egg cell membrane
25
Q

Describe how nerve cells in animals are adapted to the their function

A
  • Long Axon: allows electrical impulses to be transmitted all over the body from the central nervous system.
  • Dendrites from the cell body connects to and receive impulses from other nerve cells, muscles and glands
  • Myelin Sheath insulates the axon and speeds up the transmission of impulses along the nerve cell.
26
Q

Describe how muscle cells are adapted to their function.

A
  • Arrangement of protein filaments: Allows them to slide over each other produce muscle contraction.
  • Mitochondria: to provide energy for muscle contraction
  • Merged cells in skeletal muscle: Allow muscle fibre contraction in unison
27
Q

Describe how root hair cells are adapted to their function

A
  • Large surface area to absorb nutrients and water from surrounding soil
  • Thin walls: That do not restrict water absorption
28
Q

Describe how xylem cells in plants are adapted to their function.

A
  • No upper or lower margins between cells: to provide a continuous route for water flow
  • Thick, woody side walls: Strengthen their structure and prevent collapse
29
Q

Describe how phloem cells in plants are adapted to their function

A
  • Sieve plates: let dissolved amino acids and sugars be transported up and down the stem.
  • Companion Cells: provide energy needed for active transport or substances along the phloem
30
Q

What is cell differentiation?

A

The process by which cells become specialised.

31
Q

Why is cell differentiation important?

A

Allows production of different tissues and organs that perform various vital function in the human body.

32
Q

At what point in their life cycle do most animal cells differentiate?

A

Early in their life cycle

33
Q

For how long do plant cells retain the ability to differentiate?

A

Throughout their life cycle

34
Q

What is the purpose of cell division in mature animals?

A

Repair and replacement of cells?

35
Q

What changes does a cell go through as it differentiates?

A

Becomes specialised through acquisition of different sub-cellular structures to enable a specific function to be performed by the cell.

36
Q

Define magnification

A

The number of times bigger an image appears compared to the size of the real object.

37
Q

Define resolution

A

The smallest distance between two objects that can be distinguished

38
Q

How does a light microscope work?

A

Passes a beam of light through a specimen which travels through the eyepiece lens, allowing the specimen to be observed

39
Q

What are the advantages of light microscopes?

A

-Inexpensive
-Easy to use
-Portable
-Observe both dead and living specimens

40
Q

What is the disadvantages of light microscopes?

A

Limited Resolution

41
Q

How does an electron microscope work?

A

It uses a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image.

42
Q

Name the two types of electron microscope

A

Transmission electron microscope (TEM)

Scanning electron microscope (SEM)

43
Q

What is the advantage of electron microscopes?

A

Greater magnification and resolution.

44
Q

Why do electron microscopes have a greater magnification and resolution?

A

They use a beam of electrons which has a shorter wavelength than photons of light.

45
Q

How have electron microscopes enabled scientists to develop their understanding of cells?

A
  • Allow small sub-cellular structures (e.g. mitochondria, ribosomes) to be observed in detail.
  • Enable Scientists to develop more accurate explanations about how cell structures relates to function.
46
Q

What are the disadvantages of electron microscopes?

A
  • Expensive
  • Large so less portable
  • Require training to use
  • Only dead specimens can be observed
47
Q

How can magnification of an image be calculated?

A

magnification = size of image / size of real object

48
Q

How do bacteria multiply?

A

Binary Fission (Simple cell division)

49
Q

How often do bacteria multiply?

A

Once every 20 minutes if enough nutrients are available and the temperature is suitable

50
Q

What nutrients make up a nutrient broth solution?

A

All nutrients required for bacteria to grow including nitrogen for protein synthesis, carbohydrates for energy and other minerals

51
Q

Describe the preparation of an uncontaminated culture using aseptic technique

A
  1. Use pre-sterilised plastic petri dishes or or sterilise glass Petri dishes and agar gel before using with an autoclave.
  2. Pour the sterile agar gel into the petri dish and allow time to set.
  3. Sterilise the inoculating loop by passing it through a Bunsen burner flame.
  4. Dip the inoculating loop into the solution of microorganisms and make streaks with the loop on the surface of the agar
  5. Put the lid on the Petri dish and secure it with tape. Label accordingly then turn and store upside down.
  6. Incubate the culture at 25’C in school laboratories.
52
Q

Why must petri dishes and culture media before sterilised before use?

A

To Kill any bacteria already present.

53
Q

Why must inoculating loops be sterilised by passing them through Bunsen burner flame?

A

To kill any bacteria present on the inoculating loop.

54
Q

Why must the petri dish lid be secured with adhesive tape and the whole dish stored upside down?

A

Stops the bacteria in the air contaminating the culture.

The lid is not fully sealed to prevent the growth of anaerobic bacteria in a lack of oxygen.

Upside down to prevent condensation from forming and dripping down onto the colonies

55
Q

Why are cultures incubated at 25’C in school laboratories?

A

Harmful pathogens are less likely to grow at this temperature

56
Q

What is the formula used to calculate cross - sectional area of a bacterial colony or clear area around a bacterial colony?

A

πr(2)

= 3.14

r = radius (diameter/2)

57
Q

How is the number of bacteria in a population after a certain time calculated from the mean division time?

A
  1. Calculate the number of times the bacteria will divide in the given time period from the mean division time.
  2. Use the following equation to calculate the number of bacteria.

Number of bacteria in population at end of time period = number of bacteria at the beginning of the time period x 2

Express the answer in standard form if possible.

58
Q

Calculate the number of bacteria that will be present after 3hrs for a population that divides every 15 minutes and has 5 bacterium present now.

A

15 minutes = 0.25 Hours

3/0.25 hours = 12 divisions

5 x 12^12) = 20480 or 2.048 x 10^4

Biology PMT (24 decks)

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