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(MY) BIOLOGY SL > Topic 1 - CELL BIOLOGY > Flashcards

Topic 1 - CELL BIOLOGY Flashcards

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1
Q

The cell theory is a fundamental idea of biology.

What are the three principles of cell theory?

+1

A
  1. All organisms are composed of 1+ cells
  2. Cells are the smallest unit of life
  3. All cells come from pre existing cells

The cell contains inherited information (genes) that are used as instructions for growth, functioning and development

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2
Q

What is the method of scientific progress for evidence testing?

A
  1. Observation
  2. Hypothesis
  3. Test
  4. Refute (reject) or corroborate (share results)
  5. If corroborate, then repeat
  6. Theory is produced
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3
Q

Define unicellular organism

Give examples (2)

A

Fully functioning as once cell, and can carry out all basic functions of life

Eg.
Paramecium
Chlorella

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4
Q

What are the 7 functions of life?

MR. GREHN

A

Metabolism - chemical reactions take place in all living organisms eg. Respiration to release energy

Response - reacting to environmental changes

Growth - when enough nutrition is present etc

Reproduction - producing offspring sexually and asexually

Excretion - release of waste materials /chemicals formed inside of the cell

Homeostasis - keeping conditions within tolerable limit

Nutrition - obtaining food to provide energy needed for growth

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5
Q

Features of a LIGHT microscope:

Cost

State of specimen

Magnification

Specimen prep

Appearance of results

A

Light microscopes are:

Inexpensive

Dead or alive specimen are used

Magnification: 2000 x

Prep of specimen is simple

See in colour

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6
Q

Features of a ELECTRON microscope:

Cost

State of specimen

Magnification

Specimen prep

Appearance of results

A

Electron microscopes are:

Expensive

Dead specimen are fixed to a plastic slide

Magnification: 50 000 x

Prep of specimen is complex

See in black and white

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7
Q

What is the difference between these two electron microscopes:

Scanning

Transmission

A

Scanning - takes 3D images, external, colours may be applied, electrons are bounced off the specimen surface

Transmission - 2D, internal, slicing, series of photos in layers (imagine something chopped in half)

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8
Q

What do microscopes do?

A

Magnify an object, NOT improve detail

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9
Q

Define resolution

What is the result of a higher resolution?

A

Ability to distinguish between two points

Higher resolution = more detail

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10
Q

How do you concert from:

m -> mm -> um -> nm

A

m -> mm etc. = x1000

m

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11
Q

How do you calculate magnification?

  I  A      M
A

Magnification = Image size
—————
Actual size

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12
Q

How do you calculate surface area to volume ratio?

A

Surface area
——————
volume

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13
Q

Do smaller things have a smaller /larger sa:v ratio?

What does this allow for?

A

Smaller things have more sa:v ratio

This allows for faster movements and disffusion

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14
Q

How do unicellular eukaryotes reproduce?

A

Asexually, by binary fission

Or sexually (fusion of gametes to produce a zygote)

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15
Q

Maths calculations

Sphere:
Surface area

Volume

A

Sa = 4 x pi x r^2

Volume = 4/3 x pi x r^2

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16
Q

What happens to the sa and volume of an object as it’s width increases

A

As the width increases, both the sa and volume increase

But sa increases at a slower rate than the volume

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17
Q

Define diffusion

Is it less /more efficient in cells with a small sa?

A

The net movement of particles from area of high conc -> area of low conc

Less efficient in cells with small sa relative to their volume

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18
Q

Why is the controlling factor of a cells size?

How do large organisms overcome this?

A

Effectiveness of diffusion is the controlling factor

Large organisms overcome this by being multicellular

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19
Q

Single cells organism:

Give an example

Size

Describe sa:v

Are requirements easily met for transport of substances?

What does the plasma membrane do?

A

Eg. Amoeba

Small

Large sa

Cells requirements met by diffusion /active transport of materials into /out of the cell

Plasma membrane: regulates movements of substances into /out of the cell

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20
Q

Multicellular organism:

Give an example

Size

Describe sa:v

Are requirements easily met for transport of substances?

What specialised features does it have?

A

Eg. Plants and animals

Large

Have a small sa:v ratio

Requirements are not easily met, need specialised systems to transport the materials needed to /from cells and tissues in the body

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21
Q

Embryonic cells:

Type (—potent wise)

Do they retain their potency?

What are they used for?

How are they obtained?

Is it ethical?

Where are they derived from?

A

Pluripotent - can differentiate into any cells of body, not placental though

Yes, they retain their potency through multiple cell divisions

Used in therapeutic cases - regenerative medicine and tissue replacement

Involves the deliberate creation and destruction of embryos

Unethical

Derived from inner mass of blastocysts (50-150 cells)

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22
Q

Adult stem cells:

Type (—potent wise)

What are they used for?

Is it ethical?

Where are they found?

A

Multipotent - can differentiate into limited number of cells, usually related to the tissue of origin

Used to treat diseases such as Leukemia and blood disorders

Fewer ethical issues as no embryo destruction involved

Found in (adult): bone marrow, brain, fat, liver
(children): umbilical coed blood
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23
Q

Define stem cells

A

Undifferentiated cells found in multicellular organisms

Unspecialised and can give rise to many cell types that make up tissues and organs of multicellular organisms

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24
Q

Stem cell categories
Define:

Totipotent (totally)

Pluripotent (plural)

Multipotent

A

Totipotent - differentiate into all cells of an organism

Pluripotent - give rise to any cell of body (not extra embryonic cells eg. Placenta)

Multipotent - give rise to limited cell types related to their tissue of origin

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25
Q

Proteins within a membrane
What is:

Enzymatic action?

A

Enzymatic action - membrane enzymes have many activities incl. catalysing biochemical reactions inside cells
Eg. Kinase

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26
Q

Proteins within a membrane
What is:

Cell adhesion?

A

Cell adhesion - allow cells to stick to eo/ and surroundings (proteins located in cell surfaces)

CAM - Cell Adhesion Molecules

27
Q

Proteins within a membrane
What is:

Pumps for active transport?

A

Pumps and active transport - special proteins embedded in cell membrane for transport.
Eg. Sodium potassium pump (Na+ -> K- ions)

Use ATP chemical energy

Have receptors that bind to specific molecules and transport them across membrane

28
Q

Proteins within a membrane
What is:

Channels for passive transport

A

Channels for passive transport - channel proteins and carrier proteins allow solutes to cross membranes (from tunnel for molecules /ions to cross)

29
Q

Proteins within a membrane
What is:

Cell to cell communication

A

Cell to cell communication - receptors relay signals between cell internal /external environments

Membrane signalling involves proteins shaped into receptors embedded in cell membrane that biophysically connect triggers external environment

30
Q

Proteins within a membrane
What is:

Hormone binding sites?

A

Amino acid derived proteins bind to receptors in a plasma membrane
This activated a protein which activated adenylyl
Converts ATP -> CAMP (2nd messenger mediates cell specific response)

Hormones react w/ receptors to induce changes in metabolism and activity of cell

31
Q

What is a passive process?

Do molecules move up /down the conc gradient?

List 3 examples relating to membrane crossing

A

A process that doesn’t require energy

Molecules move down their conc gradient

  • diffusion
  • osmosis
  • facilitated diffusion
32
Q

What is an active process?

Do molecules move up /down the conc gradient?

List 2 examples relating to membrane crossing

A

A process that uses energy in the form of ATP

Molecules move up OR down the conc gradient

  • active transport
  • bulk transport (eg. Waste /protein particles,, big molecules)
33
Q

Define diffusion (in terms of membrane crossing)

Conc?

A

Substances other than water move between the phospholipid molecules or through proteins that posses channels

High -> low conc

34
Q

Define osmosis (in terms of membrane crossing)

A

Only water moves through the membrane using aquaporins, which are proteins w/ specialised channels for water movement

Water high -> low conc

Across a pp membrane

35
Q

What is facilitated diffusion in terms of membrane crossing?

A

Non channel protein carriers change shape to allow movement of substances other than eager

Proteins help (facilitate) things pass

36
Q

Define active transport in terms of membrane crossing

A

Against conc gradient
Low -> high

Requires ATP energy

37
Q

What is a sodium-potassium pump in terms of membrane crossing?

A

Action potention for nervous transmission

ATP fuels for proteins that carry the molecule (helps go against the conc gradient)

38
Q

What is the difference between ENDOcytosis and EXOcytosis?

A

ENDOcytosis - allows macromolecules to enter the cell

EXOcytocis - allows macromolecule to exit the cell

39
Q

Define phagocytosis

A

The intake of large particulate matter

40
Q

Define pinocytosis

A

The intake of extra cellular fluids

41
Q

What is the plasma membrane?

Who has one?

A

A lipid bilayer w/ proteins moving freely within it

All cells have one (bacteria, fungi, plants etc also have a cell wall outside of the cell membrane)

42
Q

What is the accepted model for the membrane structure?

A

The fluid mosaic model

43
Q

What was the process of Louis Pasteurs experiment?

A
  1. Boil nutrient broth to sterilise it
  2. Place in 3 flasks, incubation over a period of time
  3. Sample of each flask is transferred to plate containing afar and was incubated

Flask1 - open
Flask2 - plugged w/ a bung
Flask3 - attached to tunnel w/ distilled water in it

44
Q

What did Pastuers experiment prove /disprove?

A

Disproved and falsified the concept of spontaneous generation

45
Q

What is a scientific theory?

A

An explanation of a scientific event supported by scientific evidence

46
Q

What was the main ideas of Lynn Margulis’ endosymbiotic theory? (1981)

A
  • 2 billion years ago, bacteria cell took residence in eukaryotic cell
  • the eukaryotic cells acted as a ‘predator’, formed symbiotic relationship
  • bacterial cell went through changes to become mitochondrion
47
Q

What evidence of mitochondrion proves the endosymbiotic theory?

A
  • mitochondrion is same size as bacterial cell
  • they both divide by fission
  • they both have naked DNA, and so can survive on their own
48
Q

What modern day evidence is there to support the endosymbiotic theory?

Eg. Protist: Hatena

   Slug: Elysia Chlorotica
A

Hatena: can infest green alga and form symbiotic relationships

Elysia Chlorotica ingests algae. Algae’s chloroplasts retained one the indigestive tract.
Light carries our photosynthesis, and so doesn’t have to move
Large sa to absorb light

49
Q

Why do cells divide? (4 reasons - 3 mitosis, 1 meiosis)

A

Mitosis:
Growth
Repair
Replacement of worn out cells

Meiosis:
Reproduction

50
Q

The cell cycle
What happens in:

G1?

S?

G2?

M?

A

Growth 1 - major growth, du cellular structures grow. Organelles and proteins replicate

Synthesis - DNA synthesis (DNA replicates)

Growth 2 - DNA condenses from chromatin -> chromosomes. Microtubules begin to form

Mitotic phase - where actual division takes place

51
Q

What are cyclins?

What do they do?

A

Cyclins are the proteins that control the cell cycle

They bind to CDK (Cyclin Dependent protein Kinases) and act as activated enzymes to allow cell to pass onto the next phase

52
Q

What is the G0 phase?

Give 2 examples of cells that enter G0 phase

A

Some cells stop after G1 and enter a non growing state

Eg. Nerve and muscle cells

53
Q

Why are the following exceptions to the cell theory:

The alga Caulerpa

Muscle fibres

Some fungi

A

Caulerpa - consists of one multi-uncleated cell, yet grows to the size of a large plant. Shape maintained by cell wall and microtubules, but there are no separate cells

Muscle fibres - form from the fusion of many myoblasts (individual muscle stem cells) producing large multi-nucleated fibre. These fibres can be 20cm+ long

Fungi - produce hyphae that lack cross walls dividing the hyphae into cells. They are known as asephate hyphae (as opposed to separate hyphae that do not contain cross walls)

54
Q

Why are cells limited in size?

What happens if they get too big?

A

They need nutrients and minerals in order to grow

If they get too big then they won’t be able to carry out their functions

55
Q

How does new evidence influence theories?

Give an example of a theory that was changed

A

New evidence brings about falsification of other /older theories

Eg. Plum pudding model

56
Q

What does cholesterol do for membranes?

What would happen wo/ it?

A

Cholesterol allows for membrane fluidity at a wide range of temps

Wo/ it, it would become rigid

57
Q

What is polarity /a polar molecule?

A

When a neutral molecule has a positive area at one end and a negative area at the other

58
Q

Define these properties of stem cells:
Self renewal

Potency

A

Self renewal - the ability to divide many times while maintaining an unspecialised state

Potency - the ability to differentiate into specialised cells

59
Q

Define compartmentalised

A

Compartmentalised - membrane bound

60
Q

What is a scientific theory?

A

An explanation of a scientific event supported by scientific evidence

61
Q

Define autotrophic

Give an example

A

Autotrophic - produces own food

Eg. Plants

62
Q

What is the interphase of the cell division cycle?

What stages does it include?

A

The largest and longest phases

Incl. G1, S, G2

63
Q

What is mitotic index?

A

Tells us what % of cells are in mitosis

64
Q

How do you calculate mitotic index?

A

No. Cells in mitosis
————————— x100
Total no. Cells

(MY) BIOLOGY SL (1 decks)

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