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

Topic 1 - CELL BIOLOGY Flashcards

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
Proteins within a membrane What is: Enzymatic action?
Enzymatic action - membrane enzymes have many activities incl. catalysing biochemical reactions inside cells Eg. Kinase
26
Proteins within a membrane What is: Cell adhesion?
Cell adhesion - allow cells to stick to eo/ and surroundings (proteins located in cell surfaces) CAM - Cell Adhesion Molecules
27
Proteins within a membrane What is: Pumps for active transport?
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
Proteins within a membrane What is: Channels for passive transport
Channels for passive transport - channel proteins and carrier proteins allow solutes to cross membranes (from tunnel for molecules /ions to cross)
29
Proteins within a membrane What is: Cell to cell communication
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
Proteins within a membrane What is: Hormone binding sites?
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
What is a passive process? Do molecules move up /down the conc gradient? List 3 examples relating to membrane crossing
A process that doesn’t require energy Molecules move down their conc gradient - diffusion - osmosis - facilitated diffusion
32
What is an active process? Do molecules move up /down the conc gradient? List 2 examples relating to membrane crossing
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
# Define diffusion (in terms of membrane crossing) Conc?
Substances other than water move between the phospholipid molecules or through proteins that posses channels High -> low conc
34
Define osmosis (in terms of membrane crossing)
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
What is facilitated diffusion in terms of membrane crossing?
Non channel protein carriers change shape to allow movement of substances other than eager Proteins help (facilitate) things pass
36
Define active transport in terms of membrane crossing
Against conc gradient Low -> high Requires ATP energy
37
What is a sodium-potassium pump in terms of membrane crossing?
Action potention for nervous transmission ATP fuels for proteins that carry the molecule (helps go against the conc gradient)
38
What is the difference between ENDOcytosis and EXOcytosis?
ENDOcytosis - allows macromolecules to enter the cell EXOcytocis - allows macromolecule to exit the cell
39
Define phagocytosis
The intake of large particulate matter
40
Define pinocytosis
The intake of extra cellular fluids
41
What is the plasma membrane? Who has one?
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
What is the accepted model for the membrane structure?
The fluid mosaic model
43
What was the process of Louis Pasteurs experiment?
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
What did Pastuers experiment prove /disprove?
Disproved and falsified the concept of spontaneous generation
45
What is a scientific theory?
An explanation of a scientific event supported by scientific evidence
46
What was the main ideas of Lynn Margulis’ endosymbiotic theory? (1981)
- 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
What evidence of mitochondrion proves the endosymbiotic theory?
- 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
What modern day evidence is there to support the endosymbiotic theory? Eg. Protist: Hatena Slug: Elysia Chlorotica
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
Why do cells divide? (4 reasons - 3 mitosis, 1 meiosis)
Mitosis: Growth Repair Replacement of worn out cells Meiosis: Reproduction
50
The cell cycle What happens in: G1? S? G2? M?
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
What are cyclins? What do they do?
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
What is the G0 phase? Give 2 examples of cells that enter G0 phase
Some cells stop after G1 and enter a non growing state Eg. Nerve and muscle cells
53
Why are the following exceptions to the cell theory: The alga Caulerpa Muscle fibres Some fungi
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
Why are cells limited in size? What happens if they get too big?
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
How does new evidence influence theories? Give an example of a theory that was changed
New evidence brings about falsification of other /older theories Eg. Plum pudding model
56
What does cholesterol do for membranes? What would happen wo/ it?
Cholesterol allows for membrane fluidity at a wide range of temps Wo/ it, it would become rigid
57
What is polarity /a polar molecule?
When a neutral molecule has a positive area at one end and a negative area at the other
58
Define these properties of stem cells: Self renewal Potency
Self renewal - the ability to divide many times while maintaining an unspecialised state Potency - the ability to differentiate into specialised cells
59
Define compartmentalised
Compartmentalised - membrane bound
60
What is a scientific theory?
An explanation of a scientific event supported by scientific evidence
61
# Define autotrophic Give an example
Autotrophic - produces own food Eg. Plants
62
What is the interphase of the cell division cycle? What stages does it include?
The largest and longest phases Incl. G1, S, G2
63
What is mitotic index?
Tells us what % of cells are in mitosis
64
How do you calculate mitotic index?
No. Cells in mitosis ————————— x100 Total no. Cells

(MY) BIOLOGY SL (1 decks)

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