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Biologia > Cells > Flashcards

Cells Flashcards

1
Q

What does the cell theory state?

A
  1. All living things are made up of 1 or more cells
  2. Cells are the smallest unit of life
  3. All cells come from preexisting cells
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2
Q

What’s the difference between unicellular and multicellular organisms?

A

Unicellular: one cell carries all functions of life
Multicelular: cellular components interact to carry out the functions (emergent properties) aka the whole is greater than the sum of its parts.

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3
Q

How does SA:V ratio limits the size of a cell?

A
  • rate of intake/expulsion of materials corresponds to cell membrane (SA)
  • rate of performance of Chem rxns corresponds to volume (V)
  • if the rate is too small (cell too big) substances won’t enter/ leave the cell quickly enough. Cell won’t b able to perform metabolism, it could overheat and thus die.
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4
Q

Differentiation

A

The development of cells in different ways to carry out specific functions.

Allows cells in a tissue to carry out their role more efficiently.

Involves the expression of some genes
Ex: rod cells in retina.

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5
Q

Why are stem cells necessary in embryonic development?

A

Because of their capacity to divide and differentiate along different pathways.

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6
Q

What are the functions of life?

A

Nutrition, growth, metabolism, response, excretion, homeostasis and reproduction

(7)

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7
Q

What are some common features of cells?

A

Membrane that separates content from the outside environment.

DNA

Chemical rxns catalyzed by enzymes

E release system

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8
Q

What are some examples of cells that challenge the cell theory?

A

Striated muscle: v large and multinucleated

Giant algae: unicellular but v long (10cm) w 1 nucleus!

Aseptate fungal hyphae: one long tube like structure w multiple nuclei

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9
Q

How does Paramecium perform the functions of life?

A

Nutrition: consumption of smaller organisms
Growth: use of C compounds
Metabolism: in cytoplasm
Response: beating of cilia
Excretion: waste diffuses through membrane
Homeostasis: contractile vacuoles fill up and expulse water
Reproduction: asexual, cell division

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10
Q

How does Chlamydomonas perform the functions of life?

A

Nutrition: photosynthesis
Growth: C compounds
Metabolism: in cytoplasm
Response: eyespot to sense for light and move towards it.
Excretion: waste diffuses through membrane
Homeostasis: contractile vaciles expulse water
Reproduction: sexual/ asexual

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11
Q

How are stem cells used to treat Stargardt’s desease?

A
  • genetic desease, causes photoreceptive cells to degenerate in children
  • trials on mice showed successful results when treating a condition similar to stargardt’s
  • human embryonic cells can be successfully developed into retina cells.
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12
Q

How can stem cells be used to treat Leukemia?

A
  • it’s a type of cancer produced by a mutation in gene that controls cell division causing an abnormally large amt of white blood cells in bone marrow.
  • chemotherapy causes bone marrow to stop producing blood cells
  • fluid from bone marrow from healthy individual w adult stem cells is infected into patient to produce blood cells.
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13
Q

What are the pros and cons of embryonic stem cells?

A
  • almost unlimited growth potential
  • more risk of tumors
  • less chance of genetic damage
  • removal of cells kills embryo
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14
Q

What are the pros and cons of cord blood stem cells?

A
  • easily obtained
  • no rejection
  • v expensive
  • limited capacity to differentiate
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15
Q

What are the pros and cons of adult stem cells?

A
  • difficult to obtain
  • less growth potential and limited capacity to differentiate
  • doesn’t kill adult but v painful
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16
Q

What are the eqns for magnification, size if specimen, field of view and length of scale bar?

A

Mag=image/actual
Size=fov/ # of times across the lens
Fov= fov on low x magnification on low/ mag

Scale bar = mag x length represented

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17
Q

What is the relation bw structure and function of cells w/in the pancreas?

A

Endocrine gland cells: secrets hormones into blood stream

Exocrine: secrete digestive enzymes

Lots of ribosomes–> synthesize proteins
Lots of Golgi apparatus–> to process them and send them out of the cell

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18
Q

Structure and function of palisade cells?

A

Main function is photosynthesis

–> lots of chloroplast

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19
Q

Why do phospholipids form bilayers?

A

Bc of amphipathic properties ( both hydrophilic/phobic parts)

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20
Q

What was the Gordon and Grendel model?

A

They extracted phospholipids from the PM of rbc. Calculated that the area of phospholipids was 2x that of the PM so concluded that there was a bilayer.

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21
Q

How did the Davesin Danielle model came to be?

A

They proposed that there were layers of protein that surrounded the phospholipid bilayer c of a railroad appearance in e- micrographs

Supported bc proteins looked dark in e-micrographs

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22
Q

What falsified the Daveson Danielle model and led to the Singer and Nicolson model?

A
  1. Freeze etched micrographs showed proteins embedded in membrane
  2. Structure of membrane proteins showed diff shapes and sizes w hydrophilic parts –> no continuous layers on membrane
  3. fluorescent antibody tagging showed membrane behaves as a fluid
23
Q

Why are some of the functions of membrane proteins?

A

Receptors/binding sites for hormones/ neurotransmitters

Cell to cell adhesion/communication

Channels/pumps

24
Q

What are integral proteins?

A

Partially hydrophobic so they’re embedded in the membrane.

Can be transmembrane (cross the entire membrane)

25
Q

What are peripheral proteins?

A

Hydrophilic on the surface so there NOT embedded in the membrane.

26
Q

What is cholesterol and what does it do?

A

Component of animal cell membrane

  • mostly hydrophobic –> reduces membrane fluidity but prevents hydrocarbon tails to behave as solid
  • reduces permeability to hydrophilic substances
  • helps w curved shape & formation of vesicles
27
Q

What is passive transport and what are the different kinds?

A

No use of ATP, substances move w conc. grad.

  • simple diffusion
  • facilitated diffusion
  • osmosis
28
Q

What’s simple diffusion?

A

Passing bw the phospholipids, small non-polar particles. Passage can be prevented by hydrophobic center (of particles)

29
Q

What’s facilitated diffusion?

A

Ions are too large to pass so protein channels are created. This channels are controlled by the cell and are substance specific.

30
Q

What’s Osmosis ?

A

Diffusion of water from low solute conc. (hypotonic) to high solute conc. (hypertonic). Aquaporins may form

31
Q

What happens when a cell is put in a hypertonic, hypotonic and isotonic solution?

A

Hypertonic: water will diffuse into cell

Hypotonic: water will diffuse into cell

Isotonic: no water diffuses

32
Q

What is active transport and what are the different types?

A

Uses ATP to move substances against conc. gradient

  • protein pumps
  • endo/exo cytosis
33
Q

What are protein pumps?

A

Proteins that change form in order to move substances against conc. gradients

34
Q

What’s endocytosis and exocytosis?

A

Endocytosis: membrane folds around a substance, forms a vesicle using ATP which then pinches off INTO cell

Exocytosis: vesicles from inside fuse w PM releasing substance out of cell

35
Q

What does exocytosis reveal about the Golgi Apparatus and the ER?

A

That they’re also made of phospholipid bilayer since they’re able to fuse w the cell.

36
Q

How do vesicles move in the cell?

A

Transport materials (e.g. Proteins made by ribosomes in rET)

–> Golgi apparatus fusing w it

–> take proteins from Golgi apparatus to PM for release

37
Q

How does the sodium potassium pump work?

A
  1. 3Na ions enter the pump from the inside of the cell and attach to bindings
  2. ATP transfers one PO4 group to pump changing its shape, closes inside
  3. Pump opens to outside releasing Na ions
  4. 2K ions from outside attach to binding sites
  5. The binding of the K causes PO4 group to be released changing its shape closing exterior and opening interior.
  6. 2K ions are released into cell and 3 Na ions can now enter
38
Q

What evidence from Pasteur’s experiments shows that spontaneous generation of cells and organisms does not occur on earth

A

He made a nutrient broth by boiling water w yeast and sugar. If the flask was sealed there would be no change

  • organisms appeared when a cotton pad w filtered air was put inside the flask
  • fungi showed only in unboiled broths
    This supported that no organisms spontaneously generate.
39
Q

What’s the endosymbiosis theory?

A

Chloroplasts and mitochondria were once free living prokaryotes.

Larger organism consumed smaller one allowing it to live w/in and grow at the same rate

Large organism would provide nutrients and the small one would provide E –> symbiotic relationship

40
Q

What evidence supports the endosymbiotic theory?

A

The following features are present in prokaryotes AND mitochondria:

  • own genes in circular DNA
  • own 70s ribosomes
  • transcribed DNA and use mRNA to synthesize own proteins
  • produced by division of preexisting mitochondria
41
Q

Phases of mitosis: interphase

A
  • V active
  • b4 mitosis
  • DNA replicates in S phase
  • protein synthesis in cytoplasm
  • duplicated chromosomes are called sis chromatids
  • mitochondria #s increase
  • PLANTS: synthesize cellulose and add it to the wall
42
Q

Phases of mitosis: prophase

A
  • nucleons breaks down
  • chromosomes condense by supercoiling
  • microtubules form spindle apparatus
  • nuclear membrane breaks down
43
Q

Phases of mitosis: metaphase

A
  • microtubules attach to centromeres

- sister chromatids align in the center of the cell

44
Q

Phases of mitosis: anaphase

A
  • daughter chromosomes separate by division of centromere forming chromosomes
  • spindle microtubules pull chromosomes to poles
45
Q

Phases of mitosis: telophase

A
  • Chromosomes reach poles and gather near centrosome
  • chromosomes uncoil
  • nucleus forms
  • division of cytoplasm begins
46
Q

Phases of mitosis: Cytokinesis

A
  • Occurs AFTER mitosis
  • animals: PM is pulled inwards by contacting proteins @ cleavage furrow & is pinched apart

-plants: vesicles move to equator forming tubular structure which merge forming a permeable membrane . Substances deposited by vesicles form cell wall

47
Q

What’s the eqn for mitificado index?

A

Mitotic index = #of cells in mitosis/ total # of cells

48
Q

What are cyclins?

A

They’re involved in the control of cell cycle.
-They’re proteins that ensure all tasks in the cell are formed at the correct time

  • bind to kinases which become active and attach PO4 groups to other proteins causing diff rxns
  • 4main types of cyclins which must reach threshold conc. for cell to move to next stage
49
Q

What are tumors?

A

Abnormal groups of cells that develop at any stage in life and in any part of the body.

Primary: benign and don’t spread
Secondary: spread and are usually life threatening

50
Q

What’s cancer?

A

Desease due to malignant tumors, can be caused by carcinogens (substance capable of causing cancer)

51
Q

What are mutagens?

A

Cause gene mutations which can cause cancer

52
Q

What are oncogenes?

A

Few genes that can become cancer-causing after mutating

53
Q

What’s metastasis?

A

Movement of cells from a primary tumor to set up secondary ones

Biologia (6 decks)

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