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Cell Biology > LECTURE 1: Intro to Cell Bio > Flashcards

LECTURE 1: Intro to Cell Bio Flashcards

1
Q

List the properties of a living cell

A
  1. Life is the most basic property of cells.
    – They are the smallest units to exhibit the property of life
    – Cells can be removed from an organism and cultured in the laboratory (CANT culture nucleus)
    – One can’t do this with the sub- compartments of a cell
  2. Cells Are Highly Complex and Organized
    – Cellular processes are highly regulated.
    – Cells from different species share similar structure, composition and metabolic features that have been conserved throughout evolution.
    - SUGGESTS we all have common ancestor

3.Cells Possess a Genetic Program and the Means to Use It
- Genes encode information to build each cell, and the organism.
– Genes encode information for cellular reproduction, activity, and structure.

  1. Cells Are Capable of Producing More of Themselves
    - Cells reproduce,andeachdaughtercells receives a complete set of genetic instructions.
  2. Cells Acquire and Utilize Energy
    – Photosynthesis provides fuel for all living organisms.
    – Animal cells derive energy from the products of photosynthesis, mainly in the form of glucose.
    – Cell can convert glucose into ATP—a substance with readily available energy.
  3. Cells Carry Out a Variety of Chemical Reactions
    – Catalyzed by enzymes
  4. Cells Engage in Mechanical Activities
    – Things are moved around within the cell via the cytoskeleton and motor proteins
    – Some cells themselves move around
  5. Cells Are Able to Respond to Stimuli
    – Receptors that sense environment & initiate responses.
    sperm cells swim!
  6. Cells Are Capable of Self-Regulation
    Cells expend energy to keep the complexity ‘in order’. Homeostasis
  7. Cells Evolve
    Evolution is not simply an event of the past, but an ongoing process that continues
    to modify cell properties that will be present in organisms yet to appear
    26
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2
Q

Describe why viruses aren’t really considered to be living

A

When they infect another cell, they hijack that cell to make many, many more viruses.
- New viruses released slowly
), or the cell bursts releasing all of them at once (which kills the cell
- They don’t do internal homeostasis, use energy, or respond to their environment on their own.
Weirder: Prions and viroids!

ARENT ALIVE

  • can’t reproduce on their own
  • completely reliant on host
  • dont fit on phylogenetic tree
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3
Q

State the three tenants of cell theory

A
  1. All organisms are composed of one or more cells.
  2. The cell is the structural unit of life for all
    organisms.
  3. Cells can arise only by division from a preexisting cell. omnis cellula e cellula (“only cells from cells”)
    - no way to create a new cell other that that cell reproducing and dividing
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4
Q

Who was Matthias Schleiden?

A

observed that all plant tissues he looked at were made of cells, and that plant embryos come from one single cell

  • cells come from cells
  • beginning to idea that plants and animals might have common ancestor
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5
Q

Describe light microscopy

A
  • original microscope
  • series of magnifying glasses with light at bottom
  • used to look at living cells and fixed samples(chemically treated to be frozen in time then sliced)
    the best resolution we can get is 200 nm.(1/2 of what we can see, we can see 400 nm)
    Thus best magnification is about 2000x
  • allow us to see individual ribosomes
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6
Q

explain why there’s a limit to resolution using light microscopy

A

the wavelengths of light are longer than electrons

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7
Q

Explain the four ways can you get fluorescence in microscopy

A

1 Say you want to see where a protein of interest is…

  1. Take an antibody (a protein that binds specifically and
    tightly to another protein) that will recognize your
    protein of interest
  2. Attach a small fluorescent molecule onto it
  3. Get it into the cells you’re going to image
    The antibody will find and bind to the target protein, and the tag will tell you where your target protein is under a fluorescence or confocal microscope!
#4 Autofluorescence of compounds already in the cell (e.g. pollen grains in
a plant anther
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8
Q

Define homeostasis

A

is the property of a system in which variables are regulated so that internal conditions remain stable and relatively constant.

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9
Q

List the major lineages of cell types

A

Prokaryotic and eukaryotic cells are distinguished by their size, type of organelles, and evolutionary history.
shared features must have evolved before the eukaryotes arose because of shared features

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10
Q

Describe how do we think eukaryotic cells arose

A

We now have good evidence that eukaryotes evolved from ancestral Archea!

We’re sure that all life came from an initial cell. Thus, prokaryotes have been evolving for the SAME amount of time as eukaryotes have!
Another cool fact: bacteria and archaea are everywhere we look on earth.

WE ALL came from the same proto cell

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11
Q

Compare the differences and similarities between prokaryotic and eukaryotic cells

A
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12
Q

List the model organisms we went over in lecture

Describe why you would use a specific model organism for research

A

E. coli (a prokaryote) –DNA replication, transcription, translation (very simple to modify to produce protein, but if your working on mammalian models of disease it isnt useful bc its not a eukaryotic cell

Saccharomyces cerevisiae – simplest eukaryote model, many mutants

Arabidopsis thaliana – fast growing plant, small genome, many mutants (easy manipluate)

Caenorhabditis elegans – ~ 1000 cells, short life cycle, developmental biology
Drosophila melanogaster – 1000s of mutants, genetic model since 1920, also developmental biology and basic human biology due to similar processes (understanding basic genetics of humans)

Zebrafish – simple vertebrate, early vertebrate development

Mus musculus – 1000s of mutants, easiest mammal for genetics studies(genetically modifying animal is very complicated

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13
Q

Explain why are cells small

A

To maintain a proper surface area/volume ratio

  • as cell size increases surface area/volume decreases
  • if SA drops its difficult to take up nutrients and rid wastes
  • large celled exceptions
  • absorptive epithelium- microvilli for absorption
  • eggs- small amount of protoplasm on big yolk
  • nerve cells- long length narrow width

cells depend on diffusion to move substances- large cells are unable to diffuse quickly
Time required for diffusion is proportional to the square of the distance traversed.
It takes O2 100 μsec to diffuse 1 μm. It takes 10 million times longer to diffuse 10 mm!

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14
Q

genome

A

an organism’s complete set of DNA, including all of its genes

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15
Q

genomics

A

the science of sequencing, assembling and analyzing genomes and transcriptomes

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16
Q

transcriptomics

A

an organism’s complete set of mRNA (protein coding)

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17
Q

metagenomics

A

collecting environmental samples and sequencing random DNA

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18
Q

Explain what can the size of a genome tell you about complexity?

A

Genome size has no correlation with ‘complexity’ of the organism

Genomes don’t just contain protein- coding genes!
Also...
• Functional RNAs (rRNA, lncRNA, miRNA)
• Functional ‘positional sequences’
• Repeat regions
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19
Q

Viruses

A

are small pieces of nucleic acid (DNA or RNA, depending on the virus type) surround by a membrane and protein ‘capsid’

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20
Q

What’s a cell?

A

is the smallest unit of life.

“a self-contained membrane-bound unit which carries out the functions of life; is organized, autonomous, and internally regulated”

  • web of interconnected things

is a system
Cells can look really different.
Structure = function!

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21
Q

System

A

a set of connected things or parts forming a complex whole.

22
Q

Emergent properties

A

occur in complex systems. “The sum is greater than the whole of the parts”

ex DNA replication by itself may not be so useful but when complexed with proteins and cytoskeleton its much more impactful and useful

23
Q

How does life emerge?

A

emerges from cell parts interacting, ‘mind’ emerges from our neurons interacting This occurs at all scales! Cells -> tissues -> organism -> populations -> ecosystems

24
Q

reductionist viewpoint

A

How we traditionally approach cell biology

25
Q

Reductionism

A

the practice of analyzing and describing a complex phenomenon in terms of phenomena that are held to represent a simpler or more fundamental level, especially when this is said to provide a sufficient explanation
try to understand how the parts work to figure out how the whole system works.

Breaking everything down into smaller parts to understand the whole

26
Q

systems biology

A

computational and mathematical modeling of complex biological systems.
We now know about enough about the ‘parts’

  • inclusive model
  • take everything we know about the little parts and dump it into computational model- can predict how cells will react given what we know
27
Q

Who is Robert Hooke

A

first observed chambers in cork, which he called ‘cells’ because they reminded him of the cells (cellula) monks lived in.

  • invented 1st microscope and coined the term cell (not live cells)
  • 1st to observe cells through microscope
28
Q

Who was Anton van Leeuwenhoek?

A

was the first to describe living cells in pond water
- Also was the first to describe bacteria (prokaryote) cells
He named these little critters ‘animalcule’

29
Q

Who was Theodor Schwann?

A

observed that animal life is made of cells too!
then proposed first two tenets of Cell Theory
did think, however, that one could get life to arise spontaneously from dead matter. It was a very popular idea at the time! For context, Mary Shelly wrote Frankenstein in 1818.

30
Q

Who was Rudolf Virchow?

A

observed a lot of cells, and most importantly cells dividing.
he published some other guy’s work (Robert Remak) as his own, but somehow historically got all the credit
Proposed the third tenet of Cell Theory

31
Q

cell biology is a….

A

multidisciplinary study of cell structure and function

is now interdisciplinary

32
Q

resolution power

A

the smallest distance between two separate points of an object, when viewed with an optical instrument, that can still be seen as distinguishable

33
Q

Describe electron microscopy

A

Electron Microscopes have better resolution
- 2 types; transmission electron microscopy and scanning electron microscopy
Electron wavelengths are much smaller than light, thus better resolution down to 1 nm and magnification of 10 million times!

CANT see live cells with this type

34
Q

Describe transmission electron micoscopy

A
  • thin um sections of dead and fixed cells are used
  • sections are coated with heavy metals for contrast
  • electrons are beamed through sample and are scattered by the metals
35
Q

Describe scanning electron microscopy

A
  • dead and fixed cells are used
  • samples are coated with heavy metals for contrast from one direction
  • electrons are scanned across the sample and are scattered by metals
36
Q

Describe Fluorescence microscopy

A

• Uses visible light, live cell imaging is possible

• Only a small bandwidth of wavelengths
illuminate the sample

  • Some molecules in the cell will absorb that wavelength, and then fluoresce at a longer wavelength (autofluorescence)
  • We use fluorescent dyes and other ‘probes’ to label other things that we want to look at (specific proteins, etc.)

Because all wavelengths aren’t used to illuminate the sample, only the fluorescently-tagged things you’re interested in observing show up on the image

*CAN look at LIVE cells

37
Q

antibody

A

a protein that binds specifically and

tightly to another protein)

38
Q

Describe Confocal microscopy

A

gives thin ‘optical sections’

Same idea as fluorescence microscopy, but a laser scans across the sample and is focused at a specific depth (thus illuminates only one plane of focus at a time)
Allows more detail to be seen because not everything above and below the plane of focus fluoresces

MOST microscopy you need a thin section BUT for confocal you dont need to slice

39
Q

Difference between Regular fluorescence microscope and Confocal fluorescence microscope

A

Regular fluorescence microscope. There’s stuff fluorescing above and below the plane of focus giving a blurry image

Confocal fluorescence microscope. Only one plane is illuminated, thus gives a more detailed picture!

40
Q

Describe Super-resolution microscopy

A

type of confocal
Fancy switching laser systems and a lot of math can now resolve things closer than 200 nm using light (down to 20 nm).
Algorithms figure it all out and produce an image.

uses 2 diff lasers:

a) to block
b) to resolve image
- gives much clearer image than fluorescence

The 2014 Nobel Prize in Chemistry was awarded to Eric Betzig, W.E. Moerner and Stefan Hell for coming up with these techniques.

41
Q

Prokaryote features

A 
(Greek: pro = before, karyon = nucleus)
 Eubacteria and Archaea
• Always single celled
• Small (1 to 10μM)
•Single plasma membrane...no membrane-bound
internal structures
•DNA lies ‘free’ in cytoplasm,not associated with
DNA binding proteins
- single circular chromsome
42
Q

Eukaryote features

A

Greek: eu= true, karyon = nucleus)
• Membrane bound nucleus, usually with much more DNA and genes
• Larger, typically 10 to 100 um in diameter
• Eukaryotic cells have organelles (nucleus, mitochondria, endoplasmic
reticulum, Golgi, etc.) which are also membrane bound
• Eukaryotic cells divide by mitosis/meiosis, prokaryotes divide by binary
fission
• Eukaryotic cells have more complex cytoskeletons and motility machinery

43
Q

Describe when prokaryotes and eukaryotes arose

A

The earth is ~ 4.5 billion years old.
The origin of life (cells) happened only once and how is still purely speculative!!

Prokaryotes are all bacteria and archaea, which arose ~ 3.7 billion years ago.

Eukaryotes include protists, animals, plants and fungi. Arose ~ 2 billion years ago. Us humans diverged from a common ancestor with chimps only 7 million years ago!

44
Q

How do we study cell bio?

A

using cell cultures and model organisms

45
Q

Cell cultures

A

are when we grow cells in a petri dish or in liquid growth media

46
Q

Cell cultures are either:

A

a. ) ‘normal’ cells taken from an organism
- these must be given specific factors (proteins,
etc. )
- these cells have a limited lifespan

b.) “immortal” cancer cell lines
- in 1951 George Gey made the first human cell
cultures from a tumor removed from Henrietta
Lacks (called HeLa cells)
- These cells will merrily divide forever
It’s relatively easy to give cell cultures drugs or other treatments and see how they
respond. It’s a simpler system than studying cells in whole tissues and/or organisms.
HeLa cells visualized by confocal microscopy

47
Q

Why are model organisms used?

A

Model organisms are used because they’re easy to manipulate/study and easy ‘transform’ = add new DNA sequences. Also easy to isolate ‘mutants’ that have ‘broken’ genes. These all now have their genome sequenced.

48
Q

List some difference between transmission and scanning electron microscopes

A

main difference is in how electrons are detected

scanning- electrons are blasted in all directions and based on how they scatter the scanener will pick up and you can get a 3D image

49
Q

Describe the diversity in prokaryotes and Eukaryotes

A
  • diversity in prokaryotes is greater inn terms of species

- eukaryotes are more diverse in terms of forms (larger more complex cells, yeats(single celled) all teh way to us)

50
Q

What are the resolution of each ,microscope?

A

light microscope- 200 nm
fluorescence- 20 nm
electron microscope- 0.2 nm

51
Q

How do fluorescent microscopes work?

A

Fluorescent dyes used for staining cells are detected with the aid of a fluorescence microscope. This is similar to an ordinary light microscope, except that the illuminating light is passed through two sets of filters (yellow). The first ( 1 ) filters the light before it reaches the specimen, passing only those wavelengths that excite the particular fluorescent dye. The second ( 2 ) blocks out this light and passes only those wavelengths emitted when the dye fluoresces. Dyed objects show up in bright color on a dark background.

Cell Biology (23 decks)

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