Chapter 1 Flashcards
State the cell theory
1- all living organisms are composed of cells
2- cells the the smallest basic unit living structure of life
3- new cells are formed by previous cells diving - omnis cellula e cellula
Schleiden and virchow
1 and 2 - scheildon
3- virchow
Describe the properties of cells
1 - autonomous 2- internally regulated 3- organized 4- self regulating 5- respond to stimuli 6- capable of movement 7- acquire and use energy 8- reproduce themselves 9- perform chemical reactions 10- self replication collection of catalysts
Describe cell as a system
A cell is a system of connected organelles and structures that work together
It also shows emergent properties
State the central dogma and explain
1- info flows from DNA to RNA to Proteins
It means that the genes in DNA provides instructions for making a protein , which is then copies by the RNA , RNA uses the instructions to make proteins. Proteins perform the function and are responsible for the function , form and behaviour of cells and organism
What are the exceptions to the central dogma
1- the flow of info is different in the virus . The info moves from DNA to RNA eg in retrovirus due to reverse transcription when virus is inside the host
2- there are more than one type of RNA eg tRNA , rRNA and mRNA however only mRNA is transcribed .
3- there are also non coding RNA types eg microRNA
EVOLUTION TREE :-
What is the ancestral cell
Prokaryotic cell
Ancestral cell is divided into
Bacteria and archea
Describe bacteria category
2 types of bacteria
1- non photosynthetic bacteria
2- photosynthetic bacteria
Describe the category of archea
Archea gave rise to SINGLE CELLED EUKARYOTIC CELLS when mitochondria (Bactria) was adapted into the cells
Single cell eukaryotic cells lead to animal, fungi and archea and plants ( this happened after another bacteria ( chloroplast was adapted inside the single celled eukaryotic cells )
Whats the evidence that eukaryotes arose from ancestral archea
Due to the structural similarities in eukaryotes, archea and bacteria
Structure =—————
Fubction
What does the rule structure = function gives rise to ? Explain
Diversity of cells
Because structure = functions , there are many different functions in the cell , organelle or organism therefore each function has a different structure of cells therefore it gives rise to diversity
How do we study cells ?
A- we approach cell biology with a REDUCTIONIST VIEWPOINT ( it is based on the premise that studying the part of a whole can explain the character of the entire organism
- The cells is similar to a working machine with many parts
- knowing how the ind parts work can explain the whole
- understanding how cells work can reveal so much about the nature of life
What is system biology
Computational and mathematical modelling of complex biological system that will eventually allow for the engineering of biological system
Cell area and volume ?
A - 4#r2
V- 4/3#r3
When cells get bigger the SA/V ration———-?
Decrease
This causes? Explain
Reduction in SA causes
1- decrease in efficiency of movement of molecules
2- decrease in efficiency of absorbing nutrients
3- difficulty in getting rid of wastes
Explanation
When the D of a cell-is 1 um , it takes 100 millisecond to diffuse oxygen , however when the D increases to 10um , it takes 10 million times longer
Cells are usually measured in
Um = 10^-6
Nm=10^-9
Whats the mag and res of light microscope
Max Mag = 2000x
Res = 100nm
Types of light microscope
1- Differential interference contrast microscope
2- Fluorescence microscope
- confocal fluorescence microscope
Describe the fluorescence microscope
This uses a fluorescence dye that absorbs certain wavelength and emits a longer wavelength
What is the max magnification and res of electron microscope
Mag - 10 million
Res - 1nm
Types of electron microscope and explain
Sem - shows the surface of dead cells
Uses metal lining
Tem - shows the cross section of dead cells
Uses metal lining
Purpose of light microscope OVERALL
- The cells can be alive
- Can view living cells by preparing a slide with water sample
- reveal SOME CELL COMPONENTS ( the bigger ones)
1- Conventional light microscope⁉️⁉️
Look at unstained living cells
a- Difference interference contrast
Three types of optics in this 1- the simplest, brightest- field optics 2- phase contrast optics 3- interference - contrast optics Used for looking at living cells
2- fluorescence microscopy
Used to look at location and specific distribution of molecule in the cells
Can also view objects even smaller then 200nm
a- Confocal fluoroscence microscopy
Generates a sharper image
Constructs a 3D image
b- Super resolution fluorescence microscope
Position of molecules accurately mapped
Build image with resolution lower at 20nm
Makes 3D image
Allows real time / live cell imaging
Electron microscope OVERALL function
Look at FINE STRUCTURE OF CELLS
a- TEM
Same - cross sectional view See DNA translation Ribosomes Mitochondria
b- SEM
3-D image of surface structure
Stomata
How is live cell imaging occurs . Explain for auto fluorescence
Fluorescence microscope has filter to filter specific wavelength. These wavelength have chromophores which some electrons in biological molecules already have so they can emit light
-Uses visible light ( for observing a molecule that already has chromophores)
- small bandwidth of wavelength illuminate the sample
- some molecules in cell will absorb that wavelength and emit a-longer wavelength (auto fluorescence) because they have chromophores
- because only some wavelength illuminate the sample ,only fluorescently tagged things will show in image
Blue - nucleus
Green - micro tubules
Red - likely auto fluorescence of pigment granules - natural - shown from molecules with natural chromophores
Use an example, how can you observe location of protein - JAKE STOUT
- protein doesn’t have chromophores therefore fluorescence dyes or probes are used
- take an antibody that binds to the specific protein
- attach a fluorescence molecule
- Release in cell
4 ways to get fluorescence and their specific purpose
1- antibody tagged with fluorescence molecule( one of the 2 below- DAPI AND GFP)- to find the location of specific protein, because this binds to it
2- DAPI - a dye that binds to DNA and fluorescence blue
purpose- localization , absence/presence of proteins
3 GFP - green fluorescence from jellyfish
Purpose- localization, distribution and properties of proteins.
4- auto fluorescence of compound already in the cell eg. pollen grain - natural emission of light from biological molecules after they have absorbed light
How is SARs - CoV2 virus imaged
Using cryogenic electron microscopy
This is a method for imaging frozen hydrated specimens at cryogenic temperature (-160C)
No need for dyes and fixatives
Gives a molecular resolution
Cryogenic microscope purpose
Generate 3-D image and v v small samples of viruses
Prokaryotes
Most abundant
Divided into archea and bacteria
Eukaryotes
Simple unicellular yeast cells
Protozoans - simple
Human and other organisms like plants- complex
Difference in prok and euk
Prokaryotes
- no nucleus
- no membrane bound organelles
- small (1-10um)
- one circular piece of DNA
- sticky capsule
- complex cell wall
- only unicellular
- Simple
- binary fission
- Small ribosomes
Eukaryotes
- nucleus
- membranes organelles
- several DNA packaged into strands called chromatin
- large 10-100um
- cilia
- cytoskeleton
- uni or multi cells
- complex
- Mitosis
- linear dna
- cell wall simple when present
- large ribosomes
Similarities in prok and euk
- plasma membrane
- cytoplasm
- DNA materials
- Ribosomes that makeprotein
Prokaryotes arose ———-
Eukaryotes arose ———-
Humans and Chimps arose ————
3.7 billion
2 billion
7 million
Cdll culture
Growing of cells on petri dish or in a liquid medium IN LAB
Helps examine the Biology, genetics and functions of different types of cells.
What is in vitro Example of in vitro
When you grow cells in LAB rather than in natural conditions like in body
Eg cell culture
Types of cell culture
Normal cells from an organism
- these must be given specific growth factor s
- limited lifespan - divide 40x
Immortal cells
George grey took cancer cells from a tumor in Henrietta lacks
Divide forever due to mutation in dna
Used in vaccines
Cells in culture display property of their origins
Fibroblasts from human skin – continue to secrete proteins that form the ECM
Human neurons make connections with one another in culture
Epithelial cells from human cervix - form a cell sheet in culture
In vitro vs In vivo
In vitro is easier. When you give drugs and other treatments to see how cells respond .
In vivo is difficult. When you study cells within the whole tissue or organism
Why is model organisms used
1- easy to manipulate
2- easy to isolate mutants with non functional genes
3 have genome sequenced
4 short lifecycle
5 easily grown
6 have a common ancestor
7 studying one model allows us to understand structure and function of the rest
Common models
1- E. coli (a prokaryote) –our first understanding of DNA replication, transcription, translation
2- Saccharomyces cerevisiae (yeast) – simplest eukaryote, many mutants
3- Arabidopsis thaliana – fast growing plant, small genome, many mutants
4- Caenorhabditis elegans – ~ 1000 cells, short life cycle
5- Drosophila melanogaster – 1000s of mutants, well characterized genome (fruit flies)
6- Mus musculus (mice) – 1000s of mutants, easiest mammal for genetics studies
Organisms and what models they serve
C. elegans– model animal
E. coli – prokaryotic model
Drosophila – insect model
Mice- often used as a mammalian model
Arabidopsis – model plant
Zebra fish- vertebrate development models
Zebra fish are transparent so you can deserve development stages such as the embryon
GFP
GFP is a reporter gene, we can use the sequence of the GFP protein and insert gene promoter to gene of interest
GFP seq (in red ) When the gene is expressed GFP protein will also be made - GENE EXPRESSION ANALYSIS
Size of atoms
0.2 nm
Size of molecules
0.2 - a bit more then 100nm
Size of organelles
100nm - 10um
Size of cells
10um - 0.2 mm (200um)
How small can Electron microscope see
0.2nm and bigger
How small can super resolution microscope see
20nm or bigger
How small can light microscope see
200nm and bigger
How small can an unaided eye see
0.2mm or ( 200um)
