lec 2 Flashcards
name the 3 domains of al microorganisms
bacteria, archaea, eukarya
how did eukarya got evolved
bacteria and archaea had the same ancestors, then they evolved and divided into the current domains of microorganism. Then archaea evolved into eukarya
prokaryotes
bacteria and archaea
agar plate
solid media which micro-organism grow on.
in an agar plate the —- increases over time and it may eventually generate a —–
biomass, colony
name the properties of all cells
1) metabolism
2) growth
3) evolution
1: metabolism
all cells can take up nutrients and modify them into building blocks or generate nrg. i.e. cell wall components
the resulting functions carried by the cell are:
1) genetic: replication, transcription, translation
2) catalytic: nrg, biosynthesis
2: growth
when the biomass is favourable, nutrients consumed by the cells are converted into new cell materials in order to create daughter cells
3: evolution
- key characteristic of life
- cells do this in order to acquire new traits or skills
- sometimes they may specialize
impacts of specialization
- cells might lose genes that t eh don’t need
- as a result they waste less nrg on unwanted sources
—– capture evolutionary relationships
phylogenic trees
name the properties of some cells
1) differentiation
2) communication
3) genetic exchange
4) motility
differentiation
e. g. some cells can differentiate into spores
- capacity to perform specific set of functions
communication
cells communicate via chemical messages
genetic exchange
cells can inset their DNA into the recipient cell
microbial cells exchange DNA via ——
horizontal gene transfer (reproduction)
motility
swim and crawl
what is a cell
a cell is a closed compartment that is constantly doing chemical reactions to make more of its constituents and make another cell
organize the following based on increasing in size:
virus, polio, vacuole
polio –> virus –> vacuole
what is the limit in cell size
0.5 micrometer - 750 micrometer
animal cell size
10 micrometer wide
the — of the cell affects the size
shape
surface volume ratio
as volume increases, there is less surface available
why is the cell size a limited number
because the surface can handle a certain amount of volume in order to transfer nutrients and other compounds
to feed the whole volume, surface must be —- bigger
x2
what is the cue for the cell to divide
just before the cell reaches the upper limit, it divides into 2 cells
bacterial shapes
spherical,rod
nucleoid
rough region with no physical barriers
- prokaryotes store their DNA in this region
functions of the cell membrane
1) permeability barrier
2) protein anchor
3) energy conservation
cell membrane – permeability barrier
- prevents form leakage
- functions as a gateway: controls what enters and washes out
cell membrane – protein anchor
- site of many proteins that participate in transport, bioenergetics and chemotaxis
- sensors, adhesins, tranposerters, enzymes
the cell is — % protein and. —-% phospholipid
50, 50
cell membrane – nrg conservation
since the membrane is impermeable to charged molecules, a membrane potential is created
- the membrane potential forces the passage of ions, therefore pmf is generated
typical phospholipid found in bacteria
phosphatidylehtanolamine
in bacteria and eukarya the glycerol backbone is connected to the fatty acids via —- linkage
ester
in archaea the glycerol backbone is connected to the fatty acids via —- linkage
ether
what are the differences among the phospholipid structure of archaea vs. bacteria and eukarya
1) ether linkage
2) the lipid part is made of isoprene
how does one polymerize isoprene
,you start with a phosphoglycerol and keep adding morello the chain one by one —> making it a monolayer
why does the monolayer nature of archaea makes them resistant
1) they become more solid and heat resistant
2) instead of dissociating, they always stay together
they lipid bilayer is stabilized by —-
sterols
structure of sterols
polar head (OH) - attached to 4 fused rings - hydrocarbon tail
name of the sterol in
1) animal cells
2) fungi
3) plant cells and some protozoans
1) cholesterol
2) ergosterol
3) stigma sterol
in bacteria and archaea sterols are —-, therefore, they are stabilized by —-
absent, hopanoids
ribosomes are composed of — and —-
DNA, RNA
location of ribosomes in bacteria and archaea
free in the cytoplasm or attached to the cytoplasmic membrane
location of ribosomes in eukarya
free in the cytoplasm or bound to the ER membrane
ribosomes in prokaryotes
50 S + 30 S = 70 S
ribosomes in eukaryotes
40 S + 60 S = 80S
Svedberg unit
describes the rate of sedimentation of a particle in an ultracentrifuge. proportional to the size, shape and density of the particle – relationship is not linear
a cell wall is absent in —- and most —-
animals, protozoans
functions of a cell wall
it forms a tough, rigid, barrier that helps protect the cell and gives it its shape
the cell wall of eukaryotes is usually composed of —-
polysaccharides
name the polysaccharides present in the cell walls of the following:
1) plants
2) fungi
1) cellulose: polymer of glucose
2) chitin: polymer of N-acetylglucosamine
the genome of eukaryotes is packed into —-
chromatin fibre
chromatin fibres are organized into —-
chromosomes
name the 2 types of chromatin
1) euchromatin
2) heterochromatin
euchromatin
loosely packed, actively transcribed, needs to be unwinded for transcription
heterochromatin
densely packed, low level of transcription
Replication and transcription of DNA in eukaryotes occurs in the —-
nucleus
translation occurs in the —-
cytoplasm
where does the mRNA for cytoplasmic proteins travel into for translations
free in the cytoplasm
where does the mRNA for membrane proteins travel to for translation
directed to the ER
what is the endoplasmic reticulum
it is a set of channels and sacs around the nucleus
- main function: conducts specific enzymatic activity
what is the ER composed of
phospholipid bilayer
rough ER
studded with ribosomes, and important for protein synthesis and modification
smooth ER
no ribosomes, involved in the synthesis of lipids
Golgi body
a set of membrane compartments involved in further processing of proteins and their distribution.
how are proteins transported from the Golgi body
they are packages into vesicles
cis Golgi
cis Golgi is on the cis side of the Golgi body and its function is to receive the biosynthetic output from the ER
trans Golgi
on the existing face of the Golgi, where the processed materials leave
most of the ATP required by cells is produced in the —-
mitochondria
structure of the outer membrane of mitochondrion
many porin proteins –> makes the membrane very permeable to small molecules
structure of the inner membrane of mitochondrion
75% proteins, 25% lipids. contains transport proteins, enzymes, cytochromes, ATPase
- produces most of the ATP
Matrix
contains the enzymes for citric acid cycle, DNA and ribosomes (70S)
outer membrane of chloroplasts
porins, similar to mitochondria
inner membrane of chloroplasts
regulated transports of proteins
thylakoid
closed system of interconnecting sacs and tubules, bordered by membranes where most photosynthetic reactions happen
- contains enzymes and pigments that harvest light nrg and the ATPase uses this to generate ATP
stroma
circular DNA, 70S ribosomes, enzymes of the Calvin cycle
In what senses are eukaryotes and mitochondria and chloroplast similar to bacteria
- 70S ribosomes
- double membranes
circular chromosomes
protein filaments that make up the cytoskeleton:
1) microtubules: alpha tubulin
2) actin filament: actin
3) intermediate filaments: keratin, desmin, vimentin
* similar protein filaments are found in non spherical prokaryotes
microtubules grow form the —-
centrosomes
structure of microtubules
helical and hollow
function of microtubules
create a network of roads inside the cell - proteins known as kinesins walk on these, by picking up vesicles from the Golgi, chloroplast, … and taking them to their destinations.
- powered by ATP
- Another protein that uses these paths is dyenin
function of centrioles
act as organizing centres for other microtubules arrays
construction of centrioles
9+0 contractions, with 400 nm and 200 nm arms
- triplets of one complete, and 2 partials arms
centrosomes have —- centrioles
2
basal body
when the centriole is located closer to the cytoplasmic membrane –> essential for flagella and cilia generation
flagella
used by protozoans or other cells for swimming in a liquid
cilia
short extensions that surround the cell for movement
flagella and cilia constructions
9+2 –> 2 extra in the centre
- 9 sets of doubles ( one complete, 1 partial, 2 pariah in the centre)
what are flagella and cilia covered by in eukaryotes
cytoplasmic membrane
what are flagella and cilia covered by in prokaryotes
plasma membrane
role of dyenin
the grab the arms and slide them past each other in a coordinated movement following the microtubules
- creates stress
