Class Notes (811,047)
Canada (494,460)
York University (33,712)
Biology (2,149)
BIOL 1000 (375)
Lecture 6

Lecture 6 - Bacteria.docx

7 Pages
Unlock Document

York University
BIOL 1000
Michael Gadsden

Lecture 6 Recap  KDL system o Apolipo protein can bind to receptors on cell and o Clatherine is the proteins that will bind to endosomes o Changes pH  This causes changes in the holding and releasing of proteins being held by the receptors o KDEL Receptors made in the ER and placed in the ER membrane as they are made and then they advance to the Golgi  Co-translational translocation o Sumanas video site o The ER membrane  Two ribosomal subunits (small and large)  Usually, signal sequence will be brought to the ER via an SRP  The Amino terminus comes first  The signal peptide (sequence/series of amino acids) is made of HYDROPHOBIC amino acids  They more often associate with hydrophobic areas such as membranes (like the phospholipid membranes)  SPECIFIC SEQUENCES DIRECT PROTEINS IN SPECIFIC AREAS  Signal sequence gets stuck in the ER membrane while the rest of the protein is secreted into the ER Lumen  The signal peptide is then cleaved off by a signal peptidase  If there is >1 hydrophobic sequence of aa (specific sequences) it would also become stuck in the membrane  See sheet (Christo’s)  This is how the receptors stay in as well as outside of the ER lumen  This is called the Stop Transfer Patch (or Stop Transfer Sequences)  Thus, there can be multiple start transfer and stop transfer sequences leading to multiple (several) transmembrane sequences on the polypeptide  On the membrane something can go through several times  See sheet  Many eukaryotic plasma membrane proteins are glycoproteins (REMEMBER THESE ARE SPECIFIC!)  Remember the sugars are INSIDE THE VESICLE but OUTSIDE THE CELL Bacteria  RECALL: DO NOT CALL ARCHAEA BACTERIA  “All cell biologists have at least two cells of interest, what they’re studying and E. coli” o This is because E. coli can be used as a vehicle of gene expression  Morphologies o See Sheet o The size range is generally 200nm  750 µm  E. coli o is approximately 1 by 2µm o ROD shaped o Multi-flagellate o Different Strains of E. coli  Culturing Cells o Liquid medium (broth)  Media have all the nutrients required for cell growth  Rich Media – an excess of nutrients, therefore no starvation risk o Rapid growth (shortest Generation time) o This occurs until growth stops due to the lack of nutrients  This elongates replication time  Waste also begins to accumulate and due to its acidic nature, the pH decreases and can be toxic  pH changes can cause immense problems such as death  pH is important for protein and macromolecule structure and thus the activity o Even in a rich media there is a limit to growth  See Growth curve on sheet  1) Lag phase: Making proteins, DNA, RNA to grow  2) Log or Exp Phase: DOUBLING a lot  3) Stationary phase: no real division, no pop growth  4) Death Phase  Some bacteria can form spores (hard membrane and cell wall – impervious to outside particles) that provides protection of molecules (like DNA) from environmental damage  No growth, but no molecular degradation  When good conditions return  cell returns to the vegetative or growing state  Most cells are strictly vegetative  Some spores have been re-vegetated from after ~2500 years as a spore  Minimal Media o Very basics and limited amounts of the nutrients o Therefore the generation time increases o Cell concentration (i.e. at stationary phase) decreases o Used when you (scientist) need to know EXACTLY what’s in the media  Selective media: o Trying to select for a particular cell type, trait or characteristic o Can be rich or minimal o E.G. selecting E. coli with plasmids with extra-chromosomal DNA often carries anti-biotic resistant genes  NB: extra-chromosomal DNA is parts of DNA not attached to the chromosomes o An example of this is a rich or minimal medium with ampicillin (this will kill all the cells without the plasmids)  This is called the “SELECTIVE PRESSURE” o Solid medium (agar plate: Broth + agar = gel like)  This is used to see where the colonies are, and they can be easily seen  See sheet for drawing
More Less

Related notes for BIOL 1000

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.