Cell Signalling - Monday, May 6

Cell Signalling

Gland - Any structure that secretes a hormone.
Hormone - Any chemical secreted by one part of the body that has its effect/s somewhere else. Two basic Types:
      1. Steroid (Fat-based - non-polar - can diffuse through cell membranes)
      2. Peptide ("Protein" - polar - bond to a receptor protein on cell surface). Pheremones - chemicals excreted by one individual that cause a physiological change in another individual.
  
I. Gonads - Primary sexual structures
           A. Ovaries - produce estrogens & progesterone - responsible for female structure, menstral cycle & pregnancy.
           B. Testes - Testosterone. Responsible for male anatomy, sperm production. How is it regulated? By the hypothalmus (Part of the brain - made up of Neurons) Pituitary (true gland) Negative Feedback System (HPNFS)
      1. Hypothalamus - raises levels of GnRH (Gonadotropin Releasing Hormone)
      2. Pituitary - is signalled by higher levels of GnRH to release LH (a gonadotropin)
      3. Testes - are signalled by higher levels of LH to produce higher levels of Testosterone.
     

Colonies- permanent association of cells, but little or no integration of cell activities.
            Volvox- unicellular green alga, colony is a hollow ball of cells.
Kingdom Protista-
Protists are the most diverse eukaryotic kingdoms.
-There are 15 distinct Phyla of Protists.
     -These are grouped into five general groups based on shared characteristics
        1. Presence/absence of flagella/cilia
        2. Presence and kinds of pigments
        3. The type of mitosis
        4. the types of cristae in mitochondrea
        5. Ribosomes are the same
      -There are five major, subdivided groups.
        1. Ameaboids- Heterotrophs with no permanent locomotor apparatus
        2. Heterotrophs with flagella
        3. Heterotrophs with restricted mobility (slime-molds)
        4. Photosynthetic protists (algae)
        5. Nonmotile spore-formers

5/2/2013

5/2/2013

Based on carbon and energy sources, prokaryotes can be divided into 4 groups

1. Photoautrouphs

• Use energy of sunlight to build organic molecules
• Cyanobacteria

1. Chemoautotrouphs

•  Obtain energy by oxidizing inorganic substances

1. Photoheterotrouphs

• Rare

1. Chemoheterotrouphs

• use organic molecules as carbon and energy sources

Viruses

• Latin for poison
• Non-celklur particle with
• DNA or RNA
• 1 or 2 Protien coats (capsids)
• May have Viral Envelope - Phosholipids

• Do Not respire or grow
• ONLY function in a living cell
• Not given Latin names like living organisms
• 4 Charicteristics - Only have 1 (Genetic material
• Made of cells
• has metabolism
• reproduces on its own
• Genitic material

Virus have 2 different cycles
Lytic cycle

• 1- Virus absorption/ attachment
• 2 - Injection/ entry
• 3- Replication of viral parts
• 4- Assembly of the Virions
• 5- Release by lysis
• cause disease, cell gets taken over and produces more viruses that bust the cell

 Lysogenic Cycle

• Lays dormant in your body, doesn't destroy host cell

Temperate Viruses do both (HIV)

Wednesday May 1, 2013

Forming Life's Building Blocks

• Concerns have been raised about the "primordial soup" hypothesis
• No oxygen=> no protective ozone layer
• therefore, the UV light would have been destroyed and the essential ammonia and methane gases
• Louis Lerman, in 1986, proposed the bubble model
• When the experiment is done one of the things formed is urisil which is found in RNA 

The First Cells

• The first step may have been the formation of tiny bubble termed microspheres 

Structure of Prokaryote

• Prokaryotes are small, simpily organized, single cells that lack a nucleus
• Include bacteria and archaea
• have a cell wall
• composed of peptidoglycan 
• network of polysaccharides linked by peptide cross-links

• bacteria are separated into two groups based on membranes
• Peptidoglycan are in either a thick layer with no outer membrane that will stain (gram-positive) or in a thin layer with an outer membrane that won't stain (gram-negative)
• Hans Christian Gram developed a stain to differentiate between the two
• When cells are stressed they pass their plasmid DNA following cell-to-cell contact
• Based on carbon and energy sources, prokaryotes can be divided into four categories
• 1. Photoautotrophs: Photosynthesizes, or plants. 
• Cyanobacteria: when a lake suddenly has an algae bloom and turns pea soup green, it's not algae, its cyanobacteria

• 2. Chemoautotrophs: use inorganic fuels as their food. 
• For example: nitrogen-fixing bacteria, nitrifiers oxidize ammonia or nitrite

• 3. Photoheterotrophs: Use light as energy and pre-formed organic molecules as carbon sources
• Purple nonsulfur bacteria
• Very Rare

• 4. Chemoheterotrophs: Use organic molecules and energy sources 
• Decomposers and most other types of bacteria.

Kingdom- Animalia
Phylum- Chordata
*Subphylum- Vertebrata
Class-  Mammalia
*Subclass- Placenta
4/30/13
Order- Primate
*Superfamily- Hominoideae
Family- Hominidae
Genus-  Homo
Species-  sapiens
*Subspecies-sapiens
II. 1st Modification
*Sub...and Super... (due to the original system being unable to fit all species being discovered)
III. 2nd Modification
Added "Domain" above kingdom. There are 3 domains of life.
A. Bacteria- Have no internal membranes-no organelles, no nucleus, Peptidoglycan in cell wall, I kind of RNA polymerase, no Introns, no Histones (protein beads that DNA wraps around) in DNA, circular chromosome, different Ribosomes.
B. Archea- No internal membranes, organelles, or nucleus. Circular DNA, no peptidoglycon, several RNA polymerases, Introns, Histones
C. Eukarya- Have internal membranes, nucleus, organelles, no peptidoglycon, rod-like DNA, several RNA polymerases, Introns, and Histones.
Archae and Bacteria are both prokaryotes, but Eukarya and Archea are more closely related to each other.

April 29, 2013

Categorizing Life

I. The Linnaeus Classification System

            Kingdom- eg. Animalia
                       Phylum- Chordata
                               
                               Class-Mammalia
                                     Order- Primates
                                           Family- Hominidae
                                                   Genus- Homo
                                                         Species- Sapiens

04/16/13

(the Carbon Cycle, Image A; the Nitrogen Cycle, Image B)

Nitrogen Cycle Continued:
Legume (any plant with seeds in a pod; examples are: alfalfa, peas)
Legumes have nitrogen fixing bacteria in their roots.
SYMBIOTIC RELATIONSHIP.