Lecture 2a- 15 September 2014

Main components of this lecture are:    a) overview of metabolism

    b) the cell and how it works in metabolism

    c) digestion and how it contributes to metabolism

A note-taker has been requested.  The note-taker is a student in this class who simply photocopies (a photocopier is available here at the centre) their notes or emails them to the Centre if they are typed. This happens from the beginning of the term and continues to do so for the remainder of the semester.  They will be paid $100 at the end of the term for hand written notes or $150 for typed notes. 

•It is most important that the notes are legible and complete.

•Any interested students to come to the Jennifer Keeping AccessAbility Centre, where the process will be further explained to you. 

•If you have any questions, please feel free to ask.

Outline of lecture 2a

a) Overview of Metabolism        -definition        -catabolism        -anabolism        -metabolic regulation                    - why is regulation necessary?

Metabolism cannot take place without the cell        b) The cell    -required as a location to house some metabolism and to produce components for metabolism no matter where such metabolism occurs

    -specific aspects of metabolism occur at specific points in the cell

    -must know where metabolism occurs to understand what is happening and why

The cell    - cell components                -plasma membrane                -cytoplasmic matrix                -mitochondrion                -nucleus                -endoplasmic reticulum                -golgi apparatus                -lysosomes and peroxisomes

The cell       -cellular proteins

                -receptors and intracellular signalling

                -transport proteins

                -catalytic proteins

The cell        -apoptosis

             -programmed cell death   

-cellular enzymes that take the cell offline-implications for disease

c) digestion and how it contributes to metabolism

         -cells are essential for digestion

        -overview of the structure of the digestive tract

        -structures of upper gastrointestinal tract

        -structures of lower gastrointestinal tract and accessory organs

-coordination and regulation of digestive processes

                -regulatory peptides                -neural regulation 

-the process of digestion-secretions and enzymes required for nutrient digestion

                -oral cavity

                -esophagus

                -stomach

                -small intestine

                -colon or large intestine 

More detailed commentsa) Overview of Metabolism        -metabolism definition-sum total of all

chemical reactions that occur in living cells

         - however the focus of this course in on metabolism as it relates to nutrition

         -consequently energy metabolism and its regulation will be the focus of this course

         -energy metabolism - how the body obtains and uses energy-yielding nutrients after they are absorbed

Energy metabolism-eg glucose from carbohydrates, glycerol and fatty acids from fat digestion and amino acids from proteins

- is this really representative of energy metabolism?

-catabolism-energy-producing reactions that occur as the result of breakdown of energy yielding nutrients-eg glucose from carbohydrates, glycerol and fatty acids from fat digestion and amino acids from protein

Energy metabolism

-anabolism-energy-using reactions that may be used to build carbohydrates, lipids, proteins and participates in the synthesis of a wide variety of molecules in the body.-eg-glycogen synthesis from glucose, triglyceride synthesis from fatty acids and glycerol, protein synthesis from amino acids.

Energy metabolism

-metabolic regulation

        -what is metabolic regulation?-orderly control of metabolic processes so that molecules are available for use when  they are needed, in the form they are needed, where they are needed, and in the quantities they are needed

Catabolic rate =anabolic rate in healthy persons-can you think of 2 exceptions to this equality?

Energy metabolism

why is regulation necessary? molecules would not be available for use when they are needed, in the form they are needed, and where they are needed and in the quantities that are needed. Catabolic rate = metabolic rate

      -note that vitamins, minerals and water assist in the regulation of energy metabolism. Water and vitamins are metabolised as the result of the metabolism of energy yielding nutrients. Such metabolic results will not be the focus of this course.

Metabolism cannot take place without the cell

b) The cell    -required as a location to house some metabolism and to produce components for metabolism no matter where such metabolism occurs

    -specific aspects of metabolism occur at specific points in the cell

    -must know where metabolism occurs to understand what is happening and why

 

Cell components  -plasma membrane

-give cell shape and separate it from extracellular environment

        -protection for cellular contents        -allows for cellular stimulation, nourishment

and excretion of cellular wastes        -bag for cell contents        -membrane proteins act as pumps, gates,

receptors, energy transducers and enzymes

        -made up of lipids, proteins and carbohydrates

 

Cell components

-cytoplasmic matrix or cytoplasm or cytoplast

-has microtrabecular lattice and fluid environment

         -site of glycolysis, hexose monophosphate shunt, glycogenesis and glycogenolysis,

and fatty acid synthesis 

Cell components

-mitochondrion(mitochondria)

-generation of most of adenosine triphosphate (metabolic energy)

          -oxidative metabolism(catabolism) of

carbohydrate, lipids and proteins

Cell components

-nucleus

-contains DNA-the brains of the operation

-DNA initiates and regulates most cellular activities

 

Cell components

-endoplasmic reticulum-network of membranous channels in cytoplast                                                  

-rough-has ribosomes                                      - protein synthesis

                           -smooth-no ribosomes                                         -lipid synthesis

-golgi apparatus-trafficking and sorting of proteins  

Cell components

-lysosomes-digestion of lipids, proteins and polysaccharides within the cell                                                  

-peroxisomes-fatty acid oxidation and amino acid catabolism 

Cell components

-cellular proteins

        -receptors and intracellular signalling                       

eg insulin docks to its receptor and sets up a series of intracellular signalling processes by which glucose is

transported into the cell. 

Cell components

-cellular proteins

-transport proteins-regulate flow of nutrients into and out of cell

                            -can be carriers, pumps or pores 

Cell components

-cellular proteins

-catalytic proteins

            -enzymes that result in reactions taking place more easily in the body

             -are all enzymes contained in cells? 

The cell-apoptosis

                -programmed cell death- certain enzymes take the cell offline-implications for metabolism and health?- why not just have cells live on forever and reproduce forever?