Exam 1

BIOL 224 MT I Guide Fall 2022 

Define Physiological Homeostasis

• Maintenance of a relatively constant physiological environment despite constantly changing ambient conditions

Understand and use common examples to two describe the two types of feedback mechanisms

• Negative Feedback
  • Definition: maintains a fairly constant level of a physiological variable
  • Blood sugar regulation blood glucose rises, and insulin is secreted up until equilibrium is reached
• Positive Feedback
  • Definition: increase in a variable stimulates a further increase until the stimulus removed
  • Baby sucking on mother's breast stimulates milk production which causes further feeding

 Describe and provide an example of the three types of chemical bonds as discussed in the lecture

• Ionic Bonds: Sharing of the smaller valence electrons between two or more atoms

  • NaCl

• Covalent Bonds: Sharing of electrons between two or more atoms

  • CH4

• Hydrogen Bonds

  • form due to the attraction of the hydrogen atom of one molecule for a strongly electronegative atom (N, O, F) in an adjacent molecule H2O
  • H2O

What is the definition of an Acid or Base?

• Acids are proton donators 
• Bases are proton acceptors

How is the pH scale measured?

• pH is from 1-14
• 1-6 is an acid
• 8-14 is a base

What are the four major kinds of organic biological polymers and what are the monomeric subunit that comprises them?

• Carbohydrates; Monosaccharides
• Lipids; Fatty acids and 3 glycerols (triglycerides)
• Protein; amino acids
• Nucleotides; nucleic acids

How are the covalent bonds that link biomolecules formed?

• It is created by a process of dehydration synthesis in which a water molecule is released

What is a phospholipid and why are these molecules so important to cellular structure and physiological function

• Phospholipids are amphipathic molecules meaning it's a chemical substance that reduce the surface tension of water
• In terms of cellular function, it's a component in the plasma membrane called a phospholipid bilayer. Protection from the outside environment

Be able to draw and label the components of a typical animal cell

** **

• Cell membrane:
• Cytoplasm: gel-like matrix in lattice/netword of fibrous protienms 
• Cytoskeleton: same
• Lysosomes: sac of digestive enzymes
• Peroxisomes: H2O2 producing enzymes
• Mitochondria: cellular energy (ATP)
• Endoplasmic Reticulum: Manufacture, storage
• Golgi apparatus: packaging, distribution
• Nucleus: DNA envelope

Describe the Structure, chemical nature and properties of the plasma membrane

• The plasma membrane consists of a phospholipid bilayer and special protein carriers
• The plasma membrane acts as a barrier which is also semi-permeable to some small molecules via AQUAPORINS. Special protein carriers allow impermeable molecules to come through via Active transport

What is the central dogma of biology?

• Genetic Control is the central dogma of biology

What is an enzyme?

• An enzyme is a catalyst that speeds up chemical reactions in biological systems

Describe the “lock and key” model for reactions.

• Enzymes are substrate-specific so only certain substrates can fit in the enzyme

Bioenergetics: Coupled reactions, how does the body derive usable energy from the compound ATP?

• ATP Hydrolysis is the process in which ATP is catabolized into ADP+Pi via an enzyme 
• Energy is released from the phosphate bond

REDOX reactions: using NAD, and NADH + H+, FAD and FADH2 as examples  describe how electrons are transferred to couple a set of reactions (i.e., Kreb’s  cycle and ETS = electron transport system

• The Krebs cycle produces reducing equivalents NADH+(H+), and FADH2 which it is sent to the electron transport chain

Cellular respiration (1 molecules of glucose = ???)

•  1 molecules of glucose produces 32-36 ATP

What is the first step in the chain of cellular reactions that catabolize glucose?

• Glucose is broken down in glucose 6-phosphate?

Where does glycolysis take place in the cellular environment?

• It takes place in the cytoplasm of the cell

Name the 3-carbon product of glycolysis in the absence of adequate oxygen.

• Pyruvate or pyruvic acid

Where (i.e., what organelle) are the enzymes for Kreb’s cycle and ETS located? 

• Located in the mitochondria

Define oxygen debt. 

• The oxygen consumed above the resting resting levels required to process products on anaerobic respiration

How does an individual maintain or increase energetic output above VO2 max? 

• ASL OAWKD

Membrane transport mechanisms; Compare and contrast

\n \n

Primary vs secondary active transport

• Primary uses sodium-potassium pumps (Na+/K+ATPases)
• Secondary uses glucose-Sodium pumps (Glucose/Na+)

What is the resting membrane potential?

• About -61mv (millivolts)
• The resting membrane potential is charge differential between both sides of the membrane resulting in a slight negative charge inside and positive outside.

How is it measured?

• It is measured Via the net positive charge outside and the net negative charge inside the cell
• \

How is it maintained?

• It is maintained via Na/K+ pumps and the semi-permeability of the plasma membrane

• As concentration increases inside the cell more is pushed out resulting in an equilibrium

  \n

What are the principle ions involved in establishing it?

• The principle ions are sodium, potassium, and chloride

  \n

What does the Nernst equation predict? Is it realistic?

• The Nernst equation predicts the potential voltage across the membrane that prevents net movement of a single ion in either direction
• ASK PROFFESOR

Define the equilibrium potential for a single ion.

• The voltage produced if one ion were able to diffuse through the membrane

What are the 2 broad chemical and functional classes of hormones as described in the lecture?

1. Peptide Based hormones Protein Based hormones

• 2nd Messenger system

  \n

1. Direct Gene activation

• Lipophilic hormones

How do peptide & protein-based hormones stimulate intracellular responses?

• The first messenger binds to G protein-coupled receptor which then releases a g-protein subunit that binds/activates Adenylate Cyclase. In which the second messenger is released 

Contrast the mechanism you described above with that of lipophilic 

\n

Which of these 2 categories of hormones is faster acting? Why? 

• The second messenger system is faster because everything is already in place, all it needs to do is have it's on switch flipped then everything activates one after another.

List the primary endocrine glands of the body. Briefly describe the regulatory role of each. 

• Pineal: secrets melatonin to regulate day/night cycle
• Pituitary gland: controlling growth and development and the functioning of the other endocrine glands
• Hypothalamus: manages hormones
• Thyroid: controls the rate of many activities in your body
• Parathyroid: controls calcium levels in your blood
• Thymus: producing and maturing lymphocytes, or immune cells.
• Adrenals: produce hormones that help regulate your metabolism, immune system, blood pressure, response to stress, and other essential functions
• Pancreas: enzymes break down sugars, fats, and starches
• Ovaries: control your menstrual cycle and pregnancy
• Testies:  responsible for sex drive, fertility, and the development of muscle and bone mass.
• Kidneys: renin, which keeps blood pressure normal
• Gi Tract:  regulation of secretion, absorption, digestion, and gut motility

Why is describing the pituitary as the “master endocrine gland” somewhat inaccurate/misleading?

• The hypothalamus really the master gland in managing hormones

  \n

How are adenohypophyseal/anterior pituitary hormones regulated?

• These are regulated by negative feedback

What are the primary tropic hormones secreted by the anterior pituitary? 

• TSH (thyroid stimulating hormone), ACTH (Adrenocorticotropic Hormone), and FSH (follicle stimulating, LH(luteinizing hormones)

How is the secretion of these hormones regulated in each case?

• Regulated by the release of (Releasing Hormones and Inhibiting Hormones) via hypothalamic control

  \n