Biology Do Now 2-25-19 Directions: Take out a sheet of notebook (Do Now sheet) and, then answer each question based on Friday’s lab.   What was the name of the enzyme we used in Friday’s lab? What was the source of the enzyme we used in Friday’s lab? What factors did we expose the enzyme to (think of the hypotheses you tested)? Which factor did the enzyme work the best (OPTIMUM)? Which factor did the enzyme work the worst?

Biology Do Now 2-25-19 Key What was the name of the enzyme we used in Friday’s lab? catalase What was the source of the enzyme we used in Friday’s lab? potato What factors did we expose the enzyme to (think of the hypotheses you tested)? pH, salt, temperature (hot/cold) Which factor did the enzyme work the best (OPTIMUM)? In the presence of salt, catalase produced lots of bubbles. Which factor did the enzyme work the worst? In the presence of hot temperatures, catalase did not produce bubbles.

Objective Students will know the structure and functions of positive and negative feedback loops, cell membrane and the delivery of water to cell through osmosis by taking notes, comparing/contrasting cells and completing a POGIL on membranes. Mastery level: 75% or better

Vocabulary Words Feedback loop Positive feedback loop Negative feedback loop Cell membrane Semipermeable/selectively permeable Bilayer Phospholipid Hydrophilic head (phosphate) Hydrophobic tail (fatty acid) Transport Osmosis Receptor Effector Stimulus

TAKE OUT A SHEET OF PAPER. ON THE NEXT SLIDE ARE THREE CELLS TAKE OUT A SHEET OF PAPER. ON THE NEXT SLIDE ARE THREE CELLS. HOW ARE THEY ALIKE? HOW ARE THEY DIFFERENT?

Sample answers similarities differences Cell membrane DNA Cytoplasm Structures inside 1 doesn’t have a cell wall 1 has a tail 1 doesn’t have a nucleus 1 has a nucleoid

HOMEOSTASIS & FEEDBACK LOOPS Biology 2/25/19

WHAT IS HOMEOSTASIS? the maintenance of a constant internal environment in response to changes in:

HOW IS HOMEOSTASIS ACHIEVED? structural: the animal or plant has particular physical features which help its survival in an otherwise hostile environment.

HOW IS HOMEOSTASIS ACHIEVED? functional: the metabolism of the animal or plant is able to adjust to changes in conditions as they are detected.

FEEDBACK MECHANISMS Feedback mechanisms are the general mechanism of regulation (control) in animals. Negative feedback is when the response diminishes (decreases) the original stimulus. Positive feedback is when the response enhances (increases) the original stimulus.

FEEDBACK LOOPS Stimulus: The change from ideal or resting conditions. Receptor: The cells or tissue which detect(s) the change due to the stimulus. Relay: The transmission of the message, via nerves or hormones or both, to the effector.

FEEDBACK LOOPS Effector: The cells or tissue which cause the response to happen. Response: An action which occurs because of the stimulus. Feedback: The consequence (result) of the response on the stimulus

Negative Feedback -

Positive Feedback +

Negative feedback is most common in biological systems.

Negative Feedback

Examples of Negative Feedback Blood glucose concentrations rise after a sugary meal (the stimulus), the hormone insulin is released and it speeds up the transport of glucose out of the blood and into selected tissues (the response), so blood glucose concentrations decrease (thus decreasing the original stimulus).

Examples of Negative Feedback Exercise creates metabolic heat which raises the body temperature (the stimulus), cooling mechanisms such as vasodilatation (flushed skin) and sweating begin (the response), body temperature falls (thus decreasing the original stimulus).

Positive feedback is less common, which is understandable, as most changes to steady state pose a threat, and to enhance them would be most unhelpful.

Examples of Positive Feedback A baby begins to suckle her mother's nipple and a few drops of milk are released (the stimulus). This encourages the baby and releases a hormone in the mother which further stimulates the release of milk (the response). The hungry baby continues to suckle, stimulating more milk release until she stops.

Examples of Positive Feedback A ripening apple releases the volatile plant hormone ethylene (the stimulus). Ethylene accelerates the ripening of unripe fruit in its vicinity so nearby fruit also ripens, releasing more ethylene (the response). All the fruit quickly becomes ripe together.

Cell Membrane (Transport) Notes Cell Membrane and Cell Wall: ALL cells have a cell membrane made of proteins and lipids Cell Membrane lipid bilayer protein channel protein pump Layer 1 Layer 2 SOME cells have cell membranes and cell walls – ex: plants, fungi and bacteria Cell Membrane Cell Wall

Plant cells have a cell wall made of cellulose – that cellulose is fiber in our diet Bacteria and fungi also have cell walls, but they do not contain cellulose Cell membranes and cell walls are porous allowing water, carbon dioxide, oxygen and nutrients to pass through easily

Function of the Cell Membrane: Cell membrane separates the components of a cell from its environment—surrounds the cell “Gatekeeper” of the cell—regulates the flow of materials into and out of cell—selectively permeable Cell membrane helps cells maintain homeostasis—stable internal balance

Passive Transport A process that does not require energy to move molecules from a HIGH to LOW concentration Diffusion Facilitated Diffusion Osmosis

Diffusion is the movement of small particles across a selectively permeable membrane like the cell membrane until equilibrium is reached. These particles move from an area of high concentration to an area of low concentration. outside of cell inside of cell

HIGH to LOW concentration Diffusion HIGH to LOW concentration

Semi-permeable membrane is permeable to water, but not to sugar Osmosis is the diffusion of water through a selectively permeable membrane like the cell membrane Water diffuses across a membrane from an area of high concentration to an area of low concentration. Semi-permeable membrane is permeable to water, but not to sugar

Membrane Structure & Functions POGIL Students will need to work in groups of 4 to complete the POGIL and decide who will serve in the following roles: facilitator (manager), spokesperson (presenter), process analyst (reflector/strategy analyst), quality control (recorder).