monday, february 25th
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Monday, February 25th. Thank you for submitting your quizzes! Friday’s Enzyme Lab: You must have your Question, Prediction, Hypothesis, Materials and Procedure by Thursday (see chart paper posted around the room) Today: Lecture #5. Enzyme Lab. - PowerPoint PPT PresentationTRANSCRIPT
Monday, February 25thThank you for submitting your quizzes!
Friday’s Enzyme Lab: You must have your Question, Prediction, Hypothesis, Materials and Procedure by Thursday (see chart paper posted around the room)
Today: Lecture #5
Enzyme LabQuestion: How does temperature affect enzyme
function?Prediction: Temperature will have a negative effect
on enzyme function.Hypothesis: As temperature increases, enzymes will
begin to denature.Tests/Experiments (Procedure): Design a
procedure that is based on your prediction, hypothesis and prior knowledge to observe an expected result. If we increase the temperature of this liquid, the enzyme will not function. (need to know the variables)
VariablesVariables are all of the factors involved in a reaction.
Examples:Time, amount, size, temperature, weight, height, type
of chemicalIn order to understand how a variable influences a
reaction, it must be isolated from all other variables.Dependent Variable: is the measureable or
observed outcome of the experiment. It depends on what happens to the independent variable. There is the possibility of multiple variables, but not if an experiment is controlled properly.
Variables cont’dIndependent VariableIs the factor that is isolated from all other variablesIt is manipulated or changed in order to observe an
expected result.There should only ever be ONE independent variableControl VariablesRemain the same for every trial or test in the
experimentThere are always several variables that must be
controlled.
Cell Structure and Function
Cell StructuresJust as our organs complement each
other in both form and function, so do the organelles in eukaryotic cells
We will focus on the organelles inside eukaryotic plant and animal cells
All organelles are found within the cytosol of the cell and it’s all held in by the plasma membrane
Nucleus Consists of two main parts: the nuclear envelope and the nucleolus
Contains ALMOST all the DNA in a cell
The nucleus protects the DNA from the metabolic reactions that happen in the cytosol that could damage it
Nuclear EnvelopeDouble membraneConsists of two lipid bilayers folded
togetherThe outer layer is connected to the rough
endoplasmic reticulum Two kinds of membrane proteins are
embedded in the lipid bilayers (receptors and transporters) which work to transport molecules across the membrane
NucleolusA dense and
irregularly shaped region
Creates subunits of ribosomes from proteins and RNA
The Endomembrane SystemA group of interacting organelles found between the nucleus and the plasma membrane
Main function is to make lipids, enzymes and other proteins that are found in cell membranes
Also specializes in destroying toxins and recycling wastes
Endomembrane System Organelles Rough Endoplasmic Reticulum: translates RNA in the cytosol into polypeptide chains by ribosomes found on the rough ER
Vesicles: bud off of the rough ER and carry some of the new proteins to the golgi body
Endomembrane System Organelles Smooth Endoplasmic Reticulum: take
some polypeptide chains from the rough ER as enzymes which produce most of the cell’s membrane lipids, as well as breaking down carbohydrates, fatty acids and some drugs and poisons
Golgi Body: modifies proteins arriving from the rough ER into their final form, then sorts and sends them to the plasma membrane or lysosomes
MitochondriaProduce ATP (Adenosine triphosphate
– a coenzyme used in cells containing chemical energy) in a series of reactions that require oxygen
Contain their own DNA and ribosomes and divide independently of the cell – making scientists believe they evolved from aerobic bacteria that took up permanent resident in a host cell
Mitochondion
PlastidsUsed for photosynthesis or storage
in plant cells for example:Chloroplasts specialize in
photosynthesis by catching light energy
Chromoplasts make and store pigments (other than chlorophyll) that colour flowers, leaves, fruits and roots
Amyloplasts store starch grains in stems and seeds
Chloroplast: Type of Plastid
Cell MembraneSemipermeable membrane allows
the uptake of nutrients and the elimination of wastes
Current views of membrane structure are based on the fluid mosaic model – membranes are not rigid with molecules locked into place, but consist of lipid molecules in which proteins are embedded and float freely
Role of the PhospholipidsPolar (hydrophilic)
heads stick together on both sides
Non-polar (hydrophobic) tails stay in the middle to spontaneously form a bilayer
Role of Membrane ProteinsLipid molecules are the backbone of the membrane, but the proteins associated with it determines function and makes it unique
Proteins are responsible for: transport, enzymatic activity, triggering signals, attachment and recognition