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INTRODUCTION TO INTRODUCTION TO UNIT ONE BIOLOGY: UNIT ONE BIOLOGY:
UNITY AND DIVERSITYUNITY AND DIVERSITY
Teachers: Ms Archer
Email: [email protected]
Office location: Senior Centre
Area of Study 1: Cells in ActionArea of Study 1: Cells in Action
On completion of this unit the student should be able to design, conduct and report on a practical investigation related to cellular structure, organisation and processes.
Key knowledge – Area of study Key knowledge – Area of study 11
•cell structure: prokaryotic and eukaryotic cells at light and electron microscope levels; cellular organisation;
•cell functioning: specialised parts of cells and their functions; biochemical processes including photosynthesis and cellular respiration in terms of inputs and outputs; general role of enzymes in biochemical activities of cells;
•composition of cells: major groups of organic and inorganic substances including carbohydrates, proteins, lipids, nucleic acids, water, minerals, vitamins; their general role in cell structure and function;
•internal and external environments of cells; plasma membranes; membrane transport including diffusion, osmosis, active transport; surface area to volume ratio;
•cell replication: purposes of cell replication (mitosis and cytokinesis); cell growth, cell size and cell division.
Area of Study 2: Functioning organisms
On completion of this unit the student should be able to describe and explain the relationship between features and requirements of functioning organisms.
Key knowledge – Area of study Key knowledge – Area of study 22
Common requirements of living things • obtaining nutrients: organic and inorganic requirements;
autotrophs; heterotrophs • obtaining energy: inputs and outputs of photosynthesis;
structural features of photosynthetic organisms • processing nutrients: features of effective systems in
heterotrophs; examples of systems in different animals • distributing materials: features of effective transport
systems; examples of transport systems in multicellular organisms
• removing wastes: nature of waste products and toxic substances; excretory mechanisms and systems
• exchanging gases: features of effective surfaces of gaseous exchange; mechanisms and systems of gaseous exchange in multicellular organisms; process of diffusion;
Reproduction: asexual and sexual reproduction; mechanisms and systems of reproduction in unicellular and multicellular organisms;
Key science skillsKey science skills
Investigate and inquire scientifically:Formulate questions/hypotheses, experimental design, evaluating results, presenting, recording and analysing data, drawing conclusions, acting responsibly and safely
Apply biological understandings:new contexts, make connections between concepts, solve problems, analyse issues, evaluate reliability of information
Communicate biological information and understandingsInterpret and communicate information, use scientific terms and conventions, adapt to audience and purpose
AssessmentAssessmentYour level of achievement in Unit 1 will be determined by:
For Outcome 1: design, conduct and report on a practical investigation
related to cellular structure, organisation and processes.
For Outcomes 1 and 2: at least three from the following: practical activities multimedia or web page presentation; response to a media article; oral presentation; annotated poster; data analysis; problem solving; test, multiple choice and/or short answer and/or extended
response.
Assessment overviewAssessment overview•O
utcome 1: Area of Study 1 Practical investigation – 20%
•Outcome 2:
•AOS 1 Project – 20%•AOS 2 Project – 20%•Other practical reports – 20% (NB. You need to complete at least 80% of set pracs and your mark will be based on this. If you submit more than the quota, the others will be added on as bonus marks. If you submit less, you will be given zero for the ones under the quota and this will affect your overall mark•Tests and Exam- 20%
EL: To find out what you already know about cells and re-introduce you to the microscope
CELLS IN ACTION 1
Important Information!!!!
You’ll need to work out of both chapter 1, 2 &3 over the next few weeks, so please bring all of them to every class.
What do we already know?
•The biosphere is made up of all the worlds ecosystems.
•Ecosystems are made up of biotic communities and their interactions with abiotic factors.
•Communities are made up of different populations (one type of species in an area)
•Populations are made up of a particular organism.
What now?
•What makes up an organism?
•How do organisms live?
•We our now going inside the organism from the macro to the micro.
Body Tube
Nosepiece
Objectives
Stage Clips
Light
Ocular lens(Eyepiece)
Arm
Stage
Coarse Adjustment
Fine Adjustment
Base
Diaphragm
How to use a microscope1. Carry the microscope by the handle and the base.
2. Begin with the lowest power lens.
3. Put the slide on the stage.
4. While looking from the side, move the objective lens close to the slide. It MUST NOT touch the slide.
5. Keep looking through the eyepiece. Focus by moving the objective lens UP. Use the diaphragm to adjust the light if needed.
6. Look at the slide and move the lens to the next highest power, being careful not to break the slide. Re-establish your focus.
7. Look at the slide and move the lens to the next highest power, being careful not to break the slide. Re-establish your focus – you should only need to use the fine adjustment knobs at this point.
To calculate the power of magnification, multiply the power of the ocular lens by the power of the objective.
What would be the magnification power of these two lenses?
What’s my power?
We can see better details with higher the powers of magnification, but we cannot see as much of the image.
Which of these images would be viewed at a higher power
of magnification?
Comparing powers of magnification?
What microscopes see
and units of measurment
Activity
•Complete Activity 1.1 (Nelson Biology Activity Manual) and hand in completed worksheets as part of your prac assessment
•Early finishers/Homework (you’ll also get time next lesson):• Read Chapter 1 pages 10-18• Copy key ideas from page 18• Complete and self correct
• qu 8-11 on page 18• Biochallenge qu 1-6 page 19• Chapter review question 2,3, & 4
Reflection
•Rate your current knowledge and understanding on a scale of 1 (terrible) to 10 (awesome) on:
• Cells• Microscopes
EL: To continue to develop our microscope skills and learn about how to section a specimen
CELLS IN ACTION 2
Activity
•Finish Activity 1.1 “Microscopes and cells” (Nelson Biology)
•Activity 1.2 PART B, task 3 - answer qu 11-13 (Nature of Biology)*
•Activity 1.1 “What’s in a shape” – answer qu 1-6 (Nature of Biology)*
*For both activities, you need to answer the questions onto loose leaf and hand them in for assessment
•Early finishers, please go on with chapter one questions from last class
Reflection
•How are your microscope skills progressing?
EL: To begin learning about cells and the types of cells
CELLS IN ACTION 3
CELL THEORY• All living things are made cells – they are the building blocks from
which living things are made.
• New cells are produced from existing cells.
History of cell discovery•R
ead Chapter 1 pages 6-9 (up to life span of cells)
•Complete a timeline of discoveries with the key people and discoveries
Where do cells fit in to the bigger picture?
Where do cells fit in to the whole organism?
ATOM
CELL
TISSUE
ORGAN
MOLECULE
ORGANELLE
ORGANISM
One cell or many?•S
ome organisms are one cell (uni cellular)
•Other organisms have more than one cell (multi cellular)
Prokaryotes vs Eukaryotes•R
ead Chapter 2 page 24 “Looking at cells” and complete a Venn diagram of the similarities and differences between prokaryotic and eukaryotic cells
http://www.flickr.com/photos/sprinkles123/3971395958/
Prokaryotes vs Eukaryotes
Prokaryotes and Eukaryotes•P
rokaryotic
• Very small: less than 2m in diameter
• Lack membrane bound organelles
• Circular DNA (not in a nucleus)
• Bacteria and archaeans
•Eukaryotic
• Much larger: 10-100m in diameter
• Have membrane bound organelles
• Linear DNA in a nucleus• Animals, plants, fungi and
protists
Activity/homework
•Read “Life span of cells” – Chapter 1 page 9
•Complete Chapter 1 questions 1-6 on page 9 (Chapter 1) & Ch 2 Biochallenge qu 1 on page 47
Reflection
•What was your key learning about cells today?
EL: To learn about types of eukaryotic cells and observe them using the microscopes
CELLS IN ACTION 4&5
Eukaryotes: Producer vs consumer cells
•We know about producers (autotrophs) and consumers (heterotrophs)
•What would producer and consumer cells have in common and what would they have that would be different.
EUKARYOTIC CELLS
Protist
Plant vs Animal Cells•L
ook at the diagram in Chapter 2 on page 41
•Complete a Venn diagram of organelles shared by both types of cells and organelles that are only found in plants or in animals
Plant cells vs animal cells
Plant vs Animal Cell
Plant cell - onion
Animal cells
Microscope drawing
DOES NOT have to be a work of art, but should be detailed
MUST be done in greylead – NO COLOUR!!!!
Magnification should be shown (e.g. x 40)
Should have a heading and RULED labels
Can also include a written description
ACTIVITY
•Complete Activity 1.2 “Investigating Cells” (Nelson)
•Hand in your completed worksheets as part of your prac assessment
•You may have some time next lesson to complete this task, but there are some questions you could also complete for homework
Reflection
•How are your microscope skills progressing?
•What is the key knowledge you gained today?
EL: To begin learning about eukaryotic cell structure and function, and the molecules they
are made of
CELLS IN ACTION 6
What is a cell?
CELL BOUNDARY (PLASMA MEMBRANE)
INTRACELLULAR AQUEOUS
ENVIRONMENT – CYTOSOL
EXTRACELLULAR AQUEOUS
ENVIRONMENT
A fluid filled compartment containing atoms and molecules
WHAT IS A CELL?
Outputs: useful products for export
(biomacromolecules)
Chemical reactions between inputs driven by
energy in response to external/internal signals
Inputs(small molecules)
Signals
Output: waste products
A chemical factory
Outputs: useful products for export
(biomacromolecules)
WHAT IS A CELL?
Outputs: useful products for export
(biomacromolecules)
Chemical reactions between inputs driven by
energy in response to external/internal signals
Inputs(small molecules)
SignalsOutput: waste products
A chemical factory
Outputs: useful products for export
(biomacromolecules)
CELL STRUCTURE: MEETING THE NEEDS OF MOLECULES
•Molecules need to:• move in and around cell at a certain rate to reach sites of specific activity (ie where they will react with other molecules)
• be in adequate concentrations (ie there needs to be enough of them) for chemical reactions to occur at the right rate.
•Cell structure therefore needs to facilitate the movement of molecules and maintain them in adequate concentrations to maintain cell function (ie so the cell doesn’t die)
Organelles•L
arge eukaryotic cells increase their surface area by having folded membranes and internal compartments called organelles
•Organelles also allow different chemical reactions to occur at the same time in different places without interfering with each other
•Organelles maintain the concentration of molecules at levels that ensure they will react with each other at optimum rates
What are cells made of?
Six atoms make up most of the matter in living organismsCarbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus
These atoms can combine to form large molecules
Molecules
Non-polar molecules•Molecules that have no overall charge are called non-polar. •They are not attracted to water molecules and are described as hydrophobic (water fearing)
Polar molecules•Molecules that have regions of positive and/or negative charge are called polar. •They are attracted to other polar molecules, like water, and are described as hydrophillic (water loving)
Water molecules
•Cells contain and are surrounded by water molecules – H2O
•Many reactions occur more easily in solution, and water is the main solvent in living things
•Water is called a polar molecule Each hydrogen atom is linked to the oxygen
atom by a strong covalent bond The oxygen atom attracts the electrons it shares
with the hydrogen atoms more strongly This makes the oxygen atom slightly negative
and the hydrogen atoms slightly positive ()
Water moleculesThe slightly negative () oxygen atom of one water molecule attracts the slightly positive () hydrogen atom of another water molecule - this is called hydrogen bonding and is weaker than the covalent bonds inside the water molecule
Organic molecules
•Many molecules contain carbon due to its ability to form strong stable covalent bonds with carbon and other atoms
•Each carbon atom can form four covalent bonds – these bonds can be single (saturated), double or triple (unsaturated)
•Carbon, oxygen and hydrogent based compounds are called organic molecules
BIOMACROMOLECULESLarge organic molecules that are integral to the structure and function of cells are called biomacromolecules.
There are four types:
Carbohydrates Proteins
Lipids Nucleic acids
BIOMACROMOLECULES
Cells make biomacromolecules from smaller subunits, calles monomers
Each kind of biomacromolecule has characteristics or properties that make it effective for carrying out its particular function
Making a BIOMACROMOLECULE
Biomacromolecules are synthesised inside cells. This involves linking smaller sub-units to form large chains.
Carbohydrates, proteins and nucleic acids are formed when sub-units called monomers link to form a polymer
Lipids are not polymers as they are composed of distinct chemical groups of atoms that don’t link to form a chain of monomers
Activity•C
omplete Chapter 3 Qu 1-3 on page 55
Type of biomacromolec
ule
Atoms in molecule
Sub-units Examples and Cellular
functions
Organelle Structure Function Organisms found in?
Cell membrane
Chloroplasts
Mitochondria
Nucleus
Ribosomes
Endoplasmic reticulum and Golgi complex
Lysosomes
Cytoskeleton & extracellular matrix
LIPIDS AND MEMBRANES
Lipids•M
ade of C, H and O atoms
•Subunits are fatty acids or glycerol
•Insoluble in water due to non-polar HC regions
•Three important cellular functions
• Chemical energy storage (store two times as much energy as carbohydrates)
• Structural• Chemical signal
LipidsType Function
Fatty acids (eg stearic acid, oleic acid)
Energy sourceSubunit of other lipids
Triglycerides Energy storage
Phospholipids Structural component of plasma membranes
Glycolipids Recognition sites on plasma membranes
Steroids (eg cholesterol, sex hormones)
Component of plasma membranes (regulates fluidity)Signaling molecule
Terpenes (eg Vitamin A) Antioxidant
Lipids
•Saturated•single covalent bonds between atoms
•Straight molecule
•Solid at room temperature
•Unsaturated•Double or triple covalent bonds between molecules
•Bent molecule•Liquid at room temperature
Triglyceride
Glycerol plus three fatty acid tails
phospholipids
•Phospholipids have:
• a hydrophobic tail of two fatty acids attached to a glycerol
• A hydrophillic phosphate head replaces the third fatty acid tail
The Surface area conundrum
•Cells need to maximise their surface area to ensure the rapid movement of molecules
•Problem:• As volume increases, surface area decreases!• How do cells deal with this?
Membranes
Activity•C
omplete Activity 3.2 – Surface area and volume (Nelson)
•Hand in as part of your prac assessment
Reflection•W
hat is something else, other than a chemical factory, you could compare a cell to?
EL: To continue learning about eukarytotic cell structure and function, and the molecules they are made of
CELLS IN ACTION 7
phospholipids
•Phospholipids have:• a hydrophobic tail of two fatty acids attached to a glycerol
• A hydrophillic phosphate head replaces the third fatty acid tail
Cell membrane - structure
A plasma membrane is an ultra thin and pliable layer with an average thickness of less than 0.01 μm
Cell membrane - structure•C
alled fluid mosaic model
•Lipids are the fluid part of the membrane
•Proteins are the mosaic part of the membrane
Cell membrane - functions
•Define cell boundary
•Provide sites for specific functions
•Regulate transport of solutes
•Detect electrical and chemical signals
•Assists in cell to cell communication
•Provide permeability barrier (acts like a sieve)
Type Description Molecules
Diffusion
Osmosis
Facilitated diffusion
Active transport
Endo/Exocytosis
1. Diffusion
The movement of molecules from areas of high solute concentration to area of low
solute concentration.
i.e.. Down the concentration gradient.
No energy is involved!
Permeable membranePermeable membrane
Concentration GradientsD
iffusion
High concentration
Low concentration
EquilibriumOnce diffusion is complete the molecules keep moving but the overall distribution
remains constant
Partially Permeable Membrane
If the membrane is partially permeable, the solvent can move through but the solute
cannot.
Concentration GradientsP
artially permeable membrane
High concentration
Low concentration
2. OsmosisA special type of diffusion!
The solute cannot cross the membrane. To try and balance the concentrations, the water molecules move to dilute the most concentrated solution.
High concentration solute
Low concentration solute
Osmotic Gradient
Concentrated solute
Dilute solute
The pressure that makes the water move is called the osmotic pressure.
Isotonic = extra and intracellular fluid are same concentration and there will be no net movement of water
Hypertonic = extracellular fluid higher concentration than intracellular fluid and water will diffuse out of cells making it flaccid
Hypotonic = extracellular fluid lower concentration than intracellular fluid and water will diffuse into cell making it turgid
•Most molecules are too large or too polar to cross membrane by simple diffusion
•Protein assisted movement down a concentration gradient – facilitated diffusion can occur in a few different ways
HIGH
LOW
CONCENTRATION GRADIENT
3. Facilitated Diffusion
Facilitated Diffusion
Special proteins in the membrane help the diffusion.
No energy is used.
4. Active transportWhen the cell spends energy to move molecules against the concentration
gradient.
Concentration GradientsA
ctive transport
High concentration
Low concentration
Against the concentration gradient!
5. CytosisWhen the cell spends energy to move
LARGE molecules.
Moving large molecules
•Sometimes, large molecules need to be moved around in the cell, stored within, or moved outside the cell
•To do this, cells make very small containers or sacs called vesicles from the plasma membrane
•Transporting out of the cell: exocytosis
•Transporting into of the cell: endocytosis
EndocytosisPlasma
membrane
Cell cytoplasm
Materials that are to be collected and brought into the cell are engulfed by an invagination of the plasma membrane.
1
Vesicle buds off from the plasma membrane.
2
The vesicle carries molecules into the cell. The contents may then be digested by enzymes delivered to the vacuole by lysosomes.
3
During endocytosis the plasma membrane invaginates (folds in) around the molecules to be transported into the cell.
Exocytosis
Vesicle carrying molecules for export moves to the perimeter of the cell.
1
Vesicle fuses with the plasma membrane.
2
The contents of the vesicle are expelled into the intercellular space (which may be into the bloodstream).
3Exocytosis occurs by fusion of a vesicle
membrane with the plasma membrane.
The vesicle contents are then released to
the outside of the cell.
There are two types of transport in a cell.1. Passive (not requiring energy)
diffusion and facilitated diffusionOsmosis
Facilitated diffusion
2. Active or energy requiringActive transportCytosis (exocytosis, endocytosis etc)
Summary
SUMMARY
Summary: crossing the cell membrane
TypeType DescriptionDescription MoleculesMoleculesSimple diffusionSimple diffusion Unassisted (passive) movement of solutes down a Unassisted (passive) movement of solutes down a
concentration gradient (ie from area of concentration gradient (ie from area of high solute high solute concentrationconcentration to area of to area of low solute concentration)low solute concentration)
Lipophillic molecules Lipophillic molecules and Small polar or non and Small polar or non polar molecules, eg polar molecules, eg oxygen, carbon oxygen, carbon dioxide dioxide
OsmosisOsmosis Simple diffusion of Simple diffusion of waterwater from an area of from an area of low solute low solute concentrationconcentration to an area of to an area of high solute high solute concentrationconcentration
WaterWater
Facilitated Facilitated diffusiondiffusion
Protein assisted movement Protein assisted movement downdown a concentration a concentration gradient gradient
Larger moleculesLarger molecules
Active transportActive transport Protein assisted movement Protein assisted movement up (ie from low up (ie from low concentration to high concentration) concentration to high concentration) a a concentration gradient, requiring energy inputconcentration gradient, requiring energy input
Nutrients, glucose, Nutrients, glucose, waste productswaste products
Endo/ExocytosisEndo/Exocytosis Movement of large molecules into (Movement of large molecules into (endocytosiendocytosis) or s) or out of (out of (exocytosisexocytosis) the cell) the cell
Large molecules or Large molecules or groups of groups of macromolecules (eg macromolecules (eg hormones, mucus)hormones, mucus)
Activity
•Chapter 2•page 31 qu 1-3•page 47 Biochallenge qu 2-4•Chapter review page 48-49, qu 2 & 4
•Chapter 3• Page 60 qu 6• Chapter review page 73 qu 3
Reflection•W
hat process did you understand the least today? What strategies will you use to better understand it?
EL: To practically demonstrate the process of osmosis
CELLS IN ACTION 8
Activity•C
omplete Activity 2.2 (PART A ONLY) – “Crossing membranes” (Nature of biology)
•Write up as a formal prac report (ie including abstract and intro) and hand in as part of your prac assessment
•Complete Activity 1.1 “Microscopes and cells” (Nelson Biology Activity Manual) and hand in completed worksheets as part of your prac assessment
•Read Chapter 1 pages 10-18, Copy key ideas from page 18, complete and self correct qu 8-11 on page 18, Biochallenge qu 1-6 page 19, Chapter review question 2, 3, & 4
•Activity 1.2 “Exploring… the microscope” PART B ONLY (Nature of Biology, task 3 - answer qu 11-13) and Activity 1.1 “What’s in a shape” (Nature of Biology), answer qu 1-6. For both activities, you need to answer the questions onto loose leaf paper and hand them in for assessment
•Complete Chapter 1 questions 1-6 on page 9 (Chapter 1) & Chapter 2 Biochallenge qu 1 on page 47
•Complete Activity 1.2 “Investigating Cells” (Nelson) and hand in your completed worksheets as part of your prac assessment
•Complete Chapter 3 Qu 1-3 on page 55
•Complete Activity 3.2 “Surface area and volume” (Nelson) and hand in
•Chapter 2 page 31 qu 1-3, page 47 Biochallenge qu 2-4, Chapter review page 48-49, qu 2 & 4
•Chapter 3 Page 60 qu 6, Chapter review page 73 qu 3
•Complete Activity 2.2 “Crossing membranes” PART A ONLY – (Nature of biology) as a FORMAL prac report
Reflection•D
o you think your microscope skills are improving? If not, what are the areas you need most help with.
•Did you successfully demonstrate osmosis today? How do we know it is osmosis we are demonstrating and not diffusion?
