IB Biology HL Cumulative
Hydrophobic
"Water-fearing"; nonpolar molecules (or parts of molecules) that do not dissolve in water.
Hydrophilic
"Water-loving"; polar molecules (or parts of molecules) that are soluble in water
List some of the adaptations used by cells to maximize SA: Vol ratio.
- Cell Division (speeds up diffusion) - Cells Compartmentalize
Cell Theory
- Cells are the smallest units of life - All living things are made of cells (except amoebae, fungal hyphae, or muscle cell) - All cells come from existing cells (through mitosis and meiosis; except blood cells and neurons)
Outline the advantages of cells differentiating to carry out specific functions:
- Cells can specialize certain areas of themselves - Cells become more efficient at doing a single job - Labor is divided and easier to do
70S ribosomes
smaller ribosomes found in prokaryotes
State the functions of these plasma membrane components = Glycoproteins & Cholesterol
- Glycoproteins: Often involved in cell recognition (immunity) and as receptors in cell signaling. Combined with carbohydrates to make chemical receptors. - Cholesterol: affects membrane fluidity at different temperatures (Saturated: viscous, non-fluid. Unsaturated: fluid)
Modern Technology that proved Cell Theory:
- In-Vitro Fertilization - Light and Electron Microscopes - Stem Cell Research
State the advantages of maximizing the surface area: volume ratio in a cell.
- More membrane per unit area of cell -Can supply its needs more sufficiently
Exceptions to Cell Theory:
- Muscle Cells and Fungal Hyphae: multi-nucleated, continuous cytoplasm, chitin-cell wall - Viruses: Do not exhibit all signs of life - Amoebae: Single celled organisms capable of all life processes
List some adaptations used by multi-cellular organisms to maximize SA: Vol ratio
- Organisms fold-up to maximize ratio - Efficient food absorption
Multicellular Organisms
- Organisms with more than one cell - Have developed separate systems/organelles to carry out these processes
Unicellular Organisms
- Organisms with only one cell - carry out functions of life within that one cell
Describe how a large SA: Vol ration can be harmful or costly to small animals
- Will lose heat to environment quickly - Will need to eat at all times to replace lost energy
List six functions of the plasma membrane.
-Cell Adhesion -Active Transport Pumps -Cell Receptors for Communication -Hormone Binding Sites -Channels for facilitated diffusion - Fixed enzymes
Match membrane proteins with their functions: 1.) Channel/Carrier Proteins 2.) Protein Pumps 3.) Receptor Proteins 4.) Enzymes 5.) Adhesion Proteins 6.) Neurotransmitter Receptors
1.) Passive transport across the membrane 2.) Active transport across the membrane 3.) Hormone binding and recognition 4.) Used in cell surface reactions 5.) Used in binding cells together 6.) Used in communication between cells
List four ways to maximize the rate of diffusion of a substance across a membrane.
1.) SA to Vol. Ratio- increase SA, shortens diffusion path 2.) Concentration Gradient (diff. in concentrations between two locations). Increase C.G. through faster diffusion. Decrease C.G. through slower diffusion. 3.) Increase temperature 4.) Embed more proteins within the membrane
Millimetre (mm)
1/1000 of a metre
Micrometre (µm)
1/1000 of a mm
Nanometre (nm)
1/1000 of a µm
Phospholipid bilayer
A double layer of phospholipids that makes up cell membranes
Tissue
A group of similar cells with a common function and structure.
System
A level of organization that includes organs, tissues and cells.
Scale bar
A line on a microscope image which is labelled with the actual size of the line. From this the magnification can be calculated.
Phospholipid
A lipid with a phosphate group in its hydrophillic head. The main consituent of cell membranes.
Davson-Danielli model
A model of cell membranes in which phospholipid bilayer is cover in a layer of protein.
Fluid mozaic model (Singer-Nicholson)
A model of cell membranes in which proteins are embedded in a phospholipid bilayer.
Emergent property
A property of a system that does not appear in any of its component parts; e.g. brain (which thinks) is composed of many neurones (which don't).
Glycoprotein
A protein with one or more carbohydrates attached.
Surface area to volume ratio
A ratio that decreases as cells grow larger. Above a certain size cells do not have a large enough surface to exchange gases or nutrients to support the volume of the cell
Define the plasma membrane.
A selectively permeable membrane, which encloses the cell. Also known as a cell membrane. - The plasma membrane is called a Phospholipid bilayer because the structure is composed of TWO layers of phospholipids.
Paramecium
A single-celled organism. It moves using cilia and feeds using an oral groove.
Cholesterol
A steroid that forms an essential component of animal cell membranes.
Formula for Actual Size
AS = size of image (with ruler) ÷ magnification
Explain how ATP releases energy.
ATP releases energy by bonding of adenosine, diphosphate and phosphate
Metabolism
All of the chemical reactions that occur within an organism or within a cell.
Eukaryote
An organism that consists of eukaryotic cells. Examples are: animals, plants, fungi, protists.
Golgi apparatus
a series of flattened membrane sacs that processes proteins before secretion
State the method by which bacteria reproduce:
Binary Fission
collagen
a structural protein consisting of long fibres
Stem cells
Cells that divide and remain undifferentiated. Two types are totipotent and pluripotent.
Define "Stem Cells":
Cells within an organism that retain their ability to divide and differentiate into various cell types.
naked DNA
DNA that is not arranged into chromosomes or attached to proteins
Define "diffusion"
Diffusion - the passive (no energy needed) net movement (overall movement) of particles from areas of high to low concentration through selectively permeable membranes.
Simple diffusion
Diffusion of particles through water or air or through a living or artificial membrane, down their concentration gradient, without the aid of membrane carriers
Primary active transport
Direct transport of solute particles by an ATP-using membrane pump
smooth endoplasmic reticulum (ER)
an ER that lacks ribosomes
electron micrograph
an image made by an electron microscope
Growth
an increase in physical size.
Describe the components and functions in a 'Fluid Mosaic Model"
Integral Proteins - have enzymes (sites for chemical reactions) and pumps (for active transport of molecules) Peripheral Proteins - act as receptors and 'recognize' other cells Cholesterol - affects membrane fluidity at different temperatures Channel Proteins - carry molecules through the plasma membrane Glycoproteins - combine with carbohydrates to make chemical reactions
Formula for Magnification
M = size of image (with ruler) ÷ Actual size of object (according to scale bar)
Basic functions of life (6)
Movement Growth Response to stimulus Reproduction Homeostasis Nutrition Phrase to help you remember: Molly Gets Really Really Hungry @ Noon
Vesicular (Bulk) Transport
Movement of fluid and particles through a plasma membrane by way of membrane vesicles; consumes ATP
Carrier-Mediated Transport
Movement of material through a cell membrane with the aid of carrier proteins
Transport Without Carriers
Movement of material without the aid of carrier proteins
Filtration
Movement of water and solutes through a selectively permeable membrane as a result of hydrostatic pressure
Characteristics of living things
Movement, growth, reproduction, sensitivity, excretion, nutrition, respiration, homeostasis.
Osmosis
Net flow of water through a selectively permeable membrane, driven by either a difference in solute concentration or a mechanical force
Define "osmosis"
Osmosis - molecules of a solvent (liquid-H2O) pass through permeable membrane from a low to high concentration. Equalizing the concentration from each side of the membrane.
Receptor-mediated endocytosis
Phagocytosis or pinocytosis in which specific solute particles bind to receptors on the plasma membrane, and are then taken into the cell in clathrin-coated vesicles with a minimal amount of extraneous matter
Homeostasis
Process by which organisms maintain a relatively stable internal environment.
Exocytosis
Process of eliminating material from a cell by means of a vesicle approaching the cell surface, fusing with the plasma membrane, and expelling its contents; used to release cell secretions, replace worn-out plasma membrane, and replace membrane that has been internalized by endocytosis
Phagocytosis
Process of engulfing large particles by means of pseudopods; "cell eating"
Pinocytosis
Process of imbibing extracellular fluid in which the plasma membrane sinks in and pinches off small vesicles containing droplets of fluid
List some therapeutic uses of stem cells
Replacement of lost differentiated cells due to injury and disease - Bone marrow stem cells for cancer : produce red blood cells, white blood cells and platelets in the body. - These stem cells can be used in bone marrow transplants to treat people who have certain types of cancer. -Parkinson's and Alzheimer's disease : caused by loss of brain cells. It is hoped that implanted cells could replace these.
Define "selectively permeable"
Selectively permeable (membrane) - controls the exit or entry of molecules. Some molecules are able to pass through because there is a size limit for molecules to pass into or out the permeable membrane.
Distinguish between "solute", "solvent" and "solution"
Solute: a component in a solution, dissolved in a solvent (i.e. salt, sugar) Solvent: able to dissolve other solutes (i.e. liquids, water) Solution: liquid mixture in which a solute is distributed within the solvent (i.e. salt water, sugar water, soup)
Permiability
The ability of membrane to let things in and out
Differentiation
The alteration of a cell's shape and function through gene expression.
Objective lens
The part of the microscope that is nearest the object / specimen.
Explain how hydrophobic and hydrophilic properties of the phospholipid bilayer allow a membrane to maintain its structure.
The plasma membrane is a phospholipids bilayer structure, where there are two opposite strands of phospholipids. A phospholipid is composed of a hydrophilic (attract water) phosphate head and two hydrophobic (repel water) fatty acid tails. The head and tails purpose is to create a barrier between the internal and external environments of the cell. The polar head, shields the non-polar tails from the surrounding polar fluid. The fluidity of the phospholipid bilayer allows it to break and remake the membrane
Explain why the plasma membrane described as a fluid mosaic model.
The plasma membrane is described as a fluid mosaic model because its made up of a phospholipid bilayer, allowing it easily to bend and move
As the volume of a cell increases, what happens to the production of waste products?
The production of waste products increases.
Magnification
The ratio of image size to actual size.
As the volume of a cell increases, what happens to the surface area: volume ratio?
The surface area: volume ratio decreases as volume increases.
As the volume of a cell increases, what happens to the usage of nutrients and oxygen?
The usage of nutrients and oxygen increases.
Cell theory
Theory stating that all organisms are composed of cells, smallest unit of life is a cell and that all cells come from pre-existing cells.
Facilitated diffusion
Transport of particles through a selectively permeable membrane, down their concentration gradient, by a carrier that does not directly consume ATP
Active transport
Transport of particles through a selectively permeable membrane, up their concentration gradient, with the aid of a carrier that consumes ATP
Secondary active transport
Transport of solute particles by a carrier that does not in itself use ATP but depends on concentration gradients produced by primary active transport
Outline the process of cell differentiation that leads from an uncommitted cell to a specialized cell.
Uncommitted stem cell--> Chemical Signal--> Key Genes activated--> Cell changes/differentiation--> Specialized Cells
Endocytosis
Vesicular transport of particles into a cell
binary fission
a form of asexual reproduction in prokaryotes where one "parent" cell splits in half to produce two new "daughter" cells
Eukaryotic cells
a group of cells that contain a nucleus and other organelles made of membranes.
lysosome
a membrane bound organelle that stores digestive enzymes
electron microscope
a microscope that uses electrons rather than light to take images. Has a resolution of 0.05nm, whereas a powerful light microscope has a resolution of 200nm.
flagella
a whip-like structure projecting from cells, normally used for locomotion. In prokaryotes flagella are solid protein structures with a corkscrew shape, in eukaryotes they are protrusions of the plasma membrane.
rough endoplasmic reticulum (ER)
an organelle composed of flattened sacs of membrane with ribosomes attached to it. Is where proteins are synthesised that will eventually be secreted from the cell.
mitochondrion
an organelle that carries out aerobic respiration
cell wall
forms a protective layer that prevents damage from outside and gives the cell shape made of cellulose in plants.
pili
hair-like structures projecting from the cell wall of prokaryotic cells, can be ratcheted in and out and used to attach to neighbouring cells.
80S ribosomes
larger ribosomes found in eukaryotes
nucleoid
region of the cytoplasm in prokaryotes that contains naked DNA.
ribosomes
small granular structures made of protein and ribosomal RNA (rRNA) that synthesise proteins by translating messenger RNA
nucleus
stores the genetic material
extracellular matrix
structures that exist outside the cell membrane, in animals this is usually collagen and glycoproteins
cytoplasm
the mainly water-based substance inside a cell excluding the nucleus
nuclear envelope
the membrane that forms the outer layer of the nucleus
plasma membrane
the membrane that surrounds the cell, controls entry and exit of substances, pumping some of them in by active transport.
compartmentalisation
the separation of cellular activities into various compartments or organelles inside the cell
