Key Terms from textbook + additional info Flashcards
Learn the full glossary!
Aminoacyclase
Enzyme used to produce pure samples of L-amino acids
Abiotic Factors
Non-living conditions in a habitat
Abscission
The fall of leaves
Acetyl Coenzyme A
A molecule that enters the Krebs cycle from glycolysis through a linking reaction when coenzyme A combines with an acetyl group
Acetylation
Addition of an acetyl group
Action Potential
The change in the potential difference across the neurone membrane of the axon when stimulated (approx + 40mV)
Activation Energy
The energy required to initiate a reaction
Active Site
Area of an enzyme with a shape complementary to a specific substrate, allowing the enzyme to bind a substrate with specificity.
Active Transport
Movement of particles across a plasma membrane against a concentration gradient. Energy (ATP) is required
Adenosine Diphosphate (ADP)
A nucleotide composed of a nitrogenous base (adenine), a pentose sugar and two phosphate groups. Formed by the hydrolysis of ATP (which contains three phosphate groups), releasing a phosphate ion and energy through the process of dephosphorylation.
Adenosine Triphosphate (ATP)
A nucleotide composed of a nitrogenous base (adenine), a pentose sugar and three phosphate groups. The universal energy currency for cells.
Agglutinins
Chemicals (antibodies) that cause pathogens to clump together so they are easier for phagocytes to engulf and digest.
Alcoholic Fermentation
Fermentation that results in the production of ethanol
Alkaloids
Bitter-tasting compounds found in plant leaves that may affect the metabolism of animals or insects eating them or poison them. Are also the basis of many drugs. E.g: caffeine
Allele
Version of a gene
Allele Frequency
The relative frequency of a particular allele in a population at a given time
Alleles
Different versions of the same gene
Allopatric speciation
Speciation that occurs as a result of a physical barrier between populations
Amino Acids
Monomer used to build polypeptides and thus proteins
Ammonification
Conversion of nitrogen compounds in dead organic matter or waste into ammonium compounds by decomposers.
Anabolic Steroids
Steroid drugs used illegally by some athletes and body builders to increase muscle mass.
Anabolism (Anabolic)
Reactions of metabolism that construct molecules from smaller units. These reactions require energy from thy hydrolysis of ATP.
Anaerobic respiration
Respiration in the absence of oxygen
Analogous structures
Structures that have adapted to perform the same function but have a different origin.
(Used in comparative anatomy and within convergent evolution)
Anaphase
Third stage of mitosis when chromatids are separated to opposite poles of the cell.
Antibiotic-resistant bacteria
Bacteria that undergo mutation to become resistant to an antibiotic and then survive to increase in number.
Antibiotics
A chemical or compound that kills or inhibits the growth of bacteria.
Antibodies
Y-shaped glycoproteins made by B cells (plasma) of the immune system in response to the presence of an antigen.
Antidiuretic hormone (ADH)
Hormone that increases the permeability of the distal convoluted tubule and the collecting duct to water.
Antigen
Identifying chemical on the surface of a cell that triggers an immune response
Antigen-antibody complex
The complex formed when an antibody binds to an antigen
Antigen-presenting cell (APC)
A cell that processes and displays foreign antigens complexed with major histocompatibility complexes on their surfaces for recognition by certain lymphocytes (T cells). E.g: dendritic cells, macrophages, langerhans cells and B cells
Antisense strand
The strand of DNA that runs 3’ to 5’ and is complementary to the sense strand. It acts as a template strand during transcription
Anti-toxins
Chemicals (antibodies) that bind to toxins produced by pathogens so they no longer have an effect
Apical Dominance
The growth and dominance of the main shoot as a result of the suppression of lateral shoots by auxin.
Apoplast
The cell walls and intercellular spaces of plant cells.
Apoplast Route
Movement of substances (water and dissolved mineral ions) through the cell walls and cell spaces by diffusion and into the cytoplasm by active transport.
Apoptosis
Programmed and controlled cell death. Important in controlling the body form and in the removal of damaged or diseased cells.
Arrhythmia
An abnormal rhythm of the heart
Artefacts
Objects or structures, seen through a microscope, that have been created during the processing and preparation of a specimen on a microscopic slide.
Artificial Active Immunity
Immunity which results from exposure to a safe form of a pathogen, E.g: by vaccination
Artificial Passive Immunity
Immunity which results from the administration of antibodies from another animal against a dangerous pathogen
Artificial selection (selective breeding)
Only a few individuals within a population are selected for their advantageous characteristics and bred. E.g: the breeding of pedigree animals or of human food crops.
Artificial twinning (Embryo splitting)
The process of producing monozygotic twins artificially.
Aseptic techniques
Techniques used to culture microorganisms in sterile conditions so they are not contaminated with unwanted microorganisms.
Asexual reproduction (mitosis)
The production of genetically identical offspring from a single parent.
Assimilates
the products of photosynthesis that are transported around a plant E.g: sucrose
Atrial Fibrillation
An abnormal rhythm of the heart when the atria beat very fast and incompletely.
Atrio-ventricular node (AVN)
Stimulates the ventricles to contract (through electrical conduction) after imposing a slight delay to ensure atrial contraction is complete.
Autoimmune disease
A condition or illness resulting from an autoimmune response. E.g: Rheumatoid Arthritis, Lupus, Type 1 diabetes
Autoimmune response
Response when the immune system acts against its own cells and destroys healthy tissue in the body
Autonomic nervous system
Part of the nervous system that is under subconscious control. (input from internal sensory receptors + output to smooth muscle and glands)
Autosomal Linkage
Genes present on the same, non-sex chromosome
Autotrophic
Organisms that synthesize complex organic molecules from inorganic molecules via photosynthesis E.g: plants
Auxins
Plant hormones that control cell elongation, prevent leaf fall, maintain apical dominance, produce tropic responses, and stimulate the use of ethene in fruit ripening.
B effector cells
B lymphocytes that divide to form plasma cell clones
B lymphocytes (B cells)
lymphocytes which mature in the bone marrow and that are involved in the production of antibodies
B memory cells
B lymphocytes that live a long time and provide immunological memory of the antibody needed against a specific antigen
Baroreceptors
receptors which detect changes in pressure
Batch fermentation
an industrial fermentation that runs for a set time (antibiotics E.g: penicillin and Enzymes)
Belt transect
Two parallel lines are marked along the ground and samples are taken of the area at specified points
Benedict’s reagent
An alkaline solution of copper(II) sulfate used in the chemical tests for reducing (all monosaccharides) and non-reducing sugars (most commonly sucrose). A brick-red precipitate indicates a positive result.
Beta pleated sheet
sheet-like secondary structure of proteins, contains hydrogen bonds.
Binomial nomenclature
the scientific naming of a species with a Latin name made of two parts- first genus (capital letter), second is species (all lower case). In italics - when writing underline.
Biodiversity
the variety of living organism present in an area.
Bioinformatics
the development of the software and computing tools needed to analyse and organise raw biological data E.g: algorithms, mathematical models and statistical tests that help make sense of enormous quantities of data.
(new area of bioscience that was developed due to the development of DNA profiling and DNA sequencing)
Biomass
mass of living material
Bioremediation
the use of microorganisms to break down pollutants and contaminants in the soil or water.
E.g: naturally using bacteria in the sea after an oil spill. Artificially using GM bacteria to remove mercury contamination in water
Biotic factors
Living components of an ecosystem
Biuret test
Chemical test for proteins; peptide bonds form violet coloured complexes with copper ions in alkaline solutions.
Bohr effect
The effect of carbon dioxide concentration on the uptake and release of oxygen by haemoglobin.
As the partial pressure of carbon dioxide rises, haemoglobin gives up oxygen more easily.
Bohr shift
As the proportion of carbon dioxide increases, the oxygen dissociation curve for haemoglobin moves to the right.
Bowman’s capsule
Cup-shaped structure that contains the glomerulus and is the site of ultrafiltration in the kidney.
Bradycardia
A slow heart rhythm of 60 beats per minute
Breathing rate
the number of breaths (inhalation and exhalation) taken per minute
Bulk transport
A form of active transport where large molecules or whole bacterial cells are moved into or out of a cell by endocytosis or exocytosis.
Bundle of His
Conducting tissue composed of purkyne fibres that passes through the septum of the heart.
Callose
A polysaccharide contained Beta 1-3 linkages and Beta 1-6 linkages between the glucose monomers that is important in the plant response to an infection.
Callose is deposited between plant cell walls + plasma membranes + at the plasmodesmata during times of stress E.g: pathogen invasion limiting their spread
Calvin Cycle
The cyclical light independent reactions of photosynthesis.
- Occurs in the stroma of the chloroplasts
- Here, the ATP and reduced NADP from the light dependent stage supply the energy and hydrogen to make glucose from CO2.
- 3 stage Cycle: Carbon fixation (CO2 + RuBP using Rubisco = 2GP), Reduction (light dependent products used to reduce + phosphorylate 2GP = 2TP), Regeneration (left TP into RuBP)
Carbaminohaemoglobin
The compound formed when carbon dioxide combines with haemoglobin
Carbohydrates
Organic polymers composed of the elements carbon, hydrogen and oxygen, usually in the ratio Cx (H20)y. Also known as saccharides or sugars.
Carbonic anhydrase
Enzyme which catalyses the reversible reaction between carbon dioxide + water = carbonic acid
Cardiac cycle
The events of a single heartbeat composed of diastole and systole.
- Diastole (both atria + ventriles relax, pressure in arteries > ventricles = closing of semi-lunar valves [middle], blood flows into the atria)
- Atrial Systole (both atria contract same time, pressure in atria > ventricles, blood flows through open AV valves into ventricles)
- Ventricular systole (both ventricles contract same time, pressure ventricles > atria + arteries = AV valves close + semi-lunar valves open, blood leaves heart)
Carrier
A person who has one copy of a recessive allele coding for a genetically inherited condition.
E.g: sex linked condition; female hemophiliac carriers
Carrier Proteins
Membrane proteins that play a part in the transport of substances through a membrane.
Carrying Capacity
The maximum population size that an environment can carry
Cartilage
Strong, flexible connective tissue found in many areas of the bodies of humans and other animals.
E.g: incomplete rings in trachea to prevent collapsing, bronchi (smaller)
Catabolism (Catbolic)
Reactions of metabolism that break molecules down into smaller units. These reactions release energy.
Catalase
An enzyme that catalyses the breakdown of hydrogen peroxide
Cell cycle
The highly ordered sequence of events that takes place in a cell, resulting in division of the nucleus and the formation of two genetically identical daughter cells.
- Interphase (G1, G2, S)
- Mitosis
- Cytokinesis
Cell Signalling
A complex system of intercellular communication.
Cellulose
A polysaccharide formed from beta glucose molecules where alternate beta glucose molecules are turned upside down. It is unable to coil or form branches but makes hydrogen bonds with other cellulose molecules to produce strong and insoluble fibres. Major component of plant cell walls.
Cell wall
A strong but flexible layer that surrounds some cell-types. E.g: plant cells
Central Nervous System (CNS)
Consists of the brain and spinal cord
- relay neurones
Centrioles
Small, hollow cylinders that are a component of the cytoskeleton of most eukaryotic cells (all animal cells, some plant cells), composed of microtubules (tiny protein cylinders)
- forms spindle fibres to move chromosomes during mitosis + meiosis
Cerebrum
Controls voluntary actions, such as learning, memory, personality and conscious thought.
Cerebellum
Co-ordinates and controls unconscious functions such as posture, balance and non-voluntary movement.
Centromere
Region at which two chromatids are held together
Channel Proteins
Membrane proteins that provide a hydrophilic channel through a membrane
Checkpoints
Control mechanisms of the cell cycle
- G1 checkpoint: cell checks that the chemicals needed for replication are present and for any damage to the DNA before entering S phase
- G2 checkpoint: cell checks whether all the DNA has been replicated without any damage before the cell can enter mitosis
- Metaphase checkpoint: cell checks that all the chromosomes are attached to the spindle before mitosis can continue
Chemiosmosis
The synthesis of ATP driven by a flow of protons across a membrane
Chemoreceptors
Receptors which detect chemical changes
Chi-squared formula
Formula used to determine the significance of the difference between observed and expected count data.
Chiasmata
Sections of DNA, which became entangled during crossing over, break and rejoin during anaphase 1 of meiosis sometimes resulting in an exchange of DNA between bivalent chromosomes, forming recombinant chromatids and providing genetic variation.
Chloride shift
The movement of bicarbonate ions into the red blood cells as hydrogen ions move out to maintain the electrochemical equilibrium.
Chlorophyll
Green pigment that captures light in photosynthesis. Chlorophyll a (primary pigment) and chlorophyll b (accessory pigment).
Chloroplasts
Organelles that are responsible for photosynthesis in plant cells. Contain chlorophyll pigments, which are the site of the light reactions of photosynthesis.
Chromatids
Two identical copies of DNA (a chromosome) held together at the centromere
Chromatin
Uncondensed DNA in a complex with histones
Chromosomes
Structures of condensed and coiled DNA in the form of chromatin. Chromosomes become visible under the light microscope when cells are preparing to divide (prophase).
Crossing Over
During Prophase 1 of meiosis 1, homologous pairs of chromosomes come together and pair up. The chromatids twist around each other and bits of chromatids swap over. The chromatids still contain the same genes but now have a different combination of alleles.
Circulatory system
The transport system of an animal
Citrate
Six carbon molecule formed in Krebs cycle by the combination of oxaloacetate and acetyl coenzyme A.
Climax Community
Final stage in succession, where the community is said to be in a stable state.
Clonal Expansion
The mass proliferation of antibody-producing cells by clonal selection.
Clonal Selection
The theory that exposure to a specific antigen selectively stimulates the proliferation of the cell with the appropriate antibody to form numerous clones of these specific antibody-forming cells (clonal expansion)
Clones
The genetically identical offspring produced as a result of cloning.
Cloning
A way of producing offspring by asexual reproduction
Closed circulatory system
A circulatory system where the blood is enclosed in blood vessels and does not come into direct contact with the cells of the body beyond the blood vessels.
E.g: Fish and mammals
Clostridium difficile (C. difficile)
A species of Gram positive bacteria that is resistant to most antibiotics
Codominance
When different alleles of a gene are equally dominant and both are expressed in the phenotype. Ratio 2:1:1
Codon
A three-base sequence of DNA or RNA that codes for an amino acid
Coenzyme A
Coenzyme with important roles in the oxidation of pyruvate in Krebs cycle and in the synthesis and oxidation of fatty acids.
Cofactors
Non-protein components necessary for the effective functioning of an enzyme.
E.g: iron, calcium, chloride, zinc ions
Cohesion-tension theory
The best current model explaining the movement of water through a plant during transpiration
Collecting duct
Final part of the tubule that passes through the renal medulla and the place where the hypertonic urine is produced if needed. The permeability of the walls is affected by ADH levels and it is the main site of water balancing.
Communicable diseases
Diseases that can be passed from one organism to another, of the same or different species.
Community
All the populations of living organisms in a particular habitat.
Companion cells
The active cells found next to sieve tube elements that supply the phloem vessels with all of their metabolic needs. Used in translocation.
Competitive inhibitor
An inhibitor that competes with a substrate to bind to active site on an enzyme due to its similar shape with the substrate.
Complementary base pairing
Specific hydrogen bonding between nucleic acid bases. Adenine(A) binds to thymine(T) or uracil(U) with two bonds and cytosine(C) binds to guanine(G) with three bonds.
Compound light microscope
A light microscope which uses two lenses to magnify an object; the objective lens - placed near to the specimen, and an eyepiece lens - through which the specimen is viewed
Condensation Reaction
A reaction between two molecules resulting in the formation of a larger molecule and the release of a water molecule. The opposite reaction to a hydrolysis reaction.
Computational Biology
The study of biology using computational techniques to analyse large amounts of data.
- builds theoretical models or biological systems
- which can be used to predict what will happen in different circumstances
- developed bioscience due to the development of DNA profiling + DNA sequencing
Conservation
The maintenance of biodiversity through human action or management
Consumer
Organism that obtains its energy by feeding on another organism.
Continuous fermentation
An industrial fermentation where culture broth is removed continuously and more nutrient medium added
Continuous variation
A characteristic that can take any value within a range e.g. height.
Contrast
staining or treating specific cell components so they are visible compared to untreated components
Convergent evolution
Organisms evolve similarities because the organisms adapt to similar environments or other selection pressures
Correlation coefficient
Statistical text used to consider the relationship between two sets of data.
Cortex
The dark outer layer of the kidney containing the Bowman’s capsules and glomeruli
Countercurrent exchange system
A system for exchanging materials or heat when the two different components flow in opposite directions past each other.
E.g: in the circulatory system of fish
Counterstain
Application of second stain with a contrasting colour to sample for microscopy.
Cristae
Fold of inner mitochondrial membranes, increases the surface area where reactions of the electron transfer chain can take place. Site of oxidative phosphorylation
Culture
Growing living matter in vitro E.g: microorganisms in specifically prepare nutrient medium.
cyclic AMP
Cyclic adenosine monophosphate, a molecule that acts as an important second messenger in many biological systems
E.g: lac operon
cycic photophosphorylation
Synthesis of ATP involving only photosystem 1
Cytokines
Cell-signalling molecules produced by mast cells in damaged tissues that attract phagocytes to the site of infection or inflammation
Cytokinesis
Cell division stage in the mitotic phase of the cell cycle that results in the production of two identical daughter cells.
Cytolysis
The bursting of an animal cell caused by increasing hydrostatic pressure as water enters by osmosis.
Cytoplasm
Internal fluids of cells, composed of cytosol (water, salts and organic molecules), organelles and cytoskeleton. Where majority of cell reactions take place.
Cytoskeleton
A network of fibres in the cytoplasm of a eukaryotic cell.
Major type of filaments that make up cytoskeleton:
- actin filaments
- microtubules
- intermediate filaments
Deamination
The removal of the amino group from amino acids.
E.g: it is the most important role of the liver in protein metabolism. Converts amino acids into ammonia through deamination
Decarboxylation
The removal of carbon dioxide
Deciduous Plants
plants that lose their leaves for part of the year
Decomposer
Organism that breaks down dead organisms releasing nutrients back into the ecosystem
E.g: bacteria, fungus
Decomposition
Chemical reaction in which a compound is broken down into simpler compounds or into its constituent elements.
Dehydrogenation
The removal of a hydrogen atom
Deletion
A mutation where one or more nucleotides are deleted and lost from the DNA strand
Denitrification
conversion of nitrates to nitrogen gas
Denatured
Change in tertiary structure of a protein or enzyme, resulting in loss of normal function
Deoxyribonucleic acid (DNA)
The molecule responsible for the storage of genetic information
Depolarisation
A change in potential difference from negative to positive across the membrane of a neurone.
Detoxification
Removal or breakdown of toxins
Detritivore
Organism which speeds up decay by breaking down detritus into smaller pieces.
E.g: earthworm
Diabetes mellitus
medical condition which affects a person’s ability to control their blood glucose concentration
Diastole
The stage in which the heart relaxes and the atria and then the ventricles fill with blood
Dicotyledonous plants (dicots)
Plants that produce seeds containing two cotyledons, which act as food stores for the developing embryo and form the first leaves when the seed germinates.
Differential staining
Using specific stains to distinguish between different types of cells.
Differentiation
The process of a cell becoming differentiated. Involves the selective expression of genes in a cell’s genome.
Digenic inheritance
A characteristic controlled by two genes
Dihybrid inheritance
A characteristic inherited on two genes. Ratio 9:3:1:1
Diploid
Normal chromosome number; two chromosomes of each type - one inherited from both parents
Directional selection
Natural selection that favours one extreme phenotype
E.g: peppered moths during industrial revolution
Disaccharide
A molecule comprising two monosaccharides, joined together by a glycosidic bond
E.g: Lactose (glucose + galactose), Sucrose (glucose + fructose), Maltose (glucose + glucose)
Discontinuous variation
A characteristic that can only result in discrete values
E.g: blood type
Disruptive selection
Natural selection that favours both extremes of a given phenotype
Distal convoluted tubule
The second twisted section of the nephron where the permeability of the walls varies in response to ADH levels in the blood
Divergent evolution
Species diverge over time into two different species, resulting in a new species becoming less like the original one
DNA helicase
Enzyme that catalyses the unwinding and separating of strands in DNA replication.
DNA polymerase
Enzyme that catalyses the formation of phosphodiester bonds between adjacent nucleotides in DNA replication.
DNA profiling (DNA finger printing)
Producing an image of the patterns in the non-coding DNA of an individual.
Used in:
- forensics
- paternal testing
- likelihood of inheriting a genetic disease
DNA replication
The semi-conservative process of the production of identical copies of DNA molecules
DNA sequencing
Working out the sequence of bases in a strand of DNA
Dominant allele
Version of the gene that will always be expressed if present
Dominant species
The most abundant species in an ecosystem
Double circulatory system
A circulatory system where the blood travels twice through the heart for each complete circulation of the body. In the fist circulation blood is pumped by the heart to the lungs. In the second circulation oxygenated blood is pumped by the heart to the brain and body to supply cells with oxygen
E.g: In humans
Ecological efficiency
Efficiency with which energy or biomass is transferred from one trophic level to the next
Ecosystem
All the interacting living organisms and the non living conditions of a given area, it is dynamic.
Ecotourism
Tourism directed towards natural environments, intended to support conservation efforts.
Ectopic heartbeat
Extra heartbeats that are out of the normal rhythm
Ectotherms
Animals that use their surroundings to warm their bodies so their core temperature is heavily dependent on the environment.
E.g: reptiles
Effector
Muscle or gland which carries out body’s response to a stimulus.
Elastic recoil
The ability to return to original shape and size following stretching. Particularly of the alveoli of the lungs and of the arteries.
Electrocardiogram (ECG)
A technique for measuring tiny changes in the electrical conductivity of the skin that results from the electrical activity of the heart. This produces a trace which can be used to analyse the health of the heart.
Electron carriers
Proteins that accept and release electrons
Electron microscopy
Microscopy using a microscope that employs a beam of electrons to illuminate the specimen. As electrons have a much smaller wavelength than light they produce images with higher resolutions than light microscopes
Electrophoresis
A type of chromatography that relies on the way charged particles move through a gel under the influence of an electrical current. It is used to separate nucleic acid fragments or proteins.
Electroporation
The use of a very tiny electric current to transfer genetically engineered plasmids into bacteria or to get DNA fragments directly into eukaryotic cells (e.g in somatic cell nuclear transfer)
Emulsion test
Laboratory test for lipids using ethanol - a white emulsion indicates the presence of a lipid.
End-product inhibition
The product of a reaction inhibits the enzyme required for the reaction.
Endocrine glands
Group of specialized cells which secrete hormones
Endocytosis
The bulk transport of materials into cells via invagination of the cell-surface membrane forming a vesicle
Endosymbiosis
The widely-accepted theoretical process by which eukaryotic cells evolved from prokaryotic cells.
Endothermic
Reactions that absorb energy
Endotherms
Animals that rely on their metabolic processes to warm their bodies and maintain their core temperature
Enucleated
With the nucleus removed
Enzyme-product complex
Complex formed as a result of an enzyme-catalysed reaction, when a substrate is converted to a product or products while bound to the active site of an enzyme
Enzymes
Biological catalysts that interact with substrate molecules to facilitate chemical reactions. Usually globular proteins
Enzyme-substrate complex
Complex formed when a substrate is bound to the active site of an enzyme
Epidemic
When a communicable disease spreads rapidly to a lot of people at a local or national level
Epigenetics
External control of genetic regulation
Epistasis
The effect of one gene on the expression of another gene. The interaction of genes at different loci.
E.g: gene regulation
Euchromatin
loosely packed DNA
Eukaryotes
multicellular eukaryotic organisms like animals, plants and fungi and single-celled protoctista.
Eukaryotic cells
Cells with a true nucleus and other membrane-bound organelles.
ex situ conservation
Conservation methods out of their natural habitats
E.g: zoos, aquariums, seed banks
Exchange surfaces
Surfaces over which materials are exchanged from onw area to another
Excretion
The removal of the waste products of metabolism from the body.
Exocytosis
The bulk transport of materials out of cells. Vesicles containing the material fuse with the cell-surface membrane and the contents are released to the outside of the cell
E.g: the neurotransmitter acetylcholine in a cholinergic synapse
Exoskeleton
An external skeleton of some organisms
E.g: insects
Exothermic
Reactions that release energy
Expiratory reserve volume
The extra amount of air that can be forced out of the lungs over and above the normal exhalation (tidal volume)
Facilitated Diffusion
Diffusion across a membrane through protein channels
Facultative anaerobes
Organisms that can respire anaerobically or aerobically
E.g: yeast
FAD
A coenzyme that acts as a hydrogen acceptor in Krebs cycle
Fatty acids
Long chain carboxylic acids used in the formation of triglycerides and phospholipids
- Unsaturated (at least one double bond)
- Saturated (no double bonds)
Fermentation
Anaerobic respiration without the involvement of an electron transport chain
Fibrous Proteins
Long, insoluble, structural proteins
E.g:
- Collagen = mechanical strength, withstand high pressures; bones, tendon cartilage, connective tissue
- Keratin = many disulfide bridges, hard and strong; fingernails, hair, horns, hooves, feathers
- Elastin = elastic, stretch + recoil; skin, lungs, blood vessels, bladder
Fluid-mosaic model
Model of the structure of a cell membrane in which phospholipids within the phospholipid bilayer are free to move and proteins of various shapes and sizes are embedded in various positions.
Forensics
The application of science to the law, commonly in solving crimes
Fossils
The remains or impression of science to the law, commonly in solving crimes
Founder Effect
When a few individuals of a species colonise a new area, their offspring initially experience a loss in genetic variation, and rare alleles can become much more common in the population.
Fungi
Biological kingdom containing yeasts, moulds and mushrooms
Gametes
Haploid sex cells produced by meiosis in organisms that reproduce sexually
Gaseous exchange system
The complex systems in which the respiratory gases oxygen and carbon dioxide are exchanged in an organism
Gene
A section of DNA that contains the complete sequence of bases (codons) to code for a protein
Gene banks
Store of genetic material
- keep samples of wild + domesticated seed varieties
-store biological samples such as sperm + eggs, frozen
= used to increase genetic diversity by outbreeding
Gene flow
When alleles are transferred from one population to another by interbreeding
Gene pool
Sum total of all the genes in a population at a given time
Genetic bottleneck
When large numbers of a population die prior to reproducing, leading to reduced genetic biodiversity within the population.
Genetic code
The sequences of bases in DNA are the ‘instructions’ for the sequences of amino acids in the production of proteins
Genetic drift
Random change of allele frequency
Genetic variation
A variety of different combinations of alleles in a population
Genome
All of the genetic material of an organism
Genotype
Genetic makeup of an organism
Geotropism
The growth response of plants towards gravity
Germ line gene therapy
Inserting a healthy allele into the germ cells (gametes) or into a very early embryo (zygote)
Gibberellins
Plant hormones that cause stem elongation, trigger the mobilisation of food stores in a seed at germination and stimulate pollen tube growth in fertilisation
Gills
The gaseous exchange organs of fish, comprised of gill plates, gill filaments and gill lamellae.
Globular proteins
Spherical, water-soluble proteins
Glomerular filtration rate (GFR)
A test used to estimate the volume of blood filtered by the glomeruli each minute, used to indicate a loss of function in the kidneys.
Glucoamylase
Enzyme used to convert dextrins to glucose
Gluconeogenesis
Production of glucose from non-carbohydrate sources
Glucose
A monosaccharide with the chemical formula C6H12O6. One of the main products of photosynthesis in plants
Glucose isomerase
Enzyme used to produce fructose from glucose
Glycerate-3-phosphate
Compound formed in Calvin Cycle after carbon fixation
Glycerol
Alcohol found in trigylcerides (1 glycerol ester bond 3 fatty acids producing 3 water mols)
Glycogen
A branched polysaccharide formed from alpha glucose molecules. A chemical energy store in animal cells.
Glycogenesis
Production of glycogen from glucose
Glycogenolysis
Process in which glycogen stored in the liver and muscle cells is broken down into glucose
Glycolipids
Cell-surface membrane lipids with attached carbohydrate molecules of varying lengths and shapes
Glycoproteins
Extrinsic membrane proteins with attached carbohydrate molecules of varying lengths and shapes
Glycosidic bond
A covalent bond between two monosaccharides
Goblet cells
Differentiated cells specialised to secrete mucus
Golgi Apparatus
Organelle in most eukaryotic cells formed from an interconnected network of flattened, membrane-enclosed sacs, or cisternae. Plays a role in modifying and packaging proteins into vesicles.
Gram negative bacteria
Bacteria with cell walls that stain red with Gram stain
Gram positive bacteria
Bacteria with cell walls that stain purple-blue with Gram stain
Granum (plural grana)
A structure inside chloroplasts composed of a stack of several thylakoids. Contains chlorophyll pigments, where light reactions occur during photosynthesis.
Guard cells
Cells that can open and close the stomatal pores, controlling gaseous exchange and water loss in plants.
Habitat Biodiversity
The number of different habitats found within an area
Haemoglobin
The red, oxygen-carrying pigment of red blood cells
Haemoglobinic acid
The compound formed when haemoglobin accepts free hydrogen ions in its role as a buffer in the blood.
Haemolymph
The transport medium or ‘blood’ in insects
Haploid
Half the normal chromosome number; one chromosome of each type
Hardy-Weinberg equation
Formula used to calculate the frequency of alleles in a population (pop has to be stable and not evolving)
Hepatocytes
liver cells
Herbivory
The process of animals eating plants
Heterochromatin
Tightly packed DNA
Heterotrophic
Organisms that acquire nutrients by the ingestion of other organisms
Heterozygous
Two different alleles for a characteristic
Hexose bisphosphate
The compound that results from the phosphorylation of glucose in glycolysis.
Hexose monosaccharide
A monosaccharide composed of six carbons
High throughput sequencing (Next Generation sequencing)
New methods of sequencing DNA that are automated, very rapid and much cheaper than the original techniques.
Histamines
Chemicals produced by mast cells in damaged tissues that make the blood vessels dilate (causing redness and heat) and the blood vessels leaky (causing swellin and pain)
Histones
Proteins that form a complex with DNA called chromatin
Homeobox genes (Hox genes)
Regulatory genes responsible for the development of body plans through apoptosis and mitosis
Homeodomain
A conserved motif of 60 amino acids found in all homeobox proteins. It is the part of the protein that binds to DNA allowing the protein to act as a transcriptional regulator.
Homeostasis
The maintenance of a stable equilibrium in the conditions inside the body.
Homologous chromosomes
Matching pair of chromosomes, one inherited from each parent.
Homologous structure
A structure which appears superficially different but has the same underlying structure. E.g pentadactyl limb
Homozygous
Two identical alleles for a characteristic
Hormone
Chemical messengers which travel around the body in the blood stream
Humus
Organic component of soil formed by the decomposition of leaves and other plant material by soil microorganisms
Hydrolysis reaction
The breakdown of a molecule into smaller molecules requiring the addition of a water molecule. Opposite to condensation reaction
Hydrophilic
The physical property of a molecule that is attracted to water
Hydrophobic
The physical property of a molecule that is repelled by water
Hydrophytes
Plants with adaptations that enable them to survive in very wet habitats or submerged at the surface of water E.g: water lillies, water cress, duck weeds, yellow iris;
- thin, waxy cuticle
- many always open stomata on upper surface
- reduced structure to plant
- wide, flat leaves
- small roots
- large SA of roots and stems under water
- air sacs
Hydrostatic pressure
The pressure created by water in an enclosed system
Hypothalamus
Regulatory centre for temperature and water balance. The region of the brain above the pituitary gland that contains osmoreceptors involved in osmoregulation and thermoreceptors involved in thermoregulation.
Immobilised Enzymes
Enzymes that are attached to an inert support system over which the substrate passes and is converted to product
- adsorption
- ionic/covalent bonding
- entrapment
- encapsulation
Immune Response
A biological response that protects the body by recognising and responding to antigens and by destroying substances carrying non-self antigens
Immunoglobulins
y-shaped glycoproteins that form antibodies
in situ conservation
conservation methods within the natural environment
E.g;
-national parks/wildlife reserves, marine conservation (protected areas)
inbreeding
breeding between closely related organisms
inbreeding depression
reduced biological fitness due to inbreeding
independent assortment
The arrangement of each homologous chromosome pair (bivalent) in metaphase 1 and metaphase 2 of meiosis is independent of each other and results in genetic variation
Inflammation
Biological response of vascular tissues to pathogens, damaged cells, or irritants, resulting in pain, heat, redness and swelling
Inhibitor
A factor that prevents or reduces the rate of an enzyme catalysed reaction
Inner mitochondrial membrane
The inner most of the two mitochondrial membranes. Separates the mitochondrial matrix from the intermembrane space. Is the site where the electron transport chain takes place
Insertion
A point mutation where one or more extra nucleotides are inserted into a DNA strand
Inspiratory Reserve Volume
The maximum volume of air that can be breathed in over and above a normal inhalation (tidal volume)
Insulin
A globular protein involved in the regulation of blood glucose concentration.
Produced by beta cells in islets of langerhans (pancreas) when blood glucose level is too high:
- Insulin binds to membrane-bound receptors on liver and muscle cells (first messenger)
- Activates a secondary messenger resulting in:
- more glucose channels on membrane = more glucose enters cells
- glycogenesis for storage
- more glucose converted to fatss
- increased rate of respiration
- stops cells using sources other than glucose as an energy source
Whereas, glucagon is detected and acts on liver cells
Intercostal muscles
The muscles between the ribs that pull the ribs upwards during inhalation (internal intercostal muscles) and downwards during forced exhalation (external intercostal muscles)
Interleukins
A type of cytokine produced by T helper cells
Interphase
Growth period of the cell cycle, between cell divisions (mitotic phase). Consists of stages G1, G2, S:
- G1 = Cell grows, new organelles + proteins are made
- S= Cell replicates its DNA, ready to divide by mitosis
- G2= Cell keeps growing + proteins needed for cell division are made
Interspecific competion
Competition between organisms of different species for the same resource
Interspecific variation
The differences between organisms of different species
Intraspecific variation
The differences between organisms of the same species
Intraspecific competion
Competition between organisms of the same species for the same resource
Introns
Regions of non-coding DNA or RNA
Iodine test
A chemical test for the presence of starch using a potassium iodide solution. A colour change to purple/black indicates a positive result
Ion
An atom or molecule with an overall electric charge because the total number of electrons is not equal to the total number of protons. Anion or Cation
Ionic bond
A chemical bond that involves the donating of an electron from one atom to another, forming positive and negative ions held together by the attraction of the opposite charges.
Islets of langerhans
Clusters of specialised cells within the pancreas responsible for producing insulin (beta cells) and glucagon (alpha cells LARGER)
Endocrine glands - secreted directly into blood capillaries
Acinar cells
Exocrine cells of pancreas that secretes digestive enzymes into pancreatic ducts into the small intestine:
- Amylase
- Lipase
- Trypinogen (inactive protease)
- Sodium Hydrogen Carbonate (as acidity of stomach denatures enzymes)
Keystone Species
Species which are essential for maintaining biodiversity - they have a disproportionately large effect on their environment relative to their abundance
Kingdom
The second biggest and broadest taxonomic group
- Animalia
- Plantae
- Fungi
- Protoctista
- Bacteria/Prokaryote
Lac operon
Operon responsible for the metabolism of lactose
Lactase
Enzyme used to hydrolyse lactose to glucose and galactose and produce lactose-free milk
Lactose
A disaacharide made up of galactose and glucose monosaccharide
Lactate dehydrogenase
Enzyme used in the conversion of pyruvate to lactate
Lactate fermentation
Fermentation (in anaerobic respiration) that results in the production of lactate in animal cells
Integranal lamellae
Membranous channels which join grana together in a chloroplast
Laser scanning confocal microscope
A microscope that employs a laser beam and a a pin-hole aperture to produce an image with a very high resolution
Light harvesting system
A group of protein and chlorophyll molecules found in the thylakoid membranes of the chloroplasts in a plant cell.
Light microscope
An instrument that uses visible light and glass lenses to enable the user to see objects magnified many times
Limiting factor
A factor which limits the rate of a process
Line breeding
A form of inbreeding using less closely related organisms
Line transect
A line is marked along the ground and samples are taken at specified points
Linked genes
Genes present on the same chromosome
Lipids
Non-polar macro-molecules containing the elements carbon, hydrogen and oxygen. Commonly known as fats (solid at room temp) and oils (liquid at room temp)
Loop of Henle
A long loop of nephron that creates a steep concentration gradient across the medulla
Lung surfacant
Chemical mixture containing phospholipids and both hydrophilic and hydrophobic proteins, which coats the surfaces of the alveoli and prevents them collapsing after every breath
Lymph
Modified tissue fluid that is collected in the lymph system
Contains:
- White blood cells = Most white blood cells, only enter tissue fluid when there’s an infection
- Antibodies(only proteins) = Most plasma proteins are too big to get through capillary walls
- Water = Both tissue fluid and lymph have a higher water potential than blood
- Dissolved solutes (e.g salt) = move freely between blood, tissue fluid and lymph
Lymphocytes
White blood cells that make up the specific immune response
Lysosomes
Specialised vesicles containing hydrolytic enzymes for the breakdown of waste materials within a cell e.g. phagocytosis
Macromolecules
Large complex molecules with a large molecular weight
Maltose
Disaacharaide composed of two glucose molecules linked by a 1,4 glycosidic bond
Mass transport system
A transport system where substances are transported in a mass of fluid
mature mRNA
mRNA after the removal of introns and any other post-transcriptional changes to the per-mRNA, e.g:
- a tail (long chain of adenine nucleotides) added to the 3’ end
- a cap (modified nucleotide) added to 5’ end - aids binding of mRNA to ribosomes
BOTH help to stabilise mRNA and delay degradation in cytoplasm
Medulla
The lighter inner layer of the kidney made up of the loops of henle + part of collecting duct
Meiosis
Form of cell division where the nucleus divides twice (meiosis 1 and meiosis 2) resulting in a halving of the chromosome number and producing four haploid genetically different daughter cells from one diploid cell
Membrane
A selectively permeable barrier surrounding all cells and forming compartments within eukaryotic cells.
Membrane proteins
Protein components of cell-surface membranes
- extrinsic
- intrinsic
Meristematic tissue (meristems)
Tissue found at regions of growth in plants. Contains stem cells.
messenger (m) RNA
Short strand of RNA produced by transcription from the DNA template strand. It has a base sequence complementary to the DNA from which it is transcribed, except it has uracil (U) in place of thymine)
Metaphase
Second stage of mitosis when chromosomes line up at the meta phase plate, spindle attaches to chromatids at centromere
Methylation
The addition of methyl group
Micropropagation
The process of making very large numbers of genetically identical offspring from a single parent plant using tissue culture techniques. (plants)
Mitosis
Nuclear division stage in the mitotic phase of the cell cycle
Mitotic Phase
Period of cell division of the cycle . Consists of the stages mitosis (PMAT) and cytokinesis
Cytokinesis
The stage in mitotic phase when the cytoplasm divides. to produce two genetically identical diploid daughter cells. In animal cells, a cleavage furrow forms to divide the cell membrane. Usually begins in anaphase and ends in telophase. Its a separate process to mitosis
Mitochondrial DNA
DNA present within the matrix of mitochondria
Mitochondrial matrix
The part of the mitochondria enclosed by the inner mitochondrial membrane which contains enzymes for the Krebs cycle and the link reaction.
Monoclonal antibodies
Antibodies from a single clone of cells that are produced to target particular cells or chemicals in the body
Monoculture
The cultivation of a single crop in a given area
- reducing the species biodiversity.
Monogenic inheritance
A characteristic inherited on a single gene
Monomers
Individual molecules that make up a polymer
Monosaccharide
A single sugar molecule
Monozygotic twins
Twins formed from a single fertilized egg
mRSA (methicillin-resistant Staphylococcus aureus)
A mutated strain of the bacterium Staphylococcus aureus that is resistant to the antibiotic, methicillin
Mucous membranes
Membranous linings of body tracts that secrete a sticky mucus
Multiple alleles
A gene with more than two possible alleles e.g: blood type
Multipotent
A stem cell that can only differentiate into a range of cell types within a certain type of tissue
Mutagens
Chemical or physical agent which causes mutation
Mutation
A change in the genetic material which may affect the phenotype of the organism
Myelin sheath
Membrane rich in lipid which surrounds the axon of some neurones, speeding up impulse transmission, produced by schwann cells.
Myofibril
Long cylindrical organelles found in muscle which are made of protein and specialised for contraction
Myogenic
Muscle which has its own intrinsic rhythm e.g. heart muscle
Satellite DNA
Short sequences of DNA that are repeated many times
Minisatellite
A sequence of 20-50 base pairs, repeated from 50 to several hundred times. Occurs at more than 1000 locations in the genome. Known as Variable number tandem repeats (VNTRs)
Microsatellite
A smaller region than VNTRs of just 2-4 base pairs that are repeated only 5-15 times. Always appear on the same positions on the chromosome and are known as Short tandem repeats (STRs)
NAD
A coenzyme found in all living cells involved in cellular respiration
NADP
A coenzyme which acts as a final electron acceptor in photosynthesis
Natural active immunity
Immunity which results from the response of the body to the invasion of a pathogen
Natural passive immunity
The immunity given to an infant mammal by the mother through the placenta and the colostrum
Natural selection
The process by which organisms best suited to their environment survive and reproduce, passing on their characteristics to their offspring through their genes. Over time, the proportion of the population possessing the advantageous adaptations increases. Over generations this leads to evolution as the favourable adaptations become more common in the population.
Nephrons
Tubules that make up the main functional structures of the kidneys.
Neurone
Specialised cell which transmits impulses in the form of action potentials.
Neurotransmitter
Chemical involved in communication across a synapse between adjacent neurones or a neurone and muscle cell e.g. acetylcholine
Nitrification
Conversion of ammonium compounds into nitrites (nitrosomonas) and nitrates (nitrobacter) through oxidation
Nitrile Hydratase
Enzyme used to convert acrylonitrile to acrylamide for use in the plastics industry
Nitrogen fixation
Conversion of nitrogen gas to ammonium compounds by nitrogen fixing bacteria azotobacter (soil) and rhizobium (root nodules in leguminous plants - symbiotic mutualistic relationship)
Non-competitive inhibitor
An inhibitor that binds to an enzyme at an allosteric site
Non-cyclic photophosphorylation
The synthesis of ATP and reduced NADP involving photosystems 1 and 2
Non-random sampling
An alternative sampling method to random sampling, where the sample is not chosen at random. It can be opportunistic, stratified or systematic.
Normal distribution
A distribution of continuous data where the mean, median, and mode have the same value, there is symmetry around the mean with most data points being close to the mean and fewer data points further away from the mean. When plotted produces a bell-shaped or normal distribution curve.
Nucleic acids
Large polymers formed from nucleotides. Contain the elements carbon, hydrogen, phosphorous, and oxygen. E.g: DNA + RNA
Nucleotides
The monomers used to form nucleic acids. Made up of a pentose monosaccharaide, a phosphate group and a nitrogenous base.
Obligate Aerobes
Organisms that can only respire aerobically E.g. mammals
Obligate Anaerobes
Organisms that cannot live in environments containing oxygen, mainly prokaryotes + some fungi
Open circulatory system
A circulatory system with a heat but few vessels to contain the transport medium, e.g. insects
Operculum
The bony flap covering the gills of bony fish. Part of the mechanism that maintains a constant flow of water over the gas exchange surfaces
Operon
A group of genes that are under the control of the same regulatory mechanism and are expressed at the same time
Opportunistic sampling
Sampling using the organisms that are conveniently available. The weakest form of sampling as it may not be representative of the population.
Opsonins
Chemicals that bind to pathogens and tag them so they are recognized more easily by phagocytes, e.g.antibodies
Organelle
Membrane-bound compartments with varying functions inside eukaryotic cells.
Ornithine cycle
A series of enzyme controlled reactions in the liver converting ammonia formed by deamination of amino acids into urea.
2 Ammonia + Carbon dioxide + 3 ATP = Urea + Water + 3 ADP
Osmoreceptors
Sensory receptors that respond to changes in the water potential of the blood
Osmoregulation
The balancing and control of the water potential of the blood
Osmosis
Diffusion of water through a partially permeable membrane down a water potential gradient. A passive process
Outbreeding
Breeding of distantly related organisms
Outer mitochondrial membrane
The membrane that separates the contents of the mitochondrion from the rest of the cell, creating a cellular compartment with ideal conditions for aerobic respiration
Oxaloacetate
Four carbon molecule present at the beginning of Krebs cycle that combines with acetyl coenzyme A to form citrate
Oxidation
Removal of electrons or hydrogen
Oxygen dissociation curve
Graph showing the relationship between oxygen and haemoglobin at different partial pressures of oxygen
Oxygenated blood
Blood that has passed through the gas exchange organs e.g. lungs, and his high in oxygen
Pandemic
When a communicable disease spreads rapidly to a lot of people across a number of countries
Partially permeable
Membrane that allows some substances to cross but not others
Passive transport
Transport that is a passive process (does not require energy) and does not use energy from cellular respiration
Pathogens
Microorganisms that cause disease
- Bacteria e.g. Tuberculosis (Mycobacterium tuberculosis + M.bovis, Bacterial Meningitis (Streptococcus pneumoniae), Ring rot in potatoes and tomatoes (Clavibacter michiganensis)
- Virus e.g. HIV/AIDS (retrovirus), Influenza, Tobacco Mosaic virus
- Protoctista e.g. Malaria (Plasmodium carried in female vector Anopheles mosquito), Potato/Tomato late blight (the oomycete - Phytophthora infestans)
- Fungi e.g. Black sigatoka (Mycosphaerella fijiensis), Ring worm, Athlete’s foot (Tinia pedia)
Oomycete
Fungus like protoctista
Bacteria
Pathogen that produces toxins that can damage cell membranes, inactivate enzymes and interfere with metabolism. E.g TB, Bacterial meningitis and ring rot
Protoctista
Pathogen that does not insert new DNA but digest cells, replicate inside cell and burst out. E.g. malaria, potato/tomato late blight
Fungi
Pathogen that digests cells and destroys them E.g. black sigatoka, ring worm and athlete’s foot
Virus
Pathogen that inserts new DNA into cells, takes over its cell metabolism and replicate inside cell then burst out. E.g. tobacco mosaic virus, influenza, HIV/Aids
Parasites
Organism that live on or in a host, harming it, it may cause disease but causes damage that allows a second infection, that also live part or all of their life in/on host.
Pelvis
The central chamber of the kidney where urine collects before passing out down the ureter
Penicillin
The first widely used, safe antibiotic, derived from a mould, Penicillium notatum
Penicillin acyclase
Enzymes used to make semi-synthetic penicillins from naturally produced penicillins.
Pentose monosaccharide
A monosaccharide composed of five carbons
Peptide bond
A bond formed between two amino acids
Peptides
Chains of two or more amino acid molecules
Peripheral nervous system (PNS)
Consists of all the neurones that connect the CNS to the rest of the body (motor and sensory)
Phagocytosis
Process by which white blood cells called phagocytes recognise non-self cells, engulf then digest them within a vesicle called a phagolysosome.
Phagosome
The vesicle in which a pathogen or damaged cell is engulfed by a phagocyte.
Pharming
The use of genetically modified animals to produce pharmaceuticals
Phenotype
Observable characteristics of an organism
Phloem
Plant transport tissue that carries the products of photosynthesis (assimilates) to all cells of the plant.
Phosphodiester bonds
Covalent bonds formed between the phosophate group of one nucelotide and the hydroxyl (OH) group of another.
Phospholipid bilayer
Arrangement of phospholipids found in cell membranes; the hydrophilic phosphate heads from both the inner and outer surface of a membrane, sandwiching the fatty acid tails to form a hydrophobic core.
Phosphorylation
The addition of a phosphate group to a molecule
Phospholipids
Modified triglycerides, where one fatty acid has been replaced with a phosphate group. 1 phosphate and two fatty acid chains
Photosynthesis
Synthesis of complex organic molecules using light
Photosystem
Protein complexes involved in the absorption of light and electron transfers in photosynthesis.
Phototropism
The growth response of plants to unilateral light
Phylogeny
The evolutionary relationships between organisms
Pigment
Molecules that absorb specific wavelengths of light
Pinocytosis
Endocytosis of liquid materials
Pioneer species
The first organisms to colonise an area E.g. algae and lichen
Plagioclimax
Stage in succession where artificial (human) or natural factors prevent the natural climax community from forming
Plasma
The main component of blood, a yellow fluid containing many dissolved substances (glucose, amino acids, mineral ions, hormones and large plasma proteins) and carrying blood cells, white blood cells and platelets
Plasma cells
B lymphocytes that produce about 2000 antibodies to a particular antigen every second and release them into the circulation.
Plasma membrane
All the cell surface membranes of cells, which have the same basic structure described by the fluid mosaic model.
Pluripotent
A stem cell that can differentiate into any type of cell, but not form a whole organism
Polymerase chain reaction (PCR)
A process by which a sample of DNA can be amplified using specific enzymes and temperature changes
- Denaturation - temp 95 degrees Celsius, breaks hydrogen bonds between adjacent nucleotides leaving template single strands of exposed bases
- DNA primer annealing - temp decrease to 52 degrees Celsius, short sections of DNA (primers) anneal to end of DNA fragments
- Synthesis of DNA - temp increases 72 degrees Celsius taq polymerase (type of thermophilic DNA polymerase) optimum temp, binds to primers and transcribe along fragments adding bases building up complementary strands of DNA
Polymers
Long-chain molecules composed of linked (bonded) multiple individual molecules (monomers) in a repeating pattern.
Polymorphic allele
A gene with more than two possible alleles
Polypeptide
Chains of three or more amino acids
Polysaccharide
A polymer made up of many sugar monomers (monosaccharides)
Posterior pituitary gland
The posterior part of the pituitary gland in the brain where ADH is stored ready for release into the blood
Predation
The capturing of prey in order to sustain life
Preservation
Protection of an area by restricting or banning human use - so that the ecosystem is kept exactly as it is.
Primary immune response
The relatively slow production of a small number of the correct antibodies the first time a pathogen is encountered
Primary or pre mRNA
The mRNA transcribed from the DNA before any post-transcriptional regulation to remove introns etc.
Producer
Organism that converts light energy into chemical energy
Prokaryotes
Single-celled prokaryotic organisms from the kingdom Prokaryotae
Prokaryotic cells
Cells with no membrane-bound nucleus or organelles]
- Extremely small cells (less than 2 um diameter)
- Circular DNA
- No nucleus - DNA is free in cytoplasm
- Cell wall made of a polysaccharide, but not cellulose or chitin
- Few organelles and no membrane-bound organelles, e.g. no mitochondria
- Flagella, if present, made of the protein flagellin, arranged in a helix
- Small ribosomes (70s)
Eukaryotic cells
- Larger cells (about 10-100 um diameter)
- Linear DNA
- Nucleus present - DNA is inside nucleus
- No cell wall in animals, cellulose cell wall in plants, chitin cell wall in fungi
- Many organelles present + membrane-bound e.g. mitochondria
- Flagella, if present, made of microtubule proteins arranged in a ‘9 + 2’ formation
- Larger ribosomes (80s)
Prophase
First stage of mitosis when chromatin condenses to form visible chromosomes and the nuclear envelope breaks down
Prosthetic group
Non-protein component of a conjugated protein E.g. haem group in haemoglobin
Proteases
Enzymes that catalyse the breakdown of proteins and peptides into amino acids
Proteins
One or more polypeptides arranged as a complex macromolecule
Proteomics
The study and amino acid sequencing of an organisms entire protein complement
Protista
Biological kingdom containing unicellular eukaryotes
Proximal convoluted tubule
The first twisted section of the nephron after the Bowman’s capsule where many substances (glucose, amino acids, vitamins and some salts and some urea) are reabsorbed into the blood by active transport and facilitated diffusion
Purines
Big double-ringed, nitrogenous bases that form part of a nucleotide (Adenine and Guanine)
Purkyne fibres
Tissue that conducts the wave of excitation to the apex of the heart
Pyrimidines
Smaller single-ringed, nitrogenous bases that form part of a nucleotide (Thymine, Uracil and Cytosine)
Pyruvate
Three carbon product of glycolysis that feeds into Krebs cycle in the presence of oxygen
Quaternary structure
The association of two or more protein subunits
Random sampling
Sampling where each individual in the population has an equal likelihood of selection
Receptors
Extrinsic glycoproteins that bind chemical signals, triggering a response by the cell
Recessive allele
Version of a gene that will only be expressed if two copies of this allele are present in an organism
Recombinant
New combination of alleles/DNA from two sources
Recombinant chromatids
Chromatids with a combination of DNA from both homologous chromosomes, formed by crossing over and chiasmata in meiosis.
Recombination frequency
A measure of the amount of crossing over that has happened in meiosis it is the proportion of recombinant offspring resulting from a cross
Recombination frequency = number of recombinant offspring over total number of offspring
Reducing sugars
Saccharides (sugars) that donate electrons resulting in the reduction (gain of electrons) of another molecule
Reduction division
Cell division resulting in the production of haploid cells from a diploid cell; meiosis
Reflex action
Involuntary response to a sensory stimulus
- knee-jerk
- eye blinking
Regulatory gene
A gene that codes for proteins involved with DNA regulation
E.g. regulatory gene (lacI) in lac operon that codes for repressor protein
Renal dialysis
A process where the functions of the kidney are carried out artificially to maintain the salt and water balance of the blood
Repolarisation
A change in potential difference from positive back to negative across the membrane of a neurone back to resting potential
Repressor protein
Protein synthesised by regulatory genes that binds to operator affecting the rate of transcription
Respiration
Breakdown of complex organic molecules linked to the synthesis of ATP
Respiratory quotitent
Ratio of carbon dioxide produced to oxygen used in respiration
RQ = CO2 produced over O2
Respiratory substrates
Organic molecules broken down in respiration
Residual volume
The volume of air that is left in the lungs after forced exhalation. It cannot be measured directly
Resolution
The shortest distance between two objects that are still seen as separate objects. The ability to see individual objects as separate entities.
Response
The way a body reacts to stimulus
Resting potential
The potential difference across a membrane of the axon of a neurone at rest, normally about -65mV to -70mV
Restriction endonucleases
Enzymes that chop a strand of DNA into small fragments
R-Groups
Variable groups on amino acids
ribonucleic acid (RNA)
Polynucleotide molecules involved in the copying and transfer of genetic information from DNA. The monomers are nucleotides consisting of a ribose sugar and one of four bases; uracil, cytosine, adenine and guanine
Ribose
The pentose monosaccharide present in RNA molecules
ribosomal (r) RNA
Form of RNA that makes up the ribosome
Ribulose bisphosphate
Five carbon molecule at the beginning of Calvin cycle
Ribulose bisphosphate carboxylase (RuBisCo)
Key enzyme involved in the first step of carbon fixation in photosynthesis
RNA polymerase
Enzyme that catalyses the formation of phosphodiester bonds between adjacent RNA nucleotides
Root hair cells
Cells found just behind the growing tip of a plant root that have long hair-like extensions that greatly increase the surface area available for the absorption of water and minerals from the soil
Root pressure
The active pumping of minerals into the xylem by root cells that produces a movement of water into the xylem by osmosis.
Saprophytic/saprotrophic
Organisms that acquire nutrients by absorption - mainly of decaying material
Sarcomere
Functional unit of myofibril
Scanning electron microscopy (SEM)
An electron microscope in which a beam of electrons is sent across the surface of a specimen and the reflected electrons are focused to produce a three-dimensional image of the specimen surface.
Secondary immune response
The relatively fast production of very large quantities of the correct antibodies the second time a pathogen is encountered as a result of immunological memory - the second stage of a specific immune response.
Seed bank
A store of genetic material from plants in the form of seeds
Selection pressure
Factors that affect an organism’s chance of survival or reproductive success
Selective breeding
Selection of individuals for breeding with desirable characteristics
Selective toxicity
The ability to interfere with the metabolism of a pathogen without affecting the cells of the host
Selective reabsorption
The reabsorption of selected substances, i.e. those needed by the body, in the kidney tubules
Selectively permeable
Plasma membrane with protein channels that allow specific substances to cross only
Semi-conservative replication
DNA replication results in one old strand and one new strand present in each daughter DNA molecule
Sense strand
The strand of DNA that runs 5’ to 3’ and contains the genetic code for a protein
Sensory receptor
Specialised cell which detects a stimulus
Seral stages
The steps in succession
Sex linked genes
Genes carried on the sex chromosomes
Sliding filament model
Movement of actin and myosin filaments in relation to each other to cause contraction in muscles
Sieve plates
Areas between the cells of the phloem where the walls become perforated giving many gaps and a sieve-like appearance that allows the phloem contents to flow through
Sieve tube elements
The main cells of the phloem that have a greatly reduced living content and sieve plates between the cells
Simpson’s Index of Biodiversity (D)
A measure of biodiversity between 0 and 1 that takes place into account both species richness and species evenness
Species richness
The number of different species living in a particular area
Species evenness
A comparison of the numbers of individuals of each species living in a community
Single circulatory system
A circulatory system where the blood flows through the heart and is pumped out to travel all around the body before returning to the heart. E.g: fish and annelid worms
Sinks (in plants)
Regions of a plant that require assimilates to supply their metabolic needs, e..g roots, fruits
Sino-atrial node (SAN)
Region of the heart that initiates a wave of excitation that triggers the contraction of the heart. The hearts natural pacemaker
Somatic cell gene therapy
Replacing a faulty gene with a healthy allele in affected somatic cells.
Somatic cell nuclear transfer
A method of producing a clone from an adult animal by transferring the nucleus from an adult cell to an enucleated egg cell and stimulating development.
Somatic nervous system
Part of the nervous system that is under conscious control
- myelinated
- connections to effectors only exists of one neurone
- cell bodies of the motor neurones are found in the CNS
- includes all sensory neurones and motor neurones that carry information to the skeletal muscles
Autonomic Nervous system (details)
- non-myelinated
- connections to effectors always consists of at least two neurones (which connects at a swelling called a ganglion)
- the cell bodies of motor neurones are found outside the CNS in the autonomic ganglia
- includes all the motor neurones that communicate with internal organs
- responsible for controlling most homeostatic processes
- controls all the activity of smooth muscle e.g. walls of arterioles and gut
- controls the heart rate
- controls the activity of exocrine glands e.g. salivary
Somatic motor pathway
motor neurone to skeletal muscle
Autonomic motor pathway
preganglionic neurone to autonomic ganglion (sympathetic) to motor neurone to smooth muscle inside organ
Smooth endoplasmic reticulum
Endoplasmic reticulum lacking ribosomes; the site of lipid and carbohydrate synthesis, and storage.
Sources (in plants)
Regions of a plant that produce assimilates e.g. glucose/sucrose by photosynthesis or from storage materials, e.g. leaves, storage organs
Spearman’s rank correlation coefficient
A specific type of correlation test that compares the ranked orders of two data sets in order to consider their relationships
Specialised
Having particular structures to serve a specific function
Speciation
The formation of new species
- Allopatric (physical barrier making some members of a pop separated from the rest by a physical barrier making them geographically isolated)
- Sympatric (same habitat)
Species
The smallest and most specific taxonomic group
Specific immunity
Also known as active immunity or acquired immunity - the immune system ‘remembers’ an antigen after an initial response to subsequent encounters
Spiracles
Small openings along the thorax and abdomen of an insect that open and close to control the amount of air moving in and out of the gas exchange system and the level of water loss from the exchange surfaces.
Stabilising selection
Natural selection that favours the average phenotype
Stage graticule
A slide with a scale in micrometers (um) etched into it. Used to measure the size of a sample under a light microscope
Stains (staining)
Dyes used in microscopy sample preparation to increase contrast or identify specific components
Starch
A polysaccharide formed from alpha glucose molecules either joined to form amylose or amylopectin
Stem cells
Undifferentiated cells with the potential to differentiate into a variety of the specialised cell types of the organism
Stimulus
Detectable change in external or internal environment of an organism
Stomata
Pores in the surface of a leaf or stem that may be opened and closed by guard cells
Stratified sampling
Sampling where populations are divided into sub-groups (strata) based on a particular characteristic. A random sample is then taken from each of these strata proportional to its size.
Stroma
Fluid interior of chloroplasts containing enzymes controlling the carbon fixation reactions.
Structural genes
Genes that code for structural proteins or enzymes not involved in DNA regulation
Student’s t-test
Statistical test used to compare the means of data values of two populations
Substrate
A substance used, or acted on, by another process or substance. For example a reactant in an enzyme-catalysed reaction
Substitution
A point mutation where one or more nucleotides are substituted for another in a DNA strand
Substrate level phosphorlyation
Synthesis of ATP by transfer of phosphate group from another molecule
- The production of ATP involving the transfer of a phosphate group from a short-lived, highly reactive intermediate such as creatine phosphate
Succession
The progressive replacement of one dominant type of species or community by another in an ecosystem, until a stable climax community is established
Sucrose
A dissacharide made up of a fructose and glucose monosaccharides
Summation
Build up of neurotransmitter in a synapse to sufficient levels to trigger an action potential
Sustainable development
Economic development that meets the needs of people today, without limiting the ability of future generations to meet their needs.
Sustainable resource
A renewable resource which is being economically exploited in such a way that it will not diminish or run out
Sympatric speciation
Speciation that occurs when there is no physical barrier between populations so occurs in the same habitat
Symplast
The continuous cytoplasm of living plant cells connected through the plasmodesmata
Symplast route
Movement of water and solutes through the cytoplasm of the cells via plasmodesmata by diffusion (passive)
Synapse
The junction (small gap) between two neurones, or a neurone and an effector. Consists of a synaptic bulb, synaptic cleft and post synaptic neurone. Important for:
- unidirectional
- removing low level summation
- nerve networks
- learning and memory
Synthetic biology
The design and construction of novel biological pathways, organisms or devices, or the redesign of existing natural biological systems
Systematic sampling
Different areas of a habitat are identified and sampled separately. Often carried out using a line or belt transect
Systole
The stage of the cardiac cycle in which the atria contract, followed by the ventricles, forcing blood out of the right side of the heart to the lungs and the left side of the heart to the body
T helper cells
T lymphocytes with CD4 receptors on their cell-surface membranes, which bind to antigens on antigen-presenting cells and produce interleukins, a type of cytokine
T killer cells
T lymphocytes that destroy pathogens carrying a specific antigen with perforin
T lymphocytes
Lymphocytes which mature in the thymus gland and that both stimulate the B lymphocytes and directly kill pathogens
T memory cells
T lymphocytes that live a long time and are part of the immunological memory
T regulatory cells
T lymphocytes that suppress and control the immune system, stopping the response once a pathogen has been destroyed and preventing an autoimmune response.
Tachycardia
An abnormally fast heart rhythm of over 100 beats per minute at rest
Tannins
Bitter tasting chemicals produced to prevent animals eating plant leaves; toxic to many insects
Target cells
Specific cells which hormones act on
Taxonomic group
The hierarchical groups of classification - domain, kingdoms, phylum, class, order, family, genus, species
Telophase
Fourth stage of mitosis when chromosomes assemble at the poles and the nuclear envelope reforms
Temperature coefficient (Q10)
A measure of how much the rate of a reaction increases with a 10 degrees Celsius temperature increase
Template strand
The antisense strand of DNA that acts as template during transcription so that the complementary RNA strand formed carries the same code for a protein as the DNA sense strand
Terpenoids
Chemicals found in plant leaves that may act as toxins to insects or fungi attacking the leaves. Compound forms essential oils that can be insect repellents.
Pheremones
Chemical that allows plants to communicate
Volatile Organic Compounds (VOCs)
Compounds that attracts predators (insects) for protection
Tertiary structure
Further folding of the secondary structure of proteins involving interactions between R-groups
- hydrogen bonds
- ionic bonds
- disulfide bridges
- hydrophobic and hydrophilic interactions
Test cross
A cross used to determine genotype, involving a backcross with a homozygous recessive parent
Thermoregulation
The maintenance of a relatively constant core temperature
Thin layer chromatography
A technique for separating different pigments through the rate at which they move across an inert surface carried by a solvent.
Thylakoid
Series of membranous compartments in a chloroplast that contain chlorophyll and molecules needed for light-dependent reaction.
Tidal volume
The volume of air which moves into and out of the lungs with each resting breath
Tissue
A collection of differentiated cells that have a specialised function or functions in an organism
Tissue fluid
The solution surrounding the cells of multicellular animals
Biotechnology
Applying biological organisms or enzymes to the synthesis, breakdown or transformation of materials in the service of people e.g. food, DNA manipulation and drugs
Tonoplast
Membrane forming a vacuole in a plant cell
Total lung capacity
The sum of the vital capacity and the residual volume
Totipotent
A stem cell that can differentiate into any type of cell and form a whole organism
Trachea
The main airway, supported by incomplete rings of cartilage, which carries warm moist air down from the nasal cavity into the chest
Tracheal fluid
Fluid found at the ends of the tracheoles in insects that helps control the surface area available for gas exchange and water loss
Transcription
The process of copying sections of DNA base sequence to produce smaller molecules of mRNA, which can be transported out of the nucleus via the nuclear pores to the site of protein synthesis
Transcription factors
Proteins that bind to DNA to switch genes on or off by affecting the rate of transcription (increase - activators or decrease - repressors)
transfer (t) RNA
Form of RNA that carries an amino acid specific to its anticodon to the correct position along mRNA during translation
Translation
The process by which the complementary code carried by mRNA is decoded by tRNA into a sequence of amino acids. This occurs at a ribosome
Translocation
The movement of organic solutes around a plant in the phloem
Transmission electron microscopy (TEM)
An electron microscope in which a beam of electrons is transmitted through a specimen and focused to produce an image
Transpiration
The loss of water vapour from the stems and leaves of a plant as a result of evaporation from cell surfaces inside the leaf and diffusion down a concentration gradient out through the stomata
Transpiration stream
The movement of water through a plant from the roots until it is lost by evaporation from the leaves
Transport system
The system that transports required substances around the body of an organism
Triglyceride
A lipid composed of one glycerol molecule and three fatty acids
Triose phosphate
A molecule that is an intermediate in both photosynthesis and respiration and acts as a starting material for the synthesis of carbohydrates, lipids and amino acids
Triplet code
The genetic code is a sequence of three nucleic acid bases, called a codon. Each codon codes for one amino acid.
Trophic level
Stage in a food chain
Tropism
A growth response by a plant in response to a unidirectional stimulus
- phototropism
- geotropism
- tropisms as response to environmental cues
Turgor
The pressure excreted by the cell-surface membrane against the cell wall in a plant cell
Ultrafiltration
The process by which blood plasma is filtered through the walls of the Bowman’s capsule under pressure
Ultrastructure
The ultrastructure of a cell is those features which can be seen by using an electron microscope
- microtubule network
- vesicles
- nucleolus
- nucleus
- golgi apparatus
- cell-surface membrane
- cytosol
- ribosome
- centriole
- RER
- SER
- cytoskeleton
- secretory vesicles
- mitochondria
Undifferentiated
An unspecialised cell originating from mitosis or meiosis
Urea
Nitrogenous waste produced from the deamination of excess amino acids in the liver and ornithine cycle
Ureters
Tubes carrying urine from the kidneys to the bladder
Urethra
Tube carrying urine from the bladder to the outside of the body
Vaccine
A safe form of an antigen, which is injected into the bloodstream to provide artificial active immunity against a pathogen bearing the antigen
Vacuoles
Membranous sacs used to transport materials in the cell
Vascular bundle
The vascular system of herbaceous dicots, made up of xylem and phloem tissue + cortex
Vascular system
A system of transport vessels in animals or plants
Vector
A living or non-living factor that transmits a pathogen from one organism to another e.g. female malaria mosquito
Vector (in genetic modification)
A means of inserting DNA from one organisms into the cells of another organism
Vegetative propagation
The artificial production of natural clones for use in horticulture and agriculture
Ventilation rate
The total volume of air inhaled in one minute. Ventilation rate = tidal volume x breathing rate (per minute)
Vital capacity
Volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath
Vmax
Maximum initial velocity or rate of an enzyme-catalysed reaction
Water potential (trident symbol)
Measure of the quantity of water compared to solutes, measured as the pressure created by the water molecules in kilopascals (kPa)
Wild types
The allele that codes for the most common phenotype in a natural population
Xerophytes
Plants with adaptations that enable them to survive in dry habitats or habitats where water is in short supplying the environment E.g. marram grass, cacti
- thick waxy cuticle
- sunken stomata located in pits = reduced air movement + produces humid climate reducing transpiration
- reduced numbers of stomata
- reduced leaves
- thin needles reduce SA
- hairy leaves create humid microclimate
- curled leaves confines stomata in microenvironment of still, humid air
- leaf loss
- mass of widespread deep roots
Xylem
Plant transport tissue that carries water and dissolved minerals from the roots to the other parts of the plant as a result of physical forces
Zygote
The initial diploid cell formed when two gametes are joined by means of sexual reproduction. Earliest stage of embryonic development
