Key Words Flashcards
Monomer
Small unit from which larger molecules are made
Polymer
Molecules made from a large number of monomers joined together
Isomer
Molecules which have the same chemical formula but a different structure
Monosaccharide
The monomer from which larger carbohydrates are made
Disaccharide
Molecules made from two monosaccharides joined by a condensation reaction
Polysaccharide
Molecules made from many monosaccharides joined together by condensation reactions
Saturated fatty acid
Only single bonds between the carbon atoms
Unsaturated fatty acid
There are double bonds between two or more of the carbon atoms
Dipeptide
Molecules made from two amino acids joined by a condensation reaction
Polypeptide
Molecules made from many amino acids joined together by condensation reactions
Primary structure
The sequence of amino acids
Secondary structure
Formed by the regular folding or coiling of the primary structure, (held by hydrogen bonding)
Tertiary structure
The further folding of the secondary structure to make a specific shape, (held together by hydrogen, ionic and disulphide bonding between the variable groups)
Quaternary structure
More than one polypeptide chain
Induced fit model
The approach of the substrate causes a change in the shape of the enzyme – such that the active site and substrate become (fully) complementary
DNA helicase
An enzyme which unwinds the coiled DNA and breaks the hydrogen bonds between bases so separating strands of DNA
DNA polymerase
An enzyme which catalyses the condensation reaction which forms a phosphodiester bond between adjacent DNA nucleotides together
Nucleus
Organelle which contains the cell’s chromosomes and nucleoli
Nucleolus
Where rRNA and ribosomes are made within the nucleus
Mitochondria
Site of aerobic respiration
Chloroplasts
Absorb light and use it for photosynthesis
Golgi apparatus
modify, package, transport and store proteins (and lipids)
Lysosomes
Contain hydrolytic enzymes (called lysozymes)
Ribosomes
Site of protein synthesis
RER
Ribosomes are attached on the surface and are the site of protein synthesis
Proteins are folded inside the RER and can be transported around the cell
SER
A site of lipid (/phospholipid/cholesterol steroid) synthesis and storage. Also stores ions in the cell
Tissue
Formed of a group of cells which all perform a similar function
Organ
Formed of a group of tissues which perform a variety of functions
Prokaryotic cell
Cells which lack membrane bound organelles
Capsid
A protein structure which holds the nucleic acids in a virus
Interphase
DNA replication occurs
Prophase
- Spindle fibres migrate to opposite poles of the cell
- Chromosomes coil and condense and become visible (each chromosome is made of two sister chromatids held together by a centromere)
- The nuclear membrane breaks down
Metaphase
- spindle fibres are produced and attach to the centromeres of the chromosomes
- chromosomes line up along the equator of the cell
Anaphase
• Spindle fibres shorten and separate the sister chromatids which are pulled to opposite poles of the cell
Telophase
- Nuclear envelopes reform
* Chromosomes decondense
Cytokinesis
• Cytoplasm divides
Binary fission
The process by which prokaryotic cells divide
Carrier protein
A protein which undergoes a conformation change in shape in order to move substance(s) across a membrane
Channel protein
A protein which forms an aqueous pore across a membrane which when open, allows one or more specific substances to pas through by diffusion.
Diffusion
The net movement of a substance from a higher concentration to a lower concentration
Facilitated diffusion
The net movement of a substance from a higher concentration to a lower concentration via specific channel or carrier protein
Osmosis
The net movement of water from a higher water potential to a lower water potential through a partially permeable membrane. But to note that biological membranes are selectively permeable
Active transport
The movement of a substance from a lower concentration to a higher concentration via/using a carrier protein using energy from ATP
Pathogen
A disease causing agent.
Toxin
A poison produced by a living organism
Antigen
A foreign protein or glycoprotein which stimulates an immune response
Clonal selection
Activation of a specific B cell that produces the antibody specific to an antigen. The B cell divides to produce a genetically identical clone of plasma cells, each producing large amounts of this specific antibody.
Monoclonal antibody
Antibodies which are identical and come from plasma cells belonging to one/the same clone. They are all specific to only one antigen
Antibody
A protein produced by B plasma cells which binds to a specific, complementary antigen
Agglutination
The clumping together of antigen-bearing cells in the presence on their complementary antibody
Vaccine
A vaccine contains an antigen, or several antigens from a pathogen that stimulate an immune response.
Herd immunity
When enough individuals are immune to prevent the spread of a pathogen, because of the lack of susceptible hosts.
Active immunity
Immunity which results from the production of antibodies by the immune system
Passive immunity
Immunity which results from the introduction of antibodies from another person or animal. This provides short term immunity.
Tracheoles
Network of tubes within an insect which transport air for gas exchange
Spiracles
Pores on the surface of an insect which allow air in and out
Xerophyte
A plant adapted to live in a very dry environment
Diaphragm
Muscle which separates the abdomen and thorax
Intercostal muscles
Muscles found between the ribs and are responsible for moving them during ventilation
Digestion
When large molecule are hydrolysed to form smaller molecules
Endopeptidase
An enzyme which hydrolyses any peptide bond apart from the terminal ones in a polypeptide chain.
Exopeptidase
An enzyme which hydrolyses the terminal peptide bond in a polypeptide chain.
Dipeptidase
An enzyme which hydrolyses dipeptides into amino acids
Micelles
An aggregate of lipid molecules within an aqueous solution
Mass transport
The bulk movement of substances over a large distance within an organism.
The Bohr effect
Haemoglobin’s affinity to oxygen is inversely related to the concentration of CO2 and acidity.
Xylem
Vascular tissue in plants which carries water and dissolved nutrients from the roots up the plant
Cohesion tension theory
- The water potential in the leaf cells decreases
- This causes water to move out the xylem into surrounding tissues by osmosis
- This creates tension on the water in the xylem
- The water in the xylem is in a continuous column due to cohesion between water molecules due to H-bonds
- The column doesn’t break due to adhesion (H-bonds between the water molecules and the walls of the xylem)
Phloem
Vascular tissue in plants which carries sugars around the plant from sources to sinks – e.g. could be from leaves or it could be from underground storage tissues in spring
Gene
a base sequence of DNA that codes for the amino acid sequence of a polypeptide or for a functional RNA
Universal
The same three bases code for the same amino acid in all organisms
Degenerate
There is more than one set of three bases that codes for each amino acid
Non overlapping
Each base is only part of one ‘triplet’ (it is only ‘read’ once)
Exon
A base sequence within a gene which codes for a sequence of amino acids
Intron
A base sequence within a gene which is non-coding
Genome
The complete set of genes in a cell
Proteome
The full range of proteins that a cell is able to produce
mRNA
A linear strand of RNA which is transcribed from a DNA template and has no H-bonds. Its length depends on the length of the gene.
tRNA
A folded strand of RNA which is held in a clover shape due to H-bonds. Each tRNA carries a specific amino acid.
rRNA
rRNA is a component of a ribosome.
Transcription
The production of pre-mRNA from DNA - except in (most) prokaryotes, where there are no introns, so mRNA produced by transcription
RNA polymerase
The enzyme which forms the phosphodiester bond between RNA nucleotides in the new strand of pre-mRNA
Translation
The production of polypeptides at ribosomes, using information in the sequence of codons carried by mRNA
Triplet
A sequence of the three bases on DNA which code for an amino acid
Codon
A sequence of the three bases on mRNA which code for an amino acid
Anticodon
A sequence of the three bases on tRNA which are complementary to a codon. The tRNA carries a specific amino acid
Mutation
A change in the base sequence of a DNA
Non disjunction
When homologous pairs of chromosomes do not separate during meiosis. This results in daughter cells which either have extra chromosomes or have chromosomes missing.
Diploid cell
These cells contain two copies of each chromosome (one copy from each parent)
Haploid cell
These cells contain one copy of each chromosome or gene
Homologous chromosomes
Chromosomes that have the same genes at the same loci
Independent segregation
Independent segregation occurs when the homologous pairs separate and go to opposite poles of the cell. It means that the combination of chromosomes that go into each gamete is random.
Crossing over
Exchange of alleles between homologous chromosomes
Genetic diversity
The number of different alleles of genes in a population
Directional selection
Selection that may vary in one direction from the mean of the population. Extreme phenotypes have a selective advantage and this results in the characteristics of the population changing over time.
Stabilising selection
Selection that favours average individuals. This preserves the characteristics of a population
Species
A group of similar organisms which are able to interbreed to produce fertile offspring
Courtship
Behaviours shown between male and female organisms which can lead to copulation/mating
Hierarchy
Small groups are placed within larger groups, with no overlap between groups
Tax on
Phylogenetic groups
Biodiversity
The range of living organisms
Species richness
A measure of the number of different species in a community
Index f diversity
A measure of biodiversity which takes into account the number of species in a community and the number of individuals in each species
Standard deviation
The spread of data around the mean
