Studied by 2 people
Species
A group of similar organisms that can reproduce to give fertile offspring
Population
A group of organisms of the same species living in a particular area at a particular time
Gene pool
The complete range of all the alleles of all the genes of all the individuals present within a population at a given time
Allele frequency
How often / how many times an allele occurs in a population
Variation
The differences that exist between individuals
Selection Pressure
Anything that affects an organisms chance of survival and reproduction
Evolution
A change in allele frequencies over time
Stabilising selection
Where individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
Directional selection
Where individuals with alleles for characteristics towards one end of the range are more likely to survive and reproduce
Disruptive selection
Where individuals with alleles for characteristics towards both ends of the range are more likely to survive and reproduce
Speciation
The development of a new species from an existing species
Geographical isolation
Individuals are completely separated by a physical barrier
Allopatric speciation
Speciation due to geographical isolation
Sympatric isolation
Speciation that does not require geographical isolation
Reproductive isolation
Individuals from different populations have changed so much that they can no longer breed with one another to give fertile offspring
Genetic drift
When chance rather than environmental factors dictate which individuals survive breed and pass on their genes
Gene
A sequence of bases on a DNA molecule that codes for a polypeptide
Allele
A different version of a gene
Genotype
The alleles an organism possesses
Phenotype
The expression of the genotype of an organism - an organisms characteristics
Dominant
An allele whose characteristic is expressed in the phenotype even if there is only one copy
Recessive
An allele whose characteristic only appears in the phenotype if there are two copies present
Codominant
Two dominant alleles that are both expressed in the phenotype
Locus
The fixed position of a gene on a chromosome
Carrier
A person carrying an allele which is not expressed in their phenotype but can be passed onto offspring
Sex-linked genes
Genes carried on the sex chromosomes
Autosome
Any chromosome that isnt a sex chromosome
Epistasis
One gene affects / masks the expression of another gene
Chi-squared test
A statistical test used to see if the results of an experiment support a theory
Habitat
The place where an organism lives
Population
All the organisms of one species in a habitat
Community
Populations of different species in a habitat
Ecosystem
A community and all the abiotic conditions in the area which it lives
Abiotic
The non living features of an ecosystem
Biotic
The living features of an ecosystem
Niche
The role of a species within its habitat, such as what it its and when and where it feeds
Adaptation
A feature that members of a species have that increase their chances of survival and reproduction
Physiological adaptations
Adaptations that change the physical processes inside an organisms body
Behavioural adaptaions
Adaptations that change the way an organism acts
Anatomical adaptations
Adaptations that change the structural features of an organisms body
Population size
The total number of organisms of one species in a habitat
Carrying capacity
The maximum stable population size of a species that an ecosystem can support
Interspecific competition
Competition between different species for the same resources
Intraspecific competition
Competition within a species for the same resources
Predation
Where an organism kills and eats another organism
Dynamic
Constantly changing
Primary succession
Occurs on land thats been newly formed or exposed, starts when a new species colonise a new land surface
Secondary succession
Happens on land thats been cleared of all the plants but where soil remains - happens in the same was as primary succession but starts at a later stage, with larger plants as there is already a soil layer
Climatic climax
The climax community for a particular climate
Plagioclimax
The climax community when succession is stopped artificially
Conservation
The protection and management of ecosystems in a sustainable way
Sustainable
Enough resources are taken to meet the needs of people today, without reducing the ability of people in the future to meet their own needs
Succession
The process by which the structure of a biological community evolves over time
Mutation
Any change to the base sequence of DNA
Substitution
One or more bases swapped for another
Deletion
One or more bases are removed
Addition
One or more bases are added
Duplication
One or more bases are deleted
Inversion
A sequence of bases is reversed
Translocation
A sequence of bases is moved from one location in the genome to another. This could be movement within the same chromosome or movement to a different chromosome
Hereditary mutations
Mutations passed from parents to the offspring via gametes
Frame shift
A shift in the bases that follow after a mutation, could be to the left or right
Downstream
The base triplets that follow on after a mutation
Mutagenic agennts
Things that can increase the rate of mutation
Acquired mutations
Mutations that occur in an individual after fertilisation
Cancerous tumours
A mass of abnormal cells that form a tumour which grows rapidly and invades and destroys surrounding tissue. Cells can break off and form tumours elsewhere in the body
Benign tumours
Non-cancerous tumours that grow slowly and are covered in fibrous tissue that stops cells invading other tissues. They are harmless but can cause blockages and put pressure on organs
Genetic factor
A factor that is linked to the alleles an individual has
Environmental factor
A factor not linked to the alleles an individual has
Proto-oncogenes
Genes that stimulate cell division by producing proteins that make cells divide
Oncogene
A mutated proto-oncogene
Tumour suppressor genes
Genes which slow cell division by producing proteins that stop cells dividing or causes them to self destruct
Stem cells
Unspecialised cells which can develop into other types of cell
Totipotent
Stem cells that can mature into any type of body cell, including those of the placenta. They are only present in the first few cell divisions of an embryo
Pluripotent
Embryonic stem cells which have lost the ability to become cells that make up the placenta, but can still become any other body cell
Multipotent
Stem cells which are able to differentiate into a few different cell types, eg cells that are found in the bone marrow can become red or white blood cells
Unipotent
Stem cells that can only differentiate into one type of cell
Cardiomyocytes
Heart muscle cells that make up a lot of the tissue found in hearts
Adult stem cells
Stem cells which are obtained from the body tissues of an adult
Embryonic stem cells
Stem cells which are obtained from embryos at an early stage of development
iPS cells
Stem cells that are made by reprogramming already specialised adult body cells by making them express genes associated with pluripotency
Genome
The entire set of DNA including all the genes in an organism
Human genome project
A 2003 project which mapped the whole sequence of the human genome for the first time
Proteome
All the proteins produced by an organism
Regulatory genes
Genes that determine when other genes that code for particular proteins should be switched on and off
Transgenic organisms
Organisms that contain transferred DNA
Recombinant DNA technology
Transferring a fragment or DNA from one organism to another
Target gene
The gene you are interested in when making DNA fragments
cDNA
The complimentary DNA produced when making the DNA fragments using reverse transcriptase
Palindromic sequence
Sequences of DNA which consist of antiparallel base pairs, that are read the same in opposite directions
Recognition sequences
Another name for palindromic sequences
Sticky ends
Small tails of unpaired bases at each end of a DNA fragment
Gene machine
A machine that synthesises DNA fragments from scratch without the need for a preexisting template
Protecting groups
Groups that make sure nucleotides are joined at the right points in a gene machine to prevent unwanted branching
why is a membrane structure model called a fluid mosaic?
Phospholipids and proteins are abks to move. And embedded proteins vary in structure and size.
phospholipid bilayer
a double layer of phospholipid molecules that form membranes in cells. Hydrophilic head and hydrophobic tail forms a hydrophobic region.
Golgi apparatus
modifies and packages proteins for export by the cell
Why is cholesterol important?
Reduces membrane fluidity and permeability (binds hydrocarbon tails together reducing spaces for diffusion).
Unsaturated membrane
A more liquid membrane as they have kinks in tails so are more loosely packed.
Saturated membrane
A more solid membrane as they are long and straight so more tightly packed.
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