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Unit 4 - Coggle Diagram
Unit 4
4.5 Species and Taxonomy
Classification - The organisation of living organisms into groups. Taxonomy - The study and science of classification.
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Artificial classification - grouping according to characteristics. Phylogenetic classification - Based on evolutionary relationships between organisms and their ancestors.
Classification systems consist of a hierarchy in which groups are contained within larger, composite groups, with no overlap. Domain is the highest taxonomic rank, split into three groups.
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Archaea - Single celled prokaryotes, originally classed as bacteria but they differ because: Their genes and protein synthesis are more similar to eukaryotes and they have a more complex form of RNA polymerase.
Eukarya - Organisms with one or more eukaryotic cells, they have membrane bound organelles and their ribosomes are larger than their counterparts.
The Linnaean System. Kingdom, Phylum, Class, Order, Family, Genus, Species.
Courtship behaviour - A specialised behaviour that ensures the fertilisation of eggs by a male. It is necessary to precursor successful mating and is used in species recognition
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4.2 Protein Synthesis
Genome, complete set of genes in a cell. Proteome, full range of proteins produced by the genome.
Transcription: DNA helicase breaks the hydrogen bonds. Only one coding strand acts as a template. RNA nucleotides are attracted to the bases according to complementary base pairing rule. RNA polymerase joins two nucleotides together by a phosphodiester bond.
Exons - Expressed, code for proteins. Introns Invisible, don't code
Translation: mRNA attaches to ribosomes. tRNA anticodons bind to complementary mRNA codons and bring a specific amino acid. Amino acids join by peptide bonds, using ATP. The tRNA is released.
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4.3 Genetic diversity
Mutation
Change to DNA nucleotide base sequence, due to mistakes in DNA replication etc. Could be insertion, substitution or deletion. My lead to a change in amino acid sequence, causing a change in function and tertiary structure of a protein. Structure of organism can change.
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Nucleotides lost from DNA sequence, results in a frame shift of nucleotides to the left by one or more bases.
Nondisjunction - One or more pairs of chromosomes fail to separate during meiosis. Usually results in gametes having more/fewer chromosomes.
Division/Variation
Mitosis - Chromosomes coil/condense. Then appear as two sister chromatids joined at centre. Chromosomes line up at the equator and are attached to spindle fibres by their centromeres. The centromere splits/divides and sister chromosomes are pulled to opposite ends of the cell.
Meiosis. Produces 4 daughter nuclei, each with half the number of chromosomes of the parent cell.
Meiosis 1: homologous chromosomes pair up, crossing over occurs, one chromosome from each homologous pair goes into each daughter cell
Meiosis 2: The sister chromatids separate, moving to opposite poles. 4 genetically different haploid cells are formed.
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