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whats VARIATION?

• DIFFERENCES within a SPECIES

whats a GENOME?

• all of the GENETIC MATERIAL

• of an ORGANISM

whats PHENOTYPE?

• the OBSERVABLE CHARACTERISTICS of an ORGANISM

what are the two TYPES of VARIATION?

• genetic

• environmental

whats GENETIC VARIATION?

• characteristics are INHERITED from your parents

• eg. blood group, eye colour

whats ENVIRONMENTAL VARIATION?

• caused by the ENVIRONMENT

• eg. accent, scars

what can VARIATION be?

• CONTINIOUS

• DIScontinuous

whats CONTINUOUS variation?

• can take ANY VALUE within a RANGE

• caused by BOTH

• CONTROLLED by MULTIPLE genes

• displayed on a HISTOGRAM

• eg. height

whats DISCONTINUOUS variation?

• can take results in DISCRETE values

• caused by GENETIC

• CONTROLLED by ONE or a FEW genes

• displayed on a BAR CHART

• eg. eye colour, gender

whats a CLONE?

• an ORGANISM thats GENETICALLY IDENTICAL

• to its PARENT

what does HAPLOID mean?

• only contains HALF the amount of CHROMOSOMES

• eg. gametes

what happens in fertilisation?

• two HAPLOID cells join to make a DIPLOID cell (zygote)

• divides many times by MITOSIS to make an organism

what does MEIOSIS produce?

• 4 HAPLOID cells from one DIPLOID parent cell

whats the FIRST STAGE of MEIOSIS?

MITOSIS:

1. chromosomes are copied

2. LINE up along the EQUATOR in PAIRS

3. CHROMOSOMES are PULLED to opposite POLES

4. CELL divides in TWO (cytokinesis)

whats the SECOND STAGE of MEIOSIS?

• chromosomes LINE up along the EQUATOR

• PULLED in HALF (so a SINGLE COPY of each chr moves to the POLES)

• EACH cell DIVIDES in TWO

what is VARIATION CAUSED by?

1. RANDOM assortment of CHROMOSOMES at the EQUATOR

2. CROSSING over of the CHROMOSOMES

3. RANDOM fertilisation

what are ALLELES?

• DIFFERENT FORMS of the SAME GENE

whats a DOMINANT ALLELE?

• expressed when ONE or TWO of the ALLELES are present

• CAPITAL LETTER

whats a RECESSIVE ALLELE?

• only expressed if BOTH ALLELES are recessive

• lowercase letter

whats a GENOTYPE?

• a COMBINATION of all of the ALLELES

• present in an ORGANISM

whats HOMOZYGOUS DOMINANT?

• two copies of the same DOMINANT ALLELE are present

• eg. BB

whats HOMOZYGOUS RECESSIVE?

• two copies of the same RECESSIVE ALLELE are present

• eg. bb

whats HETEROZYGOUS?

• the two alleles are DIFFERENT

• eg. Bb

whats MUTATION?

• the CHANGE in BASE SEQUENCES in DNA

what INCREASES the CHANCES of MUTATION?

• ionising radiation (uv)

• certain chemicals (ethanol)

whats GENETIC VARIATION?

• DIFFERENT versions of an ALLELE

• arises from a MUTATION in the DNA

what are the effects of mutations?

• show no effect on the phenotype

• influence the phenotype

• determine the phenotype (leads to genetic variation within a species)

what happens to the DNA bases?

• can get CHANGED (the amino acid that codes for the protein, therefore effects the phenotype)

• more can be ADDED

• some can be DELETED

what happens if the AMINO ACID sequence is CHANGED?

• effects the way the protein FOLDS

• or the WRONG PROTEIN could be made

what do START CODONS do?

• found BEFORE each gene in the NON-coding section of DNA

• (triggers TRANSCRIPTION)

• if mutations occur at the START of the CODON

• , gene will NOT be TRANSCRIBED

• and the PROTEIN won’t be made

whats EVOLUTION?

• the GRADUAL change of a SPECIES over time

what are the steps to NATURAL SELECTION?

1. variation within a species

2. survival of the fittest (best adapted characteristics)

3. reproduction

4. passing on the advantage

5. repeat, development of a new species

what are FOSSILS?

• formed when the REMAINS of animals / plants become MINERALISED

• (changed into rocks)

whats a FOSSIL RECORD?

• fossil LAYERS form a SEQUENCE

• showing how the organism has CHANGED over time

• its EVIDENCE FOR EVOLUTION

what do fossils SHOW?

• that closely related ORGANISMS have evolved from the SAME ANCESTOR

what else is evidence for evolution?

• molecular COMPARISON of DNA + PROTEINS

• ,CLOSELY related = SIMILAR patterns

how do we PRESERVE BIODIVERSITY?

• by using SEEDBANKS

• if you need to preserve an organism to use later on, you store the seeds

whats CLASSIFICATION?

• storing living organisms into GROUPS

• based on similar CHARACTERISTICS

why do scientists CLASSIFY organisms?

• to PREDICT characteristics

• to IDENTIFY species

• and to SHOW evolutionary links

whats the 7 TAXONOMIC levels?

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

what are the 5 KINGDOMS?

• plants

• animals

• fungi

• prokaryotes

• protoctists

whats a SPECIES?

• a group of ORGANISMS

• that are able to PRODUCE

• FERTILE offspring

what the ARTIFICIAL CLASSIFICATION system?

• uses OBSERVABLE CHARACTERISTICS

• DOESN’T consider EVOLUTIONARY relationships

whats NATURAL CLASSIFICATION?

• based on EVOLUTIONARY relationships

• determined through DNA ANALYSIS

whats PHYLOGENY?

• study of EVOLUTIONARY LINKS

• THROUGH the study of DNA