Flashcards
Biology-genetic variation
Cards in this deck (41)
- 1GeneA section of DNA which codes for a protein that holds the code for a specific trait.
- 2AlleleDifferent version of the same gene "Alternative form of a gene."
- 3ChromosomeSingle piece of DNA. Genes, segments of DNA arranged on a chromosome, can have 100's-1000's of genes.
- 4Homologous ChromosomeSome genes arranged in same order but slightly different to DNA sequence.
- 5Parts of a Chromosome-single chromosome made up of DNA wound tightly around a protein.
-Replicated chromosomes - 6locus (loci)The location of a gene on a chromosome
- 7LAW- SegregationIndependent separation of alleles on different chromosome.
essential for sexual reproduction
During meiosis the two alleles separate, one of each allele is passed onto offspring. - 8LAW_Crossing Over & Recombinationoccurs during Prophase 1
parts of the chromosome of non-sister chromatids can cross at the point called Chiasma.
result-re-combinations that contain mix of parental alleles. - 9LAW- Independent Assortmentoccurs when homologous chromosomes line up-randomly during metaphase
results-gametes with unique combinations. - 10Advantages -Asexual -SexualAsexual only one parent needed, very quick, little energy wasted in the process of mating.
Sexual- main adv genetic variation
mix of inherited genes, differing in strength and weakness therefore greater survival of species. - 11Disadvantages -Asexual -SexualAsexual-NO GENETIC VARIATION unless genetic mutation Eg. Bacteria, Yeast, Starfish
Sexual-Takes a lot of energy to find a mate, then to mate and have offspring. Eg. majority animals and plants. - 12Parts of a Chromosome-single chromosome is made up of DNA wound tightly around protein
-replicated chromosome consists of two sister chromotids
-centromere joins chromotids together.
-after cell division, daughter chromosomes produced. - 13Random FertilisationFertilization-fusion of sperm & ovlum, bringing the chromosome # to 2n in Zygote. Chance the sperm fertilizes egg is random event. Result-unique individual, own set of unique combo of alleles due to other 3 laws.
- 14MUtationsA permanent change in the base sequence of DNA.
- 15MutagensAre environmental factors that induce a change in the base sequence of an individual's DNA. Eg. Radiation, chemicals, viruses.
- 16Point Mutations (gene mutations)alter the sequence of bases in a single in a single gene. may produce a new version of a gene.
- 17Chromosome Mutationchromosome mutation (block mutation) occur as a result in crossing over during meiosis. can be induced by certain mutagens. Four types: Deletion, Translocation, Replication & Inversions.
- 18Complete Dominanceone allele is expressed over the other. Phenotype dominant homo-zygote and hetrozygote are the same.
- 19Incomplete Dominancealleles in a hetrozygous individual are both expressed producing an intermediate phenotype. Eg. RR-Red, R'R'-White, RR;-pink
- 20Co-dominanceTwo Alleles in a hetrozygous individuals are both expressed; producing a 'combination' phenotype . eg. animal coat pattern, flower petals. RR-red, WW-white, RW- red & white petals.
- 21Lethal Allelessome genes are required to survival, mutations in these genes= lethal, as protein produced in missing or function incorrectly. can prevent cell division occurring, cause incorrect development.
- 22Multiple AllelesTwo different traits exist for the same trait. an individual can show one of several different phenotype not just one of two.
- 23Pure Breeding Test Cross-no variation in the trait ie. parents have the same phenotype.
- to determine if an organism is pure bred. involves mating individual with an homozygoes recessive. to get reliable results many test crosses have to be done. - 24Evolutionprocess of change in trait that are selected over several generations. formation of diversity across biological populations.
- 25Speciesa group of organisms that can interbreed to produce fertile offspring
- 26Gene PoolA gene pool is the sum total of the genes (and alleles) present in the population
- 27Populationcomprises of the total number of one species in a particular area over a certain period of time.
- 28Allele Frequencyproportions of each allele within a population.
(number of dominant alleles/total number of alleles) x 100 - 29Factors that affect allele frequency-Mutations
-Gene Flow= Immigration, emigration
-selection=natural selection, artificial selection, sexual selection.
-genetic drift=founder effect, population bottleneck. - 30Gene Flowmovement of genes into and out of a population,
Immigration-enter population.
emigration-leave population.
reduces differences between populations, greater effect on small populations. - 31Natural selectionfittest individuals have greater reproductive success, pass on their successful genes to a greater number of offspring. as result of frequency of alleles that code for their adaptions over subsequent generations.
- 32Genetic Biodiversitymeasure of the total amount of genetic variation in a population.
1. high-likely to have evolution as can respond to enviro &situational changes.
2. low-unlikely because cannot respond. - 33Stabilizing selectionselection pressures select against extreme phenotype, median phenotype retained and most common.
- 34Directional Selectionselection pressures selects against an extreme trait, population's trait distribution shifts to the opposite extreme.
- 35disruptive selectionacts against individuals of median phenotype, =2 extremes creates own distribution curves, =speciation.
- 36Artificial Selectionwhen humans select particular individuals from a population based on desired phenotype.
- 37Sexual Selectionwhen one sex (usually female) acts as selection agent. selecting 'fittest' individual results in inheritance of 'best' genes.
- 38Selective Pressuresfactors that cause certain traits to become more common in a population over time.
-may include-limited food source
-existence of threats (diseases, weather, predators) - 39Genetic Driftthe change in allele frequencies in populations due to chance. ( not selection pressures)
- 40Founder Effectoccurs when a small group of individuals colonizes new isolated area. Range of alleles present likely unrepresentative of the original ancestral population.
-undergoes genetic drift, reduced range of allele frequency & genetic biodiversity, evolution occurs faster, inbreeding. - 41Population Bottleneckoccurs when a population is suddenly reduced to a small size, after a catastrophic, environmental event (eg. flood, earthquake) or human actions or predators. (eg. deforestation, pests, poisons)
-same results as founder effect
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- NCEA Level 2 Biology Flashcards on Biology-genetic variation, created by Anjana Naidu on 16/08/2016.
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- Anjana Naidu · Aug 2016
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- Aug 23, 2016
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