Flashcards
Topic 4: Genetics
Cards in this deck (47)
- 1Eukaryote chromosomes are made of?DNA and proteins
- 2GeneA heritable factor that controls a specific characteristic and consists a length of DNA occupying a specific position on a chromosome (locus)
- 3AlleleOne specific form of a gene, differing from other alleles by one or a few bases only and occupying the same locus as other alleles of the gene
- 4GenomeThe whole of the genetic information of an organism
- 5Gene mutationA change in the nucleotide sequence of a section of DNA coding for a particular feature
- 6Base substitutionChange of the base sequence of a gene
- 7Example of base substitutionsickle cell anemia
- 8CAUSE of sickle cell anemiaChange of a single base in a sequence of DNA, resulting in a change to a single mRNA codon during transcription.
Codon changes.
Change in mRNA.
Change in amino acid.
Alters structure of haemoglobin. - 94 consequences of sickle cell anemia1) Sickle cells tend to form clots which block blood vessels to vital organs and cause health problems
2) Sickle cells are destroyed at a greater rate than normal, thus cause anemia
3) Insoluble Haemoglobin in sickle cells cannot effectively carry oxygen. and can cause individual to feel tired.
4) Increased resistance to malaria - 10MeiosisReduction division of a diploid nucleus to form haploid nucleus (gametes).
2 divisions.
#1 Reduction division of the diploid nucleus to from haploid nucleus
#2 Separates sister chromatids - 11Homologous chromosomesSame structural features
Same genes at the same loci positions - 12Definition of non-disjunctionChromosomes failing to separate correctly, resulting in gametes with one extra, or one missing chromosome.
Occurs in Anaphase I (resulting in 4 affected daughter cells) or Anaphase II (resulting in 2 affected daughter cells) - 13Example of disjunctionDown syndrome (trisomy 21), 3 copies of chromosome 21
- 14KaryotypeVisual profile of the chromosomes arranged in pairs according to their structure
- 15Karyotyping involves 3 steps1) Harvesting cells
2) Chemically inducing cell division and then halting during mitosis when chromosomes condense
3) Staining and photographing chromosomes - 16Karyotyping is performed by using cells extracted in 2 ways1) Chorionic villus sampling
2) Amniocentasis - 17AmniocentasisNeedles is inserted into amniotic cavity in the uterus and a sample of amniotic containing foetal cells is taken
- 18Chorionic villus samplingTube is inserted into the chorionic villi from the placenta, and a sample is taken
- 19GenotypeAlleles possessed by an organism
- 20PhenotypeCharacteristics of an organism
- 21Dominant alleleAn allele that has the same effect on the phenotype whether it is present in the homozygous or heterozygous state
- 22Recessive alleleAn allele that only has an effect on the phenotype when it is present in the homozygous state
- 23Codominant allelesPairs of alleles that both affect the phenotype when present in a heterozygote
- 24LocusParticular position on homologous chromosomes of a gene
- 25HomozygousHaving 2 identical alleles of a gene
- 26HeterozygousHaving 2 different alleles of a gene
- 27CarrierAn individual that has a recessive allele of a gene that does not have an effect on their phenotype
- 28Test crossTesting an unknown organism/ heterozygote with a known homozygous recessive
- 29Example of codominanceBlood groups
- 30X and Y chromosomeY chromosome is shorter than X chromosome and some genes present on X chromosomes may be absent on Y chromosomes
- 31Sex linkageWhen a gene controlling a characteristic is found on a sex chromosome
- 32Examples of sex linkageColour blindness and haemophilia
- 33With respect to sex-linked genes, state and explain human female chromosomes' chacteristicsCan be homo or hetero
Female carriers are x linked recessive alleles - 34Pedigree chart symbolsSquare: male
Circle: female - 35Polymerase chain reaction (PCR)Copy and amplify minute quantities of DNA
- 36Outline process of PCR1) Denaturation: DNA sample is heated to separate it into 2 strands
2) Annealing: DNA primers attach to opp ends of the target sequence
3) Elongation: A heat-tolerant DNA polymerase copies the strands - 37Example of using gel electropheresisDNA profiling
- 38Outline 2 applications of DNA profiling1) Paternity test: Comparing DNA of offspring with potential fathers (half of the bands should be the same)
2) Forensic investigation: identifying suspects/victims based on crime-scene DNA (DNA profiles should match) - 39Human genome projectInternational programme that aims to improve understanding of human hereditary
- 40Three outcomes of the sequencing of the complete human genome1) Screening: Identification of genetic diseases
2) Mapping: We now know the number, location and basic sequence of the human genome
3) Medicine: Discovery of new proteins and function can develop improved treatments - 41Name 3 steps in gene transfer1) DNA extraction
2) Digestion and Ligation
3) Transfection and expression - 422 e.g. of currents uses of genetically modified crops1) Bt maize: engineered to protect from insects by becoming toxic to corn borers
2) Flavr savr tomatoes: extend shelf life of fresh produce by switching off the gene for ripening and thus, delay the natural process of softening of fruit - 43CloneA group of genetically identical organisms/group of cells derived from a single parent cell
- 44Potential benefits of Bt maize1) Less pest damage, higher crop yields
2) Less land needed for crop production and become areas for wildlife conservation
3) Less use of insectide sprays (v. expensive) - 45Potential harmful effects of Bt maize1) Humans/animals that eat Bt maize may be harmed by the toxin in it
2) Insects that are not pests may be affected by it as well. Dispersal of Bt maize (e.g. by wind) may even affect organisms far away from the vicinity of the Bt maize
3) Populations of wild plants might be changed. Cross pollination may pass Bt toxin to other plants and may have an advantage over other plants who are struggling for survival. - 46Arguments for therapeutic cloning1) Embryonic stem cells save lives and reduce suffering
2) Cells can be removed from embryos that have stopped developing so would have died
3) Cells are removed at a stage when embryos have no nerve cells and cannot feel pain - 47Arguments against therapeutic cloning1) Every human embryo is a potential human being, which should be given a chance to develop
2) More embryos are produced than needed, and they will be killed off
3) There is a danger embryonic stem cells will develop into tumour cells
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- High school Biology Flashcards on Topic 4: Genetics, created by 13yuengr1 on 27/04/2015.
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