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Patterns of Inheritance
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- 1Define genotypeGenetic makeup of an organism
- 2Define phenotypeVisible characteristics of an organism
- 3What are mutagens?Are certain physical and chemical agents that increase the rate of mutation
- 4Example of physical agents?•X-rays
•gamma rays
•UV light - 5Example of chemical agents?•benzopyrene (found in tobacco smoke)
•mustard gas
•nitrous acid
•aromatic amines (some synthetic dyes)
•reactive oxygen species
colchicine - 6Example of biological agents?•some viruses
•transposons (jumping genes, remnants of viral nucleic acids incoporated into our genomes
•food contaminants (chemicals in charred meat and alcohol) - 7Types of chromosome mutations?•deletion
•inversion
•translocation
•duplication
•non-disjunction
•aneuploidy
•poluploidy - 8What is deletion?Part of chromosome, containing genes and regulatory sequences, is lost
- 9What is inversion?A section of a chromosome may break off, turn 180 degrees and then join again
Genes may be too far away from regulatory nucleotide sequence to be expressed properly - 10What is translocation?A piece of one chromosome breaks off and then becomes attached to another chromosome
May interfere with the regulation of the genes on the translocated chromosome - 11What is duplication?A piece of a chromosome may be duplicated
Overexpression of genes can be harmful, too many of certain proteins or gene-regulating nucleic acid may disrupt metabolism - 12What is non-disjunction?One pair of chromosomes or chromatids fails to separate, one gamete has an extra chromosome
Zygote will have one extra chromosome, e.g. Down syndrome or trisomy 21 - 13What is aneuploidy?Chromosome number is not an exact multiple of the haploid number for the organism (chromosomes/chromatids fail to separate - trisomy)
- 14What is polyploidy?When diploid gamete is fertilised by a haploid gamete, zygote will be triploid
Fusion of two diploid gametes can make a tetraploid zygote (like plants) - 15How does genetic variation arise during meiosis?•allele shuffling (swapping over of alleles between non-sister chromatids)
•independent assortment of chromosomes during metaphase/anaphase 1 and metaphase/anaphase 2 - 16How does fertilisation lead to genetic variation•Gametes produced by meiosis are genetically dissimilar and haploid
•Random fusion of gametes creates more genetic diversity
•Gametes can potentially combine at any time - 17How can phenotypic variation can be caused by environmental factors only?•speaking with a particular regional dialect
•losing a digit/ limb or having a scar following an injury - 18How can phenotypic variation be caused by the environment interacting with genes?•Plants kept in dim lights after germination do not have enough magnesium to develop chlorophyll resulting in a yellow colour
•Known as Chlorosis, plant cannot photosynthesis - 19Define alleleA version of a gene
- 20Define heterozygousNot true breeding
Have different alleles at a particular gene locus on a pair of homologous chromosomes - 21Define homozygousTrue-breeding
Having identical alleles at a particular gene locus on a pair of homologous chromosomes - 22Define monogenicDetermined by a single gene
- 23One fruit fly parent is homozygous for normal wings and the other parent is homozygous for vestigial wings. What is the genotypes of the second generation?
- 24Define dihybrid inheritanceInheritance of two characteristics controlled by different genes
- 25The parents are heterozygous and both have a round and yellow seed. What is the genotype of the offspring an calculate the ratio?
- 26What is the phenotypic ratio of the F2 generation in a dihybrid cross?9:3:3:1
- 27What are multiple alleles?Characteristic for when there are three if more alleles in the population's gene pool
- 28What are the four blood groups• Group A
•Group B
•Group AB
•Group O - 29What is codomiance?Where both alleles represent in the genotype of a heterozygous individual contribute to the individual's phenotype
- 30What alleles are codominant and recessive for blood groups?•Iº is recessive
•Iᴬ and Iᴮ are codominant - 31What blood group will the offspring be of a parent who is heterozygous for blood group A and a parent heterozygous for blood group B
- 32Define sex-linked?Gene present on (one of) the sex chromosomes
- 33What are autosomes?Not sex chromosomes
Are homolougous - 34What the human sex chromosomes?Females: XX
Male: XY - 35State the expected ratio for F2 generation for monohybrid, dihybrid and codominant
- 36What the main differences in the male sex chromosomes?•The Y chromosome is a smaller than the X chromosome and carries fewer genes - most genes carried on X chromosome
•Only carry one X chromosome for only carry one allele, so are more likely to express recessive phenotypes - 37Give examples of genetic disorders caused by faulty alleles on sex chromosomes•Haemophilia
•Colour blindness - 38Explain why the phenotypic ratio is 3:1 when a heterozygous normal vision female have children with a normal vision male
- 39Why are genes on the same autosome linked?They will stay together on during indepednet assortment of meiosis 1 and alleles will be passed on to offspring together
Only own't happen if crossing over occurs - 40What is codominant?Where both alleles present in the genotype of a heterozygous individual contribute to an individual's phenotype
- 41What is the MN blood group systemThe Gene M and N codes for a particular protein on the surface of erthryocytes ad are codiminant
- 42Explain why the phenotypic ratio is 2:1:1 for the offspring of parents who have sickle-cell trait
- 43Define epistasisInteraction of non-lined gene loci where one masks the expression of the other
(stoppage) - 44What is recessive epistasis
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- Patterns of Inheritance flashcards for OCR biology A A-Level
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