WJEC (Eduqas) Biology A-level Inheritance Flashcards PDF

WJEC (Eduqas) Biology A-level Topic 2.5 - Inheritance Flashcards This work by https://bit.ly/pmt-edu-cc PMT Education is licensed under https://bit.ly/pmt-cc CC BY-NC-ND 4.0 https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a gene? https://bit.ly/pmt-edu https://bit.ly/pmt-...

WJEC (Eduqas) Biology A-level Topic 2.5 - Inheritance Flashcards This work by https://bit.ly/pmt-edu-cc PMT Education is licensed under https://bit.ly/pmt-cc CC BY-NC-ND 4.0 https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a gene? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a gene? A length of DNA on a chromosome that codes for the production of one or more polypeptide chains and functional RNA. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define genotype. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define genotype. The genetic constitution of an organism. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define phenotype. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define phenotype. The expression of an organism’s genetic constitution, combined with its interaction with the environment. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a locus? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a locus? The fixed position on a DNA molecule occupied by a gene. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is an allele? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is an allele? Different forms of a particular gene, found at the same locus on a chromosome. A single gene could have many alleles. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define homozygous https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define homozygous Having two identical alleles of a gene e.g. FF or ff https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define heterozygous https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define heterozygous Having two different alleles of a gene e.g. Ff https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a dominant allele? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a dominant allele? An allele that is always expressed Represented with a capital letter e.g. F https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a recessive allele? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a recessive allele? An allele that is only expressed in the absence of a dominant allele. Only expressed if 2 copies are present Represented with a small letter e.g. f https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is meant by codominant alleles? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is meant by codominant alleles? Two dominant alleles that both contribute to the phenotype, either by showing a blend of both characteristics, or the characteristics appearing together. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is an autosome? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is an autosome? A chromosome that is not an X or Y chromosome. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a sex chromosome? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a sex chromosome? A chromosome that determines the sex of an organism, e.g. X and Y chromosomes in humans and other mammals. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the F1 generation? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the F1 generation? The first generation of offspring resulting from the cross of two individuals in the parental generation. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the F2 generation? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the F2 generation? The second generation of offspring resulting from the cross of two individuals in the F1 generation. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define monohybrid inheritance. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define monohybrid inheritance. Where one phenotypic characteristic is controlled by a single gene. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is Mendel’s first law of inheritance? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is Mendel’s first law of inheritance? Law of segregation Alleles separate randomly into gametes Each parent passes one allele to their offspring https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is Mendel’s second law of inheritance? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is Mendel’s second law of inheritance? Law of independent assortment The alleles of genes assort independently of other genes during gamete formation https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Draw an example of a genetic cross diagram. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Draw an example of a genetic cross diagram. Parental phenotypes Brown eyes Blue eyes Parental genotypes Bb B Gametes Offspring genotypes (draw a Punnett square) Offspring phenotypes b bb b b Bb, Bb, bb, bb 2:2 brown eyes:blue eyes https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc A female who is homozygous recessive for cystic fibrosis (ff) has a child with a heterozygous male (Ff). Draw a punnett square to illustrate this monohybrid inheritance. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc A female who is homozygous recessive for cystic fibrosis (ff) has a child with a heterozygous male (Ff). Draw a punnett square to illustrate this monohybrid inheritance. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc PKU is a recessive condition. Two heterozygous parents have offspring. Predict the proportion of offspring that will have PKU. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc PKU is a recessive condition. Two heterozygous parents have offspring. Predict the proportion of offspring that will have PKU. 75% chance of normal phenotype 25% chance of PKU phenotype https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the purpose of a test cross? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the purpose of a test cross? Used to determine whether an individual with a dominant trait is heterozygous or homozygous dominant. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe how a test cross is carried out. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe how a test cross is carried out. An individual of unknown genotype is bred with a homozygous recessive individual Offspring phenotypes are observed to determine the genotype of the unknown individual https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define dihybrid inheritance. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define dihybrid inheritance. The determination of a trait by the inheritance of two genes. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What does Mendelian inheritance assume? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What does Mendelian inheritance assume? It assumes that the genes involved are not linked. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is meant by sex-linkage? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is meant by sex-linkage? An allele is located on one of the sex chromosomes Its expression depends on the sex of the individual https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give an example of a phenotype which shows sex-linkage. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give an example of a phenotype which shows sex-linkage. Haemophilia Duchenne muscular dystrophy https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe haemophilia. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe haemophilia. X-linked recessive condition Results in excessive bleeding and blood that is slow to clot https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe Duchenne muscular dystrophy. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe Duchenne muscular dystrophy. X-linked recessive condition Characterised by muscle degeneration and weakness https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Why are haemophilia and Duchenne muscular dystrophy more common in males? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Why are haemophilia and Duchenne muscular dystrophy more common in males? They are X-linked recessive conditions. Males only inherit one X chromosome so are more likely to express the gene in their phenotype. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is linkage? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is linkage? Two or more genes positioned on the same autosome Unlikely to be separated by crossing over during meiosis so often inherited together https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the chi-squared test? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is the chi-squared test? A statistical test used to determine whether the difference between observed and expected data is due to chance or a real effect. Can be used to compare expected phenotypic ratios with observed ratios. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How is a chi-squared test performed? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How is a chi-squared test performed? Make a null hypothesis Used Mendelian ratios to calculate the expected numbers Calculate chi-squared value using chi-squared equation Calculate the degrees of freedom Select an appropriate significant level (normally 0.05) Find the critical value Compare the chi-squared value with the critical value Accept or reject the null hypothesis https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How are degrees of freedom calculated? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How are degrees of freedom calculated? The number of categories minus 1. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc If the chi-squared value is greater than or equal to the critical value, is the null hypothesis accepted or rejected? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc If the chi-squared value is greater than or equal to the critical value, is the null hypothesis accepted or rejected? Rejected https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What does it mean if the null hypothesis is rejected? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What does it mean if the null hypothesis is rejected? There is a significant difference between the observed and expected results. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc If the chi-squared value is less than the critical value, is the null hypothesis accepted or rejected? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc If the chi-squared value is less than the critical value, is the null hypothesis accepted or rejected? Accepted https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What does it mean if the null hypothesis is accepted? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What does it mean if the null hypothesis is accepted? No significant difference between the observed and expected results. The results occured due to chance. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a mutation? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a mutation? An alteration to the volume, arrangement or structure of DNA May affect a single gene or a whole chromosome https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc When do most mutations occur? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc When do most mutations occur? Crossing over in prophase I Non-disjunction in anaphase I and II https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a gene mutation? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a gene mutation? A change to at least one nucleotide base in DNA or the arrangement of bases May occur spontaneously during DNA replication and can be beneficial, damaging, or neutral https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give an example of condition caused by a gene mutation. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give an example of condition caused by a gene mutation. Sickle cell anaemia https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe sickle cell anaemia. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe sickle cell anaemia. Recessive genetic disorder caused by a substitution mutation on chromosome 11 Results in abnormal haemoglobin which distorts red blood cells https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a chromosome mutation? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a chromosome mutation? A change in the structure or number of chromosomes, affecting many genes. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give an example of condition caused by a chromosome mutation. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give an example of condition caused by a chromosome mutation. Down’s syndrome https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe Down’s syndrome. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Describe Down’s syndrome. Genetic disorder characterised by delayed development and learning disabilities Due to non-disjunction, an affected individual possesses three copies of chromosome 21 https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is chromosome nondisjunction? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is chromosome nondisjunction? Failure of homologous chromosomes to separate in meiosis I or sister chromatids to separate in meiosis II. Results in gametes with one extra or less chromosome than normal. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a mutagen? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a mutagen? A chemical, biological or physical agent that increases the rate of gene mutations above normal level. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give some examples of mutagens. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Give some examples of mutagens. Ionising radiation (gamma radiation, UV, X-rays) Chemicals (e.g. polycyclic hydrocarbons) https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a carcinogen? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is a carcinogen? A type of mutagen that causes cancer. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is an oncogene? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc What is an oncogene? Mutations of proto-oncogenes that are activated continuously, resulting in uncontrolled cell division. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define epigenetics. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc Define epigenetics. The study of changes in gene expression that are not due to alterations in the nucleotide base sequence of DNA. https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How can histone modification affect gene expression? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How can histone modification affect gene expression? Alteration of histones by the addition of methyl, acetyl or phosphate groups Increases or decreases gene expression by causing the histone to coil more tightly or loosely https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How can DNA methylation affect gene expression? https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc How can DNA methylation affect gene expression? Addition of a methyl (CH3) group to cytosine bases Prevents recognition of the bases, reducing gene expression https://bit.ly/pmt-edu https://bit.ly/pmt-cc https://bit.ly/pmt-cc