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A permanent change in the bases on the DNA. It is the only way of
creating new alleles
creating new alleles
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A TYPE OF cell division where a single cell divide (segregate) twice to produce four daughter cells. the purpose of meiosis is to produce gametes (sex cells). each of these daughter cels are haploid which only contains one set of chromosomes (23)
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GENETICS BIO
| Question | Answer |
|---|---|
| A permanent change in the bases on the DNA. It is the only way of creating new alleles | MUTATION |
| A TYPE OF cell division where a single cell divide (segregate) twice to produce four daughter cells. the purpose of meiosis is to produce gametes (sex cells). each of these daughter cels are haploid which only contains one set of chromosomes (23) | MEIOSIS |
| SINGLE SET/ HALF THE NUMBER OF CHROMOSOMES (23) and are found in egg or sperm cells (gametes) | HAPLOID |
| A cell or an organism consisting of two sets of chromosomes: usually, one set from the mother and another set from the father. (46) | DIPLOID |
| A kind of dominance where the dominant alleles completely mask the recessive allele showing up as a heterozygous genotype E.G: RR (RED) + rr (WHITE) = Rr (RED) | COMPLETE DOMINANCE |
| Heterozygous individuals have a phenotype that is intermediate between the two homozygous phenotypes. E.G: RR (RED) + rr (WHITE) = Rr (PINK) | INCOMPLETE DOMINANCE |
| Heterozygous individuals express both phenotypes equally from the parent genotypes, rather than one masking the other. E.G: RR (RED) + rr (WHITE) = Rr (RED&WHITE) | CO-DOMINANCE |
| a type of allele that causes the death of an organism when having two copies of it. If an organism inherits this allele from both parents, it will not survive. | LETHAL ALLELES |
| a process that occurs during meiosis where pairs of alleles are seperate as homologous chromosomes split, this ensures that each gamete receives only one allele from each pair. | SEGREGATION |
| The way the homologous chromosomes randomly line up at the equator during meiosis, which leads to the independent distribution of maternal and paternal chromosomes into gametes | INDEPENDANT ASSORTMENT |
| Movement of organisms into (immigration) and out (emigration)of a population, which can introduce new allele or remove existing ones. | MIGRATION |
| The movement of an organism moving INTO area to another. For example, a bird may immigrate to a new island from another island. | IMMIGRATION |
| The movement of an organism moving OUT of an area to another. For example, a butterfly moving from A to B has emigrated from patch A and immigrated to patch B. | EMIGRATION |
| any movement of individuals, and/or the genetic material they carry, from one population to another. | GENE FLOW |
| The total number of genetic characteristics within a population of species | GENETIC DIVERSITY |
| Occurs during meiosis, specifically prophase I, when homologous chromosomes exchange genetic material, leading to genetic variation | CROSSING OVER |
| What happens to both alleles in a heterozygous organism when co-dominance occurs? | BOTH ALLELES ARE FULLY EXPRESSED |
| Body cells, e.g. skin cells, if a mutation occurs in these cells it will not be passed on to offspring. | SOMATIC CELLS |
| Sex cells, e.g. sperm, egg, pollen and ova, cells with half the chromosome number. If a mutation occurs in one of these cells and that cell results in a zygote, all cells in the offspring will have that mutation | GAMETIC CELLS |
| What would the heterozygous genotype display in a Punnett square for co-dominance? | BOTH DOMINANT TRAITS |
| In co-dominance, what is the phenotype ratio observed when crossing two parents that are heterozygous for both alleles? | 1 : 2 : 1 |
| How does the heterozygous genotype differ between co-dominance and complete dominance? | In co-dominance, both traits are shown; in complete dominance, one trait masks the other. |
| when there are more than two variations of that particular allele | MULTIPLE ALLELES |
| an allele that only causes death in a homozygous recessive organism. Two copies of the recessive allele are required to be lethal | recessive alleles |
| when better suited organisms are better adapted to their environment are more likely to survive and reproduce, while passing on their advantageous to the next generation | natural selection |
| the inheritance of two different genes, each with two alleles | DIHYBRID INHERITANCE |
| why don't linked genes assort independently? | they are close to each other on the same chromosome and dont assort independently during meiosis. This violates Mendel's law of independent assortment. that genes located on different chromosomes will assort independently. |
| What happens to the probability of recombination between two genes if they are very close to each other on a chromosome? | When two genes are very close to each other on a chromosome, the chance of recombination occurring between them is low. This reduces/decreases the likelihood of the genes being separated during meiosis. Consequently, their genetic linkage is maintained. |
| What can cause the observed phenotypic ratios in offspring to differ from the expected Mendelian ratios? | GENETIC LINKAGE |
| WHAT IS GENETIC LINKAGE | THE OCCURENCE OF GENES LOCATED CLOSE TO EACH OTHER ON THE SAME CHROMOSOME THAT TEND TO BE INHERITED TOGETHER |
| WHAT HAPPENS TO LINKED GENES DURING MEIOSIS | THEY DO NOT ASSORT INDEPENDENTLY. |
| Genes located on the same chromosome that tend to be inherited together, because they do not assort independently during meiosis | LINKED GENES |
| How does crossing over contribute to genetic variation? | BY CREATING NEW ALLELE COMBINATIONS THAT ARE NOT FOUND IN EITHER PARENT |
| During which phase of meiosis does crossing over occur? | PROPHASE I |
| What is one consequence of lethal alleles in a population? | they tend to reduce overall genetic diversity |
| What typically happens to homozygous recessive individuals with two lethal alleles? | they usually die before or shortly after birth |
| which lethal alleles are more common, dominant lethal alleles or recessive lethal alleles? | RECESSIVE LETHAL ALLELES |
| WHY DO HETEROZYGOUS INDIVIDUALS WITH ONE LETHAL ALLELE HAVE A SELECTIVE ADVANTAGE? | because they often have increased survival or reproductive success compared to other genotypes which helps maintain the allele in the population |
| How does the presence of lethal alleles in a population affect genetic diversity? | The presence of lethal alleles in a population tends to reduce the overall genetic diversity because affected individuals do not reproduce. |
| How can a lethal allele be maintained in a population? | Through the selective advantage of heterozygous individuals. |
| How do lethal alleles affect population ratios in predictions made with Punnett squares? | They skew the expected ratios by reducing the number of surviving offspring with certain genotypes. |
| What describes the allele characteristics in incomplete dominance? | neither allele is completely dominant nor completely recessive |
| what happens in incomplete-dominance? | neither allele is completely masks the other. instead, the phenotype of heterozygous individuals is an intermediate blend of both homozygous phenotypes (E:G: red and white flowers resulting in pink flowers from a cross ) |
| example of incomplete dominance? | the flower colour in snapdragons (E:G:: red flower and white flower which results in offspring with an intermediate pink colour) |
| what does a heterozygous individual show in cases of incomplete dominance? | a blend of both the parent phenotypes because neither allele is completely dominant over the other, leading to an intermediate phenotype |
| In incomplete dominance, how does the phenotype of heterozygous individuals compare to the phenotypes of homozygous individuals? | it is an intermediate phenotype between both homozygous parent forms |
| What key event occurs during prophase I of meiosis? | homologous chromosomes exchange segments of genetic material |
| TRUE OR FALSE: Genes that are close together on a chromosome are more likely to undergo crossing over than genes that are further apart. | FALSE: because genes that are further apart have more opportunities to be separated during this process |
| TRUE OR FALSE: Crossing over can result in new combinations of alleles. | TRUE: because it involves the exchange of genetic material between homologous chromosomes during meiosis |
| Why do linked genes tend to be inherited together? | Linked genes tend to be inherited together because they are located close together on the same chromosome and do not assort independently. |
| What can crossing over produce by breaking the linkage between genes? | Crossing over can produce recombinant chromosomes. |
| What new genetic outcome results from crossing over that is different from either parent? | NEW ALLELE COMBINATIONS |
| What is the relationship between the distance between linked genes on a chromosome and the frequency of recombination? | The frequency of recombination between linked genes is proportional to the distance between them on the chromosome. |
| What information is used to create linkage maps? | RECOMBINATION FREQUENCY |
| Which event during prophase I of meiosis contributes to genetic diversity by exchanging genetic material between homologous chromosomes? | CROSSING OVER |
| During a lab experiment, students observed that crossing over during meiosis in fruit flies led to the appearance of new traits not seen in the parent generations. What genetic mechanism does this describe? | CROSSING OVER: it can break the linkage between genes and produce new combinations of alleles, resulting in recombinant chromosomes |
| How can a scientist estimate the distance between two genes on the same chromosome? | RECOMBINATION FREQUENCY |
| In a species of flower, linked genes controlling petal colour and scent are on the same chromosome but are quite far apart. Why is it that new combinations of these traits are observed frequently? | The genes are far apart, so the frequency of recombination is high due to crossing over. |
| In a pea plant, two traits - seed shape and flower colour - are coded by genes on the same chromosome. When crossover during meiosis introduces new combinations of alleles for these traits, which genetic process explains this increased variation? | Crossing over |
| In the absence of crossing over, how would genes located close together on a chromosome be inherited? | THEY WOULD BE INHERITED TOGETHER |
| the total number of genes and their alleles present in a population. it encompasses all the genetic diversity within that population | GENE POOL |
| A type of natural selection in which one extreme phenotype is favoured over others. | DIRECTIONAL SELECTION |
| an event that drastically reduces the size of a population, leading to a decrease in genetic diversity. this can occur in events such as natural disasters or overhunting | POPULATION BOTTLE NECK |
| are chromosomes that are similar but not identical , as they carry the same genes in the same order, but alleles for each trait can vary | HOMOLOGOUS CHROMOSOMES |
| a diagram that that diagrams the inheritance of a trait or health condition through generations of a family | PEDIGREE CHART |
| the change in the frequency of an allele in a population due to sampling and random chance. often shows more significant effect in smaller populations | GENETIC DRIFT |
| involves two parents and the fusion of gametes (sex cells), specifically a sperm and egg, to produce an offspring | SEXUAL REPRODUCTION |
| THE MEASURE OF RELATIVE FREQUENCY OF AN ALLELE AT THE GENETIC LOCUS IN A POPULATION | ALLELE FREQUENCY |
| a type of natural selection in which individuals near the centre of a distribution curve have a higher fitness than individuals at either ends of the curve | STABILIZING SELECTION |
| are located on different chromosomes, making them less likely to be inherited together during meiosis | UNLINKED GENES |
| the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population | FOUNDER EFFECT |
| involves only one parent and typically results in the offspring being genetically identical to the parent | ASEXUAL REPRODUCTION |
| different versions of a gene that can result in variations in traits E.G: brown eyes vs blue eyes | ALLELE |
| the diversity of phenotypes or genotypes within a population of species | VARIATION |
Created by:
celine.taing