concept 15 - BIO10008

what are the different outcomes of mitosis and meiosis

meiosis generate genetically different cells where these cells go through PMAT two times to create haploid cells 2n → n, meiosis also includes crossing over…

mitosis generates exact copies from the parent chromosome to the daughter cells, mitosis only has PMAT once. they have copies of diploid cells so therefore, two diploids identifical to the parent (two chromosome in each cell)

prior to meiosis 1 what is the ploidy of the cell and what does this mean in relation to the number of copies of each chromosome and their replication status

ploidy is the number of chromosome occuring in the nucleus of the cell. prior to meiosis 1 there is diplod cells (2n) (INTERPHASE OF S PHASE HAS BEEN COMPLETED AFTER DNA REPLICATION) therefore this means that there is two complete sets of chromosomes due to DNA replication after parents give theirs to offspring. this is indicating there is two copies of each chromosome in each nuclei, one from each parent. This replication results in each chromosome duplicated into two identical sister chromatids

what is the difference between a chromosome containing two sister chromatids and those that have one chromatid

X shaped chromosome carries two replicated sister chromatids held by the centromere whilst L shape chromosome do not have a replicate yet

what is the key difference between meiosis 1 and 2

meiosis 1 involves the crossing over of sister chromatids but meiosis 2 does not and separates two sister chromatids in telophase 2 where meiosis 2 skips DNA replication

why is meiosis 1 the reductional division

meiosis 1 is the reductional division as it turns diploids into haploids, thus a reductional division (it halves the amount of chromosomes)

specifically, separating the homologous chromosome into separate nucleis → cells with half the original number of chromosomes.

how meiosis provides different genetic outcomes

meiosis provides different genetic variety due to the crossing over of sister chromatids in prophase 1 at meiosis 1 where chiasma is formed

whats the difference between meiosis 1 and meiosis 2

meiosis 1 demonstrates the independent assortment, but meiosis 2 separates the sister chromatids from the centromere into I shapes when condensed.

how does the law of segregation relate to the partitioning of chromosomes during meiosis

the law of segregation means the two alleles of a gene will separate to give away one allele to a gamete. during meiosis 1 crossing over happens so there is a homologous chromosome pair however, in anaphase 1 they are pulled to each side leaving the cell formed only ONE copy of the parent’s chromosome

what does it mean when a parent is homozygous

that means they have the same exact alleles in their gene, BB/bb this is the genotype

why might it be important for a monohybrid cross that the parents are homozygous

because due to mendel’s law of segregation, if the parents were homozygous then the offspring will recieve one copy from each parent leading to a monohybrid offspring (F1 - heterozygous)

why are the offspring of the cross (F1) all identical with respect to the genotype and phenotype

they are all identical because they received one copy from each of their parents, this leads to the dominant phenotype expressed over the recessive so they look the same.

what generation is the 3:1 ratio observed for a monohybrid cross

F2

explain the purpose of completeing a chi-squared analysis

to check whether there is a significant difference between an expected value and an observed value. it enables us to accept or reject the null hypothesis based on how much the observed value deviate from the expected values.

how to determine the expected number of each phenotypic class of progeny

total observed plants/total expected plant = expected value

expected mendelian ratio for incomplete dominance

1:2:1

does the separation of different alleles into daughter cells occur during mitosis, meiosis 1 and meiosis 2