Studied by 1 personWhat are homologous chromosomes?
Two chromosomes with the same set of genes, sometimes with different alleles
What is a gene?
basic unit of heredity and a sequence of nucleotides in DNA or RNA
What is an allele?
Different forms of a gene
Purpose of meiosis
produce gametes
Why in meiosis the chromosome number is halved?
Halves the sex cells in half, so that in fertilization, it will result in a normal amount of chromosomes (46 -> 23)
What is the end product of meiosis?
4 haploid cells
stages of meiosis in order
Interphase, Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II
What happens in meiosis I?
Homologous chromosomes pair up
Homologous chromosomes separates
Two haploid cells are made with their sister chromatids still joined.
What happens in meiosis II?
Sister chromatids separate
4 haploid daughter cells are formed
Significance of meiosis
Causes genetic variation
How is genetic variation achieved?
crossing over
independent assortment
random fertilization
mutations
What is crossing over?
exchange of genetic material between homologous chromosomes
How does crossing over contribute to genetic variation?
Crossing over creates new combinations of genes in the gametes that are not found in either parent
What is independent assortment ?
random separation of homologous chromosomes
How does independent assortment contribute to genetic variation?
each gamete ends up with a different set of DNA
independent assortment affects which chromosomes end up in each cell
How does random fertilization contribute to genetic variation?
each parent to randomly contributes a unique set of genes to a zygote
What is a recessive allele?
A form of a gene that is not expressed when paired with a dominant allele
What is a dominant allele?
A form of a gene that is fully expressed, even when two different alleles are present
What is the law of segregation?
Parents pass on only one allele for each gene
What is the law of independent assortment?
during gamete formation, different pairs of alleles segregate independently of each other
EX. which allele a gamete receives for gene A has no bearing of which allele a gamete receives for gene B
ONLY DEALS WITH UNLINKED GENES
What are unlinked genes?
genes located on different chromosomes
What are linked genes?
genes located on the same chromosome that tend to be inherited together
What is a punnett square?
A chart that shows all the possible combinations of alleles that can result from a genetic cross
What is a dihybrid cross?
a cross that examines the inheritance of two different traits
What is the probability rule regarding multiplication?
Independent events that occur in a sequence; "AND"
What is the probability rule regarding addition?
Events not happening in a sequence; "OR"
What is incomplete dominance?
when one allele is not completely dominant over the other; blending of traits from parents (red+white=pink)
What is codominance?
both alleles contribute to the phenotype
How does the environment affect phenotype?
Exposure to certain things in the environment can affect gene expression and what phenotype is displayed.
What is a pedigree?
a chart that tracks which members of a family have a particular trait
What is autosomal recessive?
no skipping, many affect; two recessive needs to be present in order for the disease or trait to develop.
What is autosomal dominant?
Dominant in a trait that is not directly involved in determining sex; no skipping and many affected
What are sex-linked traits?
Traits controlled by genes located on sex chromosomes.
What is X-linked recessive?
mother/son and father/daughter links, skipping of gen
What is x linked dominant?
Expressed in female in one copy
more males affected
What is mitochondrial inheritance?
trait inherited from the moms and passes down to all kids
What is a genetic map?
ordered list of the genetic loci along a particular chromosome
What is nondisjunction?
Failure for chromosomes to separate properly.
What can nondisjunction lead to?
genetic abnormalities and chromosomal disorders
Name the 5 altercations of chromosome structure (mutations).
deletion
insertion
duplication
translocation
inversion
What is a deletion mutation?
one nucleotide is taken away from a gene or DNA sequence
What is an insertion mutation?
The addition of a single nucleotide
What is a duplication mutation?
repeats a segment
What is an inversion mutation?
Reverses a segment within a chromosome
BDE -> BED
What is a translocation mutation?
moves a segment from one chromosome to another, nonhomologous one
What type of chromosomal mutation is least disruptive?
point mutation because one base pair is exchanged and frame shift does not occur
What does mitosis produce?
2 identical diploid cells
What does meiosis produce?
4 differing haploid cells
What does meiosis result in?
daughter cells with half the number of chromosomes as the parent cell
What happens in anaphase II?
sister chromatids separate
Where does crossing over occur?
prophase I
Where does random assortment occur?
metaphase I
These chromosomes possess the same structure and genes, but are not identical. They contain different alleles for the same genes. Offspring receive one from each parent.
homologous chromosomes
Name the pattern of inheritance: males primarily affected. Women are typically carriers because they have 2 X chromosomes. Fathers cannot pass on to sons.
x linked recessive
once you solve for chi square to make meaning of your calculation, what is your next step?
determine the degrees of freedom
The closer two linked genes are on a chromosome, the ______ likely they are to be separated by crossing over?
less
the environment can change the ________ of an organism
phenotype
Choose the correct genotype for two traits of a recessive individual in a pure breeding parent generation
aabb
a type of mutation where chromosomes do not separate properly during meiosis
nondisjunctional
Diploid number is 50, what is haploid number?
25
process by which sexually reproducing organisms produce genetically diverse haploid gamates?
meiosis
crossing over results in…
recombinant chromatids
Name the inheritance pattern: affected mothers with all affected children
mitochondrial
two genes on the same chromosomes have a recombination frequency of 25%. How many map units are they apart from each other?
25 map units
How many cell divisions are in meiosis?
2
During crossing over ________ exchange genetic information
non sister chromatids of homologous chromosomes
Name the pattern of inheritance: unaffected parents have affected offspring
autosomal recessive
Chromosomes moving to opposite ends of the cell during anaphase takes place during….
both mitosis and meiosis
Due to light level changes in the environments, an arctic hare’s fur changes from white to brown depending on the season. How has the hare changed?
the phenotype changed
T/F Homologous chromosomes separate during anaphase I
TRUE
Mutations during _______ can be passed on to offspring
meiosis
Chi square vale is 6.2. Critical value is 7.81.
fail to reject the null. results are due by chance, the chi square value is less than the critical
3 ways meiosis contributes to genetic diversity
fertilization, crossing over, random assortment
reproduction that does not require the production and fusion of gametes?
asexual reproduction
a benefit of sexual reproduction
increases genetic diversity
Choose the correct genotype for an individual who is homozygous dominant for two traits
AABB
Chromosomes lining up in the middle of the cell takes place in….
both mitosis and meiosis
T/F When genes are linked the majority of the phenotypes of the offspring will resemble the phenotypes of the parents
TRUE
Note 
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