Unit 5 Part 1 Flashcards
What’s genetics
The study of heredity and heredity variation
What’s heredity
The transmission of traits form one generation to the next
What are genes
Segments of dna that code for basic units of heredity
Asexual reproduction individuals
1 individual
Asexual gametes?
No fusion of gametes
Asexual makes:
clones of the parent, variation only happens through mutations
Sexual reproduction individuals
2 individuals
Sexual: offspring are
Unique and genetically varied
Homologous chromosomes are?
Pair of chromosomes that are same size same length same centromere position
What’s a karyotype
display of chromosome pairs ordered by size and length
Diploid =
Two complete sets of each chromosome
Haploid =
One set of chromosomes
What’s a life cycle
Sequence of stages in the reproductive history of an organism from conception to its own reproduction
What’s meiosis
Process that creates 4 haploid gamete cells
Meiosis I: interphase
cell goes through G1, S, and G2
Meiosis I: prophase
Synapsis: homologous chromosomes pair up and physically connect to each other forming a tetrad
Crossing over (recombination) occurs at the chiasmata and DNA is exchanged between the homologous pairs
Metaphase I
Independent orientation: tetrads line up at the metaphase plate
Anaphase I
Pairs of homologous chromosomes separate, sister chromosomes are still attached
Telophase I and Cytokenesis
Nuclei and cytoplasm divide, there is now a haploid set of chromosomes in each daughter cell
Prophase II
No crossing over, spindle forms
Metaphase II
Chromosomes line up at metaphase plate, because of crossing over in meiosis I chromatids are unique
Anaphase II
sister chromatids separate and move towards opposite poles
How does meiosis lead to genetic variation?
Crossing over, independent assortment of chromosomes, random fertilization
What is P generation
Parental generation, true-breeding
F1 generation?
First filial, hybrid offspring of P generation
F2 generation
Second filial, offspring of F1 generation
Testcrosses are for??
Determine if the dominant trait is homozygous dominant or heterozygous
Test crosses are between
Unknown parent and recessive parent
Dominant to recessive ratio
3:1
Alleles definition
Alternative versions of a gene
The law of independent assortment
Genes for one trait are not inherited with genes of another trait
What does the law of independent assortment NOT apply to
Linked traits
Unique gamete formula=
2^n
in 2^n, n is
The number of heterozygous pairs
How to solve genetics problems
Write down symbols for alleles
Write down genotypes given
Write out cross as [genotype] x [genotype]
Set up Punnett square
Independent events =
Multiply!
Ex: if you flip a coin twice what is the probability that it will land heads up both times
Mutually exclusive events
Addition!!!!!!!!!!!!
usually has word OR
Ex: what is the chance of rolling a dice and it lands on a 1 or 6?
Pedigrees: if a trait is dominant….
1 parent must have the trait
Dominant traits do not skip a generation
Pedigrees: if a trait is recessive…
It can be found in either sex but generally skips a generation
Pedigrees: if a trait is X-linked…
Males are more commonly affected than females
What are multiple alleles
Genes that exist in forms with more than two alleles
What is epistasis
The phenotypic expression of a gene at one locus affects a gene at another locus
Polygenic inheritance??
The effect of two or more genes acting on a single phenotype
Ex: height, human skin color
Fathers can pass x-linked alleles to lol of their daughters,
but none of their sons
Mothers can pass x-linked alleles to
Both daughters and sons
What’s hemizygous?
If an X-linked trait is due to a recessive allele, males only have one X and will express the trait if they inherit it from their mother
What’s a Barr body?
Most of the X chromosome in each cell becomes inactive, inactive X in each cell of a female condenses into a Barr body
Genetic recombination is?
Production of offspring with a new combination of genes from parents
Parental types
Offspring with the parental phenotype
Recombinants
Offspring with phenotypes that are different from the parents
One map unit is
Equivalent to a 1% recombination frequency
50% recombination means
The genes are far apart on the same chromosome or on two different chromosomes
All mitochondrial dna is
Maternally inherited
How to calculate degrees of freedom
Number of categories - 1
Interpreting results and degrees of freedom chart
If X^2 > critical value: Theres a statistically significant difference between the actual and expected values
