week 5, mar 7th - 11th Flashcards
What does meiosis in animals form
Gametes
What is the female and male gametes
Ovum and sperm (both haploid)
How many nuclear divisions does meiosis have
2
Describe prophase I
Synapsis = joining of homologous chromosomes
4 visible chromosomes
Nuclear envelope fragments
Mitotic spindle growing
What is the first source of variation in meiosis I and when does it happen
Crossing over = exchanging genes between non sister chromatids
Prophase I
What are homologues
Chromosome pair, same genes in same squence
What is a tetrad
Pair of homologous chromsomes
What is structure chiasma
Pair of homologous chromsomes after crossing over
Describe metaphase I
Tetrads align at metaphase plate
Kinetochore plates attach chromosomes at mitotic spindle
Second source of variation
What is the second source of variation
Independant assortment = random alignment of members of a tetrad
Calculated with 2^n n = haploid #
Couple = man and woman (offspring) = 2^n x 2^n
If asks for gametes = just 2^n
Describe anaphase I
Tetrads seperate and move to opposite poles
Describe telophase I
Cytokinesis = division of cytoplasm
Cleavage furrow
Nuclear envelope reforms or not (depends on species)
What happens inbetween telophase I and meiosis II
G2 of interphase
Replicates centrosomes/centrioles
Describe prophase II
Two haploid daughter cells undergoing meiosis II
Describe metaphase II
Individual chromosomes align at the metaphase plate
Kinetochore plates anchor chromosomes to mitotic spindle
Describe anaphase II
Chromatids seperate and move to opposite poles (now referred to as chromosomes)
Describe telophase II
Cytokinesis
Nuclear envelope reforms
Produces 4 different haploid daughter cells
Which phases of mitosis and meiosis are similar
Metaphase —> metaphase II
Anaphase —> anaphase II
What is a carpel
Femake reproductive part (for flowers)
What does a stigma do
Receives pollen
What does the ovary do
Holds ovules
What is the stamen and what does it do
Male reproductive part
Anther makes and stores the pollen grains (sperm)
What do flowers do
Self pollinate
Describe what mendel did
Cross pollinated two varieties of pea plants that differed for one trait (monohybrid cross)
- pure breed homozygous dominant purple flower was dusted with pollen of homozygous recessive white flower and it produced a first generation of heterozygous purple flowers
What is used to signify a dominant trait
Capital letter
What is used to signify recessive trait
Lower case letter
What is an allele
Alternate form of a gene
What is the locus
Site/position of a gene
What is genotype
Genetic makeup
What is phenotype
Expression of a gene
What does PP make
Homozygous dominant
2 of same alleles
What does Pp make
Heterozygous
2 different alleles
What does pp make
Homozygous recessive
2 same alleles non dominant
How does a punnet square work
Put one flowers information on top and other on the left side of square. Gives genotypic and phenotypic ratios
How are genotypic and phenotypic ratios different
Phenotypic = what you see
= 3 purple flowers : 1 white flower
Genotypic = contents of punnet square
= 1PP : 2Pp : 1pp
What is a test cross
Cross pollinate an unknown genotype with known genotype (help determines genotype of 2nd generation)
Known genotype = pp (since white is recessive)
What is incomplete dominance
When both alleles are expressed
Ex: white flower with red flower = pink flower
What are multiple alleles
When there are more than 2 alleles
Describe alleles in relation to blood type
IA & IB & i Blood type A: IA IA or IA i Blood type B: IB IB or IB i Blood type AB: IA IB Blood type O: i i
What blood type produces children with all possible blood types
IA i & IB i
produces A, B, AB, O
What produced the first law of segregation (separation)
Mendels complete dominance/monohybrid cross
What is the first law of segregation (separation), for Mendels complete dominance
- Individuals are diploid (2 alleles)
- Gametes have one allele (ie 2 alleles separate during gamete formation)
- The cross pollination of the two pure breeds forms a heterozygous (having 2 different alleles)
How many chromosomes do humans have
2n (diploid) = 46
