Unit 10 Test Flashcards
Reproduction Division
Meiosis splits the chromosomes in half, therefore, creating a haploid gamete. The diploid number is then reconstituted by fertilization and/or sexual reproduction.
Haploid vs. Diploid
Haploid cells have one set of chromosomes and diploid cells have two sets of chromosomes.
Genetic Rearrangement (Crossing Over vs. Random Assortment)
Crossing over is the exchange of DNA between non-sister homologous chromatids. Random Assortment is when chromosomes line up in a random orientation during metaphase I.
Phases of Meiosis
Meiosis I: The first meiotic division functions to separate the homologous chromosomes. Reduction division that results in the formation of 2 haploid daughter cells.
Meiosis I Phases: Prophase I, Metaphase I, Anaphase I, and Telophase I
Meiosis II: The second meiotic division functions to separate the sister chromatids.
Meiosis II Phases: Prophase II, Metaphase II, Anaphase II, and Telophase II
S-Phase What happens?
This is a phase in interphase in which DNA is replicated and chromosomes will consist of genetically identical sister chromatids.
What kinds of cells does meiosis make?
Meiosis produces four haploid gametes that are genetically unique.
Synapsis and the Chiasmata
Synapsis is the stage during prophase one in which homologous chromosomes become connected. Chiasmata are physical connections in which non-sister chromatids may recombine with their homologous partner.
Mendel’s Law of Segregation
All sexually reproducing organisms inherit one copy of a gene (i.e. allele) from each parent
Mendel’s Law of Independent Assortment
Inheritance of alleles for one gene occurs independently of all other genes
Dihybrids
Gametes use the foil method:
F- First
O- Out
I- In
L- Last
Linked vs. Unlinked
Linked genes are genes whose loci are all on the same chromosome.
Consequently, linked genes function as a single inheritable unit during meiosis.
Unlinked genes- These will form all phenotypic combinations via random assortment.
Linked genes- These will only produce recombinant phenotypes when crossing over occurs
Thomas Morgan
Thomas Morgan developed the concept of gene linkage via breeding experiments with fruit flies (Drosophila).
Monogenic vs Polygenic traits
Monogenic traits- are controlled by a single gene and show discrete variation. Examples of monogenic traits include the presence of attached earlobes / freckles.
Polygenic traits are controlled by multiple genes and show continuous variation. Examples of polygenic traits include human height, weight and skin colour.
Gene Pools
Gene pools represent the sum total of alleles for all genes present in a population. Gene pools change via evolution.
Genetic Drift
Genetic drift is a change in the composition of a gene pool due to chance events.