Genetics Flashcards
(28 cards)
Meiosis I phases (in order)
Meiosis I: The reduction division
1. Prophase I
2. Metaphase I
3. Anaphase I
4. Telophase I
Where does meiosis occur and what does it produce?
OCCURS: in diploid germ cells (reproductive cells)
PRODUCES: 4 haploid gametes (sex cells/eggs and sperm
Meiosis II phases (in order)
Meiosis II: The equational division
1. Prophase II
2. Metaphase II
3. Anaphase II
4. Telophase II + Cytokinesis
What occurs during Prophase I?
- Homologous chromosome pairs line up side by side and form a tetrad
- Crossing over of non-sister chromosomes occurs in a process called synapsis
- Crossing over results in an exchange of DNA
- After synapsis, all 4 sister chromatids are genetically varied
What occurs during Metaphase I?
- Homologous pairs (tetrads) align along the equator of the cell.
- Spindle fibres attach to the pair of sister chromatids
What occurs during Anaphase I?
- Homologous chromosomes separate and move to opposite poles.
- Sister chromatids remain attached at their centromeres.
- Random Assortment of Chromosomes (Each pair of homologous chromosomes separate randomly)
What occurs during Telophase I?
Sister chromatids in each haploid daughter cell
What occurs during Prophase II?
Sister chromatids in each daughter cell have no homologous pair.
What occurs during Metaphase II?
- Sister chromatids line up along equator of cell.
- Spindle fibres attach to centromeres of sister chromatids
What occurs during Anaphase II?
Spindle fibres contract and pull sister chromatids apart (Once pulled apart each sister chromatid is called a chromosome.)
What occurs during Telophase II + Cytokinesis?
- Cells divide
- Resulting 4 cells are haploid and genetically varied.–Chromosomes are single stranded. They will uncoil becoming chromatin.
What is DNA?
contains all of the information necessary to build and maintain an organism.
What is chromatin?
tangled strands of DNA and protein within a eukaryotic nucleus
What are sister chromatids?
The identical copy of a single chromosome (remains attached to original chromosome of centromere)
What is a centriole?
an organelle that helps cells divide, or make copies of themselves
What is a centromere?
plays a key role in helping the cell divide up its DNA during division
Difference between diploid and haploid? (ploidy)
DIPLOID: a cell containing 2 copies of each chromosome (2n)
HAPLOID: a cell containing half the usual complement of chromosomes (n)
What is a gamete?
specifically sex cells that have 23 chromosomes.
What is a zygote?
fertilized egg cell that results from the union of a female gamete with a male gamete
What is the difference between genotype and phenotype?
GENOTYPE: the genetic makeup of an individual (ratios)
PHENOTYPE: outward appearance with respect to a specific characteristic (percents)
What is the law of segregation?
alleles for a trait separate in the formation of a gamete
what is the law of independent assortment?
during gamete formation, different pairs of alleles independently of all others
What is the difference between an allele vs a gene?
ALLELE: Alleles are different versions of a gene, which vary according to the nucleotide base present at a particular genome location.
GENE: Genes are chunks of DNA that contribute to particular traits or functions by coding for proteins
What is a test cross?
unknown genotype is crossed with a homozygous recessive individual to determine their genotype
