Review 3 Flashcards
Know the cell cycle: G1, S, G2, mitosis, cytokinesis, interphase
G1 (Gap 1) - Cells enters the cell cycle nearly doubles in size (growth)
S (Synthesis) - Cells DNA is copied
G2 (Gap 2) - Cell builds machinery for cell division (growth in preparation for separation)
Cytokinesis - cell division
Interphase - Cell carries out function unrelated to cell division
Know the steps of mitosis and how to identify them from a slide.
Prophase-Chromosomes condense and nuclear membranes break down
Metaphase-Chromosomes line up along the equatorial/middle plane
Anaphase- sister chromatids are pulled apart and move to opposite poles of the cell
Telophase-New nuclear membranes from around each set of chromosomes
Know the steps in meiosis. Which part is like mitosis?
1.) Meiosis I encompasses four stages: cell divide into two cells
• Prophase I - Chromosomes become visible, crossing-over occurs, the nucleolus disappears, the meiotic spindle forms, and the nuclear envelope disappears.
• Metaphase I - The pairs of chromosomes (bivalents) become arranged on the metaphase plate and are attached to the now fully formed meiotic spindle.
• Anaphase I - The two chromosomes in each bivalent separate and migrate toward opposite poles.
• Telophase I - The homologous chromosome pairs reach the poles of the cell, nuclear envelopes form around them, and cytokinesis follows to produce two cells.
2.) Meiosis II encompasses four stages: these two cells divide again to produce four haploid cells
• Prophase II - the nuclear envelope breaks down and the spindle apparatus forms.
• Metaphase II - The chromosomes become arranged on the metaphase plate, much as the chromosomes do in mitosis, and are attached to the now fully formed spindle.
• Anaphase II - The centromeres separate and the sister chromatids—now individual chromosomes—move toward the opposite poles of the cell.
• Telophase II - A nuclear envelope forms around each set of chromosomes and cytokinesis occurs, producing four daughter cells, each with a haploid set of chromosomes.
I have put two links in your favorite’s folder to show you (with animation) both the processes if mitosis and meiosis with detailed explanations of each phase
Crossing over
the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring
Independent assortment
formation of random combinations of chromosomes in meiosis and of genes on different pairs of homologous chromosomes by the passage according to the laws of probability of one of each diploid pair of homologous chromosomes into each gamete independently of each other pair.
Karyotype
the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.
Chromosome
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes
Homologue
chromosomes with the same structural features and pattern of genes
Allele
(a version of a gene) one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Autosomes
any chromosome that is not a sex chromosome
Centromere
the point on a chromosome by which it is attached to a spindle fiber during cell division
Homozygous
(Same letters) - If an organism has two copies of the same allele, for example AA or aa
Heterozygous
– (Different letters) - A gene pair having different alleles in the two chromosome sets of the diploid individual, for example Aa
Dominant
upper case letters - An allele that expresses its phenotypic effect even when heterozygous with a recessive allele; thus if A is dominant over a, then AA and Aa have the same phenotype(
Recessive
lower case letters - allele that produces its characteristic phenotype only when its paired allele is identical, example aa. (allele not expressed in a heterozygote)
