Chapter 4: Chromosome Theory of Inheritance Flashcards
God’s glory in reproduction?
God is glorified when His creation reproduces–they are obeying his command, good stewards can be involved
What is the function of chromosomes? What is important?
Transmit genetic information
- Important: the type and amount of genetic material for normal development
Types of chromosomes with respect to centromere
Metacentric: centromere in middle
Acrocentric: centromere is near one end
Chromosomes with respect to each other (three words)
Sister chromatids: identical copies of a replicated chromosome
Homologues: same set of genes, potentially different alleles
Nonhomologues: completely unrelated genes
What is a karyotype?
picture/arrangement of chromosomes by length (two of each because diploid)
What determines maleness in humans?
SRY gene,
- because of cross over SRY functional in XX males, and SRY nonfunctional in XY females
What is mitosis? What does it produce? What are the phases?
- the cell cycle with repeating patterns of cell growth and division
- produce: two genetically identical daughter cells
- mitosis/cytokinesis and interphase
What is interphase?
Period of cell growth & chromosome duplications (most of time here)
- formation of microtubule in cytoplasm
– centrosome: microtubule organizing center near the nuclear envelope
– centrioles: core of centrosome, not found in plant cells
Gap 1 phase (G1): cell growth, chromosomes not duplicating or dividing
- G0: stop dividing and arrest
Synthesis phase (S): chromosomes replicate (sister chromatids)
Gap 2 phase (G2): synthesis of proteins for mitosis
What are the stages of mitosis?
1) Prophase: chromosomes condense and become visible
2) Prometaphase: spindle forms and sister chromatids attach to microtubules from opposite centrosomes
3) Metaphase: chromosome align at the cell equator
4) Anaphase: sister chromatids separate and move to opposite poles
5) Telophase: chromosomes recondense and are enclosed in two nuclei
What are the two types of cells?
- somatic (most) in G0 or active in mitosis
- Germ cells (precursors to gametes)
– set aside during embryogenesis
– incorporated into reproductive organs
– meiosis & haploid gametes
What is the overview of meiosis?
Two rounds of cell division
- Chromosomes duplicate once; nuclei divide twice
- Meiosis II reduces the chromosomes from 2n to n
What is the overview of meiosis I?
Homologs pair, cross over, and then segregate
- sister chromatids remain intact, - maternal/paternal homologs recombine and create new combinations of alleles then segregate to different daughter cells
What are the substages of prophase I?
Homologs pair and held together by synaptonemal complex, crossing-over (recombination) occurs
- Leptotene (chromosomes visible, centrosomes opposite poles)
- Zygotene (Homologous chromosomes enter synapsis and synaptonemal complex forms
- Pachytene (synapsis complete, crossing-over occurs)
What occurs after prophase I?
Telophase I: nuclear envelope reforms, resulting in half number of chromosomes
Interkinesis: like interphase but no chromosomal duplications
What occurs in meiosis II?
sister chromatids separate and move to opposite poles
- Prophase II: chromosomes condense, centrioles moves to opposite poles, nuclear envelope breaks down
- Metaphase II: chromosomes align at metaphase plate, sister chromatids attach to spindle fibers)
- Anaphase II: centromeres divide and sister chromatids move to opposite poles
- Telophase II: chromosomes uncoil & nuclear envelopes & nucleoli reform
- Cytokinesis: cytoplasm divides
