Topic 4: the cell cycle, meiosis, mitosis Flashcards
what are the two cell types?
-gamates
-somatic cells
what are gamates?
-cells that undergo meiosis
-23 different chromosomes (haploid)
-reproductive cells (sperm or ova)
what are somatic cells?
-all cells of the body, besides those that undergo meiosis
-ex: muscle cell or nerve cell
-46 chromosomes (diploid) (23 homologous pairs)
what are homologous chromosomes?
-a chromosome pair
-one chromatid/strand from each parent join to form one chromosome
-they are the same length, centromere position, and carry the same genes in the same places
-equivalent but not identical
-this place is called a locus
what is a gene?
-a unit of heredity
-a region on a DNA strand that contains information for protein synthesis
-can have different versions of the same gene (alleles)
what are alleles?
-different versions of a gene
-code for different versions of a trait
-ex: blue eyes from dad and brown eyes from mom
what are autosomal chromosomes?
-chromosomes 1-22
-contain genes for body characteristics
which chromosome is the sex chromosome?
-chromosome 23
-determines your sex
-XX = female
-XY = male
-get an X or Y from dad and an X from mom
what is the cell cycle for?
-growth and repair of tissues
-begin as a zygote and divide and divide until we make trillions of cells
what will a single diploid somatic cell form?
-2 genetically identical somatic daughter cells (diploid)
what are the stages in the cell cycle?
-interphase
-mitotic phase
what are the 3 phases of interphase?
-G1 (first growth phase)
-S (synthesis phase)
-G2 (second growth phase)
what occurs in the G1 phase?
-growth and metabolism
-centrosome replication begins
-46 single chromosomes (46 chromatids)
what is meant by the term G0 phase?
-cells that do not divide once they are mature, stay in G1
-this is termed as G0
-ex: nerve cells and some muscle cells
what occurs in the S phase
-chromosomes replicate (still present as chromatin)
-always occurs before division
-replicates are called sister chromatids
-they attach to each other at the centromere
-46 chromosomes, 92 chromatids
what attaches to each centromere?
-kinetochore proteins
-they are produced during S phase
-attach to each centromere to form the kinetochore
what is the kinetochore?
-site of attachment for spindle microtubules
what are the 2 main parts of the mitotic phase
-mitosis
-cytokinesis
what occurs in the G2 phase
-growth and metabolism
-production of enzymes and other proteins needed for cell division
-centrosome replication is ‘;completed
what are the 4 phases in mitosis?
-prophase
-metaphase
-anaphase
-telophase
what is mitosis?
-division of nuclear material (chromosomes)
-a continuous cycle
what is cytokinesis? when does it begin?
-division of cytoplasm
-begins in anaphase
what happens when the mitotic phase ends?
-mitosis and cytokinesis are complete
-daughter cells go into interphase
-cycle repeats
what occurs in prophase?
-chromosomes condense (thicken+coil) (can now be seen individually)
-nucleoli disappear and the nuclear envelope breaks
-centrosomes move to either pole (ends of the cell)
-microtubules form the spindle apparatus
-attaches to
kinetochore
-moves
chromosomes to
the cell equators
