science unit 2b test
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- What are the 4 phases of the cell cycle?
- G1, Synthesis, G2, Mitosis
- Describe G1 phase.
- Cell growth after cell division, metabolically active especially RNA and protein synthesis
- Describe S phase.
- Dna in the nucleus replicates, a few hours long
- Describe G2 phase.
- Synthesis of RNA,proteins, various macromolecules, double the amount of DNA, a few hours in length
- Describe M phase.
- Chromosomes are visible, chromosome separation and formation of 2 nuclei and 2 offspring cells
- Chromosomes
- Rod like strands of DNA and proteins, located in the nucleus, Have the genetic information of the organism, blueprints of organism, have chromatins and centromeres
- chromatin
- long, thin, twisted strands of chromosome material
- centromeres
- the center part of a chromosome where sprindle fibers attach
- centrioles
- in animal cells-make spindle fibers
- spindle fibers
- fibers which pull chromosomes apart
- Mitosis
- Asexual, process of chromosome replication and division, called nuclear division, cytoplasmic division
- cytoplasmic division
- the cell divides into 2 new cells, they are identical, same number of chromosomes as the original cell
- ORder of mitosis phases
- interphase, prophase, metaphase, anaphase, telophase
- Interphase
- nucleus, 1 set of chromsomes, 2 centrioles
- Prophase
- Nucleus starts to break apart, chromsomes replicated, centrioles start to move apart
- Metaphase
- no nucleus, Chromsomes line up in middle, centrioles are on opposite ends connectted by sprindle fibers
- Anaphase
- Chromosomes pull apart
- telophase
- 2 new complete cells are formed
- Binary fission
- equal division of nuclear materials and cytoplasm resulting in 2 new organisms- ameba,paramecium, one-celled organisms
- budding in yeast
- undergo mitosis but there is an unequal distribution of cytoplasm
- budding in hydra
- multicelluluar outgrowth from the parent organism is formed
- Sporulation
- Single, specialized cells are released from the parent and can develop into new individuals, fungi and spores
- Regeneration
- the development of an entire new organism from a part of the original organism -replacement of lost structures (starfish, lobster)
- Vegetative propogation
- new individual plants can be developed from roots, stems, or leaves of the parent plant
- examples of vegetative propogation
- bulbs, tubers, rhizomes, runners, grafting, cuttings
- advantages of vegetative propogation
- no variations, speed is faster, seedless fruits, combination of desirable characteristics
- concept of sexual reproduction
- production of gametes, fertilization to make a zygote
- gametes
- eggs and sperm
- zygote
- fertilized egg cell
- monoploid or haploid (n)
- having one copy of each chromosome
- diplod
- having 2 copies of each chromosomem(2n)
- meiosis
- one replication, 2 divisoins (creates gametes with half the number of chromosomes as parents)
- location of meiosis
- occurs only in the cells of the gonads that make gametes
- comparisons between mitotis and meiosis
- mitosis-growth and asexual reproduction, 2 daughter cells identical to parents, meiosis-sexual, 4 haploid daughter cells
- gametogenesis
- making gametes
- spermatogenesis
- making male gametes-occurs in male gonads-a primary sex cell undergoes meiosis to make 4 haploid cells which mature into a sperm cell
- oogenesis
- making female gametes, occurs in female gonads, undergoes meiosis to make 1 haploid egg and 3 polar bodies
- external fertilization
- gametes fuse outside of the body (fish and amphibeans)
- internal fertilization
- gamtes fuse in the reproductive tract of the female (most terrestrial vertabrae animals)
- cleavage
- rapid cell divison with no incease in cell size
- blastula
- hollow ball of single layer cells
- gastrulation
- indenting of the blastula to form a gastrula with germ layers
- ectoderm
- nervous systema and epidermis
- mesoderm
- muscles, skeleton, circulatory, excretory, reproductive
- endoderm
- lining of digestive and respiratory tracts, liver,pancreas